Biblio Including Abstracts, when available

Year of Publicationsort ascending Title Biblio Citation Authors Abstract Type of Publication Keywords
9998 Cuba, Puerto Rico & Climate Change Shared Challenges in Agriculture, Forestry, and Opportunities for Collaboration
Fain, S. J, W. A Gould, I. K Parés, G. Gonzalez, and K. McGinley. In Press. Gen. Tech. Rep. IITF-GTR-xx Cuba, Puerto Rico & Climate Change Shared Challenges In Agriculture, Forestry, And Opportunities For Collaboration. San Juan, PR: U.S. Department of Agriculture, Forest Service, International Institute of Tropical Forestry.
Fain, S.J.; Gould, W.A.; Parés, I.K.; Gonzalez, G.; McGinley, K. Report
9998 Using lichens as indicators of forest health in Puerto Rico. Gen. Tech. Rep. IITF-GTR-xx Mercado-Díaz, J.A.; Gould, W.A.; Gonzalez, G.; Torres-Santana, C. Report
9998 Empirical Downscaling of Historical Rainfall in Northeast Puerto Rico using Self-Organizing Maps. International Journal of Climatology Ramseyer, C.A.; Mote, T.L. Journal Article
9998 Functional and phylogenetic dimensions of tree diversity reveal shifting assembly mechanisms across regional environmental gradients in Puerto Rico Muscarella, M.; Uriarte, M.; Aide, T.M.; Erickson, D.L.; Forero-Montaña, J.; Kress, W.J.; Swenson, N.G.; Zimmerman, J.K. Journal Article
2019 Drought and the interannual variability of stem growth in an aseasonal everwet forest Hogan, J.A.; McMahon, S.M.; Buzzard, V.; Michaletz, S.T.; Enquist, B.J.; Thompson, J.; Swenson, N.G.; Zimmerman, J.K. Journal Article 2015 El Niño drought; dendrometer; tree growth
2019 SUPPLEMENTARY MATERIALS: LONG‐TERM POPULATION TRENDS IN EL YUNQUE NATIONAL FOREST (LUQUILLO EXPERIMENTAL FOREST) DO NOT PROVIDE EVIDENCE FOR DECLINES WITH INCREASING TEMPERATURE OR THE COLLAPSE OF FOOD WEBS  (831.93 KB) Willig, M.R.; Woolbright, L.; Presley, S.J.; Schowalter, T.D.; Waide, R.B.; Scalley, H.; Zimmerman, J.K.; González, G.; Lugo, A.E. We describe significant concerns related to data selection and transformation, or to the interpretation of trends related to time or temperature for walkingsticks, canopy arthropods, frogs, and birds as published by Lister and Garcia (2018; hereafter L&G). We cannot confidently identify the climatic or abundance data from El Verde that were used by L&G. In some cases, data manipulations were not described explicitly or justifiable. In other cases, the rationale for selection of temporal data for inclusion or exclusion were not apparent. Moreover, errors may have been introduced into the data that compromise its interpretation. Most importantly, L&G failed to consider the effects of disturbance and secondary succession on the abundance of animals in the Luquillo Experimental Forest of Puerto Rico. Short‐term responses to cyclonic disturbances, and trajectories of abiotic and biotic characteristics during post‐hurricane succession, play a dominant role in modulating variation in abundance of animals in the Luquillo Experimental Forest (see Walker et al. 1991, 1996; Brokaw et al. 2012). Thus, we contend that the role of warming or the suggestion of food web collapse by L&G are oversimplified or unfounded for this tropical forest ecosystem. Journal Article
2019 Habitat use and seed removal by invasive rats (Rattus rattus) in disturbed and undisturbed rain forest, Puerto Rico.  (639.92 KB) Shiels, A.B. Abstract Despite frequent occurrences of invasive rats (Rattus spp.) on islands, their known effects on forests are limited. Where invasive rats have been studied, they generally have significant negative impacts on native plants, birds, and other animals. This study aimed to determine invasive rat distribution and effects on native plant populations via short‐term seed removal trials in tropical rain forest habitats in the Luquillo Experimental Forest, Puerto Rico. To address the first objective, we used tracking tunnels (inked and baited cards inside tunnels enabling animal visitors’ footprints to be identified) placed on the ground and in the lower canopy within disturbed (treefall gaps, hurricane plots, stream edges) and undisturbed (continuous forest) habitats. We found that rats are present in all habitats tested. Secondly, we compared seed removal of four native tree species (Guarea guidonia, Buchenavia capitata, Tetragastris balsamifera, and Prestoea acuminata) between vertebrate‐excluded and free‐access treatments in the same disturbed and undisturbed habitats. Trail cameras were used to identify animals responsible for seed contact and removal. Black rats (Rattus rattus) were responsible for 65.1% of the interactions with seeds, of which 28.6% were confirmed seed removals. Two plant species had significantly more seeds removed in disturbed (gaps) than undisturbed forest. Prestoea acuminata had the lowest seed removal (9% in 10 days), whereas all other species had >30% removal. Black rats are likely influencing fates of seeds on the forest floor, and possibly forest community composition, through dispersal or predation. Further understanding of rat–plant interactions may be useful for formulating conservation strategies. Resumen A pesar de la frecuencia de ratas invasoras (Rattus spp.) en islas, lo que se conoce de sus efectos en ecosistemas forestales es limitado. Se ha encontrado que generalmente impactan negativamente a especies nativas de plantas, aves, y otros animales. Este estudio intentó determinar la distribución de ratas invasoras y sus efectos en las poblaciones de plantas nativas vía la remoción de semillas en hábitats de bosque tropical en el Bosque Experimental de Luquillo, Puerto Rico. Primero, utilizamos túneles de rastreo (tarjetas con tinta y carnada metidas en los túneles permiten la identificación de los animales visitantes) colocados en el suelo y en dosel bajo dentro de hábitats perturbados (árbol caído, parcelas de huracán, borde de quebradas) y no‐perturbadas (bosque continuo). Encontramos ratas presentes en todos estos hábitats. Segundo, comparamos la remoción de semillas de cuatro especies de árboles nativos (Guarea guidonia, Buchenavia capitata, Tetragastris balsamifera, and Prestoea acuminata) entre tratamientos de exclusión de vertebrados y libre‐acceso dentro de los mismos hábitats. Se utilizaron cámaras de rastreo para identificar los animales que tuvieron contacto con o removieron semillas. Ratas negras (R. rattus) fueron responsables por el 65.1% de las interacciones con las semillas, de las cuales 28.6% fueron removidas. Dos especies de plantas tuvieron significativamente más semillas removidas en bosque perturbado que en bosque no‐perturbado. Prestoea acuminata obtuvo el menor porciento de remoción (9% en 10 days), mientras que las otras tres especies obtuvieron >30% de remoción. Es probable que las ratas negras afectan el destino de las semillas en el suelo del bosque, y posiblemente la composición de comunidades de este, por dispersión o depredación. Mejor entendimiento sobre las interacciones rata‐planta podría ser útil para formular estrategias de conservación. Journal Article
2019 Populations are not declining and food webs are not collapsing at the Luquillo Experimental Forest Willig, M.R.; Woolbright, L.; Presley, S.J.; Schowalter, T.D.; Waide, R.B.; Scalley, H.; Zimmerman, J.K.; Gonzalez, G.; Lugo, A.E. Journal Article
2019 Species niches, not traits, determine abundance and occupancy patterns: A multi-site synthesis Marino, N.A.C.; Céréghino, R.; Gilbert, B.; Petermann, J.S.; Srivastava, D.S.; de Omena, P.M.; Bautista, F.Ospina; Guzman, L.Melissa; Romero, G.Q.; Trzcinski, K.; Barberis, I.M.; Corbara, B.; Debastiani, V.J.; Dézerald, O.; Kratina, P.; Leroy, C.; MacDonald, A.Andrew M.; Montero, G.; Pillar, V.D.; Richardson, B.A.; Richardson, M.J.; Talaga, S.; Gonçalves, A.Z.; Piccoli, G.C.O.; Jocque, M.; Farjalla, V.F. Abstract Aim Locally abundant species are usually widespread, and this pattern has been related to properties of the niches and traits of species. However, such explanations fail to account for the potential of traits to determine species niches and often overlook statistical artefacts. Here, we examine how trait distinctiveness determines the abilities of species to exploit either common habitats (niche position) or a range of habitats (niche breadth) and how niche position and breadth, in turn, affect abundance and occupancy. We also examine how statistical artefacts moderate these relationships. Location Sixteen sites in the Neotropics. Time period 1993–2014. Major taxa studied Aquatic invertebrates from tank bromeliads. Methods We measured the environmental niche position and breadth of each species and calculated its trait distinctiveness as the average trait difference from all other species at each site. Then, we used a combination of structural equation models and a meta-analytical approach to test trait–niche relationships and a null model to control for statistical artefacts. Results The trait distinctiveness of each species was unrelated to its niche properties, abundance and occupancy. In contrast, niche position was the main predictor of abundance and occupancy; species that used the most common environmental conditions found across bromeliads were locally abundant and widespread. Contributions of niche breadth to such patterns were attributable to statistical artefacts, indicating that effects of niche breadth might have been overestimated in previous studies. Main conclusions Our study reveals the generality of niche position in explaining one of the most common ecological patterns. The robustness of this result is underscored by the geographical extent of our study and our control of statistical artefacts. We call for a similar examination across other systems, which is an essential task to understand the drivers of commonness across the tree of life. Journal Article abundance; environmental niche; functional distinctiveness; functional traits; metacommunity; niche breadth; niche position; occupancy
2019 Hurricane María tripled stem breaks and doubled tree mortality relative to other major storms Uriarte, M.; Thompson, J.; Zimmerman, J.K. Tropical cyclones are expected to intensify under a warming climate, with uncertain effects on tropical forests. One key challenge to predicting how more intense storms will influence these ecosystems is to attribute impacts specifically to storm meteorology rather than differences in forest characteristics. Here we compare tree damage data collected in the same forest in Puerto Rico after Hurricanes Hugo (1989, category 3), Georges (1998, category 3), and María (2017, category 4). María killed twice as many trees as Hugo, and for all but two species, broke 2- to 12-fold more stems than the other two storms. Species with high density wood were resistant to uprooting, hurricane-induced mortality, and were protected from breakage during Hugo but not María. Tree inventories and a wind exposure model allow us to attribute these differences in impacts to storm meteorology. A better understanding of risk factors associated with tree species susceptibility to severe storms is key to predicting the future of forest ecosystems under climate warming. Journal Article
2019 Role of Microhabitats and Environment Variation on Collembola (Hexapoda: Entognatha) Populations in the Luquillo Experimental Forest: A Montane Environment Sánchez, C.Marcela Os Thesis
2019 Proposing the solar wind-energy-flux hypothesis as a driver of interannual variation in tropical tree reproductive effort tropical tree reproduction Hogan, A.; Nytch, C.J.; Bithorn, J.E.; Zimmerman, J.K. A growing body of research documents how the El Niño Southern Oscillation (ENSO) results in short-term changes in terrestrial environmental conditions, with the potential to drive ecosystem processes as the duration and severity of ENSO events increases with anthropogenic climate change. An ENSO positive phase results in anomalous patterns of rainfall and temperature throughout the tropics that coincide with leaf flush and increased fruit production in tropical forests worldwide. However, our understanding of possible mechanisms underlying this natural phenomenon is limited. Furthermore, flowering in tropical trees anticipates ENSO development, motivating the continued search for a global phenological cue for tropical angiosperm reproduction. We propose the solar energy flux hypothesis: that a physical energy influx in the Earth’s upper atmosphere and magnetosphere generated by a positive anomaly in the solar wind preceding ENSO development, cues tropical trees to increase allocation of resources to reproduction. We show that from 1994-2013, the solar wind energy flux into the Earth’s magnetosphere (Ein) is more strongly correlated with the number of trees in fruit or flower in a Puerto Rican wet forest than the Niño 3.4 climate index, despite Niño 3.4 being a previously identified driver of interannual increases in reproduction. We discuss the idea that changes in the global magnetosphere and thermosphere conditions via solar wind-effects on global atmospheric circulation, principally a weaker Walker circulation, cue interannual increases tropical tree reproduction. This may be a mechanism that synchronizes the reproductive output of the tropical trees to changes in environmental conditions that coincide with ENSO. Thus, space weather patterns may help explain terrestrial biological phenomena that occur at quasi-decadal scales. Journal Article
2019 Herbivore and detritivore effects on rainforest plant production are altered by disturbance Prather, C.M.; Belovsky, G.E. Abstract Consumer effects on rainforest primary production are often considered negligible because herbivores and macrodetritivores usually consume a small fraction of annual plant and litter production, even though consumers are known to have effects on plant production and composition in nontropical systems. Disturbances, such as treefall gaps, however, often increase resources to understory food webs, thereby increasing herbivory and feeding rates of detritivores. This increase in consumption could lead to more prominent ecosystem-level effects of consumers after disturbances, such as storms that cause light gaps. We determined how the effects of invertebrate herbivores (walking sticks) and detritivores (litter snails) on understory plant growth may be altered by disturbances in a Puerto Rican rainforest using an enclosure experiment. Consumers had significant effects on plant growth, but only in light gaps. Specifically, herbivores increased plant growth by 60%, and there was a trend for detritivores to reduce plant growth. Additionally, plant biomass tended to be 50% higher with both consumers in combination, suggesting that herbivores may mediate the effects of detritivores by altering the resources available to detritivore food webs. This study demonstrates that disturbance alters the effects of rainforest consumers, and, furthermore, that consumer activity has the potential to change rainforest successional processes. Journal Article decomposer; ecosystem process; gastropod; Light gap; phasmid; plant growth; rainforest
2019 Continental scale structuring of forest and soil diversity via functional traits Buzzard, V.; Michaletz, S.T.; Deng, Y.; He, Z.; Ning, D.; Shen, L.; Tu, Q.; Van Nostrand, J.D.; Voordeckers, J.W.; Wang, J.; Weiser, M.D.; Kaspari, M.; Waide, R.B.; Zhou, J.; Enquist, B.J. Trait-based ecology claims to offer a mechanistic approach for explaining the drivers that structure biological diversity and predicting the responses of species, trophic interactions and ecosystems to environmental change. However, support for this claim is lacking across broad taxonomic groups. A framework for defining ecosystem processes in terms of the functional traits of their constituent taxa across large spatial scales is needed. Here, we provide a comprehensive assessment of the linkages between climate, plant traits and soil microbial traits at many sites spanning a broad latitudinal temperature gradient from tropical to subalpine forests. Our results show that temperature drives coordinated shifts in most plant and soil bacterial traits but these relationships are not observed for most fungal traits. Shifts in plant traits are mechanistically associated with soil bacterial functional traits related to carbon (C), nitrogen (N) and phosphorus (P) cycling, indicating that microbial processes are tightly linked to variation in plant traits that influence rates of ecosystem decomposition and nutrient cycling. Our results are consistent with hypotheses that diversity gradients reflect shifts in phenotypic optima signifying local temperature adaptation mediated by soil nutrient availability and metabolism. They underscore the importance of temperature in structuring the functional diversity of plants and soil microbes in forest ecosystems and how this is coupled to biogeochemical processes via functional traits. Journal Article
2019 Dry conditions and disturbance promote liana seedling survival and abundance Umaña, M.Natalia; Forero-Montaña, J.; Nytch, C.J.; Thompson, J.; Uriarte, M.; Zimmerman, J.; Swenson, N.G. Abstract Species composition and community structure in Neotropical forests have been severely affected by increases in climate change and disturbance. Among the most conspicuous changes is the proliferation of lianas. These increases have affected not only the carbon storage capacity of forests but also tree dynamics by reducing tree growth and increasing mortality. Despite the importance of lianas in Neotropical forests, most of the studies on lianas have focused on adult stages, ignoring dynamics at the seedlings stage. Here, we asked whether observed increases in liana abundance are associated with a demographic advantage that emerges early in liana ontogeny and with decreased precipitation and increased disturbance. To test this, we compared patterns of growth and survival between liana seedlings and tree seedlings using a long-term data set of seedling plots from a subtropical wet forest in Puerto Rico, USA. Then, we examined the effect of precipitation and land use history on these demographic variables. We found evidence for liana seedling survival advantage over trees, but no growth advantages. This survival advantage exhibited significant temporal variation linked with patterns of rainfall, as well as differences associated with land-use history in the study area. Furthermore, we found that neighborhood density has a negative effect on liana survival and growth. Our results indicate that liana proliferation is likely related to a survival advantage that emerges in early stages and is influenced by climatic conditions and past disturbance. Predicted climatic changes in rainfall patterns, including more frequent and severe droughts, together with increases in disturbance, could have a significant effect on seedling tropical communities by favoring lianas. Journal Article community dynamics; growth; Land use history; Neotropical forest; Precipitation; seedlings crowding; survival
2019 The spatial configuration of taxonomic biodiversity along a tropical elevational gradient: α-, β-, and γ-partitions Willig, M.R.; Presley, S.J. Abstract Biodiversity at larger spatial scales (γ) can be driven by within-site partitions (α), with little variation in composition among locations, or can be driven by among-site partitions (β) that signal the importance of spatial heterogeneity. For tropical elevational gradients, we determined the (a) extent to which variation in γ is driven by α- or β-partitions; (b) elevational form of the relationship for each partition; and (c) extent to which elevational gradients are molded by zonation in vegetation or by gradual variation in climatic or abiotic characteristics. We sampled terrestrial gastropods along two transects in the Luquillo Mountains. One passed through multiple vegetation zones (tabonuco, palo colorado, and elfin forests), and one passed through only palm forest. We quantified variation in hierarchical partitions (α, β, and γ) of species richness, evenness, diversity, and dominance, as well as in the content and quality of litter. Total gastropod abundance linearly decreased with increasing elevation along both transects, but was consistently higher in palm than in other forest types. The gradual linear decline in γ-richness was a consequence of opposing patterns with regard to α-richness (monotonic decrease) and β-richness (monotonic increase). For evenness, diversity, and dominance, α-partitions and γ-partitions evinced mid-elevational peaks. The spatial organization of gastropod biodiversity did not mirror the zonation of vegetation. Rather, it was molded by: (a) elevational variation in productivity or nutrient characteristics, (b) the interspersion of palm forest within other forest types, and (c) the cloud condensation point acting as a transition between low and high elevation faunas. Abstract in Spanish is available with online material. Journal Article diversity; dominance; evenness; gastropoda; hierarchical partitioning of diversity; Puerto Rico; richness; tropical montane forest
2019 Tree crown overlap improves predictions of the functional neighbourhood effects on tree survival and growth Zambrano, J.; Fagan, W.F.; Worthy, S.J.; Thompson, J.; Uriarte, M.; Zimmerman, J.K.; Umaña, M.N.; Swenson, N.G. Abstract Investigations of forest community structure and dynamics have been facilitated by the use of neighbourhood models that examine the interactions between a focal tree and its neighbours using a fixed radius. However, different studies have chosen different radii without clear reasons, hampering the understanding of mechanisms structuring tree communities. Using functional trait and tree demography data from the Luquillo subtropical forest in Puerto Rico, we compared fixed-neighbourhood models with a canopy overlap model, in which tree crown overlap is used as an indicator of neighbourhood crowding. Analyses that combine functional trait and demographic data provide a mechanistic understanding of observed patterns of community structure and dynamics as they provide insights into the linkages between phenotypes and the environment. Overall, canopy overlap models had better support when compared to neighbourhood models using a fixed radius, suggesting that the fixed radius approach does not capture the full extent of competitive interactions among trees. Moreover, the effects of functional neighbourhood on tree survival and growth differ depending on the type of approach used and lead to different conclusions with respect to the drivers of tree community dynamics. Synthesis. In summary, our findings highlight the utility of neighbourhood models based on tree crown overlap, and suggest that applying this same approach to different plots and forests will facilitate comparisons across systems and improve our understanding of the mechanisms that drive the structure and dynamics of tree communities. Journal Article functional traits; Luquillo Forest; neighbourhood models; niche differentiation; trait hierarchy; tree competition
2019 Broadening Our Understanding of Hurricanes and Forests on the Caribbean Island of Puerto Rico: Where and What Should We Study Now? López-Marrero, T.; Heartsill-Scalley, T.; Rivera-López, C.F.; Escalera-García, I.A.; Echevarría-Ramos, M. Hurricanes shape ecosystems. A broad range of forested ecosystems is particularly affected by hurricanes, thus creating the need for studies addressing the effects of these disturbances. There is a long history of hurricane and forest research on the Caribbean island of Puerto Rico. In this study, we present results from a systematic literature review of peer-reviewed articles regarding ecological research conducted in Puerto Rico on the topic of hurricanes and forests published from 1900 through 2017. We present a summary of cyclonic activity on the island during the study period and the results from the systematic literature review within this cyclonic context. We discuss findings in terms of aspects of forests studied, geographical distribution of study areas, and time scales at which research was conducted. These findings allow us to determine what was studied about hurricanes and forests, identify gaps in the information, and suggest possible areas of research and production of new knowledge that recent and future storms can bring. We conclude with recommendations identifying research needs and propose additional approaches to complement existing information. Our goal is to generate future knowledge from hurricane and forest research with the broadest applications possible. Journal Article
2019 Species Diversity Associated with Foundation Species in Temperate and Tropical Forests Ellison, A.M.; Buckley, H.L.; Case, B.S.; Cardenas, D.; Duque, Á.J.; Lutz, J.A.; Myers, J.A.; Orwig, D.A.; Zimmerman, J.K. Foundation species define and structure ecological communities but are difficult to identify before they are declining. Yet, their defining role in ecosystems suggests they should be a high priority for protection and management while they are still common and abundant. We used comparative analyses of six large forest dynamics plots spanning a temperate-to-tropical gradient in the Western Hemisphere to identify statistical “fingerprints” of potential foundation species based on their size-frequency and abundance-diameter distributions, and their spatial association with five measures of diversity of associated woody plant species. Potential foundation species are outliers from the common “reverse-J” size-frequency distribution, and have negative effects on alpha diversity and positive effects on beta diversity at most spatial lags and directions. Potential foundation species also are more likely in temperate forests, but foundational species groups may occur in tropical forests. As foundation species (or species groups) decline, associated landscape-scale (beta) diversity is likely to decline along with them. Preservation of this component of biodiversity may be the most important consequence of protecting foundation species while they are still common. Journal Article
2019 Nutrient export and elemental stoichiometry in an urban tropical river McDowell, W.H.; McDowell, W.G.; Potter, J.D.; Ramírez, A. Abstract Nutrient inputs to surface waters are particularly varied in urban areas, due to multiple nutrient sources and complex hydrologic pathways. Because of their close proximity to coastal waters, nutrient delivery from many urban areas can have profound impacts on coastal ecology. Relatively little is known about the temporal and spatial variability in stoichiometry of inorganic nutrients such as dissolved silica, nitrogen, and phosphorus (Si, N, and P) and dissolved organic matter in tropical urban environments. We examined nutrient stoichiometry of both inorganic nutrients and organic matter in an urban watershed in Puerto Rico served by municipal sanitary sewers and compared it to two nearby forested catchments using samples collected weekly from each river for 6 yr. Urbanization caused large increases in the concentration and flux of nitrogen and phosphorus (2- to 50-fold), but surprisingly little change in N:P ratio. Concentrations of almost all major ions and dissolved silica were also significantly higher in the urban river than the wildland rivers. Yield of dissolved organic carbon (DOC) was not increased dramatically by urbanization, but the composition of dissolved organic matter shifted toward N-rich material, with a larger increase in dissolved organic nitrogen (DON) than DOC. The molar ratio of DOC:DON was about 40 in rivers draining forested catchments but was only 10 in the urban river. Inclusion of Si in the assessment of urbanization's impacts reveals a large shift in the stoichiometry (Si:N and Si:P) of nutrient inputs. Because both Si concentrations and watershed exports are high in streams and rivers from many humid tropical catchments with siliceous bedrock, even the large increases in N and P exported from urban catchments result in delivery of Si, N, and P to coastal waters in stoichiometric ratios that are well in excess of the Si requirements of marine diatoms. Our data suggest that dissolved Si, often neglected in watershed biogeochemistry, should be included in studies of urban as well as less developed watersheds due to its potential significance for marine and lacustrine productivity. Journal Article coastal; Dissolved organic carbon; dissolved organic matter; dissolved organic nitrogen; dissolved silica; nitrate; nutrients; phosphate; stoichiometry; Tropical; Urban
2019 Building a hydrologic foundation for tropical watershed management Christian, J.; Martin, J.; McKay, K.; Chappell, J.; Pringle, C.M. Here we provide an empirical hydrologic foundation to inform water management decisions in the El Yunque National Forest (EYNF) in eastern Puerto Rico. Tropical watershed hydrology has proven difficult to quantify due to high rainfall variability, high evapotranspiration rates, variation in forest canopy interception and storage, and uncertain hydrologic inputs from fog condensation in cloud forests. We developed mass-balance and observation-based water budgets for nine local watersheds within the EYNF using a novel assemblage of remotely sensed rainfall data, gaged streamflow observations, and municipal water withdrawal rates. It is important to note that, while prior budgets considered large water withdrawals outside (downstream) of EYNF boundaries, our current budget is confined to within EYNF boundaries. Here, we also base our estimates of water withdrawal volume on operational data, in contrast to prior water budgets that estimated volume based on either the capacity of known water intakes or regulatory permit limits. This resulted in more conservative and realistic estimates of withdrawals from within the EYNF. Finally, we also discuss the ecological importance of considering the effects of water withdrawals not only at an average monthly scale, but also on the basis of exceedance probability to avoid over-abstraction for the protection of native migratory fishes and shrimps. This analysis highlights a number of unique challenges associated with developing hydrologic foundations for water management in tropical ecosystems. Journal Article
2019 Warnings of an “insect apocalypse” are premature Schowalter, T.D.; Willig, M.R.; Presley, S.J.; Pandey, M. Journal Article
2019 African dust deposition in Puerto Rico: Analysis of a 20-year rainfall chemistry record and comparison with models McClintock, M.A.; McDowell, W.H.; González, G.; Schulz, M.; Pett-Ridge, J.C. Dust deposition represents an important flux of rock-derived nutrients such as phosphorus to ecosystems on highly weathered soils. Direct measurements of terrestrial dust deposition and its spatial variability are rare, yet they are essential for testing models of dust deposition processes and understanding the biogeochemical effects of dust. Long-term records of precipitation chemistry are available in the Luquillo Mountains of Puerto Rico, which are downwind of the world's largest dust source in Africa. We analyzed 20-year datasets of openfall, throughfall, and wet-only precipitation chemistry with weekly resolution at two different locations in the Luquillo Mountains to evaluate spatial and temporal variability of dust inputs and compare the observational records with models. Based on rainwater dissolved silica and total suspended solids content, the measured dust flux varied by a factor of 2 over a distance of 10 km despite similarities between sites in elevation and rainfall amount. In comparison with simulated dust deposition from ten models in the Aerosol Comparisons between Observations and Models (AeroCom) project, the empirical rainfall chemistry agrees well with the mean of the models on the seasonal distribution of wet dust distribution. Both the data and the models show a summer maximum in wet dust deposition that is consistent with variation in transport pathways and the dust source area emission strength based on environmental conditions in the Sahel region. The rainfall chemistry record and AeroCom models also agree in terms of attributing 70% of the total dust deposition overall to dry deposition, although the range of uncertainty in the models is large. The results indicate value in combining long-term analysis of rainfall chemistry with data from satellites and models, and highlight the need for accurate ground-based metrics for dry deposition to improve understanding and modeling of dust deposition processes. The dataset complements earlier studies that characterize the dust plume originating from Northern Africa and its impact on ecosystems in South America and the Caribbean. Journal Article AeroCom; Caribbean; dissolved silica; Dust deposition; Luquillo; rainfall chemistry
2019 Concluding Remarks: Moving Forward on Scientific Knowledge and Management Approaches to Tropical Forests in the Anthropocene Epoch González, G.; Lugo, A.E. The United States Department of Agriculture Forest Service International Institute of Tropical Forestry (the Institute) celebrates its 75th Anniversary with the publication of this Special Issue of Forests. This Issue is based on presentations delivered in a symposium held in San Juan, Puerto Rico in 2014. It augments a quarter century of scientific knowledge and capitalizes on a unique set of synergies chartered by a strategy based on shared stewardship, innovative transdisciplinary collaborations, and breakthroughs in science and technology. The manuscripts contained here present advancements in our approach to the development of policies for effective governance and stewardship, long-term focus for the understanding of ecosystem processes and functions, novelties given attention to cross-boundary collaborative approaches to science, and proposed alternative institutional visions in the Anthropocene. As the Institute continues to collaboratively explore new frontiers in science, we recognize advances in forestry, atmospheric sciences, modeling, hydrology, plant physiology, and microbial ecology as core to the understanding of tropical forests in the Anthropocene. Journal Article
2019 Potential of second-growth Neotropical forests for forestry: the example of Puerto Rico Forero-Montaña, J.; Marcano-Vega, H.; Zimmerman, J.K.; Brandeis, T.J. Journal Article
2019 Diversity and Dynamics of Arthropods and Microbes, and Nutrient Release during Green Litter Decomposition in a Simulated Hurricane Experiment Rosado, I.I.Moreno Thesis
2019 Hysteretic Response of Solutes and Turbidity at the Event Scale Across Forested Tropical Montane Watersheds Wymore, A.S.; Leon, M.C.; Shanley, J.B.; McDowell, W.H. Concentration-discharge relationships are a key tool for understanding the sources and transport of material from watersheds to fluvial networks. Storm events in particular provide insight into variability in the sources of solutes and sediment within watersheds, and the hydrologic pathways that connect hillslope to stream channel. Here we examine high-frequency sensor-based specific conductance and turbidity data from multiple storm events across two watersheds (Quebrada Sonadora and Rio Icacos) with different lithology in the Luquillo Mountains of Puerto Rico, a forested tropical ecosystem. Our analyses include Hurricane Maria, a category 5 hurricane. To analyze hysteresis, we used a recently developed set of metrics to describe and quantify storm events including the hysteresis index (HI), which describes the directionality of hysteresis loops, and the flushing index (FI), which can be used to infer whether the mobilization of material is source or transport limited. We also examine the role of antecedent discharge to predict hysteretic behavior during storms. Overall, specific conductance and turbidity showed contrasting responses to storms. The hysteretic behavior of specific conductance was similar across sites, displaying clockwise hysteresis and a negative FI indicating proximal sources of solutes and consistent source limitation. In contrast, the directionality of turbidity hysteresis was significantly different between watersheds, although both had strong flushing behavior indicative of transport limitation. Overall, models that included antecedent discharge did not perform any better than models with peak discharge alone, suggesting that the magnitude and trajectory of an individual event was the strongest driver of material flux and hysteretic behavior. Hurricane Maria produced unique hysteresis metrics within both watersheds, indicating a distinctive response to this major hydrological event. The similarity in response of specific conductance to storms suggests that solute sources and pathways are similar in the two watersheds. The divergence in behavior for turbidity suggests that sources and pathways of particulate matter vary between the two watersheds. The use of high-frequency sensor data allows the quantification of storm events while index-based metrics of hysteresis allow for the direct comparison of complex storm events across a heterogeneous landscape and variable flow conditions. Journal Article
2019 Impact of ecohydrological fluctuations on iron-redox cycling Calabrese, S.; Porporato, A. Because of its interaction with plants, carbon decomposition, and soil properties, soil iron cycle has been recognized as an important player in the carbon and other biogeochemical cycles. The impact of the hydrologic cycle and plants on it, however, remains largely unexplored. Here we focus on terrestrial ecosystems and develop a dynamical system to analyze the coupling between iron and carbon dynamics in the soil root zone as driven by fluctuations in soil moisture. Particular emphasis is placed on the modeling of the soil organic matter, the Fe-reducing population, the iron Fe2+-Fe3+ cycling, and the soil moisture level, which controls the redox rates. Informed by laboratory and field measurements from a tropical forest, our results suggest that soil moisture and litterfall rates are the primary drivers of iron fluctuations at daily-to-seasonal temporal scales. We also emphasize the important role of soil iron cycle in the decomposition of the organic matter. Journal Article Hydrologic control; Iron and carbon model; Plant uptake; Soil iron redox; Soil moisture variability
2019 On the Shoulders of Giants: Continuing the Legacy of Large-Scale Ecosystem Manipulation Experiments in Puerto Rico Wood, T.E.; González, G.; Silver, W.L.; Reed, S.C.; Cavaleri, M.A. There is a long history of experimental research in the Luquillo Experimental Forest in Puerto Rico. These experiments have addressed questions about biotic thresholds, assessed why communities vary along natural gradients, and have explored forest responses to a range of both anthropogenic and non-anthropogenic disturbances. Combined, these studies cover many of the major disturbances that affect tropical forests around the world and span a wide range of topics, including the effects of forest thinning, ionizing radiation, hurricane disturbance, nitrogen deposition, drought, and global warming. These invaluable studies have greatly enhanced our understanding of tropical forest function under different disturbance regimes and informed the development of management strategies. Here we summarize the major field experiments that have occurred within the Luquillo Experimental Forest. Taken together, results from the major experiments conducted in the Luquillo Experimental Forest demonstrate a high resilience of Puerto Rico’s tropical forests to a variety of stressors. Journal Article
2019 Biogeographic context dependence of trophic cascade strength in bromeliad food webs LeCraw, R.M.; Srivastava, D.S. Abstract Ecosystem functions and the biomass of lower trophic levels are frequently controlled by predators. The strength of top-down control in these trophic cascades can be affected by the identity and diversity of predators, prey, and resources, as well as environmental conditions such as temperature, moisture, and nutrient loading, which can all impact interaction strength between trophic levels. Few studies have been able to replicate a complete community over a large geographic area to compare the full trophic cascade in a manipulative experiment. Here, we identify geographic dependency in trophic cascade strength, and the driving factors and specific mechanisms behind it, by combining geographically replicated experiments with a novel approach of community analogues of common garden and transplant experiments. We studied a predator–detritivore–detritus food web in bromeliads in Puerto Rico, Costa Rica, and Brazil. We found that interaction strengths between resources, consumers, and predators were strongly site-specific, but the exact mechanism differed between trophic levels. Large bodied predators created strong interaction strengths between predator and consumer trophic levels, reducing consumer abundance regardless of the geographic location, whereas small-bodied predators created weak interactions with no impact on consumer abundances in any site. In contrast, the interaction strength between consumers and resources varied among sites, depending on the dominant species of leaf detritus. More labile leaf species in Costa Rica created a strong consumer–resource interaction and therefore strong trophic cascade, whereas tougher leaf species in Brazil created a weak consumer–resource interaction, and an overall weaker trophic cascade. Our study highlights the importance of replicating experiments over geographic scales to understand general patterns of ecological processes. Journal Article aquatic invertebrate; biogeography; bromeliad; context dependency; Decomposition; species traits; top-down control; trophic cascade strength
2019 Intraspecific variation in traits and tree growth along an elevational gradient in a subtropical forest Umaña, M.Natalia; Swenson, N.G. A conspicuous feature of natural communities is that individuals within species exhibit broad variation in their phenotype. While the phenotypic differences among species are prominent and have received considerable attention in earlier studies, recent findings suggest that about 40% of the trait variation is found within species. How this intraspecific variation is related to underlying environmental gradients and ultimately linked to performance is an outstanding question in ecology and evolution. Here, we study six broadly distributed species across an elevational gradient in a subtropical forest. We focused on five functional traits reflecting plant functional differentiation in stem transport, leaf architecture, and leaf resource acquisition. We found that leaf thickness, leaf toughness, and specific leaf area generally varied with elevation, while wood density and leaf area exhibited constrained variation. Results on multivariate trait axes also showed mixed evidence with the PC1 values (positively related to leaf toughness and negatively related to specific leaf area) shifting with elevation, while PC2 values (negatively related to wood density) did not change with elevation. We also found that, despite the important variation in some traits along the gradient, growth performance did not follow this same trend. This suggests that strong directional changes in traits along the gradient may result in similar levels of demographic performance. The results, therefore, challenge the simple expectation that a trait will correlate with a demographic rate. More nuanced approaches and additional mechanisms must be considered to advance understanding of the performance-trait relationships. Journal Article
2019 Persistent Hydrological Consequences of Hurricane Maria in Puerto Rico Miller, P.W.; Kumar, A.; Mote, T.L.; Moraes, F.D.S.; Mishra, D.R. Abstract In September 2017, Hurricane Maria severely defoliated Puerto Rico's landscape, coinciding with a series of persistent hydrological consequences involving the atmospheric, terrestrial, and marine components of the water cycle. During the defoliated period, the atmosphere's thermodynamic structure more strongly explained daily cloud activity (R2PRE = 0.02; R2POST = 0.40) and precipitation (R2PRE = 0.19; R2POST = 0.33) than before landfall, indicating that post-Maria land-atmosphere interactions were comparatively muted, with similar precipitation patterns also found following Hurricanes Hugo (1989) and Georges (1998). Meanwhile, modeled post-Maria runoff exceeded statistical expectations given the magnitude of contemporaneous precipitation. Enhanced runoff also coincided with greater sediment loads in nearshore waters, increasing sediment content greater than twofold. This study offers a holistic narrative of hydrospheric disturbance and recovery, whereby the instantaneous, large-scale removal of vegetation is accompanied by hydrologic changes “upstream” in the atmosphere and “downstream” in rivers and estuaries. Journal Article defoliation; hurricanes; hydrologic cycle; land-atmosphere interactions
2019 Leaf litter decomposition and macroinvertebrate assemblages along an urban stream gradient in Puerto Rico Classen-Rodríguez, L.; Gutiérrez-Fonseca, P.E.; Ramírez, A. Abstract Urbanization is a major land use form that has large impacts on ecosystems. Urban development in the watershed impacts stream ecosystems by increasing nutrient and organic matter loads, altering hydrology, and reducing biodiversity. Puerto Rico is an ideal location to assess and monitor the effects of urbanization on streams, because it is increasingly urbanized and streams do not receive inputs of untreated sewage, characteristic of many other tropical urban areas. The objective of this study was to determine how leaf litter decomposition and aquatic macroinvertebrate assemblages varied along a tropical urban gradient. We conducted the study in the Río Piedras watershed, San Juan Metropolitan Area, in six low-order streams that formed an urban gradient ranging from 10% to 70% urban land cover. At each stream, we placed six 5 g leaf bags of Ficus longifolia in three different pools and collected one bag on each sampling date. Decomposition rates were fast in forested streams (range 0.021–0.039/day) and decreased with increasing urbanization (range 0.007–0.008/day). Rates were strongly and negatively correlated with percent impervious surface cover (R = 0.81, p = 0.01). Functional feeding group diversity was higher in forested streams, with the presence of shredders. Decomposition rates were significantly and positively correlated with functional feeding group diversity and abundance (R = 0.66, p = 0.04). Overall, our results show that urbanization affected the environment and macroinvertebrate diversity resulting in large negative effects on stream ecosystem function. Abstract in Spanish is available with online material. Journal Article functional feeding groups; Impervious surface; leaf decomposition; macroinvertebrates; Puerto Rico; tropical streams; Urban watershed
2019 The Multiscale Signature of Ecohydrological Fluctuations on Soil Biogeochemical Cycles Calabrese, S. Thesis
2019 Comparison of discharge pulses in temperate and tropical rainforest headwater stream networks Lininger, K.B.; Raimondi, J.; Kramer, N.; Homrighausen, D.; Covich, A. We use sub-daily gage records from montane headwater channels in the Luquillo Experimental Forest of Puerto Rico (tropical rainforest) and the HJ Andrews Experimental Forest of Oregon (temperate rainforest) to characterize differences in discharge pulses (rapid, high-magnitude discharge fluctuations) and determine whether the characteristics of discharge pulses differ with respect to drainage area between these two regions. The study sites have different precipitation regimes and runoff generation mechanisms, and we quantify differences in discharge pulses between sites. The assessment of discharge pulses, which are defined as flows that are higher than one standard deviation above the historical mean flow at each site, represents a novel approach to characterizing flashy discharge events in headwater streams using high temporal resolution datasets. Our analyses indicate a clear difference between regions, with discharge in the Luquillo streams pulsing more frequently, for shorter periods of time, and at higher magnitudes than discharge in the Andrews streams. We also quantify how discharge pulses change with increasing drainage area at each of the sites. Differences in discharge pulse metrics with respect to drainage area include an increase in the number of pulses, an increase in the normalized magnitude of pulses, an increase in the standard deviation in normalized magnitude, and a decrease in kurtosis with increasing drainage area at the Luquillo site. These results indicate that there is no attenuation of discharge pulses with increasing drainage area at Luquillo. In contrast, there is a decrease in the normalized magnitude with increasing drainage area at the Andrews site, indicating some attenuation of discharge pulses with increasing drainage area. The characteristics of these pulsed events have implications for ecological processes by transporting sediment, biota, and organic matter, likely altering stream substrates, biotic communities, and organic matter retention times. Journal Article
2019 Ecological and Genomic Attributes of Novel Bacterial Taxa That Thrive in Subsurface Soil Horizons Brewer, T.E.; Aronson, E.L.; Arogyaswamy, K.; Billings, S.A.; Botthoff, J.K.; Campbell, A.N.; Dove, N.C.; Fairbanks, D.; Gallery, R.E.; Hart, S.C.; Kaye, J.; King, G.; Logan, G.; Lohse, K.A.; Maltz, M.R.; Mayorga, E.; O’Neill, C.; Owens, S.M.; Packman, A.; Pett-Ridge, J.; Plante, A.F.; Richter, D.D.; Silver, W.L.; Yang, W.H.; Fierer, N. While most bacterial and archaeal taxa living in surface soils remain undescribed, this problem is exacerbated in deeper soils, owing to the unique oligotrophic conditions found in the subsurface. Additionally, previous studies of soil microbiomes have focused almost exclusively on surface soils, even though the microbes living in deeper soils also play critical roles in a wide range of biogeochemical processes. We examined soils collected from 20 distinct profiles across the United States to characterize the bacterial and archaeal communities that live in subsurface soils and to determine whether there are consistent changes in soil microbial communities with depth across a wide range of soil and environmental conditions. We found that bacterial and archaeal diversity generally decreased with depth, as did the degree of similarity of microbial communities to those found in surface horizons. We observed five phyla that consistently increased in relative abundance with depth across our soil profiles: Chloroflexi, Nitrospirae, Euryarchaeota, and candidate phyla GAL15 and Dormibacteraeota (formerly AD3). Leveraging the unusually high abundance of Dormibacteraeota at depth, we assembled genomes representative of this candidate phylum and identified traits that are likely to be beneficial in low-nutrient environments, including the synthesis and storage of carbohydrates, the potential to use carbon monoxide (CO) as a supplemental energy source, and the ability to form spores. Together these attributes likely allow members of the candidate phylum Dormibacteraeota to flourish in deeper soils and provide insight into the survival and growth strategies employed by the microbes that thrive in oligotrophic soil environments.IMPORTANCE Soil profiles are rarely homogeneous. Resource availability and microbial abundances typically decrease with soil depth, but microbes found in deeper horizons are still important components of terrestrial ecosystems. By studying 20 soil profiles across the United States, we documented consistent changes in soil bacterial and archaeal communities with depth. Deeper soils harbored communities distinct from those of the more commonly studied surface horizons. Most notably, we found that the candidate phylum Dormibacteraeota (formerly AD3) was often dominant in subsurface soils, and we used genomes from uncultivated members of this group to identify why these taxa are able to thrive in such resource-limited environments. Simply digging deeper into soil can reveal a surprising number of novel microbes with unique adaptations to oligotrophic subsurface conditions. Journal Article
2019 Fragmentation, forest structure, and topography modulate impacts of drought in a tropical forest landscape Schwartz, N.B.; Budsock, A.M.; Uriarte, M. Abstract Climate models predict increases in drought conditions in many parts of the tropics. Yet the response of tropical forests to drought remains highly uncertain, especially with regards to the factors that generate spatial heterogeneity in drought response across landscapes. In this study, we used Landsat imagery to assess the impacts of a severe drought in 2015 across an 80,000-ha landscape in Puerto Rico. Specifically, we asked whether drought effects varied systematically with topography and with forest age, height, and fragmentation. We quantified drought impacts using anomalies of two vegetation indices, the enhanced vegetation index (EVI) and normalized difference water index (NDWI), and fit random forest models of these metrics including slope, aspect, forest age, canopy height, and two indices of fragmentation as predictors. Drought effects were more severe on drier topographic positions, that is, steeper slopes and southwest-facing aspects, and in second-growth forests. Shorter and more fragmented forests were also more strongly affected by drought. We also assessed which factors were associated with stronger recovery from drought. Factors associated with more negative drought anomalies were also associated with more positive postdrought anomalies, suggesting that increased light availability as a result of drought led to high rates of recovery in forests more severely affected by drought. In general, recovery from drought was rapid across the landscape, with postdrought anomalies at or above average across the study area. This suggests that forests in Puerto Rico might be resilient to a single-year drought, though vulnerability to drought varies depending on forest characteristics and landscape position. Journal Article Drought; landscape fragmentation; light detection and ranging (LiDAR); Puerto Rico; random forest; Remote sensing; second growth; tropical forest
2019 Incipient chemical weathering at bedrock fracture interfaces in a tropical critical zone system, Puerto Rico Moore, O.W.; Buss, H.L.; Dosseto, A. The processes that control chemical weathering of bedrock in the deep critical zone at a mm-scale are still poorly understood, but may produce 100 s of meters of regolith and substantial fluxes of silicate weathering products and thus may be important for modeling long-term, global CO2. Weathering controls are also difficult to ascertain, as laboratory determined dissolution rates tend to be 2–5 orders of magnitude faster than field determined dissolution rates. This study aims to establish (i) the incipient processes that control the chemical weathering of the Bisley bedrock and (ii) why weathering rates calculated for the watershed may differ from laboratory rates (iii) why rates may differ across different scales of measurement. We analyzed mineralogy, elemental chemistry, and porosity in thin sections of rock obtained from drilled boreholes using Scanning Electron Microscopy (SEM) with energy dispersive spectrometry, electron probe microanalysis, and synchrotron-based Micro X-ray Fluorescence (µXRF) and X-ray Absorption Near Edge Structure (XANES). Weathering ages were determined from U-series isotope analysis. Mineral specific dissolution rates were calculated from solid-state mineralogical gradients and weathering ages. Mineralogical and elemental transects across thin sections and SEM images indicate that trace pyrite is the first mineral to dissolve. Micro-XRF mapping at 2 µm resolution revealed sulfate in pore space adjacent to dissolving pyrite, indicating that the incipient reaction is oxidative. The oxidative dissolution of pyrite produces a low pH microenvironment that aids the dissolution of pyroxene and chlorite. The rate-limiting step of weathering advance, and therefore the creation of the critical zone in the Bisley watershed, is pyrite oxidation, despite the low abundance (∼0.5 vol%) of pyrite in the parent rock. The naturally determined dissolution rates presented here either approach, converge with, or in some cases exceed, rates from the literature that have been experimentally determined. The U-series weathering age data on the mm-scale integrates the weathering advance rate over the ∼4.2 ± 0.3 kyrs that the weathering rind took to form. The weathering advance rate calculated at a watershed scale (from stream chemistry data) represents a contemporary weathering advance rate, which compares well with that calculated for the weathering rind, suggesting that the Bisley watershed has been weathering at steady-state for the last ∼4 kyrs. Journal Article Critical zone; Luquillo experimental forest; U-series nuclides; Weathering rates; Weathering rinds
2019 LINX I and II: Lessons Learned and Emerging Questions Wymore, A.S.; Rodríguez-Cardona, B.M.; Herreid, A.; McDowell, W.H. The Lotic Intersite Nitrogen eXperiments (LINX I and II) were a series of replicated in situ manipulations of 15N across biomes and land-uses designed to assess the factors that control the removal, retention, and ultimate fate of inorganic nitrogen in stream ecosystems. By studying streams at the continental scale, the lessons learned provide some of the best data available to understand the functional role of streams across the landscape, the management implications of nitrogen uptake in streams and rivers, and the value of small streams in elucidating fundamental principles of ecosystem science. Because small streams are characterized by high throughput and low standing stocks of primary producers and stored carbon and nutrients, they provide unique opportunities to assess the fundamental drivers of nitrogen cycling that would be difficult to conduct in other ecosystems. In addition to the water quality implications of understanding controls on nitrogen delivery to downstream systems, LINX I and II also provide unique insights for ecosystem science and stream ecology more broadly. Here we review a series of ecosystem and network-scale lessons that can be inferred from LINX I and II. We then propose three emergent research questions motivated by the LINX projects which are amenable to future continental-scale work. LINX I and II also demonstrate the value of a highly collaborative, distributed approach to ecosystem science that requires each member of the team to conduct a standardized protocol while simultaneously encouraging team member to improve protocols and develop cross-site projects in his or her specific area of expertise. Journal Article
2019 The drivers and consequences of unstable Plasmodium dynamics: a long-term study of three malaria parasite species infecting a tropical lizard Otero, L.; Schall, J.J.; Cruz, V.; Aaltonen, K.; Acevedo, M.A. Journal Article
2018 Biodiversity and disturbance
Willig, M. R, and S. J Presley. 2018. Biodiversity And Disturbance. In The Encyclopedia of the Anthropocene, The Encyclopedia of the Anthropocene, Oxford, UK: Elsevier Ltd., 45-51.
Willig, M.R.; Presley, S.J. Book Chapter
2018 El Yunque National Forest Atlas
Quiñones, Q., I.K. Parés, W.A. Gould, G. Gonzalez, K. McGinley, and P. Rios. 2018. El Yunque National Forest Atlas. San Juan, PR: U.S. Department of Agriculture, Forest Service, International Institute of Tropical Forestry.
Quiñones, Q.; Parés, I.K.; Gould, W.A.; Gonzalez, G.; McGinley, K.; Rios, P.

El Yunque National Forest Atlas is a collaborative effort by the International Institute of Tropical Forestry and El Yunque National Forest to provide upto-date maps and analyses of spatial information of an important natural reserve in Puerto Rico and the only tropical forest in the National Forest System of the United States. El Yunque National Forest Atlas serves as a companion tool to the El Yunque National Forest 2014 Forest Plan Assessment Report, Phase One, under the U.S. Department of Agriculture (USDA), Forest Service 2012 Planning Rule. The assessment documents current ecological, socioeconomic, and cultural conditions of the forest and the surrounding landscape, as part of the El Yunque National Forest management plan revision process, which will establish requirements and constraints to make management decisions within the forest. The El Yunque National Forest 2014 Forest Plan Assessment Report is available at:

Report atlas; forest service; Technical Report
2018 Improving predictions of tropical forest response to climate change through integration of field studies and ecosystem modeling Feng, X.; Uriarte, M.; González, G.; Reed, S.; Thompson, J.; Zimmerman, J.K.; Murphy, L.

Tropical forests play a critical role in carbon and water cycles at a global scale. Rapid climate change is anticipated in tropical regions over the coming decades and, under a warmer and drier climate, tropical forests are likely to be net sources of carbon rather than sinks. However, our understanding of tropical forest response and feedback to climate change is very limited. Efforts to model climate change impacts on carbon fluxes in tropical forests have not reached a consensus. Here, we use the Ecosystem Demography model (ED2) to predict carbon fluxes of a Puerto Rican tropical forest under realistic climate change scenarios. We parameterized ED2 with species-specific tree physiological data using the Predictive Ecosystem Analyzer workflow and projected the fate of this ecosystem under five future climate scenarios. The model successfully captured interannual variability in the dynamics of this tropical forest. Model predictions closely followed observed values across a wide range of metrics including aboveground biomass, tree diameter growth, tree size class distributions, and leaf area index. Under a future warming and drying climate scenario, the model predicted reductions in carbon storage and tree growth, together with large shifts in forest community composition and structure. Such rapid changes in climate led the forest to transition from a sink to a source of carbon. Growth respiration and root allocation parameters were responsible for the highest fraction of predictive uncertainty in modeled biomass, highlighting the need to target these processes in future data collection. Our study is the first effort to rely on Bayesian model calibration and synthesis to elucidate the key physiological parameters that drive uncertainty in tropical forests responses to climatic change. We propose a new path forward for model-data synthesis that can substantially reduce uncertainty in our ability to model tropical forest responses to future climate.

Journal Article carbon flux; Climate change; ecosystem demography model; GPP; NPP; sensitivity analysis; tropical forest; variance decomposition
2018 Drought drives rapid shifts in soil biogeochemistry and greenhouse gas emissions in a wet tropical forest O'Connell, C.; Ruan, L.; Silver, W.L.

Climate change models predict more frequent and severe droughts in the humid tropics. How drought will impact tropical forest carbon and greenhouse gas dynamics is poorly understood. Here we report the effects of the severe 2015 Caribbean drought on soil moisture, oxygen, phosphorus (P), and greenhouse gas emissions in a humid tropical forest in Puerto Rico. Drought significantly decreases inorganic P concentrations, an element commonly limiting to net primary productivity in tropical forests, and significantly increases organic P. High-frequency greenhouse gas measurements show varied impacts across topography. Soil carbon dioxide emissions increase by 60% on slopes and 163% in valleys. Methane (CH4) consumption increases significantly during drought, but high CH4 fluxes post-drought offset this sink after 7 weeks. The rapid response and slow recovery to drought suggest tropical forest biogeochemistry is more sensitive to climate change than previously believed, with potentially large direct and indirect consequences for regional and global carbon cycles.

Journal Article biogeochemical processes; Biogeochemistry; disturbances; ecosystem properties; field methods; gases; Habitats; microbes; soil; terrestrial ecosystems
2018 Geographical ecology of dry forest tree communities in the West Indies Franklin, J.F.; Andrade, R.; Daniels, M.L.; Fairbairn, P.; Fandino, M.C.; Gillespie, T.W.; Gonzalez, G.; Gonzalez, O.; Imbert, D.; Kapos, V.; Kelly, D.L.; Marcano-Vega, H.; Melendez-Ackerman, E.; McLaren, K.P.; McDonald, M.A.; Ripplinger, J.; Rojas-Sandoval, J.; Ross, M.S.; Ruiz, J.; Steadman, D.W.; Tanner, E.V.J.; Terrill, I.; Vennetier, M.

Seasonally dry tropical forest (SDTF) of the Caribbean Islands (primarily West Indies) is floristically distinct from Neotropical SDTF in Central and South America. We evaluate whether tree species composition was associated with climatic gradients or geographical distance. Turnover (dissimilarity) in species composition of different islands or among more distant sites would suggest communities structured by speciation and dispersal limitations. A nested pattern would be consistent with a steep resource gradient. Correlation of species composition with climatic variation would suggest communities structured by broad-scale environmental filtering.

Journal Article beta diversity; Caribbean community composition; seasonally dry tropical forest; seed plants; species turnover; tropical dry forest; West Indies; woody taxa-primarily trees
2018 Disentangling the long-term effects of disturbance on soil biogeochemistry in a wet tropical forest ecosystem Santiago, Gdel Arroyo; Silver, W.L. Climate change is increasing the intensity of severe tropical storms and cyclones (also referred to as hurricanes or typhoons), with major implications for tropical forest structure and function. These changes in disturbance regime are likely to play an important role in regulating ecosystem carbon (C) and nutrient dynamics in tropical and subtropical forests. Canopy opening and debris deposition resulting from severe storms have complex and interacting effects on ecosystem biogeochemistry. Disentangling these complex effects will be critical to better understand the long-term implications of climate change on ecosystem C and nutrient dynamics. In this study, we used a well-replicated, long-term (10 years) canopy and debris manipulation experiment in a wet tropical forest to determine the separate and combined effects of canopy opening and debris deposition on soil C and nutrients throughout the soil profile (1 m). Debris deposition alone resulted in higher soil C and N concentrations, both at the surface (0-10 cm) and at depth (50-80 cm). Concentrations of NaOH-organic P also increased significantly in the debris deposition only treatment (20-90 cm depth), as did NaOH-total P (20-50 cm depth). Canopy opening, both with and without debris deposition, significantly increased NaOH-inorganic P concentrations from 70 to 90 cm depth. Soil iron concentrations were a strong predictor of both C and P patterns throughout the soil profile. Our results demonstrate that both surface- and subsoils have the potential to significantly increase C and nutrient storage a decade after the sudden deposition of disturbance-related organic debris. Our results also show that these effects may be partially offset by rapid decomposition and decreases in litterfall associated with canopy opening. The significant effects of debris deposition on soil C and nutrient concentrations at depth (>50 cm), suggest that deep soils are more dynamic than previously believed, and can serve as sinks of C and nutrients derived from disturbance-induced pulses of organic matter inputs. Journal Article carbon sequestration; disturbance; hurricane; Phosphorus; soil depth; Soil nutrients; tropical forest
2018 The Frequency of Cyclonic Wind Storms Shapes Tropical Forest Dynamism and Functional Trait Dispersion Hogan, A.; Zimmerman, J.K.; Thompson, J.; Uriarte, M.; Swenson, N.G.; Condit, R.; Hubbell, S.; Johnson, D.J.; Sun, F.; Chang-Yang, C.H.; Su, S.H.; Ong, P.; Rodriguez, L.; Monoy, C.C.; Yap, S.; Davies, S.J. As cyclonic wind storms (hurricanes and typhoons) increase in frequency and intensity with climate change, it is important to understand their effects on the populations and communities of tropical trees they impact. Using tree demographic data from four large, tropical forest dynamics plots that differ in cyclonic storm frequency, we compare tree population and community dynamics. Additionally, we assess the effect of cyclonic storms on three functional traits, specific leaf area, wood density, and tree height of the dynamic tree assemblages. Mortality, growth and recruitment rates and the intrinsic rates of population growth of species differed across the plots, and were most dynamic, especially for stems 1–2 cm in diameter, at the plot which had an intermediate level of cyclonic storm frequency. Functional assemblages of species had the greatest degree of temporal variation in relation to disturbance, as measured by the change in functional divergence for the two plots with more intermediate cyclonic storm recurrence. Therefore, cyclonic storms affecting these plots generally have a greater effect on forest composition and dynamism than comparable cyclonic storms do on the plot which experiences cyclonic storms more frequently. Thus, we provide some evidence that community-wide demographic resistance to cyclonic storms is generally lower at an intermediate frequency of storms. While cyclonic storm strength and timing are important determinants of the within forest variation in tree dynamics and functional trait assemblages, we also show that cyclonic storm timing and frequency shapes tropical forest dynamics and functional composition across forests. We conclude that, over a given time interval, sites with intermediate levels of damaging cyclonic wind disturbance express a greater potential for life-history variation in the forest community, when compared to sites with less or more frequent disturbance. Journal Article Barrio Colorado Island; cyclonic wind disturbance; forest demography; forest resistance; functional traits; hurricanes; Luquillo; Palanan; tree growth; tree mortality; typhoons
2018 BioTIME: a database of biodiversity time series for the Anthropocene. Global Ecology and Biogeography. Dornelas, M.; al., et Motivation: The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the anthropocene. Main types of variables included: The database contains 8 773 553 species abundance records, from assemblages consistently sampled for a minimum of two, not necessarily consecutive, years. In addition, the database contains metadata relating to sampling methodology and contextual information about each record. Spatial location and grain: BioTIME is a global database of 547 161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km2 (158 cm2) to 100 km2 (1 000 000 000 000 cm2). Time period and grain: BioTIME records span from 1874 to 2016. The minimum temporal grain across all datasets in BioTIME is year. Major taxa and level of measurement: BioTIME includes data from 44 360 species across the plant an animal kingdoms, ranging from plants, plankton, and terrestrial invertebrates to small and large vertebrates. Software format: .csv and .SQL Journal Article Biodiversity; global; spatial; species richness; temporal; turnover
2018 Correlating drought conservation practices and drought vulnerability in a tropical agricultural system Álvarez-Berríos, N.; Soto-Bayó, S.; Holupchinski, E.; Fain, S.; Gould, W. Recent droughts in Puerto Rico and throughout the Caribbean have emphasized the region's agricultural vulnerability to this hazard and the increasing need for adaptation mechanisms to support sustainable production. In this study, we assessed the geographic extent of agricultural conservation practices incentivized by US Department of Agriculture Natural Resources Conservation Service (NRCS) and evaluated their large-scale contribution to drought adaptability. We identified concentrations of drought-related practices (e.g. cover crops, ponds) applied between 2000 and 2016. Using information from spatial databases and interviews with experts, we assessed the spatial correlation between these practices and areas exposed to drought as identified by the US Drought Monitor. Between 2000 and 2016, Puerto Rico experienced seven drought episodes concentrated around the south, east and southeastern regions. The most profound drought occurred between 2014 and 2016 when the island experienced 80 consecutive weeks of moderate drought, 48 of severe drought and 33 of extreme drought conditions. A total of 44 drought-related conservation practices were applied at 6984 locations throughout 860 km2 of farmlands between 2000 and 2016 through the NRCS-Environmental Quality Incentives Program (EQIP). Practices related to water availability were statistically clustered along the coasts, whereas soil and plant health practices were clustered in the mountainous region. While these concentrations strongly correlated with areas exposed to moderate drought conditions, >80% did not coincide with areas that experienced severe or extreme drought conditions, suggesting that areas highly exposed to drought conditions generally lacked drought preparedness assisted by EQIP. Climate projections indicate an increase in the frequency and intensity of drought events, particularly in the eastern region of Puerto Rico. Our analysis highlighted the need to implement more conservation practices in these areas subject to drought intensification and exposure. Government programs intended to address vulnerabilities and enhance capacity and resilience may not be reaching areas of highest exposure. Recommendations include raising producer awareness of past and future exposure and making programs more accessible to a broader audience. Journal Article Adaptation; agricultural drought; conservation programs; hotspot analysis; Puerto Rico
2018 Underuse of social-ecological systems: A research agenda for addressing challenges to biocultural diversity Mauerhofer, V.; Ichinose, T.; Blackwell, B.D.; Willig, M.R.; Flint, C.G.; Krause, M.S.; Penker, M. Conservation is often operationalized as a minimization of human intervention in nature. However, many social-ecological systems depend on human interventions to maintain characteristics of biological diversity. Therefore, reduced use or full abandonment of such systems can diminish rather than enhance biological diversity and its related cultural diversity (biocultural diversity). We link the definition of “underuse” with the extinction rate used in the planetary boundaries framework to support a more objective use of the term. We execute a structured cross-continental review of underuse in social-ecological systems of regions that contain more affluent countries to frame a global research agenda on underuse. Our working approach delineates causes, consequences, and strategies concerning underuse. Based on this comparative review, we identify causes of underuse that are similar in different continents, including globalization, and demographic or structural change in Europe, Japan and Oceania. Conservation paradigms emphasizing wilderness ideals in policies are characteristic of underuse in North America, whereas post-socialist transformation processes characterize underuse in Eastern Europe. Land abandonment and de-intensification of use are a common result, particularly in marginal and protected areas. Consequences of the loss of biocultural diversity include the loss of ecosystem services, traditional knowledge, or landscape amenities. We identified a pervasive gap in transcontinental comparative research that stymies the development of effective strategies to reduce underuse of biological diversity and thereby maintain related cultural diversity. We advocate for a global research agenda on governance approaches that address the challenges of underuse. Within this agenda, we emphasize the need for an international cross-case synthesis and a trans-continental mapping of state and civil society-based interventions and co-management approaches to re-establish humans as parts of ecological systems. Such comparative work on best practice cases in a real-world context should enhance adaptive management of biocultural diversity and prevent extinction caused by underuse. Thus, this innovative connection between underuse and the planetary boundary extinction rate, along with our new global research agenda on underuse, should initiate much needed support for policy makers and natural resource managers who must decide on appropriate types and levels of human intervention to implement, both inside and outside of protected areas. Journal Article Biocultural diversity; Biodiversity; conservation; ecosystem services; Human-intervention; social-ecological systems; Underuse
2018 Drought drives rapid shifts in tropical rainforest soil biogeochemistry and greenhouse gas emissions O'Connell, C.; Ruan, L.; Silver, W.L. Climate change models predict more frequent and severe droughts in the humid tropics. How drought will impact tropical forest carbon and greenhouse gas dynamics is poorly understood. Here we report the effects of the severe 2015 Caribbean drought on soil moisture, oxygen, phosphorus (P), and greenhouse gas emissions in a humid tropical forest in Puerto Rico. Drought significantly decreases inorganic P concentrations, an element commonly limiting to net primary productivity in tropical forests, and significantly increases organic P. High-frequency greenhouse gas measurements show varied impacts across topography. Soil carbon dioxide emissions increase by 60% on slopes and 163% in valleys. Methane (CH4) consumption increases significantly during drought, but high CH4 fluxes post-drought offset this sink after 7 weeks. The rapid response and slow recovery to drought suggest tropical forest biogeochemistry is more sensitive to climate change than previously believed, with potentially large direct and indirect consequences for regional and global carbon cycles. Journal Article
2018 Tropical herbivorous phasmids, but not litter snails, alter decomposition rates by modifying litter bacteria Prather, C.; Belovsky, G.E.; Cantrell, S.A.; Gonzalez, G. Consumers can alter decomposition rates through both feces and selective feeding in many ecosystems, but these combined effects have seldom been examined in tropical ecosystems. Members of the detrital food web (litter‐feeders or microbivores) should presumably have greater effects on decomposition than herbivores, members of the green food web. Using litterbag experiments within a field enclosure experiment, we determined the relative effects of common litter snails (Megalomastoma croceum) and herbivorous walking sticks (Lamponius portoricensis) on litter composition, decomposition rates, and microbes in a Puerto Rican rainforest, and whether consumer effects were altered by canopy cover presence. Although canopy presence did not alter consumers' effects, focal organisms had unexpected influences on decomposition. Decomposition was not altered by litter snails, but herbivorous walking sticks reduced leaf decomposition by about 50% through reductions in high quality litter abundance and, consequently, lower bacterial richness and abundance. This relatively unexplored but potentially important link between tropical herbivores, detritus, and litter microbes in this forest demonstrates the need to consider autotrophic influences when examining rainforest ecosystem processes. Journal Article ecosystem process; enclosure; Herbivory; Light gap; litter; Litterbags
2018 Reconciling biodiversity and carbon stock conservation in an Afrotropical forest landscape Van de Perre, F.; Willig, M.R.; Presley, S.J.; Andemwana, B.; Beeckman, H.; Boeckx, P.; Cooleman, S.; de Haan, M.; De Kessel, A.; Dessein, S.; Grootaert, P.; Huygens, D.; Janssens, S.; Kearsley, E.; Kabeya, M.; Leponce, M.; Van den Broeck, D.; Verbeeck, H.; Leirs, H.; Verheyen, E. Protecting aboveground carbon stocks in tropical forests is essential for mitigating global climate change and is assumed to simultaneously conserve biodiversity. Although the relationship between tree diversity and carbon stocks is generally positive, the relationship remains unclear for consumers or decomposers. We assessed this relationship for multiple trophic levels across the tree of life (10 organismal groups, 3 kingdoms) in lowland rainforests of the Congo Basin. Comparisons across regrowth and old-growth forests evinced the expected positive relationship for trees, but not for other organismal groups. Moreover, differences in species composition between forests increased with difference in carbon stock. These variable associations across the tree of life contradict the implicit assumption that maximum co-benefits to biodiversity are associated with conservation of forests with the highest carbon storage. Initiatives targeting climate change mitigation and biodiversity conservation should include both old-growth and regenerating forests to optimally benefit biodiversity and carbon storage. Journal Article
2018 Latitudinal Gradients of Biodiversity: Theory and Empirical Patterns Willig, M.R.; Presley, S.J. Increasing biodiversity from the poles toward the equator is one of the most well-established patterns in ecology and biogeography. This latitudinal gradient pertains to all major taxa and to all dimensions of biodiversity (i.e., taxonomic, functional, and phylogenetic). Latitudinal gradients in functional and phylogenetic biodiversity are strong, but not entirely a product of variation in species richness. These gradients have been attributed to many ecological and evolutionary mechanisms (e.g., environmental stability, productivity, area, evolutionary speed, diversification rate); however, it is unlikely that a single mechanism drives these patterns. Rather, a combination of mechanisms likely explain latitudinal gradients of biodiversity, with the relative importance of particular mechanisms being contingent on taxon, biogeographic region, or dimension of biodiversity. Journal Article functional biodiversity; Geometric constraints; Phenetic biodiversity; phylogenetic biodiversity; Rapoport effect; scale; species richness; Species–area relationships; taxonomic biodiversity; α diversity; β diversity
2018 Phylogenetic and functional underdispersion in Neotropical phyllostomid bat communities Presley, S.J.; Cisneros, L.M.; Higgins, C.L.; Clingbeil, B.T.; Scheiner, S.M.; Willig, M.R. Habitat conversion creates a mosaic of land cover types, which affect the spatial distribution, diversity, and abundance of resources. We used abundance, functional, and phylogenetic information to determine if Neotropical bat communities exhibited phylogenetic or functional overdispersion or underdispersion in response to habitat conversion. Overdispersion suggests the operation of intraclade competition, niche partitioning, limiting similarity, or character displacement, whereas underdispersion indicates the operation of interclade competition, abiotic filtering, or biotic filtering. We expected (1) biotic filtering in landscapes with extensive forest loss to result in underdispersion; (2) niche partitioning in heterogeneous landscapes with intermediate forest loss to result in overdispersion; and (3) intraclade competition during times of low resource abundance (i.e., dry season) to increase, resulting in overdispersion. Most bat communities exhibited phylogenetic or functional underdispersion; none exhibited overdispersion. Expectations were not met: underdispersion did not increase with forest loss, heterogeneous landscapes did not induce overdispersion, and no evidence supported the contention that intraclade competition changed with season. Empirical responses were season-specific, likely because resource availability may affect relationships between forest cover and underdispersion and between biodiversity and underdispersion. During the dry season, only high diversity sites exhibited underdispersion (i.e., functional or phylogenetic redundancy), whereas underdispersion occurred in low, intermediate, or high diversity communities during the wet season; we suggest that this difference likely arises due to changes in resource abundance. Communities with high diversity and redundancy occupied heterogeneous sites during the dry season, but communities with high redundancy were restricted to large forest reserves during the wet season. Journal Article Chiroptera; Costa Rica; Functional diversity; landscape ecology; Neotropics; overdispersion; phylogenetic diversity; underdispersion
2018 Litterfall Production Prior to and during Hurricanes Irma and Maria in Four Puerto Rican Forests Liu, X.; Zeng, X.; Zou, X.M.; Gonzalez, G.; Wang, C.; Yang, Y. Hurricanes Irma and Maria struck Puerto Rico on the 6th and 20th of September 2017, respectively. These two powerful Cat 5 hurricanes severely defoliated forest canopy and deposited massive amounts of litterfall in the forests across the island. We established a 1-ha research plot in each of four forests (Guánica State Forest, Río Abajo State Forest, Guayama Research Area and Luquillo Experiment Forest) before September 2016, and had collected one full year data of litterfall production prior to the arrival of Hurricanes Irma and Maria. Hurricane-induced litterfall was collected within one week after Hurricane Irma, and within two weeks after Hurricane Maria. Each litterfall sample was sorted into leaves, wood (branches and barks), reproductive organs (flowers, fruits and seeds) and miscellaneous materials (mostly dead animal bodies or feces) after oven-drying to constant weight. Annual litterfall production prior to the arrival of Hurricanes Irma and Maria varied from 4.68 to 25.41 Mg/ha/year among the four forests, and annual litterfall consisted of 50–81% leaffall, 16–44% woodfall and 3–6% fallen reproductive organs. Hurricane Irma severely defoliated the Luquillo Experimental Forest, but had little effect on the other three forests, whereas Hurricane Maria defoliated all four forests. Total hurricane-induced litterfall from Hurricanes Irma and Maria amounted to 95–171% of the annual litterfall production, with leaffall and woodfall from hurricanes amounting to 63–88% and 122–763% of their corresponding annual leaffall and woodfall, respectively. Hurricane-induced litterfall consisted of 30–45% leaves and 55–70% wood. Our data showed that Hurricanes Irma and Maria deposited a pulse of litter deposition equivalent to or more than the total annual litterfall input with at least a doubled fraction of woody materials. This pulse of hurricane-induced debris and elevated proportion of woody component may trigger changes in biogeochemical processes and soil communities in these Puerto Rican forests. Journal Article annual litterfall; Hurricane Irma; Hurricane Maria; Puerto Rico; subtropical forest; the Guánica State Forest; the Guayama Research Area; the Luquillo Experimental Forest; the Río Abajo State Forest; wood debris
2018 Responses of Two Litter-Based Invertebrate Communities to Changes in Canopy Cover in a Forest Subject to Hurricanes Richardson, B.A.; Richardson, M.J.; González, G.

Tropical forests are subject to seasonal hurricanes resulting in cycles of canopy opening and deposition of litter, followed by periods of recovery and canopy closure. Herein, we review two studies of litter-based communities in Puerto Rico; (i) a survey of bromeliad invertebrates in three montane forest types along an elevational gradient in 1993–1997, during a period of canopy recovery after two severe hurricanes, and the results compared with those from a resurvey in 2010, and (ii) a large scale canopy trimming experiment in the lower montane (Tabonuco) forest designed to simulate an hurricane event, and to separate the effects of canopy opening from debris deposition. Measurements of changes in invertebrate community parameters and decay rates of litter were made in a litter bag experiment as part of this major experiment. As the canopy closed, during the periods of study, bromeliad density reduced, especially in the Tabonuco forest. This was associated with a decline in both alpha and gamma invertebrate diversity, which appears to have involved the loss of rarer species. In the Tabonuco forest, two endemic bromeliad specialists were not found during resampling in 2010, though the most common species were remarkably stable over the two decades. Canopy opening significantly altered the diversity, biomass, and composition of litter communities, irrespective of litter deposition. It particularly reduced organisms responsible for comminution of litter and increased the activity of fungivores and microbiovores. Both studies showed that canopy disturbance, either indirectly or directly, adversely affects invertebrate diversity and detrital processing.

Journal Article bromeliad; Caribbean; Detritus; diversity; Ecology; hurricanes; phytotelmata; tropics
2018 Constraints on the functional trait space of aquatic invertebrates in bromeliads Céréghino, R.; Pillar, V.D.; Srivastava, D.S.; de Omena, P.M.; MacDonald, A.M.; Barberis, I.M.; Corbara, B.; Guzman, L.M.; Leroy, C.; Bautista, F.Ospina; Romero, G.Q.; Trzcinski, K.; Katrina, P.; Debastiani, V.J.; Gonçalves, A.Z.; Marino, N.A.C.; Farjalla, V.F.; Richardson, B.A.; Richardson, M.J.; Dézerald, O.; Gilbert, B.; Petermann, J.S.; Talaga, S.; Piccoli, G.C.O.; Jocque, M.; Montero, G. Functional traits are commonly used in predictive models that link environmental drivers and community structure to ecosystem functioning. A prerequisite is to identify robust sets of continuous axes of trait variation, and to understand the ecological and evolutionary constraints that result in the functional trait space occupied by interacting species. Despite their diversity and role in ecosystem functioning, little is known of the constraints on the functional trait space of invertebrate biotas of entire biogeographic regions. We examined the ecological strategies and constraints underlying the realized trait space of aquatic invertebrates, using data on 12 functional traits of 852 taxa collected in tank bromeliads from Mexico to Argentina. Principal Component Analysis was used to reduce trait dimensionality to significant axes of trait variation, and the proportion of potential trait space that is actually occupied by all taxa was compared to null model expectations. Permutational Analyses of Variance were used to test whether trait combinations were clade‐dependent. The major axes of trait variation represented life‐history strategies optimizing resource use and antipredator adaptations. There was evidence for trophic, habitat, defence and life‐history niche axes. Bromeliad invertebrates only occupied 16%–23% of the potential space within these dimensions, due to greater concentrations than predicted under uniform or normal distributions. Thus, despite high taxonomic diversity, invertebrates only utilized a small number of successful ecological strategies. Empty areas in trait space represented gaps between major phyla that arose from biological innovations, and trait combinations that are unviable in the bromeliad ecosystem. Only a few phylogenetically distant genera were neighbouring in trait space. Trait combinations aggregated taxa by family and then by order, suggesting that niche conservatism was a widespread mechanism in the diversification of ecological strategies. Journal Article aquatic invertebrates; ecological strategies; Functional diversity; functional trait space; niche hypervolume
2018 Functional traits and environmental conditions predict community isotopic niches and energy pathways across spatial scales Dézerald, O.; Srivastava, D.S.; Céréghino, R.; Carrias, J.‐F.; Corbara, B.; Farjalla, V.F.; Leroy, C.; Marino, N.A.C.; Piccoli, G.C.O.; Richardson, B.A.; Richardson, M.J.; Romero, G.Q.; González, A.L. Journal Article energy pathways; environmental heterogeneity; food webs; functional biogeography; Functional diversity; isotopic niche; metacommunity; trophic structure
2018 Hurricane Maria in the U.S. Caribbean: Disturbance Forces, Variation of Effects, and Implications for Future Storms Van Beusekom, A.E.; Alvarez-Berríos, N.L.; Gould, W.A.; Quijano, M.; Gonzalez, G.

The impact of Hurricane Maria on the U.S. Caribbean was used to study the causes of remotely-sensed spatial variation in the effects of (1) vegetation index loss and (2) landslide occurrence. The vegetation index is a measure of canopy ‘greenness’, a combination of leaf chlorophyll, leaf area, canopy cover and structure. A generalized linear model was made for each kind of effect, using idealized maps of the hurricane forces, along with three landscape characteristics that were significantly associated. In each model, one of these characteristics was forest fragmentation, and another was a measure of disturbance-propensity. For the greenness loss model, the hurricane force was wind, the disturbance-propensity measure was initial greenness, and the third landscape characteristic was fraction forest cover. For the landslide occurrence model, the hurricane force was rain, the disturbance-propensity measure was amount of land slope, and the third landscape characteristic was soil clay content. The model of greenness loss had a pseudo R2 of 0.73 and showed the U.S. Caribbean lost 31% of its initial greenness from the hurricane, with 51% lost from the initial in the Luquillo Experimental Forest (LEF) from Hurricane Maria along with Hurricane Irma. More greenness disturbance was seen in areas with less wind sheltering, higher elevation and topographic sides. The model of landslide occurrence had a pseudo R2 of 0.53 and showed the U.S. Caribbean had 34% of its area and 52% of the LEF area with a landslide density of at least one in 1 km2 from Hurricane Maria. Four experiments with parameters from previous storms of wind speed, storm duration, rainfall, and forest structure over the same storm path and topographic landscape were run as examples of possible future scenarios. While intensity of the storm makes by far the largest scenario difference, forest fragmentation makes a sizable difference especially in vulnerable areas of high clay content or high wind susceptibility. This study showed the utility of simple hurricane force calculations connected with landscape characteristics and remote-sensing data to determine forest susceptibility to hurricane effects.

Journal Article Hurricane Maria; generalized linear model; remote sensing; forest fragmentation; U.S. Caribbean; Luquillo Experimental Forest
2018 Climate sensitive size-dependent survival in tropical trees Johnson, D.J.; Needham, J.; Xu, C.; Massoud, E.C.; Davies, S.J.; Anderson-Teixeira, K.J.; Bunyavejchewin, S.; Chambers, J.Q.; Chang-Yang, C.H.; Chiang, J.M.; Chuyong, G.B.; Condit, R.; Cordell, S.; Fletcher, C.D.; Giardina, C.P.; Giambelluca, T.W.; Gunatilleke, N.; Hsieh, C.F.; Hubbell, S.P.; Inman-Narahari, F.; Kassim, A.R.; Katabuchi, M.; Kenfack, D.; Litton, C.M.; Lum, S.; Mohamad, M.; Nasardin, M.; Ong, P.; Ostertag, R.; Sack, L.; Swenson, N.G.; Sun, I.F.; Tan, S.; Thomas, D.W.; Thompson, J.; Umaña, M.N.; Uriarte, M.; Valencia, R.; Yap, S.; Zimmerman, J.K.; McDowell, N.G.; McMahon, S.M. Survival rates of large trees determine forest biomass dynamics. Survival rates of small trees have been linked to mechanisms that maintain biodiversity across tropical forests. How species survival rates change with size offers insight into the links between biodiversity and ecosystem function across tropical forests. We tested patterns of size-dependent tree survival across the tropics using data from 1,781 species and over 2 million individuals to assess whether tropical forests can be characterized by size-dependent life-history survival strategies. We found that species were classifiable into four ‘survival modes’ that explain life-history variation that shapes carbon cycling and the relative abundance within forests. Frequently collected functional traits, such as wood density, leaf mass per area and seed mass, were not generally predictive of the survival modes of species. Mean annual temperature and cumulative water deficit predicted the proportion of biomass of survival modes, indicating important links between evolutionary strategies, climate and carbon cycling. The application of survival modes in demographic simulations predicted biomass change across forest sites. Our results reveal globally identifiable size-dependent survival strategies that differ across diverse systems in a consistent way. The abundance of survival modes and interaction with climate ultimately determine forest structure, carbon storage in biomass and future forest trajectories. Journal Article Ecological modelling; forest ecology; population dynamics
2018 A 42 year inference of cloud base height trends in the Luquillo Mountains of northeastern Puerto Rico Miller, P.W.; Mote, T.L.; Ramseyer, C.A.; Van Beusekom, A.E.; Scholl, M.A.; Gonzalez, G. The Luquillo Mountains of eastern Puerto Rico are home to the only tropical rainfor- est managed by the United States Forest Service, with cloud-immersed forests historically occupy- ing the highest elevations. However, within the past 50 yr, studies of the Luquillo cloud forest have suggested an increase in cloud base heights (CBH), although the CBH in the area was not quan- tified until recently. The present work uses radiosonde observations from nearby San Juan, Puerto Rico, to contextualize the present-day CBH within a 42 yr (1975−2016) proxy record and deter- mine evidence for rising cloud base. Two key questions are addressed: (1) Can theoretical CBH calculations from San Juan provide a reasonable proxy for CBHs in the Luquillo Mountains? (2) Does a significant trend accompany the CBH lifting inferred from recent work in the region? The mean-layer lifted condensation level (MLLCL), a thermodynamic parameter expressing the alti- tude at which a rising air parcel reaches 100% relative humidity, serves as the proxy. The 42 yr MLLCL time series corroborates both the low CBHs claimed in the 1980s and the higher CBHs documented by recent work. When considering all available radiosonde data, statistically signifi- cant increasing CBH trends are detected for all seasons. However, when the record is standard- ized to correct for progressive vertical resolution improvements to radiosonde observations, recent CBH increases are more modest than initially indicated, and statistically significant increases are only apparent in the late rainfall season. Journal Article Caribbean; Cloud base height; cloud forest; Lifted condensation level; Luquillo Mountains; Tropical Rainforest
2018 Global importance of large‐diameter trees
Lutz, J. A, T. J Furniss, D. J Johnson, S. J Davies, D. Allen, A. Alonso, K. J Anderson-Teixeira, A. Andrade, J. Baltzer, K. ML Becker, E. M Blomdahl, N. A Bourg, S. Bunyavejchewin, D. FRP Burslem, C. A Cansler, M. Cao, K. Cao, D. Cárdenas, L. W Chang, W. C Chao, J. M Chiang, C. Chu, G. B Chuyong, K. Clay, R. Condit, S. Cordell, H. S Dattaraja, A. Duque, C. EN Ewango, G. A Fischer, C. Fletcher, J. A Freund, J. Giardina, S. J Germain, G. S Gilbert, Z. Hao, T. Hart, B. CH Hau, F. He, A. Hector, R. Howe, Chang-Fu Hsieh, Yue-Hua Hu, S. P Hubbell, F. Inman-Narahari, A. Itoh, D. Janík, A. R Kassim, D. Kenfack, L. Korte, K. Král, A. J Larson, Y. Li, Y. Lin, S. Liu, S. Lum, K. Ma, J. R Makana, Y. Malhi, S. M McMahon, W. J McShea, H. R Memiaghe, X. Mi, M. Morecroft, P. M Musili, J. Myers, V. Novotny, Alexandre A de Oliveira, P. Ong, D. A Orwig, R. Ostertag, G. G Parker, R. Patankar, R. P Phillips, G. Reynolds, L. Sack, G. ZM Song, S. H Su, R. Sukumar, I. F Sun, H. S Suresh, M. E Swanson, S. Tan, D. W Thomas, J. Thompson, M. Uriarte, R. Valencia, A. Vicentini, T. Vrska, X. Wang, G. D Weiblen, A. Wolf, S. H Wu, H. Xu, T. Yamakura, S. Yap, and J. K Zimmerman. 2018. Global Importance Of Large‐Diameter Trees. Global Ecology and Biogeography 27(7): 849-864.
Lutz, J.A.; Furniss, T.J.; Johnson, D.J.; Davies, S.J.; Allen, D.; Alonso, A.; Anderson-Teixeira, K.J.; Andrade, A.; Baltzer, J.; Becker, K.M.L.; Blomdahl, E.M.; Bourg, N.A.; Bunyavejchewin, S.; Burslem, D.F.R.P.; Cansler, C.A.; Cao, M.; Cao, K.; Cárdenas, D.; Chang, L.W.; Chao, W.C.; Chiang, J.M.; Chu, C.; Chuyong, G.B.; Clay, K.; Condit, R.; Cordell, S.; Dattaraja, H.S.; Duque, A.; Ewango, C.E.N.; Fischer, G.A.; Fletcher, C.; Freund, J.A.; Giardina, J.; Germain, S.J.; Gilbert, G.S.; Hao, Z.; Hart, T.; Hau, B.C.H.; He, F.; Hector, A.; Howe, R.; Hsieh, C.F.; Hu, Y.H.; Hubbell, S.P.; Inman-Narahari, F.; Itoh, A.; Janík, D.; Kassim, A.R.; Kenfack, D.; Korte, L.; Král, K.; Larson, A.J.; Li, Y.; Lin, Y.; Liu, S.; Lum, S.; Ma, K.; Makana, J.R.; Malhi, Y.; McMahon, S.M.; McShea, W.J.; Memiaghe, H.R.; Mi, X.; Morecroft, M.; Musili, P.M.; Myers, J.; Novotny, V.; de Oliveira, A.A.; Ong, P.; Orwig, D.A.; Ostertag, R.; Parker, G.G.; Patankar, R.; Phillips, R.P.; Reynolds, G.; Sack, L.; Song, G.Z.M.; Su, S.H.; Sukumar, R.; Sun, I.F.; Suresh, H.S.; Swanson, M.E.; Tan, S.; Thomas, D.W.; Thompson, J.; Uriarte, M.; Valencia, R.; Vicentini, A.; Vrska, T.; Wang, X.; Weiblen, G.D.; Wolf, A.; Wu, S.H.; Xu, H.; Yamakura, T.; Yap, S.; Zimmerman, J.K. Aim To examine the contribution of large‐diameter trees to biomass, stand structure, and species richness across forest biomes. Location Global. Time period Early 21st century. Major taxa studied Woody plants. Methods We examined the contribution of large trees to forest density, richness and biomass using a global network of 48 large (from 2 to 60 ha) forest plots representing 5,601,473 stems across 9,298 species and 210 plant families. This contribution was assessed using three metrics: the largest 1% of trees ≥ 1 cm diameter at breast height (DBH), all trees ≥ 60 cm DBH, and those rank‐ordered largest trees that cumulatively comprise 50% of forest biomass. Results Averaged across these 48 forest plots, the largest 1% of trees ≥ 1 cm DBH comprised 50% of aboveground live biomass, with hectare‐scale standard deviation of 26%. Trees ≥ 60 cm DBH comprised 41% of aboveground live tree biomass. The size of the largest trees correlated with total forest biomass (r2 = .62, p < .001). Large‐diameter trees in high biomass forests represented far fewer species relative to overall forest richness (r2 = .45, p < .001). Forests with more diverse large‐diameter tree communities were comprised of smaller trees (r2 = .33, p < .001). Lower large‐diameter richness was associated with large‐diameter trees being individuals of more common species (r2 = .17, p = .002). The concentration of biomass in the largest 1% of trees declined with increasing absolute latitude (r2 = .46, p < .001), as did forest density (r2 = .31, p < .001). Forest structural complexity increased with increasing absolute latitude (r2 = .26, p < .001). Main conclusions Because large‐diameter trees constitute roughly half of the mature forest biomass worldwide, their dynamics and sensitivities to environmental change represent potentially large controls on global forest carbon cycling. We recommend managing forests for conservation of existing large‐diameter trees or those that can soon reach large diameters as a simple way to conserve and potentially enhance ecosystem services. Journal Article forest biomass; forest structure; large‐diameter trees; Latitudinal gradient; resource inequality; Smithsonian ForestGEO
2018 Effects of hurricanes and climate oscillations on annual variation in reproduction in wet forest, Puerto Rico Zimmerman, J.K.; Hogan, J.A.; Nytch, C.J.; Bithorn, J. Interannual changes in global climate and weather disturbances may influence reproduction in tropical forests. Phenomena such as the El Niño Southern Oscillation (ENSO) are known to produce interannual variation in reproduction, as do severe storms such as hurricanes. Using stationary trap‐based phenology data collected fortnightly from 1993 to 2014 from a hurricane‐affected (1989 Hugo, 1998 Georges) subtropical wet forest in northeastern Puerto Rico, we conducted a time series analysis of flowering and seed production. We addressed (1) the degree to which interannual variation in flower and seed production was influenced by global climate drivers and time since hurricane disturbance, and (2) how long‐term trends in reproduction varied with plant lifeform. The seasonally de‐trended number of species in flower fluctuated over time while the number of species producing seed exhibited a declining trend, one that was particularly evident during the second half of the study period. Lagged El Niño indices and time series hurricane disturbance jointly influenced the trends in numbers of flowering and fruiting species, suggesting complex global influences on tropical forest reproduction with variable periodicities. Lag times affecting flowering tended to be longer than those affecting fruiting. Long‐term patterns of reproduction in individual lifeforms paralleled the community‐wide patterns, with most groups of lifeform exhibiting a long‐term decline in seed but not flower production. Exceptions were found for hemiepiphytes, small trees, and lianas whose seed reproduction increased and then declined over time. There was no long‐term increase in flower production as reported in other Neotropical sites. Journal Article El Niño Southern Oscillation; Luquillo experimental forest; North Atlantic Oscillation; phenology; Puerto Rico; Time series analysis
2018 Legume abundance along successional and rainfall gradients in Neotropical forests Gei, M.; Rozendaal, D.M.A.; Poorter, L.; Bongers, F.; Sprent, J.I.; Garner, M.D.; Zimmerman, J.K.; Brancalion, P.H.S. The nutrient demands of regrowing tropical forests are partly satisfied by nitrogen-fixing legume trees, but our understanding of the abundance of those species is biased towards wet tropical regions. Here we show how the abundance of Leguminosae is affected by both recovery from disturbance and large-scale rainfall gradients through a synthesis of forest inventory plots from a network of 42 Neotropical forest chronosequences. During the first three decades of natural forest regeneration, legume basal area is twice as high in dry compared with wet secondary forests. The tremendous ecological success of legumes in recently disturbed, water-limited forests is likely to be related to both their reduced leaflet size and ability to fix N2, which together enhance legume drought tolerance and water-use efficiency. Earth system models should incorporate these large-scale successional and climatic patterns of legume dominance to provide more accurate estimates of the maximum potential for natural nitrogen fixation across tropical forests. Journal Article
2017 Post-hurricane successional dynamics in abundance and diversity of canopy arthropods in a tropical rainforest Schowalter, T.D.; Willig, M.R.; Presley, S.J.

We quantified long-term successional trajectories of canopy arthropods on six tree species in a tropical rainforest ecosystem in the Luquillo Mountains of Puerto Rico that experienced repeated hurricane-induced disturbances during the 19-yr study (1991–2009). We expected: 1) differential performances of arthropod species to result in taxon- or guild-specific responses; 2) differences in initial conditions to result in distinct successional responses to each hurricane; and 3) the legacy of hurricane-created gaps to persist despite subsequent disturbances. At least one significant effect of gap, time after hurricane, or their interaction occurred for 53 of 116 analyses of taxon abundance, 31 of 84 analyses of guild abundance, and 21 of 60 analyses of biodiversity (e.g., richness, evenness, dominance, and rarity). Significant responses were ∼60% more common for time after hurricane than for gap creation, indicating that temporal changes in habitat during recovery were of primary importance. Both increases and decreases in abundance or diversity occurred in response to each factor. Guild-level responses were probably driven by changes in the abundance of resources on which they rely. For example, detritivores were most abundant soon after hurricanes when litter resources were elevated, whereas sap-suckers were most abundant in gaps where new foliage growth was the greatest. The legacy of canopy gaps created by Hurricane Hugo persisted for at least 19 yr, despite droughts and other hurricanes of various intensities that caused forest damage. This reinforces the need to consider historical legacies when seeking to understand responses to disturbance.

Journal Article Biodiversity; disturbance; Drought; hurricane; legacy
2017 Opposing effects of arbuscular mycorrizhal fungi and natural enemies on seedling mortality promote tree species coexistence Bachelot, B.; Uriarte, M.; Thompson, J.; Zimmerman, J.K. Journal Article
2017 Climate Impacts on Soil Carbon Processes along an Elevation Gradient in the Tropical Luquillo Experimental Forest Chen, D.; Yu, M.; González, G.; Gao, Q. Tropical forests play an important role in regulating the global climate and the carbon cycle. With the changing temperature and moisture along the elevation gradient, the Luquillo Experimental Forest in Northeastern Puerto Rico provides a natural approach to understand tropical forest ecosystems under climate change. In this study, we conducted a soil translocation experiment along an elevation gradient with decreasing temperature but increasing moisture to study the impacts of climate change on soil organic carbon (SOC) and soil respiration. As the results showed, both soil carbon and the respiration rate were impacted by microclimate changes. The soils translocated from low elevation to high elevation showed an increased respiration rate with decreased SOC content at the end of the experiment, which indicated that the increased soil moisture and altered soil microbes might affect respiration rates. The soils translocated from high elevation to low elevation also showed an increased respiration rate with reduced SOC at the end of the experiment, indicating that increased temperature at low elevation enhanced decomposition rates. Temperature and initial soil source quality impacted soil respiration significantly. With the predicted warming climate in the Caribbean, these tropical soils at high elevations are at risk of releasing sequestered carbon into the atmosphere. Journal Article Climate change; elevation gradient; soil respiration; soil translocation experiment; tropical forest
2017 Analyzing cloud base at local and regional scales to understand tropical montane cloud forest vulnerability to climate change Van Beusekom, A.E.; González, G.; Scholl, M.A. Journal Article
2017 Reassessing rainfall in the Luquillo Mountains, Puerto Rico: Local and global ecohydrological implications Murphy, S.F.; Stallard, R.F.; Scholl, M.A.; González, G.; Torres-Sánchez, A.J. Mountains receive a greater proportion of precipitation than other environments, and thus make a disproportionate contribution to the world’s water supply. The Luquillo Mountains receive the highest rainfall on the island of Puerto Rico and serve as a critical source of water to surrounding communities. The area’s role as a long-term research site has generated numerous hydrological, ecological, and geological investigations that have been included in regional and global overviews that compare tropical forests to other ecosystems. Most of the forest- and watershed-wide estimates of precipitation (and evapotranspiration, as inferred by a water balance) have assumed that precipitation increases consistently with elevation. However, in this new analysis of all known current and historical rain gages in the region, we find that similar to other mountainous islands in the trade wind latitudes, leeward (western) watersheds in the Luquillo Mountains receive lower mean annual precipitation than windward (eastern) watersheds. Previous studies in the Luquillo Mountains have therefore overestimated precipitation in leeward watersheds by up to 40%. The Icacos watershed, however, despite being located at elevations 200–400 m below the tallest peaks and to the lee of the first major orographic barrier, receives some of the highest precipitation. Such lee-side enhancement has been observed in other island mountains of similar height and width, and may be caused by several mechanisms. Thus, the long-reported discrepancy of unrealistically low rates of evapotranspiration in the Icacos watershed is likely caused by previous underestimation of precipitation, perhaps by as much as 20%. Rainfall/runoff ratios in several previous studies suggested either runoff excess or runoff deficiency in Luquillo watersheds, but this analysis suggests that in fact they are similar to other tropical watersheds. Because the Luquillo Mountains often serve as a wet tropical archetype in global assessments of basic ecohydrological processes, these revised estimates are relevant to regional and global assessments of runoff efficiency, hydrologic effects of reforestation, geomorphic processes, and climate change. Journal Article Forests; meteorology; mountains; prisms; Puerto Rico; rain; topographic maps; watersheds
2017 Critical zone structure controls concentration-discharge relationships and solute generation in forested tropical montane watersheds Wymore, A.S.; Brereton, R.L.; Ibarra, D.E.; Maher, K.; McDowell, W.H. Concentration-discharge (C-Q) relationships are poorly known for tropical watersheds, even though the tropics contribute a disproportionate amount of solutes to the global ocean. The Luquillo Mountains in Puerto Rico offer an ideal environment to examine C-Q relationships across a heterogeneous tropical landscape. We use 10–30 years of weekly stream chemistry data across 10 watersheds to examine C-Q relationships for weathering products (SiO2(aq), Ca21, Mg21, and Na1) and biologically controlled solutes (dissolved organic carbon [DOC], dissolved organic nitrogen [DON], NH14, NO– 3, PO3– 4 , K1, and SO2– 4 ). We analyze C-Q relationships using power law equations and a solute production model and use principal component analysis to test hypotheses regarding how the structure of the critical zone controls solute generation. Volcaniclastic watersheds had higher concentrations of weathering solutes and smaller tributaries were approximately threefold more efficient at generating these solutes than larger rivers. Lithology and vegetation explained a significant amount of variation in the theoretical maximum concentrations of weathering solutes (r250.43–0.48) and in the C-Q relationships of PO3– 4 (r250.63) and SiO2(aq) (r250.47). However, the direction and magnitude of these relationships varied. Across watersheds, various forms of N and P displayed variable C-Q relationships, while DOC was consistently enriched with increasing discharge. Results suggest that PO3– 4 may be a useful indicator of watershed function. Relationships between C-Q and landscape characteristics indicate the extent to which the structure and function of the Critical zone controls watershed solute fluxes. Journal Article
2017 Insights on forest structure and composition from long-term research in the Luquillo mountains Heartsill-Scalley, T. Journal Article Basal area; disturbance; hurricane; Long-term; species composition; succession; trees; tropical. Luquillo Experimental Forest
2017 Long-term Entomological Research on Canopy Arthropods in a Tropical Rainforest in Puerto Rico Schowalter, T.D. Long-term research is critical to addressing effects of environmental changes, especially climate or land use, on ecosystems and their constituent species, because short-term studies yield incomplete or even misleading impressions (Adams 2001). For example, long-term studies have revealed that community and ecosystem responses to a disturbance event reflect the legacy of disturbances and other environmental changes over periods of decades to centuries (Harding et al. 1998, Summerville et al. 2009, Schowalter et al. 2017). In other words, community structure at a point in time depends on the history of environmental changes that filter community composition in different ways; i.e., species survival and response after successive events depends on their respective tolerances to each event. Short-term studies are incapable of revealing such legacy or contingency effects. Insects provide valuable systems with which to study long-term effects of environmental changes. Insects represent the bulk of diversity (60-90% of all species) in terrestrial and freshwater ecosystems, have biomass often equal to or greater than that of more conspicuous vertebrates, and are highly responsive to changes in abiotic or host conditions (Schowalter 2016). Both above-and-below-ground arthropods have considerable capacity toalter rates and patterns of primary production, decomposition, soil properties, and biogeochemical fluxes (Mattson and Addy 1975, Belovsky and Slade 2000, Schowalter et al. 2011). Outbreaks of herbivorous species are among the most dramatic biological processes, often triggered by disturbances (Mattson and Haack 1987, Schowalter 2012). Outbreaks are capable of altering ecosystem conditions and climate in ways that may contribute to ecosystem resilience (Chapman et al. 2003, Classen et al. 2005, Fonte and Schowalter 2005, Frost and Hunter 2007, Schowalter et al. 2011, Schowalter 2016), as well as the delivery of ecosystem services (Schowalter 2013, 2016). Unfortunately, insects have received relatively little attention in long-term ecosystem studies. Entomologists traditionally have focused on the population dynamics of individual species and their associated hosts and natural enemies, whereas ecosystem ecologists tend to ignore insects or treat them as a single biotic pool (Hunter 2001). Clearly, entomologists could contribute greatly to longterm studies of ecosystem responses to environmental changes. Research sites in the U.S. Long Term Ecological Research (LTER) Network, and collaborating networks in entomologists in such studies is critical to understanding how environmental changes affect ecosystem structure, processes, and services. Journal Article arthropods response to disturbance; canopy arthropods; disturbance; effects on ecosystem processes; environmental changes; Luquillo experimental forest
2017 Climate change and sugarcane expansion increase Hantavirus infection risk Prist, P.R.; Uriarte, M.; Fernandes, K.; Metzger, J.P. Hantavirus Cardiopulmonary Syndrome (HCPS) is a disease caused by Hantavirus, which is highly virulent for humans. High temperatures and conversion of native vegetation to agriculture, particularly sugarcane cultivation can alter abundance of rodent generalist species that serve as the principal reservoir host for HCPS, but our understanding of the compound effects of land use and climate on HCPS incidence remains limited, particularly in tropical regions. Here we rely on a Bayesian model to fill this research gap and to predict the effects of sugarcane expansion and expected changes in temperature on Hantavirus infection risk in the state of São Paulo, Brazil. The sugarcane expansion scenario was based on historical data between 2000 and 2010 combined with an agro-environment zoning guideline for the sugar and ethanol industry. Future evolution of temperature anomalies was derived using 32 general circulation models from scenarios RCP4.5 and RCP8.5 (Representative greenhouse gases Concentration Pathways adopted by IPCC). Currently, the state of São Paulo has an average Hantavirus risk of 1.3%, with 6% of the 645 municipalities of the state being classified as high risk (HCPS risk  5%). Our results indicate that sugarcane expansion alone will increase average HCPS risk to 1.5%, placing 20% more people at HCPS risk. Temperature anomalies alone increase HCPS risk even more (1.6% for RCP4.5 and 1.7%, for RCP8.5), and place 31% and 34% more people at risk. Combined sugarcane and temperature increases led to the same predictions as scenarios that only included temperature. Our results demonstrate that climate change effects are likely to be more severe than those from sugarcane expansion. Forecasting disease is critical for the timely and efficient planning of operational control programs that can address the expected effects of sugarcane expansion and climate change on HCPS infection risk. The predicted spatial location of HCPS infection risks obtained here can be used to prioritize management actions and develop educational campaigns. Journal Article
2017 Improving predictions of tropical forest response to climate 2 change through integration of field studies and ecosystem 3 modelling Feng, X.; Uriarte, M.; González, G.; Reed, S.; Thompson, J.; Zimmerman, J.K.; Murphy, L.

Tropical forests play a critical role in carbon and water cycles at a global scale. Rapid climate change is anticipated in tropical regions over the coming decades and, under a warmer and drier climate, tropical forests are likely to be net sources of carbon rather than sinks. However, our understanding of tropical forest response and feedback to climate change is very limited. Efforts to model climate change impacts on carbon fluxes in tropical forests have not reached a consensus. Here, we use the Ecosystem Demography model (ED2) to predict carbon fluxes of a Puerto Rican tropical forest under realistic climate change scenarios. We parameterized ED2 with species-specific tree physiological data using the Predictive Ecosystem Analyzer workflow and projected the fate of this ecosystem under five future climate scenarios. The model successfully captured interannual variability in the dynamics of this tropical forest. Model predictions closely followed observed values across a wide range of metrics including aboveground biomass, tree diameter growth, tree size class distributions, and leaf area index. Under a future warming and drying climate scenario, the model predicted reductions in carbon storage and tree growth, together with large shifts in forest community composition and structure. Such rapid changes in climate led the forest to transition from a sink to a source of carbon. Growth respiration and root allocation parameters were responsible for the highest fraction of predictive uncertainty in modeled biomass, highlighting the need to target these processes in future data collection. Our study is the first effort to rely on Bayesian model calibration and synthesis to elucidate the key physiological parameters that drive uncertainty in tropical forests responses to climatic change. We propose a new path forward for model-data synthesis that can substantially reduce uncertainty in our ability to model tropical forest responses to future climate.

Journal Article GPP; NPP; carbon flux; climate change; ecosystem demography model; sensitivity analysis; tropical forest; variance decomposition
2017 The role of functional uniqueness and spatial aggregation in explaining rarity in trees Umaña, M.N.; Mi, X.; Cao, M.; Enquist, B.; Hao, Z.; Howe, R.; Iida, Y.; Johnson, D.; Lin, L.; Liu, X.; Ma, K.; Sun, I.F.; Thompson, J.; Uriarte, M.; Wang, X.; Wolf, A.; Yang, J.; Zimmerman, J.K.; Swenson, N.G. Aim: Determining the drivers of species rarity is fundamental for understanding and conserving biodiversity. Rarity of a given species within its community may arise due to exclusion by other ecologically similar species. Conversely, rare species may occupy habitats that are rare in the landscape or they may be ill-suited to all available habitats. The first mechanism would lead to common and rare species occupying similar ecological space defined by functional traits. The second mechanism would result in common and rare species occupying dissimilar ecological space and spatial aggregation of rare species, either because they are specialists in rare habitats or because rare species tend to be dispersal limited. Here, we quantified the contribution of locally rare species to community functional richness and the spatial aggregation of species across tree communities world-wide to address these hypotheses. Journal Article Functional diversity; functional traits; species relative abundance; temperate forests; tree diversity; tropical forests
2017 Methodological Considerations in the Study of Earthworms in Forest Ecosystems Rhea-Fournier, D.; González, G.; Chakravarty, S.; Shukla, G. Decades of studies have shown that soil macrofauna, especially earthworms, play dominant engineering roles in soils, affecting physical, chemical, and biological components of ecosystems. Quantifying these effects would allow crucial improvement in biogeochemical budgets and modeling, predicting response of land use and disturbance, and could be applied to bioremediation efforts. Effective methods of manipulating earthworm communities in the field are needed to accompany laboratory microcosm studies to calculate their net function in natural systems and to isolate specific mechanisms. This chapter reviews laboratory and field methods for enumerating and manipulating earthworm populations, as well as approaches toward quantifying their influences on soil processes and biogeochemical cycling. Book Chapter arthropod exclusions; earthworms; ecosystem engineer; electroshock; faunal manipulations; lumbricids; Soil fauna; soil methods; soil microcosms
2017 Characterizing Predictability of Fire Occurrence in Tropical Forests and Grasslands: The Case of Puerto Rico Monmany, A.C.; Gould, W.A.; Andrade-Núñez, M.J.; González, G.; Quiñones, M.; Chakravarty, S.; Shukla, G. Global estimates of fire frequency indicate that over 70% of active fires occur in the tropics, and the size and frequency of fires are increasing every year. The majority of fires in the tropics are an unintended consequence of current land-use practices that promotes the establishment of grass and shrubland communities, which are more flammable and more adapted to fire than forests. In the Caribbean, wildland fires occur mainly in dry forests and in grasslands and crop lands. Climate change projections for the Caribbean indicate increasing area of drylands and subsequent increasing potential for wildland fire. We assessed the last decade of fire occurrence records for Puerto Rico to quantify the relative importance of time, climate, land cover, and population to inform predictive models of fire occurrence for projecting future scenarios of fire risk. Kruskal-Wallis, generalized linear models, robust regression, simple and multiple regressions, and tree models were used. We found that hour of the day (time), mean minimum temperature (climate), and percent forest cover (land cover) significantly influenced fire occurrence, while population showed a weak effect. Many variable interactions showed to be important. These significant variables and interactions should be considered in fire-predicting models for the island. Book Chapter Caribbean; Climate change; tropical dry forests; wildfire; wildfire predictability
2017 Soil Biology Research across Latitude, Elevation and Disturbance Gradients: A Review of Forest Studies from Puerto Rico during the Past 25 Years González, G.; Lodge, D.J. Progress in understanding changes in soil biology in response to latitude, elevation and disturbance gradients has generally lagged behind studies of above-ground plants and animals owing to methodological constraints and high diversity and complexity of interactions in below-ground food webs. New methods have opened research opportunities in below-ground systems, leading to a rapid increase in studies of below-ground organisms and processes. Here, we summarize results of forest soil biology research over the past 25 years in Puerto Rico as part of a 75th Anniversary Symposium on research of the USDA Forest Service International Institute of Tropical Forestry. These results are presented in the context of changes in soil and forest floor biota across latitudinal, elevation and disturbance gradients. Invertebrate detritivores in these tropical forests exerted a stronger influence on leaf decomposition than in cold temperate forests using a common substrate. Small changes in arthropods brought about using different litterbag mesh sizes induced larger changes in leaf litter mass loss and nutrient mineralization. Fungi and bacteria in litter and soil of wet forests were surprisingly sensitive to drying, leading to changes in nutrient cycling. Tropical fungi also showed sensitivity to environmental fluctuations and gradients as fungal phylotype composition in soil had a high turnover along an elevation gradient in Puerto Rico. Globally, tropical soil fungi had smaller geographic ranges than temperate fungi. Invertebrate activity accelerates decomposition of woody debris, especially in lowland dry forest, but invertebrates are also important in early stages of log decomposition in middle elevation wet forests. Large deposits of scoltine bark beetle frass from freshly fallen logs coincide with nutrient immobilization by soil microbial biomass and a relatively low density of tree roots in soil under newly fallen logs. Tree roots shifted their foraging locations seasonally in relation to decaying logs. Native earthworms were sensitive to disturbance and were absent from tree plantations, whereas introduced earthworms were found across elevation and disturbance gradients. Journal Article disturbance; elevation; gradients; invertebrates; latitude; litter; microbiota; soil biota; tropical forests; wood
2017 El Servicio Forestal en Puerto Rico [English translation: The USDA Forest Service in Puerto Rico] González, G. Journal Article
2017 Sandra Brown (1944- 2017): A Distinguished Tropical Ecologist Lugo, A.E.; González, G. Journal Article
2017 Reply to “Comments on ‘Short-Term Precipitation and Temperature Trends along an Elevation Gradient in Northeastern Puerto Rico Van Beusekom, A.E.; González, G.; Rivera, M.M. Journal Article
2017 Fire weather and likelihood: characterizing climate space for fire occurrence and extent in Puerto Rico Van Beusekom, A.E.; Gould, W.A.; Monmany, A.C.; Khalyani, H.; Quiñones, M.; Fain, S.J.; Andrade-Núñez, M.J.; González, G. Assessing the relationships between weather patterns and the likelihood of fire occurrence in the Caribbean has not been as central to climate change research as in temperate regions, due in part to the smaller extent of individual fires. However, the cumulative effect of small frequent fires can shape large landscapes, and fire-prone ecosystems are abundant in the tropics. Climate change has the potential to greatly expand fire-prone areas to moist and wet tropical forests and grasslands that have been traditionally less fire-prone, and to extend and create more temporal variability in fire seasons. We built a machine learning random forest classifier to analyze the relationship between climatic, socio-economic, and fire history data with fire occurrence and extent for the years 2003–2011 in Puerto Rico, nearly 35,000 fires. Using classifiers based on climate measurements alone, we found that the climate space is a reliable associate, if not a predictor, of fire occurrence and extent in this environment. We found a strong relationship between occurrence and a change from average weather conditions, and between extent and severity of weather conditions. The probability that the random forest classifiers will rank a positive example higher than a negative example is 0.8–0.89 in the classifiers for deciding if a fire occurs, and 0.64–0.69 in the classifiers for deciding if the fire is greater than 5 ha. Future climate projections of extreme seasons indicate increased potential for fire occurrence with larger extents. Journal Article
2017 Biogeochemistry drives diversity in the prokaryotes, fungi, and invertebrates of a Panama forest Kaspari, M.; Bujan, J.; Weiser, M.D.; Ning, D.; Michaletz, S.T.; Zhili, H.; Enquist, B.J.; Waide, R.B.; Zhou, J.; Turner, B.L.; Wright, S.J. Humans are both fertilizing the world and depleting its soils, decreasing the diversity of aquatic ecosystems and terrestrial plants in the process. We know less about how nutrients shape the abundance and diversity of the prokaryotes, fungi, and invertebrates of Earth's soils. Here we explore this question in the soils of a Panama forest subject to a 13-yr fertilization with factorial combinations of nitrogen (N), phosphorus (P), and potassium (K) and a separate micronutrient cocktail. We contrast three hypotheses linking biogeochemistry to abundance and diversity. Consistent with the Stress Hypothesis, adding N suppressed the abundance of invertebrates and the richness of all three groups of organisms by ca. 1 SD or more below controls. Nitrogen addition plots were 0.8 pH units more acidic with 18% more exchangeable aluminum, which is toxic to both prokaryotes and eukaryotes. These stress effects were frequently reversed, however, when N was added with P (for prokaryotes and invertebrates) and with added K (for fungi). Consistent with the Abundance Hypothesis, adding P generally increased prokaryote and invertebrate diversity, and adding K enhanced invertebrate diversity. Also consistent with the Abundance Hypothesis, increases in invertebrate abundance generated increases in richness. We found little evidence for the Competition Hypothesis: that single nutrients suppressed diversity by favoring a subset of high nutrient specialists, and that nutrient combinations suppressed diversity even more. Instead, combinations of nutrients, and especially the cation/micronutrient treatment, yielded the largest increases in richness in the two eukaryote groups. In sum, changes in soil biogeochemistry revealed a diversity of responses among the three dominant soil groups, positive synergies among nutrients, and–in contrast with terrestrial plants–the frequent enhancement of soil biodiversity. Journal Article
2017 Toward a theory for diversity gradients: the abundance–adaptation hypothesis Weiser, M.D.; Michaletz, S.T.; Buzzard, V.; Deng, Y.; He, Z.; Shen, L.; Enquist, B.J.; Waide, R.B.; Zhou, J.; Kaspari, M. The abundance–adaptation hypothesis argues that taxa with more individuals and faster generation times will have more evolutionary ‘experiments’ allowing expansion into, and diversification within, novel habitats. Thus, as older taxa have produced more individuals over time, and smaller taxa have higher population sizes and faster generation times, the Latitudinal Diversity Gradients (LDGs) of these clades should show shallower slopes. We describe the LDGs for archaea, bacteria, fungi, invertebrates and trees from six North American forests. For three focal groups – bacteria, ants, and trees – older taxa had shallower LDG slopes than the more recent, terminal taxa. Across 12 orders of magnitude of body mass, LDG slopes were steeper in larger taxa. The slopes of LDGs vary systematically with body size and clade age, underscoring the non-canonical nature of LDGs. The steepest LDG slopes were found for the largest organisms while the smallest, from bacteria to small litter-soil invertebrates, have shallower- to zero-slope LDGs. If tropical niche conservatism is the failure of clades to adapt to, and diversify in temperate habitats, then the steep LDGs of chordates and plants likely arise from the decreased ability of clades with large individuals to adapt to the multiple challenges of extra-tropical life. Journal Article
2017 Decomposing functional diversity
Scheiner, S. M, E. Kosman, S. J Presley, and M. R Willig. 2017. Decomposing Functional Diversity. Methods in Ecology and Evolution 8(7): 809- 820.
Scheiner, S.M.; Kosman, E.; Presley, S.J.; Willig, M.R. One aspect of biodiversity, functional diversity, reflects the functional role of species within a community as measured by species characteristics. We present a new metric, functional trait dispersion, based on the concept of species distinctiveness measured as the distance among species in the multidimensional space defined by trait values. This metric can be decomposed into components of species richness, functional evenness and mean dispersion, and into parts that measure diversity within and among subgroups. Using an appropriate distance measure, mean dispersion (M′) is calculated as the average distance among all possible pairs of species. Functional evenness [qE(T)] is derived from Hill diversity based on the proportional distances between pairs of species and species richness (S). Functional trait dispersion [qD(TM)] is then computed as 1 + (S−1) × qE(T) × M′. It has a range of [1,S] and measures the effective number of functionally distinct species for a given level of species dispersion. Using constructed data, we demonstrate that qD(TM) captures appropriate ecological properties such that a community with greater species richness, greater dispersal in trait space or greater mean dispersion has greater functional diversity. Functional trait dispersion can also provide measures of within-community dispersion and the effective number of functionally distinctive compartments (groups of communities with similar functional structure). Using empirical data of bats along an elevational gradient in Peru, we demonstrate that functional trait dispersion and its components provide insights about gradients of biodiversity. Functional trait dispersion comports to reasonable criteria for a metric of functional diversity and can be decomposed in a variety of ways that facilitate understanding of patterns of variation. Other metrics of functional diversity neither integrate all three diversity components, nor can many be decomposed into variation within and among subgroups. Because functional trait dispersion measures properties of distance and the effective number of functionally distinct species, it can be used in conjunction with other biodiversity metrics that are based on species identity, abundance or phylogenetic relatedness to inform management and the preservation of biodiversity. Journal Article
2017 The Components of Biodiversity, with a Particular Focus on Phylogenetic Information Scheiner, S.M.; Kosman, E.; Presley, S.J.; Willig, M.R. We present a framework for biodiversity metrics that organizes the growing panoply of metrics. Our framework distinguishes metrics based on the type of information–abundance, phylogeny, function–and two common properties–magnitude and variability. Our new metrics of phylogenetic diversity are based on a partition of the total branch lengths of a cladogram into the proportional share of each species, including: a measure of divergence which standardizes the amount of evolutionary divergence by species richness and time depth of the cladogram; a measure of regularity which is maximal when the tree is perfectly symmetrical so that all species have the same proportional branch lengths; a measure that combines information on the magnitude and variability of abundance with phylogenetic variability, and a measure of phylogenetically weighted effective mean abundance; and indicate how those metrics can be decomposed into α and β components. We illustrate the utility of these new metrics using empirical data on the bat fauna of Manu, Peru. Divergence was greatest in lowland rainforest and at the transition between cloud and elfin forests, and least in upper elfin forests and in cloud forests. In contrast, regularity was greatest in lowland rainforest, dipping to its smallest values in mid‐elevation cloud forests, and then increasing in high elevation elfin forests. These patterns indicate that the first species to drop out with increasing elevation are ones that are closely related to other species in the metacommunity. Measures of the effective number of phylogenetically independent or distinct species decreased very rapidly with elevation, and β‐diversity was larger. In contrast, a comparison of feeding guilds shows a different effect of phylogenetic patterning. Along the elevational gradient, each guild generally loses some species from each clade–rather than entire clades–explaining the maintenance of functional diversity as phylogenetic diversity decreases. Journal Article alpha diversity; bats; beta diversity; gamma diversity; Peru; phylogenetic diversity
2017 It’s a bug’s life Schowalter, T.D. Entomologist Dr Timothy Schowalter, from Louisiana State University, investigates the intrinsic links between insect populations and the provision of ecosystem services essential for human survival. Viewing their population dynamics as a vital indicator of ecosystem health opens the possibility of using these data for improved management of global resources. In pursuit of this aim, Dr Schowalter and colleagues organise in uential symposia alongside renowned international conferences to draw together researchers in this eld. Journal Article
2017 Getting Students Jazzed about Critical Zone: Engaging students in authentic inquiry through Data Jam McGee, S.; Rodriguez, B. Journal Article
2017 Latitudinal Gradients of Biodiversity Willig, M.R.; Presley, S.J. Journal Article
2017 Ecology of Soil Arthropod Fauna in Tropical Forests: A review of studies from Puerto Rico Gonzalez, G.; Barberena-Arias, M.F. Journal Article
2017 Trophic interaction effects on nutrient release from decomposing leaves.
Cantrell, S. A, M.F. Barberena-Arias, G. Gonzalez, D.J. Lodge, and K. McGuire. 2017. Trophic Interaction Effects On Nutrient Release From Decomposing Leaves.. 9th International Latin American Mycological Congress (CLAMIX) 22-25 August 2017 8.
Cantrell, S.A.; Barberena-Arias, M.F.; Gonzalez, G.; Lodge, D.J.; McGuire, K. Conference Proceedings
2017 Arthropod diversity and nutrient mineralization in green litter decomposition in a simulated hurricane experiment Moreno-Rosado, I.; Barberena-Arias, M.F.; Cantrell, S.A.; Gonzalez, G. Hurricanes generate disturbances in forests such as canopy opening, fallen trees and leaves which alter physicochemical characteristics of the habitat. Litter decomposition depends primarily on the interaction among climate, litter quality and biota, as a consequence any change in habitats will result in changes in these factors. Our objective is to evaluate the effects of hurricane driven changes to forests on green litter decomposition, decomposer communities and nutrient ineralization. For this study, three blocks were selected, each with two plots of 20m x 20m, one plot was used for control and the other Canopy opening (Trim). In each subplot, litterbags with different mesh sizes were placed. Each of these litterbags were used as the sampling unit. In each one, decomposer fauna and nutrients were measured, and the weight of green litter from the litterbags was used for measure mass loss through time. Preliminary results suggest significant differences in abundance of decomposer fauna and in available nutrient concentration between trim and control plots, and among litterbags. For example, nitrogen and phosphorous were significantly higher in trim plots and in large mesh litterbags. Also, decomposer arthropod abundance was higher in large mesh litterbags. These results suggest that when all decomposer arthropods are present, available nutrients are higher. These results will be further analyzed, and interpreted in the context of food web dynamics. Conference Proceedings
2017 Fungal diversity in green litter decomposition in a hurricane experiment Velázquez, J.; Cantrell, S.A.

Hurricanes generate disturbances in forests such as canopy opening, fallen trees and leaves which in turn alter physicochemical characteristics of the habitat, as well as, decomposer activity. Litter decomposition depends primarily on the interaction among climate, litter quality and biota; as a consequence any change in habitats will result in changes in these factors. Identifying the changes in the fungal community structure in soil and forest floor litter can help understand the factors that influence ecosystem recovery.

Conference Proceedings
2017 The chaos after the storm: fungal community composition shifts in response to simulated hurricane disturbance Cantrell, S.A.; Purnell, K.; McGuire, K. Conference Proceedings
2017 Methodologies in manipulation and study of earthworms and soil macrofauna in forest ecosystems Rhea-Fournier, D.; Gonzalez, G.

Decades of studies have shown that soil macrofauna, especially earthworms, play dominant engineering roles in soils, affecting physical, chemical, and biological components of ecosystems. Quantifying these effects would allow crucial improvement in biogeochemical budgets and modeling, predicting response of land use and disturbance, and could be applied to bioremediation efforts. Effective methods of manipulating earthworm communities in the field are needed to accompany laboratory microcosm studies to calculate their net function in natural systems and to isolate specific mechanisms. This chapter reviews laboratory and field methods for enumerating and manipulating earthworm populations, as well as approaches toward quantifying their influences on soil processes and biogeochemical cycling.

Book Chapter arthropod exclusions; earthworms; ecosystem engineer; electroshock; faunal manipulations; lumbricids; Soil fauna; soil methods; soil microcosms
2017 Biodiversity and climate determine the functioning of Neotropical forests Poorter, L.; van der Sande, M.T.; Arets, E.J.M.M.; Ascarrunz, N.; Enquist, B.J.; Finegan, B.; Licona, J.Carlos; Martínez-Ramos, M.; Mazzei, L.; Meave, J.A.; Muñoz, R.; Nytch, C.; de Oliveira, A.A.; Pérez-García, E.A.; Prado-Junior, J.; Rodríguez-Velázques, J.; Ruschel, A.Roberto; Salgado-Negret, B.; Schiavini, I.; Swenson, N.G.; Tenorio, E.A.; Thompson, J.; Toledo, M.; Uriarte, M.; van der Hout, P.; Zimmerman, J.K.; Peña-Claros, M. Aim Tropical forests account for a quarter of the global carbon storage and a third of the terrestrial productivity. Few studies have teased apart the relative importance of environmental factors and forest attributes for ecosystem functioning, especially for the tropics. This study aims to relate aboveground biomass (AGB) and biomass dynamics (i.e., net biomass productivity and its underlying demographic drivers: biomass recruitment, growth and mortality) to forest attributes (tree diversity, community-mean traits and stand basal area) and environmental conditions (water availability, soil fertility and disturbance). Location Neotropics. Methods We used data from 26 sites, 201 1-ha plots and >92,000 trees distributed across the Neotropics. We quantified for each site water availability and soil total exchangeable bases and for each plot three key community-weighted mean functional traits that are important for biomass stocks and productivity. We used structural equation models to test the hypothesis that all drivers have independent, positive effects on biomass stocks and dynamics. Results Of the relationships analysed, vegetation attributes were more frequently associated significantly with biomass stocks and dynamics than environmental conditions (in 67 vs. 33% of the relationships). High climatic water availability increased biomass growth and stocks, light disturbance increased biomass growth, and soil bases had no effect. Rarefied tree species richness had consistent positive relationships with biomass stocks and dynamics, probably because of niche complementarity, but was not related to net biomass productivity. Community-mean traits were good predictors of biomass stocks and dynamics. Main conclusions Water availability has a strong positive effect on biomass stocks and growth, and a future predicted increase in (atmospheric) drought might, therefore, potentially reduce carbon storage. Forest attributes, including species diversity and community-weighted mean traits, have independent and important relationships with AGB stocks, dynamics and ecosystem functioning, not only in relatively simple temperate systems, but also in structurally complex hyper-diverse tropical forests. Journal Article Biodiversity; biomass; Carbon; ecosystem functioning; forest dynamics; productivity; Soil fertility; tropical forest; water
2017 Taxonomic decomposition of the latitudinal gradient in species diversity of North American floras Weiser, M.D.; Swenson, N.G.; Enquist, B.J.; Michaletz, S.T.; Waide, R.B.; Zhou, J.; Kaspari, M. Journal Article
2017 The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project
Hudson, Lawrence N, Tim Newbold, Sara Contu, Samantha LL Hill, Igor Lysenko, Adriana De Palma, Helen RP Phillips, Tamera I Alhusseini, Felicity E Bedford, Dominic J Bennett, Hollie Booth, Victoria J Burton, Charlotte WT Chng, Argyrios Choimes, David LP Correia, Julie Day, Susy Echeverría-Londoño, Susan R Emerson, Di Gao, Morgan Garon, Michelle LK Harrison, Daniel J Ingram, Martin Jung, Victoria Kemp, Lucinda Kirkpatrick, Callum D Martin, Yuan Pan, Gwilym D Pask-Hale, Edwin L Pynegar, Alexandra N Robinson, Katia Sanchez-Ortiz, Rebecca A Senior, Benno I Simmons, Hannah J White, Hanbin Zhang, Job Aben, Stefan Abrahamczyk, Gilbert B Adum, Virginia Aguilar-Barquero, Marcelo A Aizen, Belén Albertos, E. 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Reid, Yana T Reis, José MRey Benayas, Juan Carlos Rey-Velasco, Chevonne Reynolds, Danilo Bandini Ribeiro, Miriam H Richards, Barbara A Richardson, Michael J Richardson, Rodrigo Macip Ríos, Richard Robinson, Carolina A Robles, Jörg Römbke, Luz Piedad Romero-Duque, Matthias Rös, Loreta Rosselli, Stephen J Rossiter, Dana S Roth, T'ai H Roulston, Laurent Rousseau, André V Rubio, Jean-Claude Ruel, Jonathan P Sadler, Szabolcs Sáfián, Romeo A Saldaña-Vázquez, Katerina Sam, Ulrika Samnegård, Joana Santana, Xavier Santos, Jade Savage, Nancy A Schellhorn, Menno Schilthuizen, Ute Schmiedel, Christine B Schmitt, Nicole L Schon, Christof Schüepp, Katharina Schumann, Oliver Schweiger, Dawn M Scott, Kenneth A Scott, Jodi L Sedlock, Steven S Seefeldt, Ghazala Shahabuddin, Graeme Shannon, Douglas Sheil, Frederick H Sheldon, Eyal Shochat, Stefan J Siebert, Fernando AB Silva, Javier A Simonetti, Eleanor M Slade, Jo Smith, Allan H Smith-Pardo, Navjot S Sodhi, Eduardo J Somarriba, Ramón A Sosa, Grimaldo Soto Quiroga, Martin-Hugues St-Laurent, Brian M Starzomski, Constanti Stefanescu, Ingolf Steffan-Dewenter, Philip C Stouffer, Jane C Stout, Ayron M Strauch, Matthew J Struebig, Zhimin Su, Marcela Suarez-Rubio, Shinji Sugiura, Keith S Summerville, Yik-Hei Sung, Hari Sutrisno, Jens-Christian Svenning, Tiit Teder, Caragh G Threlfall, Anu Tiitsaar, Jacqui H Todd, Rebecca K Tonietto, Ignasi Torre, Béla Tóthmérész, Teja Tscharntke, Edgar C Turner, Jason M Tylianakis, Marcio Uehara-Prado, Nicolas Urbina-Cardona, Denis Vallan, Adam J Vanbergen, Heraldo L Vasconcelos, Kiril Vassilev, Hans AF Verboven, Maria João Verdasca, José R Verdú, Carlos H Vergara, Pablo M Vergara, Jort Verhulst, Massimiliano Virgilio, Lien Van Vu, Edward M Waite, Tony R Walker, Hua-Feng Wang, Yanping Wang, James I Watling, Britta Weller, Konstans Wells, Catrin Westphal, Edward D Wiafe, Christopher D Williams, M. R Willig, John CZ Woinarski, Jan HD Wolf, Volkmar Wolters, Ben A Woodcock, Jihua Wu, Joseph M Wunderle, Yuichi Yamaura, Satoko Yoshikura, Douglas W Yu, Andrey S Zaitsev, Juliane Zeidler, Fasheng Zou, Ben Collen, Rob M Ewers, Georgina M Mace, Drew W Purves, Jörn PW Scharlemann, and Andy Purvis. 2017. The Database Of The Predicts (Projecting Responses Of Ecological Diversity In Changing Terrestrial Systems) Project. Ecology and Evolution 7: 145–188.
Hudson, L.N.; Newbold, T.; Contu, S.; Hill, S.L.L.; Lysenko, I.; De Palma, A.; Phillips, H.R.P.; Alhusseini, T.I.; Bedford, F.E.; Bennett, D.J.; Booth, H.; Burton, V.J.; Chng, C.W.T.; Choimes, A.; Correia, D.L.P.; Day, J.; Echeverría-Londoño, S.; Emerson, S.R.; Gao, D.; Garon, M.; Harrison, M.L.K.; Ingram, D.J.; Jung, M.; Kemp, V.; Kirkpatrick, L.; Martin, C.D.; Pan, Y.; Pask-Hale, G.D.; Pynegar, E.L.; Robinson, A.N.; Sanchez-Ortiz, K.; Senior, R.A.; Simmons, B.I.; White, H.J.; Zhang, H.; Aben, J.; Abrahamczyk, S.; Adum, G.B.; Aguilar-Barquero, V.; Aizen, M.A.; Albertos, B.; Alcala, E.L.; Alguacil, Mdel Mar; Alignier, A.; Ancrenaz, M.; Andersen, A.N.; Arbeláez-Cortés, E.; Armbrecht, I.; Arroyo-Rodríguez, V.; Aumann, T.; Axmacher, J.C.; Azhar, B.; Azpiroz, A.B.; Baeten, L.; Bakayoko, A.; Báldi, A.; Banks, J.E.; Baral, S.K.; Barlow, J.; Barratt, B.I.P.; Barrico, L.; Bartolommei, P.; Barton, D.M.; Basset, Y.; Batáry, P.; Bates, A.J.; Baur, B.; Bayne, E.M.; Beja, P.; Benedick, S.; Berg, Å.; Bernard, H.; Berry, N.J.; Bhatt, D.; Bicknell, J.E.; Bihn, J.H.; Blake, R.J.; Bobo, K.S.; Bóçon, R.; Boekhout, T.; Böhning-Gaese, K.; Bonham, K.J.; Borges, P.A.V.; Borges, S.H.; Boutin, C.; Bouyer, J.; Bragagnolo, C.; Brandt, J.S.; Brearley, F.Q.; Brito, I.; Bros, V.; Brunet, J.; Buczkowski, G.; Buddle, C.M.; Bugter, R.; Buscardo, E.; Buse, J.; Cabra-García, J.; Cáceres, N.C.; Cagle, N.L.; Calviño-Cancela, M.; Cameron, S.A.; Cancello, E.M.; Caparrós, R.; Cardoso, P.; Carpenter, D.; Carrijo, T.F.; Carvalho, A.L.; Cassano, C.R.; Castro, H.; Castro-Luna, A.A.; Rolando, C.B.; Cerezo, A.; Chapman, K.Alan; Chauvat, M.; Christensen, M.; Clarke, F.M.; Cleary, D.F.R.; Colombo, G.; Connop, S.P.; Craig, M.D.; Cruz-López, L.; Cunningham, S.A.; D'Aniello, B.; D'Cruze, N.; da Silva, P.Giovâni; Dallimer, M.; Danquah, E.; Darvill, B.; Dauber, J.; Davis, A.L.V.; Dawson, J.; de Sassi, C.; de Thoisy, B.; Deheuvels, O.; Dejean, A.; Devineau, J.L.; Diekötter, T.; Dolia, J.V.; Domínguez, E.; Dominguez-Haydar, Y.; Dorn, S.; Draper, I.; Dreber, N.; Dumont, B.; Dures, S.G.; Dynesius, M.; Edenius, L.; Eggleton, P.; Eigenbrod, F.; Elek, Z.; Entling, M.H.; Esler, K.J.; de Lima, R.F.; Faruk, A.; Farwig, N.; Fayle, T.M.; Felicioli, A.; Felton, A.M.; Fensham, R.J.; Fernandez, I.C.; Ferreira, C.C.; Ficetola, G.F.; Fiera, C.; Filgueiras, B.K.C.; Fırıncıoğlu, H.K.; Flaspohler, D.; Floren, A.; Fonte, S.J.; Fournier, A.; Fowler, R.E.; Franzén, M.; Fraser, L.H.; Fredriksson, G.M.; Freire, G.B.; Frizzo, T.L.M.; Fukuda, D.; Furlani, D.; Gaigher, R.; Ganzhorn, J.U.; García, K.P.; Garcia-R, J.C.; Garden, J.G.; Garilleti, R.; Ge, B.M.; Gendreau-Berthiaume, B.; Gerard, P.J.; Gheler-Costa, C.; Gilbert, B.; Giordani, P.; Giordano, S.; Golodets, C.; Gomes, L.G.L.; Gould, R.K.; Goulson, D.; Gove, A.D.; Granjon, L.; Grass, I.; Gray, C.L.; Grogan, J.; Gu, W.; Guardiola, M.; Gunawardene, N.R.; Gutierrez, A.G.; Gutiérrez-Lamus, D.L.; Haarmeyer, D.H.; Hanley, M.E.; Hanson, T.; Hashim, N.R.; Hassan, S.N.; Hatfield, R.G.; Hawes, J.E.; Hayward, M.W.; Hébert, C.; Helden, A.J.; Henden, J.A.; Henschel, P.; Hernández, L.; Herrera, J.P.; Herrmann, F.; Herzog, F.; Higuera-Diaz, D.; Hilje, B.; Höfer, H.; Hoffmann, A.; Horgan, F.G.; Hornung, E.; Horváth, R.; Hylander, K.; Isaacs-Cubides, P.; Ishida, H.; Ishitani, M.; Jacobs, C.T.; Jaramillo, V.J.; Jauker, B.; Hernández, J.; Johnson, M.K.F.; Jolli, V.; Jonsell, M.; Juliani, N.; Jung, T.S.; Kapoor, V.; Kappes, H.; Kati, V.; Katovai, E.; Kellner, K.; Kessler, M.; Kirby, K.R.; Kittle, A.M.; Knight, M.E.; Knop, E.; Kohler, F.; Koivula, M.; Kolb, A.; Kone, M.; Kőrösi, Á.; Krauss, J.; Kumar, A.; Kumar, R.; Kurz, D.J.; Kutt, A.S.; Lachat, T.; Lantschner, V.; Lara, F.; Lasky, J.R.; Latta, S.C.; Laurance, W.F.; Lavelle, P.; Le Féon, V.; LeBuhn, G.; Légaré, J.P.; Lehouck, V.; Lencinas, M.V.; Lentini, P.E.; Letcher, S.G.; Li, Q.; Litchwark, S.A.; Littlewood, N.A.; Liu, Y.; Lo-Man-Hung, N.; López-Quintero, C.A.; Louhaichi, M.; Lövei, G.L.; Lucas-Borja, M.Esteban; Luja, V.H.; Luskin, M.S.; G, C.MacSwiney; Maeto, K.; Magura, T.; Mallari, N.Aldrin; Malone, L.A.; Malonza, P.K.; Malumbres-Olarte, J.; Mandujano, S.; Måren, I.E.; Marin-Spiotta, E.; Marsh, C.J.; Marshall, E.J.P.; Martínez, E.; Pastur, G.Martínez; Mateos, D.Moreno; Mayfield, M.M.; Mazimpaka, V.; McCarthy, J.L.; McCarthy, K.P.; McFrederick, Q.S.; McNamara, S.; Medina, N.G.; Medina, R.; Mena, J.L.; Mico, E.; Mikusinski, G.; Milder, J.C.; Miller, J.R.; Miranda-Esquivel, D.R.; Moir, M.L.; Morales, C.L.; Muchane, M.N.; Muchane, M.; Mudri-Stojnic, S.; Munira, N.; Muoñz-Alonso, A.; Munyekenye, B.F.; Naidoo, R.; Naithani, A.; Nakagawa, M.; Nakamura, A.; Nakashima, Y.; Naoe, S.; Nates-Parra, G.; Gutierrez, D.A.Navarre; Navarro-Iriarte, L.; Ndang'ang'a, P.K.; Neuschulz, E.L.; Ngai, J.T.; Nicolas, V.; Nilsson, S.G.; Noreika, N.; Norfolk, O.; Noriega, J.Ari; Norton, D.A.; Nöske, N.M.; Nowakowski, J.; Numa, C.; O'Dea, N.; O'Farrell, P.J.; Oduro, W.; Oertli, S.; Ofori-Boateng, C.; Oke, C.Omamoke; Oostra, V.; Osgathorpe, L.M.; Otavo, S.Eduardo; Page, N.V.; Paritsis, J.; Parra-H, A.; Parry, L.; Pe'er, G.; Pearman, P.B.; Pelegrin, N.; Pélissier, R.; Peres, C.A.; Peri, P.L.; Persson, A.S.; Petanidou, T.; Peters, M.K.; Pethiyagoda, R.S.; Phalan, B.; Philips, K.; Pillsbury, F.C.; Pincheira-Ulbrich, J.; Pineda, E.; Pino, J.; Pizarro-Araya, J.; Plumptre, A.J.; Poggio, S.L.; Politi, N.; Pons, P.; Poveda, K.; Power, E.F.; Presley, S.J.; Proença, V.; Quaranta, M.; Quintero, C.; Rader, R.; Ramesh, B.R.; Ramirez-Pinilla, M.P.; Ranganathan, J.; Rasmussen, C.; Redpath-Downing, N.A.; Reid, L.; Reis, Y.T.; Benayas, J.M.Rey; Rey-Velasco, J.Carlos; Reynolds, C.; Ribeiro, D.Bandini; Richards, M.H.; Richardson, B.A.; Richardson, M.J.; Ríos, R.Macip; Robinson, R.; Robles, C.A.; Römbke, J.; Romero-Duque, L.Piedad; Rös, M.; Rosselli, L.; Rossiter, S.J.; Roth, D.S.; Roulston, T.'aiH.; Rousseau, L.; Rubio, A.V.; Ruel, J.C.; Sadler, J.P.; Sáfián, S.; Saldaña-Vázquez, R.A.; Sam, K.; Samnegård, U.; Santana, J.; Santos, X.; Savage, J.; Schellhorn, N.A.; Schilthuizen, M.; Schmiedel, U.; Schmitt, C.B.; Schon, N.L.; Schüepp, C.; Schumann, K.; Schweiger, O.; Scott, D.M.; Scott, K.A.; Sedlock, J.L.; Seefeldt, S.S.; Shahabuddin, G.; Shannon, G.; Sheil, D.; Sheldon, F.H.; Shochat, E.; Siebert, S.J.; Silva, F.A.B.; Simonetti, J.A.; Slade, E.M.; Smith, J.; Smith-Pardo, A.H.; Sodhi, N.S.; Somarriba, E.J.; Sosa, R.A.; Quiroga, G.Soto; St-Laurent, M.H.; Starzomski, B.M.; Stefanescu, C.; Steffan-Dewenter, I.; Stouffer, P.C.; Stout, J.C.; Strauch, A.M.; Struebig, M.J.; Su, Z.; Suarez-Rubio, M.; Sugiura, S.; Summerville, K.S.; Sung, Y.H.; Sutrisno, H.; Svenning, J.C.; Teder, T.; Threlfall, C.G.; Tiitsaar, A.; Todd, J.H.; Tonietto, R.K.; Torre, I.; Tóthmérész, B.; Tscharntke, T.; Turner, E.C.; Tylianakis, J.M.; Uehara-Prado, M.; Urbina-Cardona, N.; Vallan, D.; Vanbergen, A.J.; Vasconcelos, H.L.; Vassilev, K.; Verboven, H.A.F.; Verdasca, M.João; Verdú, J.R.; Vergara, C.H.; Vergara, P.M.; Verhulst, J.; Virgilio, M.; Van Vu, L.; Waite, E.M.; Walker, T.R.; Wang, H.F.; Wang, Y.; Watling, J.I.; Weller, B.; Wells, K.; Westphal, C.; Wiafe, E.D.; Williams, C.D.; Willig, M.R.; Woinarski, J.C.Z.; Wolf, J.H.D.; Wolters, V.; Woodcock, B.A.; Wu, J.; Wunderle, J.M.; Yamaura, Y.; Yoshikura, S.; Yu, D.W.; Zaitsev, A.S.; Zeidler, J.; Zou, F.; Collen, B.; Ewers, R.M.; Mace, G.M.; Purves, D.W.; Scharlemann, J.P.W.; Purvis, A. The PREDICTS project—Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (—has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity. Journal Article Data sharing; global biodiversity modeling; global change; habitat destruction; land use
2017 Creation of forest edges has a global impact on forest vertebrates Pfeifer, M.; Lefebvre, V.; Peres, C.A.; Banks-Leite, C.; Wearn, O.R.; Marsh, C.J.; Butchart, S.H.M.; Arroyo-Rodriguez, V.; Barlow, J.; Cerezo, A.; Cisneros, L.; D’Cruze, N.; Faria, D.; Hadley, A.; Harris, S.M.; Klingbeil, B.T.; Kormann, U.; Lens, L.; Medina-Rangel, G.F.; Morante-Filho, J.C.; Olivier, P.; Peters, S.L.; Pidgeon, A.; Ribeiro, D.B.; Scherber, C.; Schneider-Maunoury, L.; Struebig, M.; Urbina-Cardona, N.; Watling, J.I.; Willig, M.R.; Wood, E.M.; Ewers, R.M. Journal Article
2017 Analysing regional climate forcing on historical precipitation variability in Northeast Puerto Rico Ramseyer, C.A.; Mote, T.L. The tropical forests of northeast Puerto Rico (NE PR) and the Luquillo Mountains (LM) are a large repository for biodiversity and have an important role in regional biogeochemical processes. Precipitation is a key driver of the productivity of these sensitive ecosystems. This study analyses historical precipitation variability from 1985 to 2014 at El Verde Field Station (EVFS) at 380 m on the north facing slope of the LM. The primary objective of this study is to identify atmospheric states that lead to extreme wet/dry conditions at EVFS. This study also investigates how those wet/dry atmospheric states change over the study period through an epoch approach on annual and seasonal timescales. Self-organizing maps (SOMs) are used to produce atmospheric states from ERA-Interim low-tropospheric moisture and circulation variables. These atmospheric states are downscaled to precipitation at the EVFS rain gauge. A probability density function of observed precipitation is calculated for each atmospheric state. Changes in node frequency, which is the number of days mapping to a particular node compared to the total number of days in the temporal period, are used to evaluate changes in wet/dry atmospheric states at EVFS. Results indicate that low-precipitation days at EVFS are associated with atmospheric states with high 1000–700 hPa bulk wind shear and decreased 700 hPa moisture. Wet days in the study region are associated with moist low-tropospheric environments with low wind shear. Our results indicate an increased frequency of dry season atmospheric states with lower 700 hPa moisture. Over the study period, the dry season has a decrease in median and extreme precipitation during rainy days (days >0 mm). A decrease in early rainfall season median precipitation on rainy days is observed despite an increase in days with measurable precipitation, likely driven by an increase in light rainfall days (<5 mm). Journal Article Climate downscaling; Northeast Puerto Rico; precipitation variability; self-organizing maps
2017 The Saharan Air Layer as an Early Rainfall Season Suppressant in the Eastern Caribbean: The 2015 Puerto Rico Drought Mote, T.L.; Ramseyer, C.A.; Miller, P.W. Eastern Puerto Rico and the surrounding Caribbean experienced a severe drought in 2015 that resulted in record-low reservoir and river levels. Rainfall deficits in April and May, which represent the period when the drought began, were more severe in 2015 than recent droughts of record. While El Niño has been associated with drought in the Caribbean, onset of the 2015 drought was strongly associated with lower-than-average values of a recently developed tool used by weather forecasters in San Juan, the Gálvez-Davison Index (GDI), which is used to measure the potential for thunderstorm development and rainfall. Persistently low GDI values indicate strong and frequent intrusions of hot, dry air in the low to middle troposphere, suppressing convection, both locally and in development regions for tropical waves that impact Puerto Rico. The Saharan Air Layer (SAL) is largely responsible for this anomalously hot, dry air, which produced thermodynamically stable conditions and limited thunderstorms and rainfall. Moreover, higher-than-normal aerosol concentrations, typically associated with SAL intrusion over the Caribbean, were recorded in April and May 2015. A comparison to advanced very high resolution radiometer aerosol optical thickness demonstrates that higher Caribbean aerosols in the early rainfall season, particularly June, are associated with decreased rainfall in eastern Puerto Rico. Results here demonstrate a direct link between the early and more pronounced SAL intrusions into the Caribbean and the suppression of the early rainfall season. More broadly, a reduction in the GDI and increase in the trade wind inversion was associated with reduced early season rainfall in the eastern Caribbean. Journal Article aerosols; Aerosols and particles; Drought; El Niño; Precipitation; Puerto Rico; Sahara Air Layer; Tropical meteorology
2017 Effects of forest height and vertical complexity on abundance and biodiversity of bats in Amazonia Martins, A.C.M.; Willig, M.R.; Presley, S.J.; Marinho-Filho, J. Anthropogenic activities have accelerated habitat change, loss, and fragmentation, threatening biodiversity over large portions of the tropics. The resulting anthropogenically created landscape mosaics often include forests of different successional stages or that have experienced different levels of anthropogenic use, which affect the physical structure of the forest (e.g., forest height, vertical complexity of vegetation). These physical characteristics of forests may affect the abundance and biodiversity of forest inhabitants, and obscure effects of landscape changes (e.g., percent forest cover) on animal species. Because bats are ecologically diverse and include seed dispersers, pollinators, and top predators, they contribute to the structure and function of forests, and directly affect forest integrity and regeneration. Thus, understanding how variation in the vegetative structure of forests affects the abundance and biodiversity of bats may provide important information to effectively manage and conserve forest fragments. We surveyed bats at 24 sites in the southern Brazilian Amazon, and quantified vegetation structure (density, height, and basal area of trees, density of understory, and canopy openness). Using generalized linear mixed-effects models, we tested simple relationships of each structural characteristic with community- (taxonomic and phylogenetic dimensions of biodiversity), guild-, and population-level attributes of bats. Models for total abundance, taxonomic biodiversity (species diversity and dominance), and phylogenetic diversity were significant, increasing with tree height and basal area, and decreasing with canopy openness. At the population level, abundances of frugivores (Carollia perspicillata, Rhinophylla pumilio, Artibeus planirostris, A. obscurus, A. lituratus, Uroderma bilobatum) and nectarivores (Lonchopylla thomasi, Glossophaga soricina) were related significantly to vegetation structure. Abundances of some understory frugivores exhibited negative relationships with tree height, choosing younger forests, whereas abundances of canopy frugivores were highest in closed canopy forests. Of the nectarivores, L. thomasi was more abundant in older forests (negative relationship with density of trees), whereas G. soricina was more abundant in areas with low canopies and low basal area (i.e., earlier successional forest). Consequently, effective management of forest fragments should include consideration of local forest age and vegetation structure, as well as forest connectivity and patch size. In general, protecting areas with large trees and closed canopies enhances the persistence of pollinators and seed dispersers. Journal Article Amazon; Bat population responses; Chiroptera; Community ecology; ecosystem services; Forest fragmentation
2016 Changing the nature of scientists: Participation in the Long-Term Ecological Research Program
Willig, M. R, and L. A Walker. 2016. Long-Term Ecological Research: Changing the Nature of Scientists Changing The Nature Of Scientists: Participation In The Long-Term Ecological Research Program. eds. M. R Willig and Walker, L. A. New York, New York: Oxford University Press.
Willig, M.R.; Walker, L.A. Book
2016 Standardized Assessment of Biodiversity Trends in Tropical Forest Protected Areas: The End Is Not in Sight Beaudrot, L.; Ahumada, J.A.; O'Brien, T.; Alvarez-Loayza, P.; Boekee, K.; Campos-Arceiz, A.; Eichberg, D.; Espinosa, S.; Fegraus, E.; Fletcher, C.; Gajapersad, K.; Hallam, C.; Hurtado, J.; Jansen, P.A.; Kumar, A.; Larney, E.; Lima, M.G.; Mahony, C.; Martin, E.H.; McWilliam, A.; Mugerwa, B.; Ndoundou-Hockemba, M.; Razafimahaimodison, J.C.; Romero-Saltos, H.; Rovero, F.; Salvador, J.; Santos, F.; Sheil, D.; Spironello, W.R.; Willig, M.R.; Winarni, N.L.; Zvoleff, A.; Andelman, S.J. Journal Article tropical climate
2016 Interspecific functional convergence and divergence, and intraspecific negative density dependence underlie the seed-to-seedling transition in tropical trees Umaña, M.N.; J. Forero-Montana; Muscarella, R.; Nytch, C.; Thompson, J.; Uriarte, M.; Zimmerman, J.K.; Swenson, N.G. Journal Article
2016 Biodiversity and metacommunity structure of animals along tropical montane forest gradients Willig, M.R.; Presley, S.J.

The study of altitudinal gradients has made enduring contributions to the theoretical and empirical bases of modern biology. Unfortunately, the persistence of these systems and the species that compose them is threatened by land-use change at lower altitudes and by climate change throughout the gradients, but especially at higher altitudes. In this review, we focus on two broad themes that are inspired by altitudinal variation in tropical montane regions: (1) dimensions of biodiversity and (2) metacommunity structure. Species richness generally decreased with increasing altitude, although not always in a linear fashion. Mid-altitudinal peaks in richness were less common than monotonic declines, and altitudinal increases in richness were restricted to amphibian faunas. Moreover, gradients of biodiversity differed among dimensions (taxonomic, phylogenetic and functional) as well as among faunas (bats, rodents, birds) in the tropical Andes, suggesting that species richness is not a good surrogate for dimensions that reflect differences in the function or evolutionary history of species. Tropical montane metacommunities evinced a variety of structures, including nested (bats), Clementsian (rodents, bats, gastropods), quasi-Clementsian (reptiles, amphibians, passerines) and quasi-Gleasonian (gastropods) patterns. Nonetheless, composit

Journal Article Clementsian structure; conservation biology; ecotones; functional biodiversity; island biogeography; metacommunity structure; nestedness; phylogenetic biodiversity; taxonomic biodiversity; tropical animal ecology
2016 Responses of tropical bats to habitat fragmentation, logging, and deforestation
Meyer, C. F, M. J Struebig, and M. R Willig. 2016. Responses Of Tropical Bats To Habitat Fragmentation, Logging, And Deforestation. In Bats in the Anthropocene: Conservation of Bats in a Changing World, Bats in the Anthropocene: Conservation of Bats in a Changing World, eds. C. Voigt and Kingston, T. Springer International Publishing, 63-103.
Meyer, C.F.; Struebig, M.J.; Willig, M.R.

Land-use change is a key driver of the global biodiversity crisis and a particularly serious threat to tropical biodiversity. Throughout the tropics, the staggering pace of deforestation, logging, and conversion of forested habitat to other land uses has created highly fragmented landscapes that are increasingly dominated by human-modified habitats and degraded forests. In this chapter, we review the responses of tropical bats to a range of land-use change scenarios, focusing on the effects of habitat fragmentation , logging , and conversion of tropical forest to various forms of agricultural production. Recent landscape-scale studies have considerably advanced our understanding of how tropical bats respond to habitat fragmentation and disturbance at the population, ensemble, and assemblage level. This research emphasizes that responses of bats are often species and ensemble specific, sensitive to spatial scale , and strongly molded by the characteristics of the prevailing landscape matrix . Nonetheless, substantial knowledge gaps exist concerning other types of response by bats. Few studies have assessed responses at the genetic , behavioral , or physiological level, with regard to disease prevalence , or the extent to which human disturbance erodes the capacity of tropical bats to provide key ecosystem services . A strong geographic bias, with Asia and, most notably, Africa, being strongly understudied, precludes a comprehensive understanding of the effects of fragmentation and disturbance on tropical bats. We strongly encourage increased research in the Paleotropics and emphasize the need for long-term studies , approaches designed to integrate multiple scales, and answering questions that are key to conserving tropical bats in an era of environmental change and dominance of modified habitats (i.e., the Anthropocene).

Book Chapter
2016 Terrestrial support of aquatic food webs depends on light inputs: a geographically-replicated test using tank bromeliads Farjalla, V.F.; González, A.L.; Céréghino, R.; Dézerald, O.; Marino, N.A.C.; Piccoli, G.C.O.; Richardson, B.A.; Richardson, M.J.; Romero, G.Q.; Srivastava, D.S. Journal Article tropics
2016 Contemporary human uses of tropical forested watersheds and riparian corridors: Ecosystem services and hazard mitigation, with examples from Panama, Puerto Rico, and Venezuela Larsen, M.C. Journal Article Venezuela
2016 Effects of Hurricane-Felled Tree Trunks on Soil Carbon, Nitrogen, Microbial Biomass, and Root Length in a Wet Tropical Forest Lodge, D.J.; Winker, D.; González, G.; Clum, N.

Decaying coarse woody debris can affect the underlying soil either by augmenting nutrients that can be exploited by tree roots, or by diminishing nutrient availability through stimulation of microbial nutrient immobilization. We analyzed C, N, microbial biomass C and root length in closely paired soil samples taken under versus 20–50 cm away from large trunks of two species felled by Hugo (1989) and Georges (1998) three times during wet and dry seasons over the two years following the study conducted by Georges. Soil microbial biomass, % C and % N were significantly higher under than away from logs felled by both hurricanes (i.e., 1989 and 1998), at all sampling times and at both depths (0–10 and 10–20 cm). Frass from wood boring beetles may contribute to early effects. Root length was greater away from logs during the dry season, and under logs in the wet season. Root length was correlated with microbial biomass C, soil N and soil moisture (R = 0.36, 0.18, and 0.27, respectively; all p values < 0.05). Microbial biomass C varied significantly among seasons but differences between positions (under vs. away) were only suggestive. Microbial C was correlated with soil N (R = 0.35). Surface soil on the upslope side of the logs had significantly more N and microbial biomass, likely from accumulation of leaf litter above the logs on steep slopes. We conclude that decaying wood can provide ephemeral resources that are exploited by tree roots during some seasons.

Journal Article bark beetle frass; coarse woody debris; fine root proliferation; nitrogen cycling; nutrient hotspots; Soil carbon; soil nitrogen; tree roots
2016 Physical, Chemical, and Biological Properties of Soil under Decaying Wood in a Tropical Wet Forest in Puerto Rico M. Zalamea; González, G.; Lodge, D.J.

Decaying wood is related to nutrient cycling through its role as either a sink or source of nutrients. However, at micro scales, what is the effect of decaying logs on the physical, chemical, and biotic characteristics of the soil underneath? We took samples from a 0 to 5 cm depth under and a 50 cm distance away from decaying logs (Dacryodes excelsa and Swietenia macrophylla at 2 stages of decay, and measured soil temperature, total and available nutrients, and root length in a tropical wet forest. We found decaying wood affected physical, chemical, and biotic properties of the underlyingsoil. Soil temperature was less variable under the decaying logs than away from the logs. Soil under the decaying wood had fewer roots, and lower NO3 and Mg2+ availability than samples collected a distance of 50 cm away from the logs. Tree species and decay stage were important factors defining the effect of decaying wood on the distribution of available nutrients. Ca2+, Mg2+, and K+ levels were higher in the soil associated with the youngest logs, and were higher near S. macrophylla logs. Heavy metals were also higher in the soil located near the younger logs independent of the species; other metal ions such as Al3+ and Fe3+ were higher in the soil associated with D. excelsa and the oldest logs. These results indicate decaying wood can contribute to and generate spatial heterogeneity of soil properties.

Journal Article available nutrients; coarse woody debris (CWD); microbial biomas; Puerto Rico; Roots; soil properties; tropical forest; wood decomposition
2016 Resource utilization by native and invasive earthworms and their effects on soil carbon and nitrogen dynamics in Puerto Rican soils Huang, C.Y.; González, G.; Hendrix, P.F.

Resource utilization by earthworms affects soil C and N dynamics and further colonization of invasive earthworms. By applying 13C-labeled Tabebuia heterophylla leaves and 15N-labeled Andropogon glomeratus grass, we investigated resource utilization by three earthworm species (invasive endogeic Pontoscolex corethrurus, native anecic Estherella sp, and native endogeic Onychochaeta borincana) and their effects on soil C and N dynamics in Puerto Rican soils in a 22-day laboratory experiment. Changes of 13C/C and 15N/N in soils, earthworms, and microbial populations were analyzed to evaluate resource utilization by earthworms and their influences on C and N dynamics. Estherella spp. utilized the 13C-labeled litter; however, its utilization on the 13C-labeled litter reduced when cultivated with P. corethrurus and O. borincana. Both P. corethrurus and O. borincana utilized the 13C-labeled litter and 15C-labeled grass roots and root exudates. Pontoscolex corethrurus facilitated soil respiration by stimulating 13C-labeled microbial activity; however, this effect was suppressed possibly due to the changes in the microbial activities or community when coexisting with O. borincana. Increased soil N mineralization by individual Estherella spp. and O. borincana was reduced in the mixed-species treatments. The rapid population growth of P. corethrurus may increase competition pressure on food resources on the local earthworm community. The relevance of resource availability to the population growth of P. corethrurus and its significance as an invasive species is a topic in need of future research.

Journal Article carbon and nitrogen mineralization; invasive earthworms; Luquillo Mountains; microbial respiration; Puerto Rico; stable isotope; tropics
2016 Natural regeneration in the context of large-scale forest and landscape restoration in the tropics Chazdon, R.L.; Uriarte, M.

Revertir la perdida y degradación de bosques a nivel global requerirá la restauración forestal a escala de paisaje y a largo plazo. Esta estrategia ofrece beneficios sociales, ambientales, y económicos que pueden sustentar poblaciones rurales, mitigar efectos del cambio climático, aumentar la seguridad alimenticia, y proteger suelos y cuencas. A pesar del demostrado alcance y viabilidad de la regeneración natural como herramienta de restauración de paisajes degradados, la mayoría de proyectos de restauración se han enfocado en plantaciones. En la mayoría de los casos se ha ignorado la regeneración natural como una opción viable. En esta edición especial de Biotropica presentamos una colección de 16 artículos que ilustran las dimensiones ecológicas, económicas y sociales de la restauración de bosques a nivel de paisaje (FLR). FLR es un enfoque a la restauración relativamente nuevo que aspira a recuperar la integridad ecológica de paisajes deforestados ó degradados y al mismo tiempo aumentar el bienestar humano. Los artículos documentan como la regeneración natural, tanto pasiva como activa, puede lograr beneficios sociales y ecológicos. FLR se enfoca en las poblaciones que viven y trabajan en el paisaje y cuyo bienestar la restauración puede mejorar y diversificar. Dada la magnitud de degradación forestal y la necesidad de mitigar el cambio climático y sustentar el bienestar humano, es fundamental aprovechar el potencial de la regeneración natural para conseguir las ambiciosas metas que motivan iniciativas globales de restauración.

Journal Article ecosystem services; forest and landscape restoration; mosaic restoration; mosaico de restauração; regeneração natural espontânea; regeneración naturalespontanea; restauração em larga escala; restauração florestal e em paisagens florestais; restauración de mosaicos; restauración forestal a escala de paisaje; servicios ecosistémicos; serviços ecossistêmicos; spontaneous natural regeneration; sustainable land use; uso sustentable del paisaje; uso sustentável da terra; wide-scale restoration
2016 Incorporating natural regeneration in forest landscape restoration in tropical regions: synthesis and key research gaps Uriarte, M.; Chazdon, R.L. Journal Article ecosystem services; forest landscape restoration; gestión del terreno; governaça; land governance; mosaic restoration; mosaicos de restauração; natural regeneration; prioridad espacial; priorização espacial; regeneração natural espontânea; regeneración natural espontanea; restauração de paisagens florestais; restauración de mosaicos; restauración forestal a escala de paisaje; servicios ecosistémicos; serviços ecossistêmicos; spatial prioritization; spontaneous sustainable land use; trade-offs; uso sustentable de la tierra; uso sustentável da terra
2016 Natural regeneration as a tool for large-scale forest restoration in the tropics: prospects and challenges Chazdon, R.L.; Guariguata, M.R.

A major global effort to enable cost-effective natural regeneration is needed to achieve ambitious forest and landscape restoration goals. Natural forest regeneration can potentially play a major role in large-scale landscape restoration in tropical regions. Here, we focus on the conditions that favor natural regeneration within tropical forest landscapes. We illustrate cases where large-scale natural regeneration followed forest clearing and non-forest land use, and describe the social and ecological factors that drove these local forest transitions. The self-organizing processes that create naturally regenerating forests and natural regeneration in planted forests promote local genetic adaptation, foster native species with known traditional uses, create spatial and temporal heterogeneity, and sustain local biodiversity and biotic interactions. These features confer greater ecosystem resilience in the face of future shocks and disturbances. We discuss economic, social, and legal issues that challenge natural regeneration in tropical landscapes. We conclude by suggesting ways to enable natural regeneration to become an effective tool for implementing large-scale forest and landscape restoration. Major research and policy priorities include: identifying and modeling the ecological and economic conditions where natural regeneration is a viable and favorable land-use option, developing monitoring protocols for natural regeneration that can be carried out by local communities, and developing enabling incentives, governance structures, and regulatory conditions that promote the stewardship of naturally regenerating forests. Aligning restoration goals and practices with natural regeneration can achieve the best possible outcome for achieving multiple social and environmental benefits at minimal cost.

Journal Article
2016 Biotic And Abiotic Variables Influencing Plant Litter Breakdown In Streams: A Global Study (Proceedings of the Royal Society of London) Boyero, L.; Pearson, R.G.; Hui, C.; Gessner, M.O.; Perez, J.; Alexandrou, M.A.; Graça, M.A.S.; Cardinale, B.J.; Albariño, R.J.; Arunachalam, M.; Barmuta, L.A.; Boulton, A.J.; Bruder, A.; Callisto, M.; Chauvet, E.; Death, R.G.; Dudgeon, D.; Encalada, A.C.; Ferreira, V.; Figueroa, R.; Flecker, A.S.; Gonçalves, J.F.; Helson, J.; Iwata, T.; Jinggut, T.; Mathooko, J.; Mathuriau, C.; M'Erimba, C.; Moretti, M.S.; Pringle, C.M.; Ramírez, A.; Ratnarajah, L.; Rincón, J.; Yule, C.M. Journal Article
2016 Biomass resilience of Neotropical secondary forests
Poorter, L., Frans Bongers, Mitchell T. Aide, Angélica MAlmeyda Zambrano, P. Balvanera, Justin M Becknell, Vanessa Boukili, Pedro HS Brancalion, Eben N Broadbent, R. L Chazdon, Dylan Craven, J. S Almeida-Cortez, George AL Cabral, B. de Jong, J.S. Denslow, D.H. Dent, S.J. DeWalt, J.M. Dupuy, S.M. Durán, M.M. Espírito-Santo, M.C. Fandino, Ricardo G César, Jefferson S Hall, José Luis Hernandez-Stefanoni, Catarina C Jakovac, André B Junqueira, Deborah Kennard, Susan G Letcher, Juan-Carlos Licona, Madelon Lohbeck, E. Marin-Spiotta, Miguel Martínez-Ramos, Paulo Massoca, Jorge A Meave, Rita Mesquita, Francisco Mora, Rodrigo Muñoz, R. Muscarella, Yule RF Nunes, Susana Ochoa-Gaona, Alexandre A de Oliveira, Edith Orihuela-Belmonte, M. Peña-Claros, Eduardo A Pérez-García, Daniel Piotto, Jennifer S Powers, Jorge Rodríguez-Velázquez, I. E Romero-Pérez, Jorge Ruíz, Juan G Saldarriaga, Arturo Sanchez-Azofeifa, N. B Schwartz, Marc K Steininger, N. G Swenson, Marisol Toledo, M. Uriarte, Michiel van Breugel, Hans van der Wal, Maria DM Veloso, Hans FM Vester, Alberto Vicentini, Ima CG Vieira, Tony Vizcarra Bentos, Bruce G. Williamson, and Danaë MA Rozendaal. 2016. Biomass Resilience Of Neotropical Secondary Forests. Nature 530(7589): 211-214.
Poorter, L.; Bongers, F.; Aide, M.; Zambrano, A.M.Almeyda; Balvanera, P.; Becknell, J.M.; Boukili, V.; Brancalion, P.H.S.; Broadbent, E.N.; Chazdon, R.L.; Craven, D.; Almeida-Cortez, J.S.; Cabral, G.A.L.; de Jong, B.; Denslow, J.S.; Dent, D.H.; DeWalt, S.J.; Dupuy, J.M.; Durán, S.M.; Espírito-Santo, M.M.; Fandino, M.C.; César, R.G.; Hall, J.S.; Hernandez-Stefanoni, J.Luis; Jakovac, C.C.; Junqueira, A.B.; Kennard, D.; Letcher, S.G.; Licona, J.C.; Lohbeck, M.; Marin-Spiotta, E.; Martínez-Ramos, M.; Massoca, P.; Meave, J.A.; Mesquita, R.; Mora, F.; Muñoz, R.; Muscarella, R.; Nunes, Y.R.F.; Ochoa-Gaona, S.; de Oliveira, A.A.; Orihuela-Belmonte, E.; Peña-Claros, M.; Pérez-García, E.A.; Piotto, D.; Powers, J.S.; Rodríguez-Velázquez, J.; Romero-Pérez, I.E.; Ruíz, J.; Saldarriaga, J.G.; Sanchez-Azofeifa, A.; Schwartz, N.B.; Steininger, M.K.; Swenson, N.G.; Toledo, M.; Uriarte, M.; van Breugel, M.; van der Wal, H.; Veloso, M.D.M.; Vester, H.F.M.; Vicentini, A.; Vieira, I.C.G.; Bentos, T.Vizcarra; Williamson, B.; Rozendaal, D.M.A. Journal Article
2016 Plant functional traits have globally consistent effects on competition
Kunstler, G., Daniel Falster, David A Coomes, Francis Hui, Robert M Kooyman, Daniel C Laughlin, L. Poorter, Mark Vanderwel, Ghislain Vieilledent, S. J Wright, Masahiro Aiba, Christopher Baraloto, John Caspersen, Hans C J. Cornelissen, Sylvie Gourlet-Fleury, Marc Hanewinkel, Bruno Herault, Jens Kattge, Hiroko Kurokawa, Yusuke Onoda, Josep Peñuelas, Hendrik Poorter, M. Uriarte, Sarah Richardson, Paloma Ruiz-Benito, Fang I. Sun, Göran Ståhl, N. G Swenson, J. Thompson, Bertil Westerlund, Christian Wirth, Miguel A Zavala, Hongcheng Zeng, J. K Zimmerman, Niklaus E Zimmermann, and Mark Westoby. 2016. Plant Functional Traits Have Globally Consistent Effects On Competition. Nature 529(7585): 204-207.
Kunstler, G.; Falster, D.; Coomes, D.A.; Hui, F.; Kooyman, R.M.; Laughlin, D.C.; Poorter, L.; Vanderwel, M.; Vieilledent, G.; Wright, S.J.; Aiba, M.; Baraloto, C.; Caspersen, J.; Cornelissen, H.C.; Gourlet-Fleury, S.; Hanewinkel, M.; Herault, B.; Kattge, J.; Kurokawa, H.; Onoda, Y.; Peñuelas, J.; Poorter, H.; Uriarte, M.; Richardson, S.; Ruiz-Benito, P.; Sun, F.; Ståhl, G.; Swenson, N.G.; Thompson, J.; Westerlund, B.; Wirth, C.; Zavala, M.A.; Zeng, H.; Zimmerman, J.K.; Zimmermann, N.E.; Westoby, M. Journal Article
2016 Carbon sequestration potential of second-growth forest regeneration in the Latin American tropics
Chazdon, R. L, Eben N Broadbent, Danaë MA Rozendaal, Frans Bongers, A. M Almeyda-Zambrano, Mitchell T. Aide, P. Balvanera, Justin M Becknell, Vanessa Boukili, Pedro HS Brancalion, Dylan Craven, J. S Almeida-Cortez, George AL Cabral, B. de Jong, Julie S Denslow, Daisy H Dent, Saara J DeWalt, Juan M Dupuy, Sandra M Durán, Mario M Espírito-Santo, María C Fandino, Ricardo G César, Jefferson S Hall, José Luis Hernandez-Stefanoni, Catarina C Jakovac, André B Junqueira, Deborah Kennard, Susan G Letcher, Madelon Lohbeck, Miguel Martínez-Ramos, Paulo Massoca, Jorge A Meave, Rita Mesquita, Francisco Mora, Rodrigo Muñoz, R. Muscarella, Yule RF Nunes, Susana Ochoa-Gaona, Edith Orihuela-Belmonte, M. Peña-Claros, Eduardo A Pérez-García, Daniel Piotto, Jennifer S Powers, Jorge Rodríguez-Velázquez, I. E Romero-Pérez, Jorge Ruíz, Juan G Saldarriaga, Arturo Sanchez-Azofeifa, N. B Schwartz, Marc K Steininger, N. G Swenson, M. Uriarte, Michiel van Breugel, Hans van der Wal, Maria DM Veloso, Hans Vester, Ima Celia G Vieira, Tony Vizcarra Bentos, Bruce G. Williamson, and L. Poorter. 2016. Carbon Sequestration Potential Of Second-Growth Forest Regeneration In The Latin American Tropics. Science Advances 2(5): e1501639.
Chazdon, R.L.; Broadbent, E.N.; Rozendaal, D.M.A.; Bongers, F.; Almeyda-Zambrano, A.M.; Aide, M.; Balvanera, P.; Becknell, J.M.; Boukili, V.; Brancalion, P.H.S.; Craven, D.; Almeida-Cortez, J.S.; Cabral, G.A.L.; de Jong, B.; Denslow, J.S.; Dent, D.H.; DeWalt, S.J.; Dupuy, J.M.; Durán, S.M.; Espírito-Santo, M.M.; Fandino, M.C.; César, R.G.; Hall, J.S.; Hernandez-Stefanoni, J.Luis; Jakovac, C.C.; Junqueira, A.B.; Kennard, D.; Letcher, S.G.; Lohbeck, M.; Martínez-Ramos, M.; Massoca, P.; Meave, J.A.; Mesquita, R.; Mora, F.; Muñoz, R.; Muscarella, R.; Nunes, Y.R.F.; Ochoa-Gaona, S.; Orihuela-Belmonte, E.; Peña-Claros, M.; Pérez-García, E.A.; Piotto, D.; Powers, J.S.; Rodríguez-Velázquez, J.; Romero-Pérez, I.E.; Ruíz, J.; Saldarriaga, J.G.; Sanchez-Azofeifa, A.; Schwartz, N.B.; Steininger, M.K.; Swenson, N.G.; Uriarte, M.; van Breugel, M.; van der Wal, H.; Veloso, M.D.M.; Vester, H.; Vieira, I.Celia G.; Bentos, T.Vizcarra; Williamson, B.; Poorter, L. Journal Article
2016 Limited Uptake Of Nutrient Input From Sewage Effluent In A Tropical Landscape Figueroa-Nieves, D.; McDowell, W.H.; Potter, J.D.; Martinez, G. Journal Article
2016 Responses Of Tropical Bats To Habitat Fragmentation, Logging, And Deforestation. In Bats in the Anthropocene: Conservation of Bats in a Changing World, Bats in the Anthropocene: Conservation of Bats in a Changing World Meyer, C.F.; Struebig, M.J.; Willig, M.R.; Voigt, C.; Kingston, T. Journal Article
2016 Impacts of climate variability on tree demography in second growth tropical forests: the importance of regional context for predicting successional trajectories Uriarte, M.; Schwartz, N.B.; Powers, J.S.; Marin-Spiotta, E.; Liao, W.; Werden, L.K.

Naturally regenerating and restored second growth forests account for over 70% of tropical forest cover and provide key ecosystem services. Understanding climate change impacts on successional trajectories of these ecosystems is critical for developing effective large-scale forest landscape restoration (FLR) programs. Differences in environmental conditions, species composition, dynamics, and landscape context from old growth forests may exacerbate climate impacts on second growth stands. We compile data from 112 studies on the effects of natural climate variability, including warming, droughts, fires, and cyclonic storms, on demography and dynamics of second growth forest trees and identify variation in forest responses across biomes, regions, and landscapes. Across studies, drought decreases tree growth, survival, and recruitment, particularly during early succession, but the effects of temperature remain unexplored. Shifts in the frequency and severity of disturbance alter successional trajectories and increase the extent of second growth forests. Vulnerability to climate extremes is generally inversely related to long-term exposure, which varies with historical climate and biogeography. The majority of studies, however, have been conducted in the Neotropics hindering generalization. Effects of fire and cyclonic storms often lead to positive feedbacks, increasing vulnerability to climate extremes and subsequent disturbance. Fragmentation increases forests’ vulnerability to fires, wind, and drought, while land use and other human activities influence the frequency and intensity of fire, potentially retarding succession. Comparative studies of climate effects on tropical forest succession across biogeographic regions are required to forecast the response of tropical forest landscapes to future climates and to implement effective FLR policies and programs in these landscapes.

Journal Article Drought; fire; hurricanes; regrowth forests; warming
2016 Impact of long-range transported African dust on cloud water chemistry at a tropical montane cloud forest in northeastern Puerto Rico Valle-Díaz, C.J.; Torres-Delgado, E.; Colón-Santos, S.M.; Lee, T.; Collett, J.L.; McDowell, W.H.; Mayol-Bracero, O.L. Journal Article
2016 Abrupt change in forest structure localized to elevation of regional knickpoints in a tropical mountain range Remote Sensing and the Environment Wolf, J.; Brocard, G.Y.; Willenbring, J.K.; Porder, S.; Uriarte, M. Journal Article
2016 Temperature mediates continental-scale diversity of microbes in forest soils Zhou, J.; Deng, Y.; Shen, L.; Wen, C.; Yan, Q.; Ning, D.; Qin, Y.; Xue, K.; Wu, L.; He, Z.; Voordeckers, J.W.; Van Nostrand, J.D.; Buzzard, V.; Michaletz, S.T.; Enquist, B.; Weiser, M.D.; Kaspari, M.; Waide, R.B.; Yang, Y.; Brown, J.H. Journal Article
2016 Variation of tropical forest assembly processes across regional environmental gradients Muscarella, R.; Uriarte, M.; Erickson, D.L.; Swenson, N.G.; Kress, J.W.; Zimmerman, J.K. Determining how the relative strength of community assembly processes varies along resource gradients is critical for understanding community responses to environmental change. A key challenge for addressing this issue at regional scales is that environmental gradients typically encompass multiple coupled resource gradients (e.g. water, light, soils), which can complicate hypotheses about the drivers of community variation. We used data on functional traits and phylogenetic relatedness to infer assembly processes of tree communities across regional environmental gradients in Puerto Rico. We censused trees in 24, 0.25-ha mature plots located along a precipitation gradient and on soils derived from two parent materials (limestone and volcanic). In each plot, we quantified abiotic conditions in terms of mean annual precipitation, canopy openness, and soil nutrients. We used three functional traits with relevance for drought tolerance and resource acquisition strategies (wood density [WD], leaf mass per area [LMA], and maximum height [Hmax]), and a molecular phylogeny, to characterize tree community composition in terms of (i) community-weighted mean trait values (i.e., plot average trait values, weighted by relative basal area), (ii) functional diversity, and (iii) phylogenetic diversity. Mean annual precipitation was negatively correlated with understory light availability (for plots on both soil types), and soil fertility (among plots on limestone soils). Soil fertility varied substantially between plots on each parent material, and was generally higher among plots on limestone-derived soils. Among the limestone soil plots, which occur on the drier half of the precipitation gradient, increasing mean annual precipitation was associated with lower community-weighted mean WD and LMA, and taller Hmax. Additionally, functional diversity (of WD and Hmax) and phylogenetic diversity increased with precipitation among limestone soil plots, suggesting an important role for abiotic filtering in driving functional and phylogenetic convergence in arid conditions. In contrast, we did not find significant relationships between environmental conditions and community-weighted mean traits or diversity metrics among plots on volcanic-derived soils, which occur along the wetter half of the precipitation gradient. Together, our results suggest that drought tolerance is the dominant assembly mechanism controlling tree composition in dry forests. In wetter forests, functional diversity appears to be maintained by a combination of hierarchical competition for light and niche partitioning. Overall, our results exhibit geographic variation in the mechanisms governing composition of tropical forests across regional environmental gradients, and highlight the importance of considering complex environmental gradients at large spatial scales. Journal Article abiotic filtering; competition; Functional diversity; LMA; Maximum height; wood density
2016 Advantages of living at the extremes: Tree seedlings at intermediate abundance in a tropical forest have the highest richness of aboveground enemies and suffer most damage Bachelot, B.; Uriarte, M.; Thompson, J.; Zimmerman, J.K. Journal Article
2016 Long-lasting effects of land use history on soil fungal communities in second-growth tropical rain forests Bachelot, B.; Uriarte, M.; Zimmerman, J.K.; Thompson, J.; Leff, J.W.; Asai, A.; Kosher, J.; McGuire, K.L. Our understanding of the long-lasting effects of human land use on soil fungal communities in tropical forests is limited. Yet, over 70% of all remaining tropical forests are growing in former agricultural or logged areas. We investigated the relationship among land use history, biotic and abiotic factors, and soil fungal community composition and diversity in a second-growth tropical forest in Puerto Rico. We coupled high-throughput DNA sequencing with tree community and environmental data to determine whether land use history had an effect on soil fungal community descriptors. We also investigated the biotic and abiotic factors that underlie such differences and asked whether the relative importance of biotic (tree diversity, basal tree area, and litterfall biomass) and abiotic (soil type, pH, iron, and total carbon, water flow, and canopy openness) factors in structuring soil fungal communities differed according to land use history. We demonstrated long-lasting effects of land use history on soil fungal communities. At our research site, most of the explained variation in soil fungal composition (R2 = 18.6%), richness (R2 = 11.4%), and evenness (R2 = 10%) was associated with edaphic factors. Areas previously subject to both logging and farming had a soil fungal community with lower beta diversity and greater evenness of fungal operational taxonomic units (OTUs) than areas subject to light logging. Yet, fungal richness was similar between the two areas of historical land use. Together, these results suggest that fungal communities in disturbed areas are more homogeneous and diverse than in areas subject to light logging. Edaphic factors were the most strongly correlated with soil fungal composition, especially in areas subject to light logging, where soils are more heterogenous. High functional tree diversity in areas subject to both logging and farming led to stronger correlations between biotic factors and fungal composition than in areas subject to light logging. In contrast, fungal richness and evenness were more strongly correlated with biotic factors in areas of light logging, suggesting that these metrics might reflect long-term associations in old-growth forests. The large amount of unexplained variance in fungal composition suggests that these communities are structured by both stochastic and niche assemblage processes. Journal Article forest soil fungi; high-throughput sequencing; Land use history; Luquillo Forest Dynamics Plot (LFDP); tropical forest
2016 Using codispersion analysis to quantify and understand spatial patterns in species-environment relationships Buckley, H.; Case, B.; Zimmerman, J.K.; Thompson, J.; Myers, J.; Ellison, A. Journal Article
2016 Predation of Telebasis vulnerata (Odonata: Coenagrionidae) eggs by detritivorous caddisfly larva, Phylloicus pulchrus (Trichoptera: Calamoceratidae) Cardona-Rivera, G.; Ramírez, A. Journal Article
2016 Nitrogen additions mobilize soil base cations in two tropical forests Cusack, D.F.; Macy, J.; McDowell, W.H. Rates of atmospheric nitrogen (N) deposition are increasing rapidly in tropical regions, which are projected to receive some of the greatest deposition levels globally in the coming decades. Tropical forests on highly weathered soils generally have high N availability, so added N is not likely to stimulate plant growth. Instead, N addition to these soils may rapidly alter the availability of other scarcer nutrients like base cations, via displacement from soil exchange sites and mobilization into solution. We hypothesized that: (1.) Addition of mineral N to highly weathered tropical soils rapidly mobilizes base cations into solution, with increasing fertilization effects over time. (2.) Nitrogen fertilization reduces cation availability on soil exchange sites, because of increased mobilization and loss down the soil profile. We assessed the short-term (1–2 year) and mid-term (4–5 year) effects of N fertilization on base cation mobilization to 40 cm depths in two distinct tropical forests. Over the first 5 years of the experiment, fertilization significantly increased calcium, magnesium, and potassium concentrations in soil solution, as well as all dissolved N chemical species. There was an increasing fertilization effect over time for all solutes across soil depths, suggestive of downward leaching. Comparing the two forests, there was no difference in the magnitude or timing of the fertilization effect on base cation mobilization, although dissolved N concentrations increased most rapidly in the upper elevation forest, where background dissolved N was also higher. Surprisingly, salt-extractable base cations also increased for fertilized versus control soils. Our results suggest that addition of mineral N to tropical forests on highly weathered soils is highly likely to mobilize base cations into solution, with subsequent leaching down the soil profile. These results imply that N deposition in tropical forests on highly weathered soils may exacerbate cation scarcity in these ecosystems, and could negatively affect long-term plant growth. Journal Article fertilization; hurricane; Montane; nutrients; Puerto Rico; rainforest
2016 Evaluación de la calidad ecológica de los ríos en Puerto Rico: principales amenazas y herramientas de evaluación Gutierrez-Fonseca, P.E.; Ramírez, A. Journal Article
2016 The interaction of land-use legacies and hurricane disturbance in subtropical wet forest: twenty-one years of change Hogan, J.A.; Zimmerman, J.K.; Nytch, C.; Thompson, J.; Uriarte, M. Disturbance shapes plant communities over a wide variety of spatial and temporal scales. How natural and anthropogenic disturbance interact to shape ecological communities is highly variable and begs a greater understanding. We used five censuses spanning the years 1990–2011 from the 16-ha Luquillo Forest Dynamics Plot (LFDP) in northeast Puerto Rico to investigate the interplay of human land-use legacies dating to the early 20th century and two recent hurricanes (Hugo, 1989 and Georges, 1998). The LFDP is a landscape mosaic comprised of an area of mature subtropical wet forest and three areas of secondary forest with differing past land-use intensities. We examined the degree to which hurricane disturbance–effect and subsequent community recovery varied across past land-use classes. We expected areas with greater intensity of human land use to be more affected by hurricane disturbance therefore exhibiting greater initial damage and longer successional recovery times. Structurally, areas of secondary forest contained smaller trees than old-growth areas; hurricanes caused widespread recruitment of shrubs and saplings that thinned with time since the first hurricane. Species richness of the plot declined over time, mostly due to the loss of rare species, but also due to the loss of some heliophilic, pioneer species that became abundant after the first hurricane. Species composition differed strongly between areas of secondary and mature forest, and these differences were largely constant over time, except for an increase in compositional differences following the second hurricane. An indicator species analysis attributed this pattern to the longer persistence of pioneer species in areas of greater past land-use intensity, likely due to the more open canopy in secondary forest. When secondary forest areas of differing past land-use intensity were considered separately, few species of low community rank were found as indicators. When these areas were combined, more and higher-ranked species emerged as indicators, creating ecologically meaningful indicator species combinations that better captured the broad-scale plant community response to past land use. Our findings support the idea that effects of past land use can persist for decades to centuries following land-use abandonment, illustrating the importance of land-use legacies in shaping regenerating tropical secondary forests. Journal Article
2016 Land-use history augments environment–plant community relationship strength in a Puerto Rican wet forest Hogan, J.A.; Zimmerman, J.K.; Uriarte, M.; Turner, B.L.; Thompson, J. Summary Environmental heterogeneity influences the species composition of tropical forests, with implications for patterns of diversity and species coexistence in these hyperdiverse communities. Many studies have examined how variability in soil nutrients and topography influence plant community composition, with differing results. None have quantified the relative contribution of environmental heterogeneity versus endogenous processes to variability in forest community composition over time and with respect to successional recovery. Using five consecutive trees censuses of a forest plot in Puerto Rico, conducted between 1990 and 2011, we evaluated the influence of edaphic and topographic variability on community composition. The plot has a well-documented land-use history and is subject to periodic hurricane disturbance. Using multiple canonical distance-based redundancy analyses, we studied how spatial heterogeneity in soil nutrients and topography structure community composition over time, as the forest recovers from long-term land-use effects and two major hurricanes in 1989 and 1998. For the entire plot, spatial variables (principle coordinates of neighbourhood matrices), representing the autocorrelation of tree species in the community, explained the majority (49–57%) of the variability in tree community composition. The explanatory power of spatial variables decreased over time, as forest structure recovered from hurricane damage and the stems in the understorey died. Soil nutrients and topography, collectively, explained a moderate portion (33–37%) of the species compositional variation and were slightly more robust in explaining compositional differences in areas of more intense past land use. Areas of less-intense past land use showed weaker community–environmental trends overall, illustrating a tendency for stronger resource competition (i.e. light, water and soil nutrients) between species in these areas. This illustrates how environmental–plant community interactions are strengthened by the lasting effects of human land-use legacies, which persist for decades to centuries. Synthesis. Our findings confirm past land use to be a fundamental driver of the structure and composition of secondary forests through its impacts on the tree community, the abiotic terrestrial environment and their interaction. Since the extent of second-growth tropical forests continues to increase, our findings highlight the importance of understanding the processes that determine the rate and nature of their succession. Journal Article beta-diversity maps; land-use legacies; Luquillo; plant–soil (below-ground) interac- tions; soil resources; spatial autoco rrelation; terrain ruggedness; topography; tropical forest; variance partitioning
2016 Confessions of a Fungal Systematist
Lodge, D. J, M. R Willig, and L. A Walker. 2016. Confessions Of A Fungal Systematist. In Long-Term Ecological Research: Changing the Nature of Scientists, Long-Term Ecological Research: Changing the Nature of Scientists, New York, New York: Oxford University Press.
Lodge, D.J.; Willig, M.R.; Walker, L.A. Book Chapter
2016 A Glimpse of the Tropics Through Odum's Macroscope
Lugo, A.E., M. R Willig, and L. A Walker. 2016. A Glimpse Of The Tropics Through Odum's Macroscope. In Long-Term Ecological Research: Changing the Nature of Scientists, Long-Term Ecological Research: Changing the Nature of Scientists, New York, New York: Oxford University Press.
Lugo, A.E.; Willig, M.R.; Walker, L.A. Book Chapter
2016 Drought in the Critical Zone: Engaging Students in Authentic Inquiry Through Data Jam McGee, S.; Rodríguez, B. Journal Article
2016 Taking students on a Journey to El Yunque. International Journal of Designs for Learning McGee, S.; Zimmerman, J.K. As the developers of Journey to El Yunque, we have taken a different approach to the process of designing a science curriculum. Rather than start with a specific set of concepts or skills to target as learning outcomes, we started by identifying a specific community of practice to which we sought to connect students. Researchers in the El Yunque rainforest in Puerto Rico have been studying the impact of hurricanes on ecosystem dynamics and have been modeling what the long-term impact would be if changes to the global climate increase the frequency of severe hurricanes. Therefore, hurricane impact became the focal phenomenon for the unit. We modeled the process of investigating hurricane impact after the long-term ecological research practices of researchers in El Yunque. Students begin by investigating the long-term impact of hurricanes on the producers in El Yunque. Next students investigate the long-term impact of hurricanes on various consumers in the rainforest. Finally, students investigate how hurricanes impact the cycling of resources directly as well as indirectly through changes in organisms’ use of those resources in the rainforest. A central tension in the design process is how to coherently represent the spatial relationships between the components of the ecosystem and the temporal dynamics of the individual components. In this paper, we present the evolution of the program as we sought to balance that design tension and build an environment that connects students to the central phenomenon and practices of the community of researchers in El Yunque. Journal Article
2016 Variation of organic matter quantity and quality in streams at Critical Zone Observatory watersheds Miller, M.P.; Boyer, E.W.; McKnight, D.M.; Brown, M.G.; Gabor, R.S.; Hunsaker, C.T.; L., I.; Inamdar, S.; Johnson, D.W.; Kaplan, L.A.; Lin, H.; McDowell, W.H.; Perdrial, J.N. The quantity and chemical composition of dissolved organic matter (DOM) in surface waters influence ecosystem processes and anthropogenic use of freshwater. However, despite the importance of understanding spatial and temporal patterns in DOM, measures of DOM quality are not routinely included as part of large-scale ecosystem monitoring programs and variations in analytical procedures can introduce artifacts. In this study, we used consistent sampling and analytical methods to meet the objective of defining variability in DOM quantity and quality and other measures of water quality in streamflow issuing from small forested watersheds located within five Critical Zone Observatory sites representing contrasting environmental conditions. Results show distinct separations among sites as a function of water quality constituents. Relationships among rates of atmospheric deposition, water quality conditions, and stream DOM quantity and quality are consistent with the notion that areas with relatively high rates of atmospheric nitrogen and sulfur deposition and high concentrations of divalent cations result in selective transport of DOM derived from microbial sources, including in-stream microbial phototrophs. We suggest that the critical zone as a whole strongly influences the origin, composition, and fate of DOM in streams. This study highlights the value of consistent DOM characterization methods included as part of long-term monitoring programs for improving our understanding of interactions among ecosystem processes as controls on DOM biogeochemistry. Journal Article
2016 Do community-weighted mean functional trait values represent optimal strategies? Muscarella, M.; Uriarte, M. The notion that relationships between community-weighted mean (CWM) traits (i.e. plot-level trait values weighted by species abundances) and environmental conditions reflect selection towards locally optimal phenotypes is challenged by the large amount of interspecific trait variation typically found within ecological communities. Reconciling these contrasting patterns is a key to advancing predictive theories of functional community ecology. We combined data on geographical distributions and three traits (wood density, leaf mass per area and maximum height) of 173 tree species in Puerto Rico. We tested the hypothesis that species are more likely to occur where their trait values are more similar to the local CWM trait values (the ‘CWM-optimality’ hypothesis) by comparing species occurrence patterns (as a proxy for fitness) with the functional composition of forest plots across a precipitation gradient. While 70% of the species supported CWM-optimality for at least one trait, nearly 25% significantly opposed it for at least one trait, thereby contributing to local functional diversity. The majority (85%) of species that opposed CWM-optimality did so only for one trait and few species opposed CWM-optimality in multivariate trait space. Our study suggests that constraints to local functional variation act more strongly on multivariate phenotypes than on univariate traits. Journal Article ecological niche models; Functional diversity; leaf mass per area; Maximum height; tropical forests; wood density
2016 Sobre ensambles y ensamblajes ecológicos-respuesta a Monge-Nájera. Ramírez, A.; Gutiérrez-Fonseca, P.E.G. Journal Article
2016 Atmospheric controls on Puerto Rico precipitation using artificial neural networks Ramseyer, C.A.; Mote, T.L. The growing need for local climate change scenarios has given rise to a wide range of empirical climate downscaling techniques. One of the most critical decisions in these methodologies is the selection of appropriate predictor variables for the downscaled surface predictand. A systematic approach to selecting predictor variables should be employed to ensure that the most important variables are utilized for the study site where the climate change scenarios are being developed. Tropical study areas have been far less examined than mid- and high-latitudes in the climate downscaling literature. As a result, studies analyzing optimal predictor variables for tropics are limited. The objectives of this study include developing artificial neural networks for six sites around Puerto Rico to develop nonlinear functions between 37 atmospheric predictor variables and local rainfall. The relative importance of each predictor is analyzed to determine the most important inputs in the network. Randomized ANNs are produced to determine the statistical significance of the relative importance of each predictor variable. Lower tropospheric moisture and winds are shown to be the most important variables at all sites. Results show inter-site variability in u- and v-wind importance depending on the unique geographic situation of the site. Lower tropospheric moisture and winds are physically linked to variability in sea surface temperatures (SSTs) and the strength and position of the North Atlantic High Pressure cell (NAHP). The changes forced by anthropogenic climate change in regional SSTs and the NAHP will impact rainfall variability in Puerto Rico. Journal Article Artificial neural networks; Climate downscaling; Daily Caribbean precipitation; Predictor variables
2016 Baseflow physical characteristics differ at multiple spatial scales in stream networks across diverse biomes Rüegg, J.; Dodds, W.K.; Daniels, M.D.; Baker, C.L.; Bowden, W.B.; Farrell, K.J.; Flinn, M.B.; Harms, T.K.; Jones, J.B.; Koenig, L.E.; Kominoski, J.S.; McDowell, W.H.; Parker, S.P.; Rosemond, A.D.; Sheehan, K.R.; Trentman, M.T.; Whiles, M.R.; Wollheim, W.M. Context Spatial scaling of ecological processes is facilitated by quantifying underlying habitat attributes. Physical and ecological patterns are often measured at disparate spatial scales limiting our ability to quantify ecological processes at broader spatial scales using physical attributes. Objective We characterized variation of physical stream attributes during periods of high biological activity (i.e., baseflow) to match physical and ecological measurements and to identify the spatial scales exhibiting and predicting heterogeneity. Methods We measured canopy cover, wetted width, water depth, and sediment size along transects of 1st–5th order reaches in five stream networks located in biomes from tropical forest to arctic tundra. We used hierarchical analysis of variance with three nested scales (watersheds, stream orders, reaches) to identify scales exhibiting significant heterogeneity in attributes and regression analyses to characterize gradients within and across stream networks. Results Heterogeneity was evident at one or multiple spatial scales: canopy cover and water depth varied significantly at all three spatial scales while wetted width varied at two scales (stream order and reach) and sediment size remained largely unexplained. Similarly, prediction by drainage area depended on the attribute considered: depending on the watershed, increases in wetted width and water depth with drainage area were best fit with a linear, logarithmic, or power function. Variation in sediment size was independent of drainage area. Conclusions The scaling of ecologically relevant baseflow physical characteristics will require study beyond the traditional bankfull geomorphology since predictions of baseflow physical attributes by drainage area were not always best explained by geomorphic power laws. Journal Article Boreal forest; geomorphology; Grasslands; Nested ANOVA; Scaling; temperate forest
2016 Insect Ecology: an Ecosystem Approach
Schowalter, T.D. 2016. Insect Ecology: An Ecosystem Approach. 4th ed. San Diego, CA.: Elsevier/Academic Press.
Schowalter, T.D. Book
2016 Taking the Long View: Growing Up in the LTER
Silver, W. L, M. R Willig, and L. A Walker. 2016. Taking The Long View: Growing Up In The Lter. In Long-Term Ecological Research: Changing the Nature of Scientists, Long-Term Ecological Research: Changing the Nature of Scientists, New York, New York: Oxford University Press.
Silver, W.L.; Willig, M.R.; Walker, L.A. Book Chapter
2016 Sustaining Long-Term Research: Collaboration, multidisciplinarity and synthesis in the Long-Term Ecological Research (LTER) Program
Waide, R. B, L. A Walker, and M. R Willig. 2016. Sustaining Long-Term Research: Collaboration, Multidisciplinarity And Synthesis In The Long-Term Ecological Research (Lter) Program. In Long-Term Ecological Research: Changing the Nature of Scientist, Long-Term Ecological Research: Changing the Nature of Scientist, New York, New York: Oxford University Press.
Waide, R.B.; Walker, L.A.; Willig, M.R. Book Chapter
2016 Changing the nature of scientists changing the nature of scientists: Participation in the Long-Term Ecological Research Program
Willig, M. R, and L. A Walker. 2016. Changing The Nature Of Scientists Changing The Nature Of Scientists: Participation In The Long-Term Ecological Research Program. In Long-Term Ecological Research: Changing the Nature of Scientists, Long-Term Ecological Research: Changing the Nature of Scientists, New York, New York: Oxford University Press.
Willig, M.R.; Walker, L.A. Book Chapter
2016 Nitrate uptake across biomes and the influence of elemental stoichiometry: A new look at LINX II Wymore, A.S.; Coble, A.A.; Rodríguez-Cardona, B.; McDowell, W.H. Considering recent increases in anthropogenic N loading, it is essential to identify the controls on N removal and retention in aquatic ecosystems because the fate of N has consequences for water quality in streams and downstream ecosystems. Biological uptake of nitrate (NO3−) is a major pathway by which N is removed from these ecosystems. Here we used data from the second Lotic Intersite Nitrogen eXperiment (LINX II) in a multivariate analysis to identify the primary drivers of variation in NO3− uptake velocity among biomes. Across 69 study watersheds in North America, dissolved organic carbon:NO3− ratios and photosynthetically active radiation were identified as the two most important predictor variables in explaining NO3− uptake velocity. However, within a specific biome the predictor variables of NO3− uptake velocity varied and included various physical, chemical, and biological attributes. Our analysis demonstrates the broad control of elemental stoichiometry on NO3− uptake velocity as well as the importance of biome-specific predictors. Understanding this spatial variation has important implications for biome-specific watershed management and the downstream export of NO3−, as well as for development of spatially explicit global models that describe N dynamics in streams and rivers. Journal Article
2016 Biotropica Issue Information Chazdon, R.L.; Uriarte, M. Journal Article
2016 Tropical water availability model (tWAM) for the El Yunque National Forest, Puerto Rico Christian, J.; Chappell, S.; McKay, S.; Pringle, C.M. Report
2016 Development of a tropical geographic unit hydrograph in the Luquillo Mountains of Eastern Puerto Rico: A novel approach Martin, J.A.

Synthetic unit hydrographs (SUHs) are useful numeric models developed to predict empirical unit hydrograph parameters as a function of watershed characteristics. These statistical equations usually relate peak flow and timing to watershed characteristics. Once produced, a SUH estimates a storm hydrograph at the outlet of a watershed for a given excess precipitation amount. A sub class of SUHs is the Geographic Unit Hydrographs (GUH), which is informed by the geographic properties of basins (i.e. average slope, average land use, annual precipitation). Recent GUH models use geographic information systems (GIS) allow scientist and engineers to model the flow path and velocity to calculate the runoff response of that basin. This Tropical Geographic Unit Hydrograph (tGUH) model is developed for a specific tropical island environment, and includes an analytical methodology to derive required empirical coefficients directly from observed geographic characteristics, which in turn can provide a more consistent runoff estimate between users. Additionally, with the tGUH described here, unit hydrograph parameters are found to be sensitive to non-stationary parameters including land use (attributable to anthropogenic change) and annual precipitation change (attributable to climate change).

Thesis GIS; Synthetic Unit Hydrographs; Tropical Hydrology; Unit Hydrograph
2016 Arbuscular mycorrhizal fungal diversity and natural enemies promote coexistence of tropical tree species Bachelot, B.; Uriarte, M.; McGuire, K.L.; Thompson, J.; Zimmerman, J.K. Journal Article tropical forest
2016 Impact of Long-Range Transported African Dust on Cloud Water Chemistry at a Tropical Montane Cloud Forest in Northeastern Puerto Rico Valle-Díaz, C.J.; Torres-Delgado, E.; Colón-Santos, S.M.; Lee, T.; Collett, J.L.; McDowell, W.H.; Mayol-Bracero, O.L. Bulk and drop size fractionated cloud water was collected at a Caribbean tropical montane cloud forest (TMCF) in northeastern Puerto Rico in the summer months of 2010–2012 and winter months of 2011 as part of the Puerto Rico African Dust and Cloud Study (PRADACS). We studied how cloud water chemistry in a Caribbean TMCF was affected by long-range transported African dust (LRTAD). Using HYSPLIT trajectories and enrichment factor analysis, the air masses influencing clouds at Pico del Este were identified as dust, marine, and dust with anthropogenic influence. Samples were analyzed for pH, conductivity, water-soluble ions, and metals. Na+ and Cl– comprised the main water-soluble ions (60– 80%) suggesting a strong marine influence. A 0.1–10% contribution of anthropogenic (nss-SO4 2–) and 0.2–13% contribution of mineral dust (nss-Ca2+) sources to the cloud chemical composition was observed. Primary aerosols (i.e., mineral dust and sea-salt) were enriched in large cloud water droplets (LCWD) and secondary aerosols (i.e., anthropogenic particles) were enriched in small cloud water droplets (SCWD). As a result, pH was found to be higher in LCWD due to the neutralizing capacity of nss-Ca2+ and lower in SCWD due to the presence of acidifying species (nss-SO4 2–, NO3 –, and organic acids). Fe and Al, indicators for mineral dust were similarly distributed across the cloud droplet size spectrum. Our results show that LRTAD events modulate bulk and size-fractionated cloud water chemistry, potentially influencing cloud microphysical properties and processes. Journal Article Sahara desert; Desert dust; Rainforest; Cloud processing
2016 Variation of organic matter quantity and quality in streams at Critical Zone Observatory watersheds Miller, M.P.; Boyer, E.W.; McKnight, D.M.; Brown, M.G.; Gabor, R.S.; Hunsaker, C.T.; Iavorivska, L.; Inamdar, S.; Johnson, D.W.; Kaplan, L.A.; Lin, H.; McDowell, W.H.; Perdrial, J.N. The quantity and chemical composition of dissolved organic matter (DOM) in surface waters influence ecosystem processes and anthropogenic use of freshwater. However, despite the importance of understanding spatial and temporal patterns in DOM, measures of DOM quality are not routinely included as part of large-scale ecosystem monitoring programs and variations in analytical procedures can introduce artifacts. In this study, we used consistent sampling and analytical methods to meet the objective of defining variability in DOM quantity and quality and other measures of water quality in streamflow issuing from small forested watersheds located within five Critical Zone Observatory sites representing contrasting environmental conditions. Results show distinct separations among sites as a function of water quality constituents. Relationships among rates of atmospheric deposition, water quality conditions, and stream DOM quantity and quality are consistent with the notion that areas with relatively high rates of atmospheric nitrogen and sulfur deposition and high concentrations of divalent cations result in selective transport of DOM derived from microbial sources, including in-stream microbial phototrophs. We suggest that the critical zone as a whole strongly influences the origin, composition, and fate of DOM in streams. This study highlights the value of consistent DOM characterization methods included as part of long-term monitoring programs for improving our understanding of interactions among ecosystem processes as controls on DOM biogeochemistry Journal Article
2016 Abrupt Change in Forest Height along a Tropical Elevation Gradient Detected Using Airborne Lidar Wolf, J.; Brocard, G.; Willenbring, J.; Porder, S.; Uriarte, M. Most research on vegetation in mountain ranges focuses on elevation gradients as climate gradients, but elevation gradients are also the result of geological processes that build and deconstruct mountains. Recent findings from the Luquillo Mountains, Puerto Rico, have raised questions about whether erosion rates that vary due to past tectonic events and are spatially patterned in relation to elevation may drive vegetation patterns along elevation gradients. Here we use airborne light detection and ranging (LiDAR) technology to observe forest height over the Luquillo Mountain Range. We show that models with different functional forms for the two prominent bedrock types best describe the forest height-elevation patterns. On one bedrock type there are abrupt decreases in forest height with elevation approximated by a sigmoidal function, with the inflection point near the elevation of where other studies have shown there to be a sharp change in erosion rates triggered by a tectonic uplift event that began approximately 4.2 My ago. Our findings are consistent with broad geologically mediated vegetation patterns along the elevation gradient, consistent with a role for mountain building and deconstructing processes. Journal Article ecology; vegetation; geology; active remote sensing; erosion; tectonics; 10Be; critical zone observatory; long-term ecological research; three-dimensional structure
2016 Climate and Biodiversity Effects on Standing Biomass in Puerto Rican Forests Muscarella, R.; Uriarte, M.; Erickson, D.L.; Swenson, N.G.; Zimmerman, J.K.; Kress, J.W. Carbon sequestration is a major ecosystem service provided by tropical forests. Especially in light of global climate change, understanding the drivers of forest productivity is of critical importance. Although abiotic conditions (e.g., precipitation) are known to influence forest productivity, ecological theory predicts that biodiversity may also have independent effects on productivity. We estimated standing aboveground biomass (AGB) in mature forests of Puerto Rico that span a strong precipitation gradient and 2 general soil types. With these data, we examined the independent and interactive effects of precipitation and 5 metrics of tree diversity (species richness, phylogenetic diversity, and three aspects of functional diversity) on spatial variation of AGB in forests on 2 soil types. Precipitation had a strong positive effect on AGB on both soil types, and we did not find evidence for an independent effect of diversity on AGB in either soil type. We found some evidence from plots on limestone soils that the increase in AGB along the precipitation gradient was less pronounced in plots where species richness was relatively high. We discuss our results in light of spatial scale and biodiversity–ecosystem function theory. Journal Article
2016 Interspecific Functional Convergence and Divergence and Intraspecific Negative Density Dependence Underlie the Seed-to-Seedling Transition in Tropical Trees Umaña, M.N.; Forrero-Montaña, J.; Muscarella, R.; Nytch, C.; Thompson, J.; Uriarte, M.; Zimmerman, J.K.; Swenson, N.G. The seed-to-seedling transition constitutes a critical bottleneck in the life history of plants and represents a major determinant of species composition and abundance. However, we have surprisingly little knowledge regarding the forces driving this ontogenetic transition. Here we utilize information regarding organismal function to investigate the strength of intra- and interspecific negative density dependence during the seed-to-seedling transition in Puerto Rican tree species. Our analyses were implemented at individual sites and across an entire 16-ha forest plot, spanning 6 years. The functional richness of seedling assemblages was significantly lower than expected given the seed assemblages, but the functional evenness was significantly higher than expected, indicating the simultaneous importance of constraints on the overall phenotypic space and trait differences for successful transitions from seed to seedling. The results were consistent across years. Within species, we also found evidence for strong intraspecific negative density dependence, where the probability of transition was proportionally lower when in a site with high conspecific density. These results suggest that filtering of similar phenotypes across species and strong negative density dependence within and among species are simultaneously driving the structure and dynamics of tropical tree assemblages during this critical life-history transition. Journal Article community assembly; functional ecology; functional richness; seed-to-seedling transition; tropical tree ecology
2016 Biogeographic patterns of soil diazotrophic communities across six forests in the North America Tu, Q.; Deng, Y.; Yan, Q.; Shen, L.; Lin, L.; He, Z.; Wu, L.; Van Nostrand, J.D.; Buzzard, V.; Michaletz, S.T.; Enquist, B.J.; Weiser, M.D.; Kaspari, M.; Waide, R.B.; Brown, J.H.; Zhou, J. Soil diazotrophs play important roles in ecosystem functioning by converting atmospheric N2 into biologically available ammonium. However, the diversity and distribution of soil diazotrophic communities in different forests and whether they follow biogeographic patterns similar to macroorganisms still remain unclear. By sequencing nifH gene amplicons, we surveyed the diversity, structure and biogeographic patterns of soil diazotrophic communities across six North American forests (126 nested samples). Our results showed that each forest harboured markedly different soil diazotrophic communities and that these communities followed traditional biogeographic patterns similar to plant and animal communities, including the taxa–area relationship (TAR) and latitudinal diversity gradient. Significantly higher community diversity and lower microbial spatial turnover rates (i.e. z-values) were found for rainforests (~0.06) than temperate forests (~0.1). The gradient pattern of TARs and community diversity was strongly correlated (r2 > 0.5) with latitude, annual mean temperature, plant species richness and precipitation, and weakly correlated (r2 < 0.25) with pH and soil moisture. This study suggests that even microbial subcommunities (e.g. soil diazotrophs) follow general biogeographic patterns (e.g. TAR, latitudinal diversity gradient), and indicates that the metabolic theory of ecology and habitat heterogeneity may be the major underlying ecological mechanisms shaping the biogeographic patterns of soil diazotrophic communities. Journal Article
2016 Deadwood, soil biota and nutrient dynamics in tropical forests: a review of case studies from Puerto Rico Gonzalez, G. Conference Proceedings biota; deadwood; nutrients; soil; tropical forests
2016 On the Role of the Saharan Air Layer in the 2015 Puerto Rico Drought
Ramseyer, C.A., T. L Mote, and P. W Miller. 2016. On The Role Of The Saharan Air Layer In The 2015 Puerto Rico Drought. In 113th Annual Meeting of the American Association of Geographers. April 5–9, 2017, Boston, MA., 113th Annual Meeting of the American Association of Geographers. April 5–9, 2017, Boston, MA., Boston, MA: American Association of Geographers (AAG).
Ramseyer, C.A.; Mote, T.L.; Miller, P.W. The Puerto Rico drought of 2015 led to water rationing throughout the eastern side of the island including San Juan. Additionally, the drought caused extensive changes to the biota and biogeochemistry in the El Yunque National Forest. We examine the drought of 2015 in northeastern Puerto Rico in comparison to the available historical record, with particular attention to 1994. In addition to examining precipitation, we examined key atmospheric variables that are strongly associated to precipitation variability, including wind shear, atmospheric moisture and pressure, and aerosols (specifically dust). Results indicate the critical role of the Saharan Air Layer (SAL) on the drought, particularly in the strengthening of the trade wind inversion. This work makes use of two unique tools that are only recently available to the research community. The DayMet 1-km daily precipitation product is used to assess the timing and magnitude of the drought in the complex topography of eastern Puerto Rico. Additionally, the experimental Gálvez-Davison Index (GDI) is used to understand the impact of SAL intrusions on precipitation. This index has been used in the operational community to forecast convective precipitation in Puerto Rico, and components of the index are well suited to capture the effect of the hot, dry air intrusions above the trade wind inversion. We believe this is the first application of the GDI to examine the impact of the SAL on precipitation. Conference Paper
2016 Assessing the mechanisms underlying land use impacts on the composition and diversity of soil fungal communities in a tropical forest Bachelot, B.; Uriarte, M.; Zimmerman, J.K.; Thompson, J.; Leff, J.W.; Kosher, J.; McGuire, K. Journal Article
2015 Long-Term Ecological Research: Changing the Nature of Scientists
Willig, M. R, and L. A Walker. 2015. Long-Term Ecological Research: Changing The Nature Of Scientists. New York, New York: Oxford University Press.
Willig, M.R.; Walker, L.A. Book
2015 Preface
Willig, M. R, and L. A Walker. 2015. Preface. In Long-Term Ecological Research: Changing the Nature of Scientists, Long-Term Ecological Research: Changing the Nature of Scientists, eds. M. R Willig and Walker, L. A. New York, New York: Oxford University Press.
Willig, M.R.; Walker, L.A. Book Chapter
2015 Tradeoffs of participation in the Long-Term Ecological Research (LTER) Program: Immediate and long-term consequences
Willig, M. R, and L. A Walker. 2015. Tradeoffs Of Participation In The Long-Term Ecological Research (Lter) Program: Immediate And Long-Term Consequences. In Long-Term Ecological Research: Changing the Nature of Scientists, Long-Term Ecological Research: Changing the Nature of Scientists, eds. M. R Willig and Walker, L. A. New York, New York: Oxford University Press.
Willig, M.R.; Walker, L.A. Book Chapter
2015 Dominant predators mediate the impact of habitat size on trophic structure in bromeliad invertebrate communities Petermann, J.S.; Farjalla, V.F.; Jocque, M.; Kratina, P.; MacDonald, A.M.; Marino, N.A.C.; de Omena, P.M.; Piccoli, G.C.O.; Richardson, B.A.; Richardson, M.J.; Romero, G.Q.; Videla, M.; Srivastava, D.S.

Local habitat size has been shown to influence colonization and extinction processes of species in patchy environments. However, species differ in body size, mobility, and trophic level, and may not respond in the same way to habitat size. Thus far, we have a limited understanding of how habitat size influences the structure of multitrophic communities and to what extent the effects may be generalizable over a broad geographic range. Here, we used water-filled bromeliads of different sizes as a natural model system to examine the effects of habitat size on the trophic structure of their inhabiting invertebrate communities. We collected composition and biomass data from 651 bromeliad communities from eight sites across Central and South America differing in environmental conditions, species pools, and the presence of large-bodied odonate predators. We found that trophic structure in the communities changed dramatically with changes in habitat (bromeliad) size. Detritivore?:?resource ratios showed a consistent negative relationship with habitat size across sites. In contrast, changes in predator?:?detritivore (prey) ratios depended on the presence of odonates as dominant predators in the regional pool. At sites without odonates, predator?:?detritivore biomass ratios decreased with increasing habitat size. At sites with odonates, we found odonates to be more frequently present in large than in small bromeliads, and predator?:?detritivore biomass ratios increased with increasing habitat size to the point where some trophic pyramids became inverted. Our results show that the distribution of biomass amongst food-web levels depends strongly on habitat size, largely irrespective of geographic differences in environmental conditions or detritivore species compositions. However, the presence of large-bodied predators in the regional species pool may fundamentally alter this relationship between habitat size and trophic structure. We conclude that taking into account the response and multitrophic effects of dominant, mobile species may be critical when predicting changes in community structure along a habitat-size gradient.

Journal Article apex predator; aquatic mesocosms; biomass; body size; food web; insects; metacommunity; multitrophic interaction; Odonata; predation; predator : prey ratio; top-down control
2015 The Stability of Invertebrate Communities in Bromeliad Phytotelmata in a Rain Forest Subject to Hurricanes Richardson, M.J.; Richardson, B.A.; Srivastava, D.S.

Communities of invertebrate animals in lower canopy and saxicolous tank bromeliads, originally studied in 1993–1997, were resampled along an elevational gradient in tabonuco, palo colorado, and dwarf or cloud forest in Puerto Rico in 2010. These Puerto Rican montane rain forests were impacted strongly by hurricanes in 1989 and 1998, so the surveys in the 1990s represented 4–8 yr of post-hurricane recovery, whereas our recent survey represents 12 yr of post-hurricane recovery. At most elevations, species diversity, both within individual bromeliads and at the forest scale, declined between the 1990s and 2010. This decline in diversity between decades is associated with reductions in bromeliad density as the canopy progressively closed during recovery from hurricane damage. The observed decline in alpha and gamma diversity appears to have involved the loss of rarer species, as might be expected from standard metapopulation theory. By contrast, the most common species were remarkably stable in abundance, composition, and frequency of occurrence over the two decades. In the lowermost tabonuco forest, two endemic bromeliad specialists, restricted to bromeliads for their entire life cycle, were not found on resampling. This study also demonstrates that, at least in Puerto Rico, sets of ten plants from each forest were sufficient to monitor bromeliad invertebrate populations and their diversity over time.Las comunidades de animales invertebrados en el dosel menor y las bromelias tanque saxícolas, estudiadas originalmente entre los años 1993–1997, fueron re-muestreadas a lo largo de un gradiente altitudinal en Tabonuco, Palo Colorado, y en bosque enano o nublado en Puerto Rico en el año 2010. Estos bosques húmedos montanos de Puerto Rico se vieron muy afectados por los huracanes en los años 1989 y 1998, por lo que los estudios realizados en la década del 1990 representaron 4.8 años de recuperación post- huracán, mientras que nuestro reciente inventario representa doce años de la recuperación posterior a los huracanes. La diversidad de especies, tanto dentro de individuos de bromelias, y a nivel del bosque, disminuyó entre los años 1990 y 2010 en la mayoría de las elevaciones. Esta disminución de la diversidad entre décadas, se asocia con reducciones en la densidad de bromelias, mientras el dosel se cierra de forma progresiva durante el proceso de recuperación de daños ocasionados por huracanes. El descenso observado en la diversidad alfa y gamma parece implicar la pérdida de especies raras, como era de esperarse según la teoría estándar de la meta-población. Por el contrario, las especies más comunes fueron notablemente estables en abundancia, composición, y en la frecuencia de ocurrencia en más de dos décadas. En las partes más bajas del bosque Tabonuco, dos bromelias endémicas especializadas, restringidas a las bromelias durante todo su ciclo de vida, no se encontraron en el re-muestreo. Este estudio también demuestra que, al menos en Puerto Rico, series de diez plantas de cada bosque fueron suficientes para monitorear las poblaciones de invertebrados de bromelias y su diversidad a través del tiempo.

Journal Article Vriesea
2015 Anthropogenic factors and habitat complexity influence biodiversity but wave exposure drives species turnover of a subtropical rocky inter-tidal metacommunity Bloch, C.P.; Klingbeil, B.T.

Coastal ecosystems are complex and species rich, but are vulnerable to degradation from a variety of anthropogenic activities. Nevertheless, information on inter-tidal community composition in the Caribbean Basin and at other oceanic sites is lacking. Such information is essential to developing a more comprehensive understanding of rocky inter-tidal systems and their responses to global change. The goals of this study were to determine the relative importance of environmental (wave power density, wave height), habitat (e.g. algal cover, slope, complexity of rock surfaces) and anthropogenic (distance to roads, population density) factors associated with the structure of local assemblages at multiple shore heights and the regional metacommunity of mobile invertebrates on oceanic rocky inter-tidal habitats. Environmental characteristics associated with habitat complexity (algal cover, rock surface complexity) and human population density were most strongly associated with abundance and biodiversity of invertebrates. Species richness was positively correlated with surface complexity, but abundance was negatively correlated with both surface complexity and per cent algal cover. By contrast, abundance of invertebrates was positively correlated with human population density, and diversity was negatively correlated with human population density. Abundance of invertebrates was greatest in the mid inter-tidal zone, whereas diversity was greatest in the lower inter-tidal zone. Metacommunity structure was Gleasonian, but the gradient along which species turnover occurred was correlated with measures of wave exposure, rather than anthropogenic activity. Unlike in previous studies, mostly at mainland sites, human activity primarily altered dominance patterns of communities, while having relatively little effect on species richness or composition.

Journal Article rocky intertidal
2015 Consequence of altered nitrogen cycles in the coupled human and ecological system under changing climate: The need for long-term and site-based research Shibata, H.; Branquinho, C.; McDowell, W.H.; Mitchell, M.J.; Monteith, D.T.; Tang, J.; Arvola, L.; Cruz, C.; Cusack, D.F.; Halada, L.; Kopacek, J.; Maguas, C.; Sajidu, S.; Schubert, H.; Tokuchi, N.; Zahora, J.

Anthropogenically derived nitrogen (N) has a central role in global environmental changes, including climate change, biodiversity loss, air pollution, greenhouse gas emission, water pollution, as well as food production and human health. Current understanding of the biogeochemical processes that govern the N cycle in coupled human-ecological systems around the globe is drawn largely from the long-term ecological monitoring and experimental studies. Here, we review spatial and temporal patterns and trends in reactive N emissions, and the interactions between N and other important elements that dictate their delivery from terrestrial to aquatic ecosystems, and the impacts of N on biodiversity and human society. Integrated international and long-term collaborative studies covering research gaps will reduce uncertainties and promote further understanding of the nitrogen cycle in various ecosystems.

Journal Article atmospheric deposition; Biogeochemistry; N2O; Nitrogen leaching; Water quality
2015 NEON and STREON: Opportunities and challenges for the aquatic sciences McDowell, W.H.

Creation of the National Ecological Observatory Network (NEON) provides unparalleled opportunities for continental-scale research and synthesis in aquatic sciences. Organizers of the NEON aquatic network will equip sites at 29 streams or small rivers across bioclimatic regions of the USA to measure O2 dynamics, aquatic community structure, and aquatic chemistry for up to 3 decades. Data will be collected via a suite of sensors and traditional measurements of a wide range of variables with standardized techniques. The availability of such data will usher in a new era for aquatic scientists, who can use the data to understand the influence of major drivers of stream ecosystem structure and function at regional to continental scales. This rich data stream also will present challenges for the aquatic community. These challenges include interpreting field measurements at distant sites, analysis and management of large data sets, development of appropriate tools for synthesis, and changes in the culture of aquatic science. With the advent of NEON, the most successful aquatic scientists in the coming decades will be equally versed in field measurements and sophisticated analysis of large data sets.

Journal Article big data; culture of science; NEON; sensor network; stream chemistry; stream ecology; stream metabolism; STREON
2015 Tropical Forest Response to Large- Scale Experiments Shiels, A.B.; González, G. Journal Article
2015 Cascading Effects of Canopy Opening and Debris Deposition from a Large-Scale Hurricane Experiment in a Tropical Rain Forest Shiels, A.B.; González, G.; Lodge, D.J.; Willig, M.R.; Zimmerman, J.K.

Intense hurricanes disturb many tropical forests, but the key mechanisms driving post-hurricane forest changes are not fully understood. In Puerto Rico, we used a replicated factorial experiment to determine the mechanisms of forest change associated with canopy openness and organic matter (debris) addition. Cascading effects from canopy openness accounted for most of the shifts in the forest biota and biotic processes, which included increased plant recruitment and richness, as well as the decreased abundance and diversity of several animal groups. Canopy opening decreased litterfall and litter moisture, thereby inhibiting lignin-degrading fungi, which slowed decomposition. Debris addition temporarily increased tree basal area. Elevated soil solution nitrate was a dominant response after past hurricanes; this effect only occurred in our experiment with simultaneous canopy-opening and debris treatments. Although debris is an important carbon and nutrient source, short-term responses to cyclonic storms appear to be largely driven by canopy opening. 

Journal Article Large-scale disturbance; Luquillo Experimental Forest biodiversity; plant–animal–microbial interactions; resistance–resilience; soil solution chemistry
2015 Diversity enhances carbon storage in tropical forests
Poorter, L., M. T van der Sande, J. Thompson, E. JMM Arets, A. Alarcón, J. Álvarez-Sánchez, N. Ascarrunz, P. Balvanera, G. Barajas-Guzmán, A. Boit, F. Bongers, F. A Carvalho, F. Casanoves, G. Cornejo-Tenorio, F. RC Costa, C. V de Castilho, J. F Duivenvoorden, L. P Dutrieux, B. Enquist, F. Fernández-Méndez, B. Finegan, L. HL Gormley, J. R Healey, M. R Hoosbeek, G. Ibarra-Manríquez, A. B Junqueira, C. Levis, J. C Licona, L. S Lisboa, W. E Magnusson, M. Martínez-Ramos, A. Martínez-Yrizar, L. G Martorano, L. C Maskell, L. Mazzei, J. A Meave, F. Mora, R. Muñoz, C. Nytch, M. P Pansonato, T. W Parr, H. Paz, E. A Pérez-García, L. Y Rentería, J. Rodríguez-Velazquez, D. MA Rozendaal, A. R Ruschel, B. Sakschewski, B. Salgado-Negret, J. Schietti, M. Simões, F. L Sinclair, P. F Souza, F. C Souza, J. Stropp, ter H. Steege, N. G Swenson, K. Thonicke, M. Toledo, M. Uriarte, P. van der Hout, P. Walker, N Zamora, and M. Peña-Claros. 2015. Diversity Enhances Carbon Storage In Tropical Forests. Global Ecology and Biogeography 24(11): 1314-1328.