Biblio Including Abstracts, when available

Year of Publication Titlesort descending Biblio Citation Authors Abstract Type of Publication Keywords
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
2006 16S rRNA gene analyses of bacteria; community structures in the soils of evergreen broad-leaved forests in SW China Chan, O.C.; Yang, W.H.; Fu, Y.; Feng, W.T.; Sha, L.Q.; Casper, P.; Zou, X.M. Journal Article T-RFLP
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
2014 A canopy trimming experiment in Puerto Rico: the response of litter decomposition and nutrient release to canopy opening and debris deposition in a subtropical wet forest González, G.; Lodge, D.J.; Richardson, B.A.; Richardson, M.J.

In this study, we used a replicated factorial design to separate the individual and interacting effects of two main components of a severe hurricane – canopy opening and green debris deposition on leaf litter decay in the tabonuco forest in the Luquillo Mountains of Puerto Rico. We quantify changes in percent mass remaining (PMR), the concentration and absolute amounts of various chemical elements using fresh (green) and senesced leaf litter contained in litterbags of two different mesh sizes. Mass loss was significantly slowed by canopy trimming. There was no significant effect of debris treatment on the PMR of the litter. Canopy trimming increased the percent of initial N, Al, Ca, Fe, and Mg remaining and decreased the percent of initial Mn remaining compared with not trimmed plots. Debris addition increased the percent of initial N and P remaining and decreased the percent of initial Al, and Fe remaining in the decomposing litter compared to no debris added plots. Of the elements studied, only Al and Fe accumulated above 100% of initial. Accumulation of Al and Fe in the canopy trimmed and no debris plots is most likely dominated by the adsorption of these ions onto the surfaces of the decaying litter. Overall, P showed a rapid initial loss during the first 0.2 yr followed by steady loss. Nitrogen was lost steadily from leaf litter. The PMR of fresh and senesced litter was significantly affected by mesh size, with a higher mass remaining in small mesh bags. Fresh litter decayed faster than senesced litter; following patterns of initial N and P concentrations (higher in the former litter type). We found a significantly negative correlation between the Margalef index of diversity for the litter arthropods contained in the litterbags and the PMR, suggesting functional complexity is an important determinant of decay in this forest. Our results imply hurricanes can differentially impact litter decomposition and associated nutrient release via canopy opening and litter inputs.

Journal Article Litter decomposition; Luquillo experimental forest; Manipulative experiment; Nutrient concentration; Nutrient release; subtropical forest
2010 A Canopy Trimming Experiment in Puerto Rico: The Response of Litter Invertebrate Communities to Canopy Loss and Debris Deposition in a Tropical Forest Subject to Hurricanes Richardson, B.; Richardson, B.; González, G.; Shiels, A.B.; Srivastava, D.S.

Hurricanes cause canopy removal and deposition of pulses of litter to the forest floor. A Canopy Trimming Experiment (CTE) was designed to decouple these two factors, and to investigate the separate abiotic and biotic consequences of hurricane-type damage and monitor recovery processes. As part of this experiment, effects on forest floor invertebrate communities were studied using litterbags. Canopy opening resulted in increased throughfall, soil moisture and light levels, but decreased litter moisture. Of these, only throughfall and soil moisture had returned to control levels 9 months after trimming. Canopy opening was the major determinant of adverse changes in forest floor invertebrate litter communities, by reducing diversity andbiomass, irrespective of debris deposition, which played a secondary role. Plots subjected to the most disturbance, with canopy removed and debris added, had the lowest diversity and biomass. These two parameters were higher than control levels when debris was added to plots with an intact canopy, demonstrating that increased nutrient potential or habitat complexity can have a beneficial effect, but only if the abiotic conditions are suitable. Animal abundance remained similar over all treatments, because individual taxa responded differently to canopy trimming. Mites, Collembola, and Psocoptera, all microbiovores feeding mainly on fungal hyphae and spores, responded positively,with higher abundance in trimmed plots, whereas all other taxa, particularly predators and larger detritivores, declined in relative abundance. Litterbag mesh size and litter type had only minor effects on communities, and canopy trimming and debris deposition explained most variation between sites. Effects of trimming on diversity, biomass, and abundance of some invertebrate taxa were still seen when observations finished and canopy closure was complete at 19 months. This suggests that disturbance has a long-lasting effect on litter communities and may, therefore, delay detrital processing, depending on the severity of canopy damage and rate of regrowth.

Journal Article canopy gaps; community composition; forest manipulation; Fungi; Litterbags; relative abundance
2012 A Caribbean Forest Tapestry: The Multidimensional Nature of Disturbance and Response N. V. L. Brokaw; Crowl, T.A.; Lugo, A.E.; McDowell, W.H.; Scatena, F.N.; Waide, R.B.

Global change threatens ecosystems worldwide, and tropical systems with their high diversity and rapid development are of special concern. We can mitigate the impacts of change if we understand how tropical ecosystems respond to disturbance. For tropical forests and streams in Puerto Rico this book describes the impacts of, and recovery from, hurricanes, landslides, floods, droughts, and human disturbances in the Luquillo Mountains of Puerto Rico. These ecosystems recover quickly after natural disturbances, having been shaped over thousands of years by such events. Human disturbance, however, has longer-lasting impacts. Chapters are by authors with many years of experience in Puerto Rico and other tropical areas and cover the history of research in these mountains, a framework for understanding disturbance and response, the environmental setting, the disturbance regime, response to disturbance, biotic mechanisms of response, management implications, and future directions. The text provides a strong perspective on tropical ecosystem dynamics over multiple scales of time and space.

1998 A comparative ecology of the Bisley Biodiversity Plot and Experimental Watershed, Luquillo Experimental Forest, Puerto Rico
Scantena, F. N. 1998. A Comparative Ecology Of The Bisley Biodiversity Plot And Experimental Watershed, Luquillo Experimental Forest, Puerto Rico. In Forest Biodiversity in North, Central and South America and the Caribbean: Research and Monitoring, Forest Biodiversity in North, Central and South America and the Caribbean: Research and Monitoring, eds. F. Dallmeier and Comisky, J. Pathernon Press, 213-230.
Scantena, F.N. Book Chapter watershed
1991 A comparison of agar film techniques for estimating fungal biovolumes in litter and soil Lodge, D.J.; Ingham, E.R. Journal Article soil ecology
2008 A comparison of current and historical fish assemblages in a Caribbean island estuary: conservation value of historical data Smith, G.C.; Corujo-Flores, I.; Pringle, C.M. Journal Article watershed change
1995 A comparison of methods for quantifying catastrophic wind damage to forests
Everham, E. 1995. A Comparison Of Methods For Quantifying Catastrophic Wind Damage To Forests. In Wind and wind-related damage to trees, Wind and wind-related damage to trees, eds. M.P. Coutts and Grace, J. Cambridge, U.K: Cambridge University Press, 340-357.
Everham, E.

Catastrophic wind events impact forests over the entire globe. Although recent examples of hurricanes in the Caribbean have led to intense examination of the impacts on, and recovery of, forests, these research efforts have largely been in isolation. Little has been done to compare the impacts of storms of varying intensity on different ecosystems. Therefore, we can not as yet fit catastrophic wind events into a general model of forest disturbance and recovery. Papers examining the impacts of 26 different wind events (cyclonic storms, tornadoes and gales) on 27 different forests are reviewed. Hurricane damage is measured as numbers or percentage: stem damage, canopy damage, biomass or stand volume loss, or mortality. The populations sampled varied from minimum stem size of 2 cm to 20 cm in diameter. Sampling methodology included small circular plots, transects, large gridded plots and remote sensing of the landscape. Plots were established 10 days to 3 years after the wind event. The implications of these different quantification systems are examined using data from a large gridded plot established in the Luquillo Mountains of Puerto Rico to study the impacts of Hurricane Hugo. Intensity of disturbance, measured as percentages of different damage types, varied depending on the minimum stem size used in the analysis. Damage to individual species also varied depending on the variable used to quantify it. Clearly, a standard measure of wind damage is needed to facilitate comparisons of the impacts of different storms on different forests. I suggest a damage measure that includes both mortality and structural loss as measured by decrease in basal area.

Book Chapter wind effect
2006 A comparison of the species-time relationship across ecosystems and taxonomic groups White, A.F.; Adl, S.M.; Lauenroth, W.K.; Gill, R.A.; Greenberg, D.; Kaufman, D.M.; Rassweiler, A.; Rusak, J.A.; Smith, G.C.; Steinbeck, J.R.; Waide, R.B.; Yao, J. Journal Article species–time relationship (STR)
2004 A comparison of two sampling strategies to assess discomycete diversity in wet tropical forests Cantrell, S.A. Journal Article Tropical
1999 A comparison of two secondary forests in the coffee zone of central Puerto Rico Popper, N.; Cristobal, D.; Santos, O.C.; Mendez-Irizarry, N.; Torres-Morales, E.; Lugo, A.E.; Rivera, H.D.; Toledo, S.; Irizarry, S.; Rivera, L.; Zayas, L.A.; Colon, J.C.Figuero Journal Article secondary forests
2011 A complex metacommunity structure for gastropods along an elevational gradient Presley, S.J.; Willig, M.R.; Bloch, C.P.; de Castro, F.; Higgins, C.L.; Klingbeil, B.T.

The metacommunity framework integrates species-specific responses to environmental gradients to detect emergent patterns of mesoscale organization. Abiotic characteristics (temperature, precipitation) and associated vegetation types change with elevation in a predictable fashion, providing opportunities to decouple effects of environmental gradients per se from those of biogeographical or historical origin. Moreover, expected structure is different if a metacommunity along an elevational gradient is molded by idiosyncratic responses to abiotic variables (expectation = Gleasonian structure) than if such a metacommunity is molded by strong habitat preferences or specializations (expectation = Clementsian structure). We evaluated metacommunity structure for 13 species of gastropod from 15 sites along an elevationaltransect in the Luquillo Experimental Forest of Puerto Rico. Analyses were conducted separately for the primary axis and for the secondary axis of correspondence extracted via reciprocal averaging. The metacommunity exhibited quasi-Clementsian structure along the primary axis, which represented a gradient of gastropod species specialization that was unassociated with elevation. The secondary axis represented environmental variation associated with elevation. Along this axis, the metacommunity exhibited Clementsian structure, with specialists characterizing each of three suites of sites that corresponded to three distinct forest types. These forest types are associated with low (tabonuco forest), mid- (palo colorado forest), or high (elfin forest) elevations. Thus, variation among sites in species composition reflected two independent processes: the first decoupled from elevational variation and its environmental correlates, and the second highly associated with environmental variation correlated with elevation.Abstract in Spanish is available at

Journal Article Clementsian distributions; coherence; environmental gradients; gastropoda; Puerto Rico; rain forest; range boundary clumping; range turnover
2004 A comprehensive evaluation on sustainable management of a mountain community: A case study on Daka village, Yunnan Han, B.; Chen, H.; Zou, X.M.; Fu, Y.N. Journal Article Yunnan
2010 A comprehensive framework for the evaluation of metacommunity structure Presley, S.J.; Higgins, C.L.; Willig, M.R.

The metacommunity framework is a powerful platform for evaluating patterns of species distribution in geographic or environmental space. Idealized patterns (checkerboard, Clementsian, evenly spaced, Gleasonian and nested distributions) give the framework shape. Each pattern represents an area in a multidimensional continuum of metacommunity structures; however, the current approach to analysis of spatial structure of metacommunities is incomplete. To address this, we describe additional non-random structures and illustrate how they may be discerned via objective criteria. First, we distinguish three distinct forms of species loss in nested structures, which should improve identification of structuring mechanisms for nested patterns. Second, we define six quasi-structures that are consistent with the conceptual underpinnings of Clementsian, Gleasonian, evenly spaced and nested distributions. Finally, we demonstrate how combinations of structures at smaller spatial extents may aggregate to form Clementsian structure at larger extents. These refinements should facilitate the identification of best-fit patterns, associated structuring mechanisms, and informative scales of analysis and interpretation. This conceptual and analytical framework may be applied to network properties within communities (i.e. structure of interspecific interactions) and has broad application in ecology and biogeography.

Journal Article
2002 A cross-system comparison of bacterial and fungal biomass in detritus pools of headwater stream Findlay, S.; Tank, J.; Dye, S.; Valett, H.M.; Mulholland, J.P.; McDowell, W.H.; Johnson, A.H.; Hamilton, L.S.; Edmonds, J.; Dodds, W.K.; Bowden, R.D.

The absolute amount of microbial biomass and relative contribution of fungi and bacteria are expected to vary among types of organic matter (OM) within a stream and will vary among streams because of differences in organic matter quality and quantity. Common types of benthic detritus [leaves, small wood, and fine benthic organic matter (FBOM)] were sampled in 9 small (1st-3rd order) streams selected to represent a range of important controlling factors such as surrounding vegetation, detritus standing stocks, and water chemistry. Direct counts of bacteria and measurements of ergosterol (a fungal sterol) were used to describe variation in bacterial and fungal biomass. There were significant differences in bacterial abundance among types of organic matter with higher densities per unit mass of organic matter on fine particles relative to either leaves or wood surfaces. In contrast, ergosterol concentrations were significantly greater on leaves and wood, confirming the predominance of fungal biomass in these larger size classes. In general, bacterial abundance per unit organic matter was less variable than fungal biomass, suggesting bacteria will be a more predictable component of stream microbial communities. For 7 of the 9 streams, the standing stock of fine benthic organic matter was large enough that habitat-weighted reach-scale bacterial biomass was equal to or greater than fungal biomass. The quantities of leaves and small wood varied among streams such that the relative contribution of reach-scale fungal biomass ranged from 10% to as much as 90% of microbial biomass. Ergosterol concentrations were positively associated with substrate C:N ratio while bacterial abundance was negatively correlated with C:N. Both these relationships are confounded by particle size, i.e., leaves and wood had higher C:N than fine benthic organic matter. There was a weak positive relationship between bacterial abundance and streamwater soluble reactive phosphorus concentration, but no apparent pattern between either bacteria or fungi and streamwater dissolved inorganic nitrogen. The variation in microbial biomass per unit organic matter and the relative abundance of different types of organic matter contributed equally to driving differences in total microbial biomass at the reach scale.

Journal Article organic matter controlling factors
2009 A decade of ecosystem reorganization following multiple disturbances in a wet tropical forest. Teh, Y.A.; Silver, W.L.; Scantena, F.N. Journal Article wet tropical forest
1996 A fifty-three year record of land-use change in the Guanica forest biosphere reserve and its vicinity
Lugo, A. E, O.M. Ramos, M. Molina, F. N Scantena, and . 1996. A Fifty-Three Year Record Of Land-Use Change In The Guanica Forest Biosphere Reserve And Its Vicinity. Rio Piedras, PR: International Institute of Tropical Forestry, USDA Forest Service.
Lugo, A.E.; Ramos, O.M.; Molina, M.; Scantena, F.N.; , Book macroecology
1998 A flood plain palm forest in the Luquillo Mountains of Puerto Rico five years after Hurricane Hugo Frangi, J.L.; Lugo, A.E.

Long-term studies are needed to understand the dynamics of tropical forests, particularly those subject to periodic disturbances such as hurricanes. We studied a flood plain Prestoea montana palm forest in the Luquillo Mountains of Puerto Rico over a 15-yr period (1980–1995), which included the passage of Hurricane Hugo in September 1989. The passage of the hurricane caused the dominant species to become more dominant and created low instantaneous tree mortality (1% of stems) and reductions in tree biomass (-16 Mg/ha/yr) and density, although not in basal area. Five years after the hurricane, the palm flood plain forest had exceeded its prehurricane aboveground tree biomass, tree density, and basal area. Aboveground tree biomass accumulated at a rate of 9.2 Mg/ha/yr, 76 percent of which was due to palms. Before the hurricane this rate was on the order of 3 Mg/ha/yr. Forest floor litter decreased to prehurricane levels (6.7 Mg/ha), within 5 yr, mostly due to the disappearance of woody litter. Thirteen tree species not represented in the canopy entered the forest by regeneration, and 2 species suffered almost 20 percent/yr mortality over a 5-yr period after the storm (floodplain average of 2%/yr). Delayed tree mortality was twice as high as instantaneous tree mortality after the storm and affected dicotyledonous trees more than it did palms. Regencration of dicotyledonous trees, palms, and tree ferns was influenced by a combination of factors including hydroperiod, light, and space. Redundancy Data Analysis showed that the area near the river channel was the most favorable for plant regeneration. Palm regeneration was higher in locations with longer hydroperiods, while regeneration of dicotyledonous trees was higher in areas with low risk of flooding. This study shows how a periodic disturbance provides long-term opportunities for species invasions and long-term ecosystem response at the patch scale of < 1 ha.

Journal Article ecological disturbance; flood plain forest; Hurrican Hugo; hurricane; Luquillo experimental forest; palms; tropical trees succession; tropical wetlands
2006 A fluorescent marking and re-count technique using the invasive earthworm, Pontoscolex corethrurus (Annelida: Oligochaeta) González, G.; Espinosa, E.; Zhigang, L.; Zou, X.M.

We used a fluorescence technique to mark and re-count the invasive earthworm, Pontoscolex corethrurus from PVC tubes established in a forest and a recently abandoned pasture in Puerto Rico to test the effects of the labeling treatment on earthworm population survival over time. A fluorescent marker was injected into the earthworms in the middle third section of the body, between inside and outside walls. Five labeled juveniles and two unlabeled adults of P. corethrurus were incubated in the PVC tubes under field conditions and retrieved after 2, 4, 8, and 16 weeks (labeled population; four PVC tubes harvested per date and site for a total of 32 tubes). Concurrently, an additional set of 8 PVC tubes contained five unlabeled juveniles and two unlabeled adults each of P. corethrurus (unlabeled population) was established in each site (forest and pasture; 16 tubes total) to compare the percent remaining of worms in tubes containing labeled and unlabeled populations after 2 and 16 weeks (4 replicates per date). We found that (1) the fluorescent marker was still present in the earthworm tissue after four months, (2) the percent remaining of the total earthworm population was not significantly different between the forest and pasture sites, and (3) thirty percent of the labeled worms were lost after 2 weeks, but the population remained stable between week two and four of the experiment. Our results suggest that fluorescent markers can be a useful tool for carrying out short term mark and re-count studies of earthworms.

Journal Article tropics
1992 A food web for a tropical rain forest: the canopy view from Anolis Dial, R.

The trophic stature of Anolis evermanni and A. stratulus is examined in light of a series of experiments and observations conducted at canopy level in a Caribbean rain forest (Puerto Rico). Trade winds are shown to play an important role as a physical transport process in rain forest canopy in the Caribbean. The supply of flying insects to Anolis communities within the forest canopy is determined by a physical transport process in a manner analogous to the way marine intertidal communities are provisioned by water currents. The result is a one-way predator-prey interaction that may enhance species co-existence. A six-month removal experiment performed at canopy level quantified the predatory role of insectivorous Anolis lizards there. Counts were made of aerial-web spiders, leaf-dwelling arthropods, and flying insects caught in sticky-traps. An index of dispersal ability was measured using cylindrical sticky-traps suspended over forest gaps. Initial densities of arboreal anoles correlated positively and significantly with flying insects caught in sticky-traps, but not with leaf-sampled arthropod abundances. Removal and exclusion of anoles from individual tree crowns of Dacryodes excelsa using trunk collars revealed strong responses in abundances of several arthropod groups, particularly those greater than 2 mm long, not cryptically colored and poorly dispersing. The effect on herbivores cascaded to plants. Prevalence of defoliation was higher in anole-removal crowns than in controls. Percentage of leaflets damaged was positively correlated with leaf-dwelling orthopteran abundance, suggesting a three-trophic-level effect of lizards on plants. The effect of lizards on small predators cascaded to the smallest prey lengths with a weak, statistical significance. The two-species guild, A. evermanni and A. stratulus, is investigated. The high degree of overlap in structural niche, solar climatic niche, limiting prey depression, and the observation of interspecific aggression suggests strong present-day competition between the two anole species. This competition is suggested to result in crown-by-crown competitive exclusion. The biology of a flesh fly (Diptera: Sarcophagidae) that lethally parasitizes anoline hosts is described. The implication of the infection on the occurrence of body spots in A. stratulus is discussed.

Thesis tropical rain forest
2008 A general theory of ecology Scheiner, S.M.; Willig, M.R.

Ecologists bemoan the dearth of theory in ecology, in particular, the lack of an overarching, general theory. These complaints largely are unjustified. The components of a general theory of ecology have existed for the past half century; ecologists simply have failed to explicitly recognize them. We present a general theory of ecology and show how it relates to ecology’s numerous constituent theories and models. The general theory consists of a description of the domain of ecology and a set of fundamental principles. The domain of ecology is the spatial and temporal patterns of the distribution and abundance of organisms, including causes and consequences. Fundamental principles are broad statements about the patterns that exist and the processes that operate within a domain. The seven fundamental principles of the theory of ecology are: the heterogeneous distribution of organisms, interactions of organisms, contingency, environmental heterogeneity, finite and heterogeneous resources, the mortality of organisms, and the evolutionary cause of ecological properties. These principles are the necessary and sufficient elements for a general theory of ecology. The propositions of any constituent theory of ecology can be shown to be a consequence of these fundamental principles along with principles from other science domains. The general theory establishes relationships among constituent theories through shared fundamental principles. The next challenge is to develop and integrate unified, constituent theories and to establish the relationships among them within the framework established by the general theory.

Journal Article theory
2011 A general theory of ecology
Scheiner, S.M., and M. R Willig. 2011. A General Theory Of Ecology. In The Theory of Ecology, The Theory of Ecology, eds. S. M Scheiner and Willig, M. R. Chicago, Illinois.
Scheiner, S.M.; Willig, M.R. Book Chapter
1992 A geographically-based ecosystem model and its application to the carbon balance of the Luquillo Forest, Puerto Rico Hall, C.A.S.; Taylor, C.M.; Everham, E. Journal Article watershed modelling
1989 A geographically-based microclimatological computer model for mountainous terrain with application to the Luquillo Experimental Forest in Puerto Rico Wooster, K.M. Thesis
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
2011 A global experiment suggests climate warming will not accelerate litter decomposition in streams but might reduce carbon sequestration Boyero, L.; Pearson, H.A.; Gessner, M.O.; Barmuta, L.A.; Ferreira, V.; Graça, M.A.S.; Dudgeon, D.; Boulton, A.J.; Callisto, M.; Chauvet, E.; Helson, J.E.; Bruder, A.; Albarino, R.J.; Yule, C.M.; Arunachalam, M.; Davies, S.J.; Figueroa, R.; Flecker, A.S.; Ramírez, A.; Death, R.G.; Iwata, T.; Mathooko, J.M.; Mathur, R.; Goncalves, J.F.; Moretti, M.S.; Jinggut, T.; Lamothe, S.; M'Erimba, C.; Ratnarajah, L.; Schindler, M.H.; Castela, J.; Buria, L.M.; Cornejo, A.; Villanueva, N.; West, C.A.

The decomposition of plant litter is one of the most important ecosystem processes in the biosphere and is particularly sensitive to climate warming. Aquatic ecosystems are well suited to studying warming effects on decomposition because the otherwise confounding influence of moisture is constant. By using a latitudinal temperature gradient in an unprecedented global experiment in streams, we found that climate warming will likely hasten microbial litter decomposition and produce an equivalent decline in detritivore-mediated decomposition rates. As a result, overall decomposition rates should remain unchanged. Nevertheless, the process would be profoundly altered, because the shift in importance from detritivores to microbes in warm climates would likely increase CO2 production and decrease the generation and sequestration of recalcitrant organic particles. In view of recent estimates showing that inland waters are a significant component of the global carbon cycle, this implies consequences for global biogeochemistry and a possible positive climate feedback.

Journal Article Carbon cycle; Climate change; detritivores; global analysis; Latitudinal gradient; Litter decomposition; microbial decomposers; streams; temperature
1999 A hemispheric assessment of scale dependence in latitudinal gradients ofspecies richness Lyons, S.K.; Willig, M.R.

Considerable controversy surrounds the importance of historical, evolution- ary, and ecological factors affecting continental patterns in species richness. Although the importance of area and latitude are both well documented, few attempts have been made to integrate their effects in a single model. Most studies have been conducted by super- imposing grids on equal-area projection maps and counting the number of species occurring within grid cells (i.e., quadrats). Unfortunately, different grid-based studies use different quadrat sizes, making comparisons tenuous. We developed a hierarchical model to evaluate the degree to which area (based on a nested series of quadrats of five sizes, 1000-25 000 km2) affects the latitudinal gradient in species richness. The model allows the relationship between latitude and area to be nonlinear and, in its simple form, evaluates how well species richness can be predicted by the additive influences of latitude and area. The complex model evaluates whether an area X latitude interaction accounts for significant additional variation in species richness above that in the simple model (i.e., assesses the scale dependence of the latitudinalgradient). For bats and marsupials, the simple model included only latitudinal effects and accounted for over half of the variation in species richness of each of the two taxa. The interactive effect was nonsignificant for each taxon, accounting for <0.1% of additional variation in species richness in each case. If other taxa or land masses produce similar relationships, then the form of the latitudinal gradient is relatively invariant with respect to area at 1000-25 000 km2 scales, and comparisons among studies at this spatial scale are straightforward.

Journal Article areography; bats; Biodiversity; geographical ecology; macroecology; marsupials; scale dependence
1991 A landscape simulation model of forest growth for the Luquillo Experimental Forest. Puerto Rico
Everham, E. 1991. A Landscape Simulation Model Of Forest Growth For The Luquillo Experimental Forest. Puerto Rico. In Toward Understanding our environment, Toward Understanding our environment, ed. J. McLeod. San Diego: The Society for Computer Simulation.
Everham, E. Book Chapter Puerto Rico
2004 A maximum-likelihood, spatially explicit analysis of tree growth and survival in a tropical forest Uriarte, M.; Canham, C.D.; Ammirati, J.; Zimmerman, J.K. Journal Article size-dependent
2009 A method to assess longitudinal riverine connectivity in tropical streams dominated by migratory biota Crook, K.E.; Pringle, C.M.; Freeman, B.J.

One way in which dams affect ecosystem function is by altering the distribution and abundance of aquatic species. Previous studies indicate that migratory shrimps have significant effects on ecosystem processes in Puerto Rican streams, but are vulnerable to impediments to upstream or downstream passage, such as dams and associated water intakes where stream water is withdrawn for human water supplies. Ecological effects of dams and water withdrawals from streams depend on spatial context and temporal variability of flow in relation to the amount of water withdrawn. This paper presents a conceptual model for estimating the probability that an individual shrimp is able to migrate from a stream's headwaters to the estuary as a larva, and then return to the headwaters as a juvenile, given a set of dams and water withdrawals in the stream network. The model is applied to flow and withdrawal data for a set of dams and water withdrawals in the Caribbean National Forest (CNF) in Puerto Rico. The index of longitudinal riverine connectivity (ILRC), is used to classify 17 water intakes in streams draining the CNF as having low, moderate, or high connectivity in terms of shrimp migration in both directions. An in-depth comparison of two streams showed that the stream characterized by higher water withdrawal had low connectivity, even during wet periods. Severity of effects is illustrated by a drought year, where the most downstream intake caused 100% larval shrimp mortality 78% of the year. The ranking system provided by the index can be used as a tool for conservation ecologists and water resource managers to evaluate the relative vulnerability of migratory biota in streams, across different scales (reach-network), to seasonally low flows and extended drought. This information can be used to help evaluate the environmental tradeoffs of future water withdrawals.

Journal Article water withdrawals
2011 A migratory shrimp’s perspective on habitat fragmentation in the neotropics: Extending our knowledge from Puerto Rico. Snyder, M.N.; Anderson, E.A.; Pringle, C.M.

Migratory freshwater fauna depend on longitudinal connectivity of rivers throughout their life cycles. Amphidromous shrimps spend their adult life in freshwater but their larvae develop into juveniles in salt water. River fragmentation resulting from pollution, land use change, damming and water withdrawals can impede dispersal and colonization of larval shrimps. Here we review current knowledge of river fragmentation effects on freshwater amphidromous shrimp in the Neotropics, with a focus on Puerto Rico and Costa Rica. In Puerto Rico, many studies have contributed to our knowledge of the natural history and ecological role of migratory neotropical shrimps, whereas in Costa Rica, studies of freshwater migratory shrimp have just begun. Here we examine research findings from Puerto Rico and the applicability of those findings to continental Costa Rica. Puerto Rico has a relatively large number of existing dams and water withdrawals, which have heavily fragmented rivers. The effects of fragmentation on migratory shrimps’ distribution have been documented on the landscape-scale in Puerto Rico. Over the last decade, dams for hydropower production have been constructed on rivers throughout Costa Rica. In both countries, large dams restrict shrimps from riverine habitat in central highland regions; in Puerto Rico 27% of stream kilometers are upstream of large dams while in Costa Rica 10% of stream kilometers are upstream of dams. Research about amphidromy specific to non-island shrimps is increasingly important in light of decreasing hydrologic connectivity.

Conference Proceedings amphidromous shrimp; Caridina leucosticta; mitochondrial DNA; NADH dehydrogenase subunit 2 (ND2); NADH dehydrogenase subunit 5 (ND5); Neocaridina denticulata denticulata; RNA gene
2006 A new poroid species of Resupinatus from Puerto Rico, with a reassessment of the cyphelloid genus, Stigmatolemma Thorn, R.G.; Moncalvo, J.M.; Redhead, S.A.; Lodge, D.J.; Martin, M.P. Journal Article Stigmatolemma
2008 A new psychodid species from Puerto Rican tank bromeliads
Wagner, R.H., B. Richardson, and B. Richardson. 2008. A New Psychodid Species From Puerto Rican Tank Bromeliads. Studies on the Neotropical Fauna and Environment 43(3): 209-216.
Wagner, R.H.; Richardson, B.; Richardson, B. Journal Article Vriesea sintenisii
2010 A new psychodid species from Saban tank bromeliads
Wagner, R.H., B. Richardson, and B. Richardson. 2010. A New Psychodid Species From Saban Tank Bromeliads. Studies on Neotropical Fauna and Environment 45: 121-127.
Wagner, R.H.; Richardson, B.; Richardson, B.

A new species of Neotropical Psychodidae, Alepia apexalba sp. nov., is described from dry-forest tank bromeliads in Saba, Netherlands Antilles. Larvae, pupae and adults are described and figured. It is possible to relate larvae and adults because the latter were reared from pupae collected from the bromeliads (Tillandsia utriculata) that also contained larvae. Bromeliads are adapted to intercept canopy litter and throughfall water, and decaying litter is washed into and retained by the leaf bases. It is from this aquatic habitat that the larvae and pupae were collected.

Journal Article Tillandsia
1998 A new Sorokina (Leotiales) from Puerto Rico Spooner, B.M.; Lodge, D.J.; Laessøe, T.

A new species of discomycete with a blue-grey hymenium, Sorokina caeruleogrisea, is described and illustrated from Puerto Rico. Other known species of the genus are also compared.

Journal Article discomycete; Puerto Rico; Sorokina caeruleogrisea
2007 A New Species for a Bromeliad Phytotelm-Dwelling Tanytarsus (Diptera: Chironomidae).
Cranston, P.S. 2007. A New Species For A Bromeliad Phytotelm-Dwelling Tanytarsus (Diptera: Chironomidae).. Annals of the Entomological Society of America 100(5): 617-622.
Cranston, P.S. Journal Article Tanytarsus bromeliad
1998 A new species of Omicrus Sharp (Coleoptera: Hydrophilidae) from Puerto Rico and its larva, the first known larva of Omicrini Hansen-Paaby, P.; Richardson, B.

A remarkable new species of bromeliadicolous Hydrophilidae, Omicrus ingens sp.n., is described from Puerto Rico. Notes on the habitat and occurrence of the species are given. Larvae found in association with adult beetles are assigned to the same species and described as such. It is the first known larva of the sphaeridiine tribe Omicrini. Comparative notes are given to other hydrophilid larvae, particularly Sphaeridiinae, and preliminary keys to larvae are presented for known subfamilies of Hydrophilidae and known tribes of Sphaeridiinae.

Journal Article sphaeridiine
1999 A nitrogen budget for late-successional hill slope tabonuco forest, Puerto Rico Chesnut, T.J.; Zarin, D.J.; McDowell, W.H.; Keller, M.

Nitrogen budgets of late successional forested stands and watersheds provide baseline data against which the effects of small- and large-scale disturbances may be measured. Using previously published data and supplemental new data on gaseous N loss, we construct a N budget for hillslope tabonuco forest (HTF) stands in Puerto Rico. HTF stands are subject to frequent hurricanes and landslides; here, we focus on N fluxes in the late phase of inter-disturbance forest development. N inputs from atmospheric deposition (4-6 kg N/ha/yr) are exceeded by N outputs from groundwater, gaseous N loss, and particulate N loss (6.3-15.7 kg N/ha/yr). Late-successional HTF stands also sequester N in their aggrading biomass (8 kg N/ha/yr), creating a total budget imbalance of 8.3-19.7 kg N/ha/yr. We surmise that this imbalance may be accounted for by unmeasured inputs from above- and belowground N-fixation and/or slow depletion of the large N pool in soil organic matter. Spatial and temporal variability, especially that associated with gaseous exchange and soil organic matter N-mineralization, constrain the reliability of this N budget.

Journal Article ecosystem studies; nutrient cycling; tropical forest
1999 A non-value based framework for assesing ecosystem integrity Vogt, D.; Vogt, D.; Boon, P.; Fanzeres, A.; Wargo, P.; Palmiotto, P.; Larson, B.; O'Hara, J.; Patel-Weynand, T.; Cuadrado, E.; Berry, J.

Indicators of ecosystem state change are currently selected based on the human value for some resource (e.g., biodiversity, water quality, etc.) or the human desired end-point of a system (e.g., existence of late successional forests, lack of insect or pathogen outbreaks, etc.). Examples are used from ecosystem studies and forest certification protocols to highlight the problems of selecting indicators based on our derived values.

Report forest; organism functions; Pacific Northwest forest; rangeland soil organism; soil organism
2005 A plot-based system of collecting population information on terrestrial breeding frogs Woolbright, L.L. Journal Article frogs
1989 A profile of the tabonuco forest in Luquillo Experimental Forest, Puerto Rico Walker, L.A.; Garcia, D.C.; Munoz, B.; Rivera, H.D. Journal Article Tabonuco
2012 A refined methodology for defining plant communities using post-agricultural data from the Neotropics Myster, R.W.

How best to define and quantify plant communities was investigated using long-term plot data sampled from a recovering pasture in Puerto Rico and abandoned sugarcane and banana plantations in Ecuador. Significant positive associations between pairs of old field species were first computed and then clustered together into larger and larger species groups. I found that (1) no pasture or plantation had more than 5% of the possible significant positive associations, (2) clustering metrics showed groups of species participating in similar clusters among the five pasture/plantations over a gradient of decreasing association strength, and (3) there was evidence for repeatable communities-especially after banana cultivation-suggesting that past crops not only persist after abandonment but also form significant associations with invading plants. I then showed how the clustering hierarchy could be used to decide if any two pasture/plantation plots were in the same community, that is, to define old field communities. Finally, I suggested a similar procedure could be used for any plant community where the mechanisms and tolerances of species form the "cohesion" that produces clustering, making plant communities different than random assemblages of species.

Journal Article
1992 A research perspective on disturbance and recovery of a tropical montane forest
Waide, R. B, and A. E Lugo. 1992. A Research Perspective On Disturbance And Recovery Of A Tropical Montane Forest. In Tropical forests in transition: ecology of natural and anthropogenic disturbance processes, Tropical forests in transition: ecology of natural and anthropogenic disturbance processes, ed. J. G Goldammer. Basel, Switzerland: Berkhauser-Verlag, 173-190.
Waide, R.B.; Lugo, A.E. Book Chapter tropical montane forest
2005 A sampler for stream macroinvertebrates and organic matter occuring on boulders and bedrock in pools Greathouse, E.; Pringle, C.M. Journal Article sampling
2008 A Soil Burn Severity Index for Understanding Soil-Fire Relations in Tropical Forests Jain, T.B.; Gould, W.A.; Graham, R.T.; Pilliod, D.S.; Lentile, L.B.; González, G.

Methods for evaluating the impact of fires within tropical forests are needed as fires become more frequent and human populations and demands on forests increase. Short- and long-term fire effects on soils are determined by the prefire, fire, and postfire environments. We placed these components within a fire-disturbance continuum to guide our literature synthesis and develop an integrated soil burn severity index. The soil burn severity index provides a set of indicators that reflect the range of conditions present after a fire. The index consists of seven levels, an unburned level and six other levels that describe a range of postfire soil conditions. We view this index as a tool for understanding the effects of fires on the forest floor, with the realization that as new information is gained, the index may be modified as warranted.

Journal Article tropical forests
1997 A study of evaporation from lowland and montane tropical rain forest Holwerda, F. Thesis tropical rain forest
2004 A survey of methods for setting minimum instream flows standards in the Caribbean Basin Scantena, F.N. Journal Article rivers
1995 A survey of patterns in fungal diversity Lodge, D.J.; Chapela, I.; Samuels, G.J.; Uecker, F.A.; Desjardin, D.E.; Horak, E.; Miller, A.J.; Hennbert, G.L.; Decock, C.A.; Ammirati, J.; Burdsall, J.H.H.; Kirk, P.M.; Minter, D.W.; Halling, R.; Laessøe, T.; Mueller, G.M.; Oberwinkler, F.; Pegler, D.N.; Spooner, B.M.; Petersen, R.H.; Rogers, J.D.; Ryvarden, L.; Watling, R.; Tunbull, E.; Whalley, A.J.S. Conference Proceedings speciation
2013 A test of the maximum power hypothesis along an elevational gradient in the Luquillo Mountains of Puerto Rico
Harris, N.L., C.A.S. Hall, and A. E Lugo. 2013. A Test Of The Maximum Power Hypothesis Along An Elevational Gradient In The Luquillo Mountains Of Puerto Rico. In Ecological Bulletins 54: Ecological gradient analyses in a tropical landscape, Ecological Bulletins 54: Ecological gradient analyses in a tropical landscape, Oxford: John Wiley & Sons, 233–243.
Harris, N.L.; Hall, C.A.S.; Lugo, A.E.

The maximum power principle predicts that maximum transformation of available energy into useful work occurs when a system operates at an intermediate rate and efficiency. This relation is apparent in everyday situations as we shift gears to keep near the middle of each gear range when we accelerate an automobile, or operate chain saws and other machines at a load about half their stalling rate. We tested the validity of the maximum power principle in a complex natural system by quantifying patterns of photosynthesis and respiration – an ecosystem’s energy currency – along an elevation gradient in a subtropical forest of Puerto Rico. This mountain system was a useful proxy for testing the hypothesis over broader climatic gradients elsewhere. Our results indicate that metabolic rates (defined as gross primary productivity) decrease up the gradient, efficiency (defined as the ratio of net to gross primary productivity) increases up this gradient, and power (defined as net primary productivity, or the amount of useful energy produced within a given ecosystem per unit time) is maximum near the midpoint of the gradient where rate and efficiency are intermediate. These observations are non-trivially consistent with the maximum power principle and support a scalable, energy-based definition of evolutionary fitness. Given a set of environmental forcing functions in a given location, those individuals (or populations or ecosystems) that optimize the trade-off between metabolic rate and efficiency to achieve maximum power will be most fit. As environmental conditions change over the long term, this rate vs efficiency optimum will shift and those that are able to achieve maximum power in the new environment will be favored over those that are maximizing power for the old environment. We think that this net energy-as-fitness view allows for a richer series of possibilities for testing the consequences of natural selection.

Book Chapter elevational gradient; Luquillo experimental forest; power; tropical forestry
2011 A Theory of Ecological Gradients: A Framework for Aligning Data and Models Fox, G.; Scheiner, S.M.; Willig, M.R. Journal Article
1996 A twelve-year comparison of stand changes in amahagony plantation and a paired natural forest of similar age Fu, S.; Pedraza, R.; Lugo, A.E. Journal Article tropical plantations
2002 A walk in through the Amazon from a biogeochemical perspective Silver, W.L.; Templer, P.M. Journal Article soil
2005 A water budget for the Caribbean National Forest with special emphasis on bi-directional riverine connectivity Crook, K.E. Thesis water budget
2014 A Well-Resolved Phylogeny of the Trees of Puerto Rico Based on DNA Barcode Sequence Data Muscarella, R.; Uriarte, M.; Erickson, D.L.; Swenson, N.G.; Zimmerman, J.K.; Kress, J.W.

Background:The use of phylogenetic information in community ecology and conservation has grown in recent years. Two key issues for community phylogenetics studies, however, are (i) low terminal phylogenetic resolution and (ii) arbitrarily defined species pools.Methodology/principal findings:We used three DNA barcodes (plastid DNA regions rbcL, matK, and trnH-psbA) to infer a phylogeny for 527 native and naturalized trees of Puerto Rico, representing the vast majority of the entire tree flora of the island (89%). We used a maximum likelihood (ML) approach with and without a constraint tree that enforced monophyly of recognized plant orders. Based on 50% consensus trees, the ML analyses improved phylogenetic resolution relative to a comparable phylogeny generated with Phylomatic (proportion of internal nodes resolved: constrained ML = 74%, unconstrained ML = 68%, Phylomatic = 52%). We quantified the phylogenetic composition of 15 protected forests in Puerto Rico using the constrained ML and Phylomatic phylogenies. We found some evidence that tree communities in areas of high water stress were relatively phylogenetically clustered. Reducing the scale at which the species pool was defined (from island to soil types) changed some of our results depending on which phylogeny (ML vs. Phylomatic) was used. Overall, the increased terminal resolution provided by the ML phylogeny revealed additional patterns that were not observed with a less-resolved phylogeny.Conclusions/significance:With the DNA barcode phylogeny presented here (based on an island-wide species pool), we show that a more fully resolved phylogeny increases power to detect nonrandom patterns of community composition in several Puerto Rican tree communities. Especially if combined with additional information on species functional traits and geographic distributions, this phylogeny will (i) facilitate stronger inferences about the role of historical processes in governing the assembly and composition of Puerto Rican forests, (ii) provide insight into Caribbean biogeography, and (iii) aid in incorporating evolutionary history into conservation planning. 

Journal Article Community ecology; Forests; Phylogenetic analysis; Phylogenetics; Plant phylogenetics; Puerto Rico; Sequence alignment; trees
2009 Abiotic and biotic drivers of seedling survival in a hurricane-impacted tropical forest Comita, L.S.; Uriarte, M.; Thompson, J.; Jonckheere, I.; Canham, C.D.; Zimmerman, J.K.

1. Many forests experience periodic, large-scale disturbances, such as hurricanes and cyclones, which open the forest canopy, causing dramatic changes in understorey light conditions and seedling densities. Thus, in hurricane-impacted forests, large variations in abiotic and biotic conditions likely shape seedling dynamics, which in turn will contribute to patterns of forest recovery. 2. We monitored 13 836 seedlings of 82 tree and shrub species over 10 years following Hurricane Georges in 1998 in a subtropical, montane forest in Puerto Rico. Wequantified changes in the biotic and abiotic environment of the understorey and linked seedling dynamics to changes in canopy openness and seedling density, and to spatial variation in soil type, topography and tree density. 3. Canopy openness was highest when first measured after Hurricane Georges and dropped significantly within c. 3 years, while seedling densities remained high for c. 5 years post-hurricane. When all species and census intervals were analysed together, generalized linear mixed effects models revealed that canopy openness, seedling and adult tree densities were significant drivers of seedling survival. 4. The relative importance of abiotic and biotic factors changed over time. Separate analyses for each census interval revealed that canopy openness was a significant predictor of survival only for the first census interval, with lower survival at the highest levels of canopy openness. The effect of conspecific seedling density was significant in all intervals except the first, and soil type only in the final census interval. 5. When grouping species into life-history guilds based on adult tree susceptibility to hurricane damage, we found clear differences among guilds in the effects of biotic and abiotic factors on seedling survival. Seedlings of hurricane-susceptible and intermediate guilds were more strongly influenced by canopy openness, while seedlings of the hurricane-resistant group were less affected by conspecific seedling density. Individual species-level analyses for 12 common species, however, showed considerable variation among species within guilds. 6. Synthesis. Our results suggest that hurricanes shape species composition by altering understorey conditions that differentially influence the success of seedlings. Thus, predicted increases in the intensity and frequency of hurricanes in the Caribbean will likely alter seedling dynamics and ultimately the species composition in hurricane-impacted forests.

Journal Article tropical forest dynamics
1991 Above and below ground organic matter storage and production in a tropical pine plantation and a paired broadleaf secondary forest Cuevas, E.; Brown, S.; Lugo, A.E.

The distribution of tree biomass and the allocation of organic matter production were measured in an 11-yr-old Pinus caribaea plantation and a paired broadleaf secondary forest growing under the same climatic conditions. The pine plantation had significantly more mass aboveground than the secondary forest (94.9 vs 35.6 t ha-1 for biomass and 10.5 vs 5.0 t ha-1 for litter), whereas the secondary forest had significantly more fine roots (⩽2 mm diameter) than the pine plantation (10.5 and 1.0 t ha-1, respectively). Standing stock of dead fine roots was higher than aboveground litter in the secondary forest. In contrast, aboveground litter in pine was more than ten times higher than the dead root fraction. Both pine and secondary forests had similar total organic matter productions (19.2 and 19.4 t ha-1 yr-1, respectively) but structural allocation of that production was significantly different between the two forests; 44% of total production was allocated belowground in the secondary forest, whereas 94% was allocated aboveground in pine. The growth strategies represented by fast growth and large structural allocation aboveground, as for pine, and almost half the production allocated belowground, as for the secondary forest, illustrate equally successful, but contrasting growth strategies under the same climate, regardless of soil characteristics. The patterns of accumulation of organic matter in the soil profile indicated contrasting nutrient immobilization and mineralization sites and sources for soil organic matter formation.

Journal Article soil organic matter
2009 Above-ground forest Biomass is not consistently related to wood density Stegen, J.; Swenson, N.G.; Valencia, R.; Enquist, B.; Thompson, J.; Zimmerman, J.K.

Aim: It is increasingly accepted that the mean wood density of trees within a forest is tightly coupled to above-ground forest biomass. It is unknown, however, if a positive relationship between forest biomass and mean community wood density is a general phenomenon across forests. Understanding spatial variation in biomass as a function of wood density both within and among forests is important for predicting changes in stored carbon in response to global change, and here we evaluated the generality of a positive biomass–wood density relationship within and among six tropical forests. Location  Costa Rica, Panama, Puerto Rico and Ecuador. Methods:   Individual stem data, including diameter at breast height and spatial position, for six forest dynamics plots were merged with an extensive wood density database. Individual stem biomass values were calculated from these data using published statistical models. Total above ground biomass, total basal area and mean community wood density were also quantified across a range of subcommunity plot sizes within each forest. Results:  Among forests, biomass did not vary with mean community wood density. The relationship between subcommunity biomass and mean wood density within a forest varied from negative to null to positive depending on the size of subcommunities and forest identity. The direction of correlation was determined by the associated total basal area–mean wood density correlation, the slope of which increased strongly with whole forest mean wood density. Main conclusions:  There is no general relationship between forest biomass and wood density, and in some forests, stored carbon is highest where wood density is lowest. Our results suggest that declining wood density, due to global change, will result in decreased or increased stored carbon in forests with high or low mean wood density, respectively.

Journal Article tropical forests
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 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
2008 Acclimation of tropical tree species to hurricane disturbance: ontogenetic differences Wen, S.; Fetcher, N.; Zimmerman, J.K. Journal Article tropical forest
2008 Acetate competition between methanogenic archaea and Fe(III)-reducing bacteria in tropical rain forest soils Teh, Y.A.; Dubinsky, E.A.; Silver, W.L.; Carlson, C.M. Journal Article methane biogeochemistry
2013 Advancements in the understanding of spatiotemporal gradients in tropical landscapes: A Luquillo focus and global perspective
González, G., M. R Willig, and R. B Waide. 2013. Advancements In The Understanding Of Spatiotemporal Gradients In Tropical Landscapes: A Luquillo Focus And Global Perspective. In Ecological Bulletins 54: Ecological gradient analyses in a tropical landscape, Ecological Bulletins 54: Ecological gradient analyses in a tropical landscape, Oxford: John Wiley & Sons, 245–250.
González, G.; Willig, M.R.; Waide, R.B.

Background The Luquillo Mountains have served as a focal point for people since pre-Columbian times. The Taíno Indians in Puerto Rico believed that the spirit of Yuquiyú – god of order, after which El Yunque National Forest (or Luquillo Experimental Forest) is named – dwelled and protected the people from Juracán (the phonetic name given by the Spanish settlers to the god of chaos and disorder believed to control the weather, particularly hurricanes). The chapters in this book illustrate how the Luquillo Mountains continue to serve as a focal point for understanding climate and for using our knowledge to better plan for and ‘protect’ people from climate-induced disturbances in the future. The juxtaposition of a rise in elevation from sea level to nearly 1100 m over the course of 10 km, the tropical climate, and the location of the Luquillo Mountains on the easternmost of the Greater Antilles, exposed to moisture laden trade winds, gives rise to gradients in rainfall, temperature, and seasonality that have structured ecological systems and human use of the landscape. Assessing the patterns and mechanisms of control along gradients that are often interdependent requires thoughtful analyses from many perspectives, rigorous experimental design, and long-term study. The value in understanding these gradients arises because knowledge is the basis for independently predicting responses to changes in rainfall, temperature, seasonality, storm intensity or frequency, and human use of the landscape. Gradient analysis uses spatial measures of physical, chemical, and biological properties of the environment to understand the spatiotemporal dynamics of species, biological communities, biogeochemical fluxes, and ecosystem properties. The study of environmental gradients traces its history to the origins of the discipline of ecology (Clements 1904, Gleason 1917, Shelford 1951, Andrewartha and Birch 1954, Odum 1959). Indeed, the relation between environmental gradients and the distribution of organisms and communities is a favorite topic of ecologists and biogeographers, and papers on the subject abound in the literature. Much of this work focuses on environmental gradients that arise in concert with changes in elevation, such as temperature and rainfall (Whittaker 1967). Thus, studies of montane ecosystems are frequent in the literature on environmental gradients, and tropical mountains, because of their high biodiversity compared to those in temperate latitudes, provide an excellent laboratory for examining ecological responses to environmental change. The chapters in this book take advantage of gradients that exist in the Luquillo Mountains, one of the most intensively studied tropical landscapes in the world (Brokaw, et al. 2012). Moreover, the work described in this book furthers the studies of ecological gradients that have been undertaken in other parts of the tropics (Olson 1963, Terborgh 1977, Patton and Smith 1992, Stevens 1992, Lieberman et al. 1996, Schneider et al. 1999, Givnish 2001, 2002, Smith et al. 2001, Ogden and Thorpe 2002, McCain 2005, Presley et al. 2012 ). The extensive literature on environmental gradients provides a general conceptual framework for studies in the Luquillo Mountains. For example, formulation of an energy-based mechanism tha provided insight into how individuals and species respond to gradients (Hall et al. 1992) stimulated development of a conceptual model for the Luquillo LTER program that uses the concept of gradients to link landscape-scale patterns and processes with disturbance regimes (Willig and Walker 1999, Waide and Willig 2012). In this model, spatial gradients of environmental factors in the landscape are dynamic. Disturbance modifies environmental conditions so that any location in the landscape is subject to a range of environmental conditions over time. The distribution and abundance of individuals and species are determined by the tolerances to this range of conditions. Much of the work reported in this volume has been stimulated by this conceptual model. Yet, the way human actions interact with the environment at all scales (e.g. global warming, urban heat island effect, land use, roads and landslides, and water extraction) make future scenarios difficult to predict. The elevational and climatic gradients within the Luquillo Mountains and northeastern Puerto Rico provide a natural in situ simulation of climate change, as a difference of about 5°C in mean annual temperature and more 3000 mm in mean annual precipitation occur from the top of the Luquillo Mountains to the coast. Thus, the use or exploration of the elevation gradient as a proxy for climate change can be a practical and informative way to study climate change scenarios, or to conduct experiments based on translocation manipulations. Manipulative experiments along elevation gradients could focus on populations, communities or ecosystem processes, and can be designed to anticipate and understand the effects of warming and drying.

Book Chapter spatial gradients
2010 Advances in the application of DNA barcodes in building a community phylogeny for tropical trees in a Puerto Rican Forest Dynamics Plot Kress, J.W.; Swenson, N.G.; Thompson, J.; Uriarte, M.; Zimmerman, J.K.

Species number, functional traits, and phylogenetic history all contribute to characterizing the biological diversity in plant communities. The phylogenetic component of diversity has been particularly difficult to quantify in species-rich tropical tree assemblages. The compilation of previously published (and often incomplete) data on evolutionary relationships of species into a composite phylogeny of the taxa in a forest, through such programs as Phylomatic, has proven useful in building community phylogenies although often of limited resolution. Recently, DNA barcodes have been used to construct a robust community phylogeny for nearly 300 tree species in a forest dynamics plot in Panama using a supermatrix method. In that study sequence data from three barcode loci were used to generate a well-resolved specieslevel phylogeny. Methodology/Principal Findings: Here we expand upon this earlier investigation and present results on the use of a phylogenetic constraint tree to generate a community phylogeny for a diverse, tropical forest dynamics plot in Puerto Rico. This enhanced method of phylogenetic reconstruction insures the congruence of the barcode phylogeny with broadly accepted hypotheses on the phylogeny of flowering plants (i.e., APG III) regardless of the number and taxonomic breadth of the taxa sampled. We also compare maximum parsimony versus maximum likelihood estimates of community phylogenetic relationships as well as evaluate the effectiveness of one- versus two- versus three-gene barcodes in resolving community evolutionary history. Conclusions/Significance: As first demonstrated in the Panamanian forest dynamics plot, the results for the Puerto Rican plot illustrate that highly resolved phylogenies derived from DNA barcode sequence data combined with a constraint tree based on APG III are particularly useful in comparative analysis of phylogenetic diversity and will enhance research on the interface between community ecology and evolution.

Journal Article DNA barcoding; Forests; Phylogenetic analysis; Phylogenetics; Plant communities; Plant phylogenetics; Sequence alignment; trees; tropical tree
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
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
2015 Allometric differences between two phenotypes of the amphidromous shrimp Xiphocaris elongata Ocasio-Torres, M.E.; Crowl, T.A.; Sabat, A.M.

The amphidromous shrimp Xiphocaris elongata(Guérin-Méneville, 1855) has a long rostrum in the presence of predatory fishes and a short rostrum above steep waterfalls where predatory fishes are absent, i.e., typically above waterfalls. Prior experiments showed that elongated rostrum in X. elongatais induced by chemical signals from the predatory fish Agonostomus monticola. We tested the hypothesis that in addition to rostrum length there are other morphometric differences between long-rostrum (LR) and short-rostrum (SR) X. elongata. We measured the post-orbital carapace length and pleon length of LR and SR shrimp and weighed both shrimp morphs. LR shrimp have significantly longer and heavier pleons than the SR shrimp. These allometric differences may affect the behavior of X. elongatashrimp in ways that, in turn, affect their interactions with predators and the environment. Our study demonstrates the importance of taking pleon measurements when studying crustaceans given that these measurements have been mostly overlooked, and may provide insight of environmental influences on crustacean morphology and behavior. This research provides data of the differences between prey phenotypes, which may alter their life-histories and interactions with the environment.

Journal Article allometry; Caribbean streams; freshwater shrimp; inducible defenses; phenotypic plasticity
1996 Amphibians
Stewart, M.M., and Lawrence L Woolbright. 1996. Amphibians. In The food web of a tropical rainforest, The food web of a tropical rainforest, eds. P.D. Reagan and Waide, R. B. Chicago, Illinois: University of Chicago Press.
Stewart, M.M.; Woolbright, L.L. Book Chapter tropical amphibians
2015 An allometry-based model of the survival strategies of hydraulic failure and carbon starvation Gentine, P.; Guérin, M.; Uriarte, M.; McDowell, N.G.; Pockman, W.T.

A simplified soil–plant–atmosphere–continuum model of carbon starvation and hydraulic failure is developed and tested against observations from a drought-manipulation experiment in a woodland dominated by piñon pine (Pinus edulis) and juniper (Juniperus monosperma) in New Mexico. The number of model parameters is reduced using allometric relationships. The model can represent more isohydric (piñon) and more anisohydric (juniper) responses. Analysis of the parameter space suggests four main controls on hydraulic failure and carbon starvation: xylem vulnerability curve, root:shoot area ratio, rooting depth and water use efficiency. For piñon, an intermediate optimal (1.5–2 m2 m−2) tree leaf area index reduces the risk of hydraulic failure. For both piñons and junipers, hydraulic failure was relatively insensitive to root:shoot ratio across a range of tree LAI. Higher root:shoot ratios however strongly decreased the time to carbon starvation. The hydraulic safety margin of piñons is strongly diminished by large diurnal variations in xylem/leaf water potential. Diurnal drops of water potential are mitigated by high maximum hydraulic conductivity, high root:shoot ratio and stomatal regulation (more isohydric). The safety margin of junipers is not very sensitive to diurnal drops in water potential so that there is little benefit in stomatal regulation (more anisohydric). Narrower tracheid diameter and a narrower distribution of tracheid diameters reduce the risk of hydraulic failure and carbon starvation by reducing diurnal xylem water potential drop. Simulated tree diameter-dependent mortality varies between these two species, with piñon mortality decreasing with increasing tree size, whereas juniper mortality increases with tree size. Juvenile piñons might thus be overimpacted by water stress. Copyright © 2015 John Wiley & Sons, Ltd.

Journal Article allometry; carbon starvation; cavitation; embolism; isohydric anoisohydric; physical model; tree diameter
1996 An altitudinal comparison of growth and species composition in hurricane-damaged forests in Puerto Rico Walker, L.A.; Zimmerman, J.K.; Lodge, D.J.; Guzman, S. Journal Article tropical forests
2000 An analysis of internode variations in Sierra palm (Prestoea montana) of the Luquillo Mountains of Puerto Rico Beldini, T.P. Thesis Sierra palm
1998 An analytical model of latitudinalgradients of species richness with an empirical test formarsupials and bats in the New World Willig, M.R.; Lyons, S.K. Journal Article stochastic model
1993 An annotated list of the flora of the Bisley area, Luquillo Experimental Forest, Puerto Rico, 1987 to 1992 Chinea, J.D.; Beymer, R.J.; Rivera, C.; de Jesus, S.; Scantena, F.N. Report flora list
2011 An Ecoinformatics Application for Forest Dynamics Plot Data Management and Sharing Chau-Chin, L.; Rahman-Kassim, A.B.D.; Vanderbilt, K.; Henshaw, D.; Melendez-Colom, E.C.; Porter, J.; Niiyama, K.; Yagihashi, T.; Tan, A.; Lu, S.S.; Hsiao, C.W.; Chang, L.W.; Jeng, M.R.

Several forest dynamics plot research projects in the East-Asia Pacific region of the International Long-Term Ecological Research network actively collect long-term data, and some of these large plots are members of the Center for Tropical Forest Science network. The wealth of forest plot data presents challenges in information management to researchers. In order to facilitate the management of these data, a Forest Dynamics Plot Database and Application Workshop was held in Taiwan 2009. This paper describes the results of the workshop that produced and tested an integrated information management framework. The goal for the framework was to demonstrate how fully documented data archives can be effectively used for data discovery, access, retrieval, analysis, and integration. Results from our work included setting up a database based on the Center for Tropical Forest Science structure on a local relational database (MySQL) server, an authentication interface, a metadata query web page, and 3 workflows to test the framework. Access article in:

Journal Article EAP ILTER; ecoinformatics; forest ecology; LTER; metadata
2003 An ecological perspective on the biodiversity of tropical island streams Smith, G.C.; Covich, A.; Brasher, A.M.D. Journal Article watershed
2002 An EMERGY evaluation of Puerto Rico and the Luquillo Experimental Forest Scantena, F.N.; Doherty, S.J.; Odum, H.T.; Karecha, P. Report tropical forest
1992 An experimental study of the slope stability of the rain forest in Puerto Rico Basnet, K. Journal Article tropical rain forest
2011 An integrated conceptual framework for long-term social-ecological research Collins, S.L.; Carpenter, S.R.; Swinton, S.M.; Orenstein, D.E.; Childers, D.L.; Gragson, T.L.; Grimm, N.B.; Grove, J.M.; Harlan, S.L.; Kaye, J.P.; Knapp, A.K.; Kofinas, G.P.; Magnuson, J.J.; McDowell, W.H.; Melack, J.M.; Ogden, L.A.; Robertson, G.P.; Smith, G.C.; Whitmer, A.C.

The global reach of human activities affects all natural ecosystems, so that the environment is best viewed as a social–ecological system. Consequently, a more integrative approach to environmental science, one that bridges the biophysical and social domains, is sorely needed. Although models and frameworks for social–ecological systems exist, few are explicitly designed to guide a long-term interdisciplinary research program. Here, we present an iterative framework, “Press–Pulse Dynamics” (PPD), that integrates the biophysical and social sciences through an understanding of how human behaviors affect “press” and “pulse” dynamics and ecosystem processes. Such dynamics and processes, in turn, influence ecosystem services –thereby altering human behaviors and initiating feedbacks that impact the original dynamics and processes. We believe that research guided by the PPD framework will lead to a more thorough understanding of social–ecological systems and generate the knowledge needed to address pervasive environmental problems. Also access article in:

Journal Article
1991 An introduction to hurricanes in the Caribbean Walker, L.A.; Lodge, D.J.; N. V. L. Brokaw; Waide, R.B. Journal Article Puerto Rico
1999 An introduction to terrestrial disturbance
Walker, L. A, and M. R Willig. 1999. An Introduction To Terrestrial Disturbance. In Ecosystem of the World 16: Ecosystems of Disturbed Ground, Ecosystem of the World 16: Ecosystems of Disturbed Ground, ed. L. A Walker. Amsterdam: Elsevier, 1-16.
Walker, L.A.; Willig, M.R. Book Chapter terrestrial disturbance
1989 An introduction to the physiography and history of the Bisley Experimental Watersheds in the Luquillo Mountains of Puerto Rico Scantena, F.N. Report physiography
2004 An updated checklist of the discomycetes for the Dominican Republic and the Caribbean Region Cantrell, S.A.; Iturriaga, T.; Pfister, D.H. Journal Article Rhytismatales
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
2004 Analysis and interpretation of fungal biodiversity patterns
Zack, J. C, and M. R Willig. 2004. Analysis And Interpretation Of Fungal Biodiversity Patterns. In Biodiversity of fungi: inventory and monitoring methods, Biodiversity of fungi: inventory and monitoring methods, eds. G.M. Mueller, Bills, G.F., and Foster, D. Burlington, Massachusetts: Elsevier Academic Press, 59-76.
Zack, J.C.; Willig, M.R. Book Chapter Neotropics
2000 Analysis of 20th century rainfall and streamflow to characterize drought and water resources in Puerto Rico Larsen, M.C. Journal Article water management
1993 Analysis of leaf and fine root litterfrom a subtropical montane rain forest by pyrolysis-gas chromatography-mass spectrometry Galletti, G.C.; Reeves, J.B.; Bloomfield, J.; Vogt, D.; Vogt, D.

As a preliminary part of a larger study on litter decomposition in tropical forests, pyrolysis—gas chromatography/mass spectrometry, Fourier transform-infrared spectroscopy (FT-IR) and conventional wet chemistry methods were used to determine the composition of tropical leaf and fine root tissue, and the quality of the tissue acting as a substrate for decay. Wet chemistry fiber analysis of Sierra Palm (Prestoea montana) and Tabonuco (Dacryodes excelsa) samples suggested high total lignin contents which were not supported by the other techniques. Results showed a high amount of phenol being produced during the pyrolysis of Sierra Palm, and lower total lignin content than that measured by wet chemistry. Typical FT-IR spectra and pyrograms with peak identification and quantitative data are reported.

Journal Article subtropical montane 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
1998 Animal community considerations in the sustainable management of tropical forests Reagan, P.D. Journal Article tropical forests
1999 Animal responses to natural disturbance and roles as patch generating phenomena
Willig, M. R, and M.A. McGinley. 1999. Animal Responses To Natural Disturbance And Roles As Patch Generating Phenomena. In Ecosystem of the World 16: Ecosystems of Disturbed Ground, Ecosystem of the World 16: Ecosystems of Disturbed Ground, ed. L. A Walker. Amsterdam, The Netherlands: Elsevier Science, 667-689.
Willig, M.R.; McGinley, M.A. Book Chapter patch habitat
1996 Anoline lizards
Reagan, P. D. 1996. Anoline Lizards. In The food web of a tropical rain forest, The food web of a tropical rain forest, eds. P. D Reagan and Waide, R. B. Chicago, Illinois: University of Chicago Press, 321-345.
Reagan, P.D.

Anoline lizards (family Polychridae, genus Anolis) are the most conspicuous and abundant vertebrates inhabiting terrestrial ecosystems on Caribbean islands (William 1969, 1976; Moermond 1979a). As a group, anoles are diurnal, predominantly insectivorous, and occur throughout all vertical strata of the ecosystems they inhabit. Anole abundance and high visibility have made them a subject of numerous studies that have contributed to our understanding of island biogeography (Williams 1969, 1972, 1983), resource partitioning (Schoener 1968, 1974), limiting factors (Licht 1974, Andrews 1976), habitat selection (Keister et al. 1975), competition (Schoener 1969a,b,c; Stamps 1977; Wright 1981; Pacala and Roughgarden 1983; Rummel and Roughgarden 1985), niche relationships (Ruibal and Philibosian 1970; Lister 1976), and foraging behavior (Moermond 1973) 1979a,b; Reagan 1986). Anoles are among the most studied of any vertebrate genus in the tropics.

Williams (1976) conducted a test analysis of the evolutionary radiation of anoline lizard on Puerto Rico because the anole fauna was relatively well-known and moderately complex. He introduced the ecomorph concept to describe the convergent evolutionary pattern of a set of animals showing similar correlations of morphology, ecology and behavior, but not lineage. While the concept has been reasonably applied to widely divergent taxa on continents (Karr and James 1975), Williams convincingly demonstrated this concept in the radiation of a single genus (Anolis) within the archipelago. He described six ecomorphs: crown giant, twig dwarf, trunk-crown, trunk, trunk-ground, and grass-bush. Williams (1983) added additional categories by recognizing obvious subdivisions of the original categories and started that for the Greater Antilles, body size and perch characteristics separate the ecomorphs. Roughgarden and Pacala (1989) summarize the current understanding of Anolis systematics for the eastern Caribbean, including Puerto Rico.

Five anoline species inhabit the tabonuco forests of Puerto Rico (Rand 1964; Turner and Gist 1970; Schoener and Schoener 1971). The Puerto Rican giant anole, Anolis cuvieri, a crown giant ecomorph, is the largest species. Three smaller anole species A. gundlachi (trunk-ground ecomorph), A. evermanni (trunk-ground ecomoprh and generalist), and A. stratulus (twig dwarf), are relatively common within the forest. A fifth species, A. occultus, occurs near the forest edge or in the openings along the streams, but it is generally rare in the tabonuco forest.

Examining various lines of evidence Williams (1972) discussed phylogenetic relationships an presented a phylogeny of Puerto Rican anoles based on ostelogical (Etheridge 1960, 1965), karyotypic (Gorman and Atkins 1969) and electrophoretic (Maldonado and Ortiz 1966) studies. These phylogenies show A. cuvieri and A. occultus as the most primitive and distinct species. A. gudlachi diverged from two closely related species, A. evermanni and A. stratulus in more recent times. Current evidence indicates that the primary route of anoline invasions of Puerto Rico was from the Hispaniola.

On the Caribbean islands where there were no large animals such as those found in mainland ecosystems (e.g., tapirs, jaguars), anoles constitute a substantial portion of the total of animal biomass. Their abundance, widespread ecological distribution, and functional role as higher order consumers make them important components of insular animal communities throughout the food webs in Caribbean islands (Schoener and Toft 1983; Schoener and Spiller 1987), and Reagan (1986) described the role of anoles as important consumers in the food web of tabonuco forest at El Verde. This chapter summarizes aspects of anole biology relevant to food web structure and organization in tabonuco forest.

Book Chapter Anolis; Anolis ecology; herpetology; LTER; phylogenetic
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 Antipredator defense mechanism in the amphidromous shrimp Xiphocaris elongata: rostrum length Ocasio-Torres, M.E.; Giray, T.; Crowl, T.A.; Sabat, A.M. Journal Article
2009 Applying lessons from ecological succession to the restoration of landslides Walker, L.A.; Velazquez, E.; Shiels, A.B.

Landslides are excellent illustrations of the dynamic interplay of disturbance and succession. Restoration is difficult on landslide surfaces because of the high degree of spatial and temporal heterogeneity in soil stability and fertility. Principles derived from more than a century of study of ecological succession can guide efforts to reduce chronic surface soil erosion and restore both biodiversity and ecosystem function. Promotion of the recovery of self-sustaining communities on landslides is feasible by stabilization with native ground cover, applications of nutrient amendments, facilitation of dispersal to overcome establishment bottlenecks, emphasis on functionally redundant species and promotion of connectivity with the adjacent landscape. Arrested succession through resource dominance by a single species can be beneficial if that species also reduces persistent erosion, yet the tradeoff is often reduced biodiversity. Restoration efforts can be streamlined by using techniques that promote successional processes.

Journal Article Soil fertility
2004 Approaches to sampling macrofungi
O'Dell, T.E., and D. J Lodge. 2004. Approaches To Sampling Macrofungi. In Measuring and Monitoring Biological Diversity: Standard Methods for Fungi, Measuring and Monitoring Biological Diversity: Standard Methods for Fungi, ed. G.M. Mueller. Chicago,USA: University of Chicago Press.
O'Dell, T.E.; Lodge, D.J. Book Chapter fungi taxonomy
1999 Aquatic ecosystem deterioration in Latin America and the Caribbean.
Pringle, C.M., and F. N Scantena. 1999. Aquatic Ecosystem Deterioration In Latin America And The Caribbean.. In Managed Ecosystems: the Mesoamerican experience, Managed Ecosystems: the Mesoamerican experience, eds. U. Hatch and Swisher, M.E. Oxford, U.K: Oxford University Press, 104-113.
Pringle, C.M.; Scantena, F.N. Book Chapter tropical streams
2004 Aquatic insect assemblages in shrimp-dominated tropical streams, Puerto Rico Ramírez, A.; Cruz, V. Journal Article top-down control
2013 Aquatic insects of Puerto Rico: a list of families Gutierrez-Fonseca, P.E.; Rosas, K.G.; Ramírez, A.

Studies on aquatic insects in Puerto Rico began early last century. Most taxa have been well documented; however, we lack informationon some taxa and there is no single document containing all the scattered information. These are major obstacles for the study of insectson the island. Here we reviewed data collected in published articles, graduate theses, university courses, environmental impact studies andreviewed material deposited in the Museum of Zoology at the University of Puerto Rico. The objective was to compile the first list of aquaticinsect families of Puerto Rico. Overall, 61 families belonging to seven insect orders were found. The best known orders were Ephemeroptera,Trichoptera and Odonata. The most diverse orders were Diptera, followed by Coleoptera and Hemiptera. Despite its small size, Puerto Ricois a diverse island compared to the remaining Greater Antilles. This study is the first attempt to develop a list with all information availableand contribute to advance our knowledge of aquatic insects. In addition, we hope to aid decision makers and encourage ecological andbiogeographical studies on aquatic ecosystems in Puerto Rico. 

Journal Article Aquatic insects; Greater Antilles; island; Puerto Rico; taxonomic richness
1996 Arboreal arachnids
Pfeiffer, W.J. 1996. Arboreal Arachnids. In The food web of a tropical rain forest, The food web of a tropical rain forest, eds. P.D. Reagan and Waide, R. B. Chicago, Illinois: University of Chicago Press, 247-271.
Pfeiffer, W.J. Book Chapter undestory predators
1996 Arboreal invertebrates
Garrison, R.W., and M. R Willig. 1996. Arboreal Invertebrates. In The food web of a tropical rain forest, The food web of a tropical rain forest, eds. P.D. Reagan and Waide, R. B. Chicago, Illinois: University of Chicago Press, 183-271.
Garrison, R.W.; Willig, M.R. Book Chapter tropical invertebrates density
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
2000 Are bats which pollinate and disperse forest plants particularly sensitive to disturbance? A case study on the effects of Hurricane Georges on bats of Puerto Rico Barlow, K.E.; Vaughan, N.; Willig, M.R.; Rodriguez-Duran, A.; Gannon, M.R. Journal Article Puerto Rico
2007 Are tropical streams ecologically different from temperate streams? Boulton, A.J.; Boyero, L.; Covich, A.; Dobson, M.; Lake, S.; Pearson, H.A. Book Chapter tropical streams
2009 Are tropical streams really different? Boyero, L.; Ramírez, A.; Dudgeon, D.; Pearson, R.G.

In the preface of a recent collection of review articles on tropical stream ecology, Dudgeon (2008) stated that there is no such thing as a “typical” tropical stream. The tropics make up the area of the globe between lat 23°N and 23°S, and include a great variety of climatic, geologic, and geomorphologic conditions (Boulton et al. 2008). Thus, tropical streams can flow through landscapes as varied as evergreen rain forests, deciduous seasonal forests, high-altitude grasslands, or even deserts. This diversity suggests that generalizations about tropical streams might be difficult to come by, but it also indicates that much is to be learned about stream ecology in tropical regions. Several major obstacles hinder the study of tropical streams. An obvious gap is our limited knowledge of their benthic faunas. European, North American, and, to a lesser extent, Australian and New Zealand stream invertebrates have been studied extensively and are well known, but this is not the case for most tropical stream invertebrates. Many insect larval stages have not been related to adults, and identification to species is not possible. Their life histories are unknown, but are often assumed (without good reason) to be similar to those of related temperate taxa. For example, certain traits, such as feeding habits, can differ among close relatives at different latitudes. Baetids and leptophlebiids (Ephemeroptera) are generally scrapers or collector-gatherers in temperate streams, but the baetids, Acanthiops from Kenya and Andesiops from Bolivia, and the leptophlebiids, Atalophlebia from the Australian Wet Tropics and Barba from Papua New Guinea, are shredders (Yule 1996, Dobson et al. 2002, Molina 2004, Cheshire et al. 2005). Studies of tropical streams have been restricted to intense activity by a small number of research groups in a few geographic regions, particularly in Costa Rica, Hong Kong, Kenya, Puerto Rico, Queensland, and Venezuela, although some important work has been done elsewhere. This geographic limitation constrains our ability to understand tropical regions in general. Moreover, it highlights the need for effective communication among dispersed groups of tropical researchers and between workers in tropical and temperate latitudes. Publication of compendia on tropical stream ecology, an activity that the Journal of the North American Benthological Society (J-NABS) has pioneered, is a powerful tool for enhancing communication and stimulating research in the tropics. The 1stJ-NABS special issue on tropical streams was published 20 y ago. It focused on unifying approaches to the study of streams in different biomes (Stanford and Covich 1988) and included topics such as spatial and temporal scales of patchiness and disturbance. The papers in the series mainly reviewed available data from the tropics and emphasized the need for a global perspective when constructing theories for the organization of stream ecosystems (Minshall 1988). The 2ndJ-NABS special issue on tropical streams was published in 1995 (Jackson and Sweeney 1995). It focused on descriptive research and included papers on invertebrate taxonomy and life histories, nutrient dynamics, pesticides, and gene flow in invertebrate populations. Only 2 papers, one on leaf-litter processing rates (Campbell and Fuchshuber 1995) and one on disturbance and recolonization of stony substrata (Rosser and Pearson 1995), focused on ecological processes. The range of topics reflected efforts to arrive at a broader understanding of tropical streams, but highlighted the limited amount of information that was applicable at the ecosystem level. The 3rdJ-NABS special issue on tropical streams was “New vistas in Neotropical stream ecology” and was published in 2006 (Wantzen et al. 2006). It included studies undertaken at sites in Central and South America and the Caribbean, and embraced an array of topics, including caddisfly biology, organic-matter processing, algal biomass, invertebrate distribution, fish biogeography, and ecological assessment. This issue was concerned solely with the Neotropics, but it demonstrated that understanding of tropical stream ecology had progressed substantially. This 4th compendium of tropical stream studies arose from a special session, “Are tropical streams ecologically different?,” during the 54th annual meeting of the North American Benthological Society (2006; Anchorage, Alaska, USA). The goals of the session were to present novel patterns and notions on the functioning of tropical streams with a special emphasis on energy sources and pathways fueling the ecosystem and the consumers they support and to provide a broad geographical context that would allow comparisons among different tropical areas. This strategy, it was hoped, would yield some generalizations about tropical stream ecosystem processes. This special issue includes most of the research presented at that session and some additions. Studies represent a wide array of tropical streams, including those in Central America (Costa Rica), South America (Venezuela), Asia (Hong Kong and Peninsular Malaysia), Africa (Madagascar), and the Pacific islands (Micronesia), and some subtropical streams (northern New South Wales, Australia). It includes an analysis of global-scale latitudinal patterns in freshwater biodiversity. Given the small number of studies making up this issue, the extent to which they reveal novel and unexpected patterns is surprising. They confirm the variability of conditions and environments in streams within the tropics and underscore the need for further studies of streams from all tropical regions. Such investigations should include basic taxonomic work, autecological studies, and elucidation of ecological processes and interactions, including foodweb structure and dynamics.

Journal Article
2007 Arthromyces and Blastosporella, two new genera of conidia-producing lyophylloid agarics (Agaricales, Basidiomycota) from the neotropics Baroni, T.J.; Franco-Molano, A.E.; Lodge, D.J.; Lindner, D.L.; Horak, E.; Hofstetter, V. Journal Article Tropical montane
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
2008 Assessing Evidence for a Pervasive Alteration in Tropical Tree Communities Chave, J.; Condit, R.; Muller, G.M.; Thomas, S.C.; Ashton, P.; Bunyavejchewin, S.

InAmazonian tropical forests, recent studies have reported increases in aboveground biomass and in primary productivity, as well as shifts in plant species composition favouring fast-growing species over slow-growing ones. This pervasive alteration ofmature tropical forestswas attributed to global environmental change, such as an increase in atmospheric CO2 concentration, nutrient deposition, temperature, drought frequency, and/or irradiance. We used standardized, repeated measurements of over 2million trees in ten large (16–52 ha each) forest plots on three continents to evaluate the generality of these findings across tropical forests. Aboveground biomass increased at seven of our ten plots, significantly so at four plots, and showed a large decrease at a single plot. Carbon accumulation pooled across sites was significant (þ0.24 MgC ha1 y1, 95% confidence intervals [0.07, 0.39] MgC ha1 y1), but lower than reported previously for Amazonia. At three sites for which we had data for multiple census intervals, we found no concerted increase in biomass gain, in conflict with the increased productivity hypothesis. Over all ten plots, the fastest-growing quartile of species gained biomass (þ0.33[0.09, 0.55]%y1) comparedwith the tree community as a whole (þ0.15%y1); however, this significant trend was due to a single plot. Biomass of slow-growing species increased significantlywhen calculated over all plots (þ0.21 [0.02, 0.37]%y1),and in half of our plots when calculated individually. Our results do not support the hypothesis that fast-growing species are consistently increasing in dominance in tropical tree communities. Instead, they suggest that our plots may be simultaneously recovering frompast disturbances and affected by changes in resource availability.More long-termstudies are necessary to clarify the contribution of global change to the functioning of tropical forests.

Journal Article tropical forests
2007 Assessing Landslide Hazards
Keefer, D.K., and M.C. Larsen. 2007. Assessing Landslide Hazards. Science 316: 1136-1138.
Keefer, D.K.; Larsen, M.C. Journal Article Natural disasters
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
2004 Asynchronous fluctuation of soil microbial biomass and plant litterfall in a tropical wet forest Ruan, H.H.; Zou, X.M.; Scantena, F.N.; Zimmerman, J.K. Journal Article Abbreviations: Annual fluctuation of soil microbial biomass and litterfall
1996 At what temporal scales does disturbance affect below ground nutrient pools? Silver, W.L.; Scantena, F.N.; Johnson, A.H.; Siccama, T.G.; Watt, F. Journal Article Forest floor; harvesting; hurricane; nutrient availability; root biomass; soil organic matter; tropical forest
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
1998 Atmospheric deposition and net retention of ions by the canopy in a tropical montane forest, Monteverde, Costa Rica Clark, D.A.; Nadkarni, N.M.; Schaefer, D.; Gholz, H.L.

Meteorological variables, bulk cloud water and precipitation (BCWP), and bulk precipitation (BP) were measured above the canopy, and throughfall (TF; n = 20) was collected beneath an epiphyte-laden canopy of a tropical montane forest (TMF) for 1 y at Monteverde, Costa Rica. Total deposition (cloud + wet + dry) of inorganic ions to the canopy was estimated using a sodium (Na+) mass balance technique. Annual BCWP and BP depths were 2678 mm and 1792 for events where mean windspeeds (u) [greater-than-or-equal] 2 m s&supminus1;, and 4077 mm and 3191 mm for all events, respectively. Volume-weighted mean pH and concentrations of nitrate-N (NO3[minus sign]-N) and ammonium-N (NH4+-N) were 4.88, 0.09 and 0.09 mg l&supminus1; in BCWP, and 5.00, 0.05 and 0.05 mg l&supminus1; in BP, respectively. Cloud water and mist deposition to the canopy was estimated to be 356 mm. Estimated deposition of free acidity (H+), NO3[minus sign]-N, and NH4+-N to the canopy was 0.49, 3.4 and 3.4 kg ha&supminus1; y&supminus1;, respectively. Mean TF depth was 1054 ± 83 mm (mean ± S.E.) for events where u [greater-than-or-equal] 2 m s&supminus1;, and 2068 ± 132 mm for all events. Volume-weighted mean pH and concentrations of NO3[minus sign]-N and NH4+-N in TF were 5.72, 0.04 mg l&supminus1;, and 0.07 mg l&supminus1;, respectively. Mean fluxes of H+, NO3[minus sign]-N, and NH4+-N in TF were 0.04 ± 0.01, 0.6 ± 0.2 and 1.3 ± 0.2 kg ha&supminus1; y&supminus1;, and percent net retention of these ions by the canopy was 92 ± 2, 80 ±6, and 61 ± 6%, respectively. Phosphate, potassium, calcium and magnesium were leached from the canopy. Seasonal data suggest that biomass burning increased concentrations of NO3[minus sign] and NH4+ in cloud water and precipitation at the end of the dry season. Regardless, a large majority of the inorganic N in atmospheric deposition was retained by the canopy at this site.

Journal Article atmospheric deposition; cloud forest; Interception loss; nitrogen retention; precipitation chemistry; throughfall; tropics
1996 Atyid shrimps (Decapoda: Atyidae)influence spatial heterogeneity of algal communities over different scales in tropical montane streams, Puerto Rico Pringle, C.M. Journal Article stream ecology
2011 Atypical soil carbon distribution across a tropical steepland forest catena Johnson, A.H.; Scantena, F.N.; Silver, W.L.

Soil organic carbon (SOC) in a humid subtropical forest in Puerto Rico is higher at ridge locations compared to valleys, and therefore opposite to what is commonly observed in other forested hillslope catenas. To better understand the spatial distribution of SOC in this system, plots previously characterized by topographic position, vegetation type and stand age were related to soil depth and SOC. Additional factors were also investigated, including topographically-related differences in litter dynamics and soil chemistry. To investigate the influence of litter dynamics, the Century soil organic model was parameterized to simulate the effect of substituting valley species for ridge species. Soil chemical controls on C concentrations were investigated with multiple linear regression models using iron, aluminum and clay variables. Deeper soils were associated with indicators of higher landscape stability (older tabonuco stands established on ridges and slopes), while shallower soils persisted in more disturbed areas (younger non-tabonuco stands in valleys and on slopes). Soil depth alone accounted for 77% of the observed difference in the mean 0 to 60 cm SOC between ridge soils (deeper) and valley soils (shallower). The remaining differences in SOC were due to additional factors that lowered C concentrations at valley locations in the 0 to 10 cm pool. Model simulations showed a slight decrease in SOC when lower litter C:N was substituted for higher litter C:N, but the effects of different woody inputs on SOC were unclear. Multiple linear regression models with ammonium oxalate extractable iron and aluminum, dithionite–citrate-extractable iron and aluminum, and clay contents explained as much as 74% of the variation in C concentrations, and indicated that organo-mineral complexation may be more limited in poorly developed valley soils. Thus, topography both directly and indirectly affects SOC pools through a variety of inter-related processes that are often not quantified or captured in terrestrial carbon models.

Journal Article organo-mineral complexation; Soil carbon; soil forming factors; topographic and vegetation interactions; Tropical steepland forest
1996 Background and catastrophic tree mortality in tropical moist, wet, and rain forests Lugo, A.E.; Scantena, F.N. Journal Article tropical forests
1999 Background canopy gap and catastrophic wind disturbances in tropical forest
Whigham, D.F., M.B. Dickinson, and N. V. L. Brokaw. 1999. Background Canopy Gap And Catastrophic Wind Disturbances In Tropical Forest. In Ecosystem of the World 16: Ecosystems of Disturbed Ground, Ecosystem of the World 16: Ecosystems of Disturbed Ground, ed. L. A Walker. Amsterdam: Elsevier, 223-252.
Whigham, D.F.; Dickinson, M.B.; N. V. L. Brokaw Book Chapter tropical forest
2009 Banana crop expansion and increased river-borne exports to the Uraba Gulf (Caribbean Coast of Colombia) Juan F Blanco Journal Article Uraba Gulf
2000 Barriers to forest regeneration in an abandoned pasture in Puerto Rico Zimmerman, J.K.; Aide, T.M.; Pascarella, J.B. Journal Article Tabebuis
1995 Base saturation, nutrient cation,and organic matter increases during early pedogenesis onlandslide scarsin the Luquillo Experimental Forest, Puerto Rico Zarin, D.J.; Johnson, A.H. Journal Article Puerto Rico
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
1998 Basidiomycetes of the Greater Antilles I: new species and new records of Alboleptonia from Puerto Rico and St. John, USVI Baroni, T.J.; Lodge, D.J. Journal Article USVI
2001 Basidiomycetes of the Greater Antilles project Cantrell, S.A.; Lodge, D.J.; Baroni, T.J. Journal Article Taxonomy
1988 Basidiomycetes reduce export of organic matter from forest slopes Lodge, D.J.; Asbury, C.E.

Export of leaf litter from forest siopes can affect soil organic matter (SOM) concentrations, soil nutrient pools, and consequently foliar nutrient concentrations in vegetation (Lang and Orndorff, 1984). Mechanisms which retain litter are especially important in maintaining soil fertility in montane forests, where a high proportion of the landscape is on steep slopes. Litter retained on slopes decomposes in situ and contributes to SOM and soil nutrients in these sites. In addition, litter mats protect surface soil from erosional losses of SOM and nutrients. (Cogo et al., 1984). This paper presents that binding of leaf litter by basidiomycetous fungi retards the export of organic matter from forests slopes.

Journal Article basidiomycetes; Fungi; organic matter; soil; soil biogeochemistry; soil ecology
2009 Bat metacommunity structure on Caribbean islands and the role of endemics Presley, S.J. Journal Article species range turnover
1992 Bat reproduction in the Luquillo Experimental Forest of Puerto Rico Gannon, M.R.; Willig, M.R. Journal Article reproductive patterns
2005 Bats of Puerto Rico: An Island Focus and Caribbean Perspective Gannon, M.R.; Duran, M.R.; Kurta, A.; Willig, M.R.

An interesting and enjoyable read. . . . Rich detail presented in well-written, logical fashion about the bat fauna of this interesting island." —Acta Chiropterologica The Caribbean islands are home to some of the most unusual species of bats. A number of them are endemic, living in no other region of the world. On Puerto Rico alone, thirteen different species have been found. Bats are the only naturally occurring mammals there; all others were introduced after settlement of the island, first by the Taíno Indians and later by the Spanish. Puerto Rico is important for study because of its human history, tropical climate, size, relief, and isolation from the mainland. It is a useful model for understanding how historical, geographic, and environmental factors interact in a controlled environment to affect the diversity and complexity of its resident species. This volume is the first complete compilation of the distribution, natural history, taxonomy, and ecology of the bats of Puerto Rico. The coauthors, all experienced researchers, introduce the book with a discussion of Puerto Rican ecosystems and an overview of facts and misconceptions about bats in general. The main text provides detailed descriptions of each of the thirteen Puerto Rican species, as well as illustrations of their faces and skulls. The book concludes with keys to the characters of these bats and a complete glossary. Maps show the distribution of each species on the island. Bats of Puerto Rico is designed to be an easily used source of information for the general public as well as a complete descriptive record for ecologists, mammalogists, and wildlife biologists.

Book Chapter Puerto Rico
1992 Belowground ecology of forests
Publicover, D.A., and D. Vogt. 1992. Belowground Ecology Of Forests. In Yearbook of Science and Technology, Yearbook of Science and Technology, New York: McGraw-Hill, 427-429.
Publicover, D.A.; Vogt, D. Book Chapter soil ecology
1993 Belowground responses a sindicators of environmental change Vogt, D.; Publicover, D.A.; Bloomfield, J.; Pérez-Jiménez, J.R.; Vogt, D.; Silver, W.L. Journal Article turnover
1994 Benthic prey avoidance behaviors in response to decapod predators:temperate and tropical comparisons Covich, A.; Crowl, A.T.; Alexander, J.E.; Vaughn, C.C. Journal Article Benthic organism; decapod predators; decapods; ecosystems comparisons
2011 Beyond carbon and nitrogen: how the microbial energy economy couples elemental cycles in diverse ecosystems Burgin, A.J.; Yang, W.H.; Hamilton, L.S.; Silver, W.L.

Microbial metabolism couples elemental reactions, driving biogeochemical cycles. Assimilatory coupling of elemental cycles, such as the carbon (C), nitrogen (N), and phosphorus cycles, occurs when these elements are incorporated into biomass or released through its decomposition. In addition, many microbes are capable of dissimilatory coupling, catalyzing energy-releasing reactions linked to transformations in the oxidation state of elements, and releasing the transformed elements to the environment. Different inorganic elements provide varying amounts of energy yield, and the interaction of these processes creates a microbial energy economy. Dissimilatory reactions involving C, N, iron, and sulfur provide particularly important examples where microbially mediated oxidation–reduction (redox) transformations affect nutrient availability for net primary production, greenhouse-gas emissions, levels of contaminants and natural toxic factors, and other ecosystem dynamics. Recent discoveries of previously unrecognized microbial dissimilatory processes are leading to reevaluation of traditional perceptions of biogeochemical cycles.

Journal Article
2006 Biocomplexity of arctic patterned-ground ecosystems. Walker, L.A.; Daanen, R.; Epstein, H.; Gould, W.A.; González, G.; Kade, A.; Kelley, A.; Krantz, W.; Kuss, P.; Michaelson, G.; Munger, C.; Nickolsky, D.; Peterson, R.; Ping, C.L.; Raynolds, M.; Romanovsky, V.; Tarnocai, C.; Vonlanthan, C.

Small-scale patterned-ground features, including non-sorted circles and small non-sorted polygons, are important features of most arctic landscapes. The size, abundance and morphology of these features are affected by complex interactions between cryological processes, soil properties, and biological processes. We examined the interactions between frost-heave, contraction cracking, soil properties, and vegetation along an 1800-km transect through 10 degrees of latitude and approximately 11 degrees C of mean July temperature. We established permanent monitoring sites at 11 locations in the 5 bioclimate subzones of the Arctic (Subzone A is the coldest; E is warmest). Patterned-ground morphology on zonal sites changes in predictable ways with differences in climate, soil-moisture, soil-texture, and the structure of the vegetation. Large well- vegetated earth hummocks 2-3 m in diameter are prevalent in forested areas and in tussock tundra areas of Subzone E. Partially vegetated and barren 1-2-m diameter non-sorted circles are dominant in the more open vegetation of subzones D and southern parts of subzone C, and small barren non-sorted polygons and turf hummocks 10-30 cm in diameter are related to small-scale contraction cracking in subzones C, B and A. Strong thermal, physical, and chemical gradients develop within frost-heave features that help to maintain the position of these features in the same locality over long time periods. Many of these gradients are related to the contrast in the vegetation mat on and between these features. This results in much warmer soil conditions within the heave features in summer and much colder conditions during the winter. Strong thermal differences drive the movement of water and the development of frost heave. Cryoturbation of organic material from the margins of frost-heave features to the permafrost table, combined with aggrading permafrost tables, acts to sequester large amounts of carbon within the permafrost of these ecosystems. Using a model (WIT3D/ArcVeg) that includes interactions between geophysical and biological processes, we were able to replicate common patterned ground forms involving differential frost heave. So far, the models have replicated the patterns in the Low Arctic where differential frost heave is the dominant process. Contraction cracking is the dominant process in the High Arctic and new models will be needed to elucidate this process. The presence of non- sorted circles affects active-layer depths, carbon storage and flux rates, and is likely to affect the rate at which Arctic systems will adjust to climate change. Analysis of a 14-yr record of greening near Toolik Lake, Alaska indicate that areas with abundant non-sorted circles experience more rapid change than stable areas without circles, suggesting that landscapes with a significant amount of disturbance, whether caused by natural or anthropogenic forces, will change most rapidly under a warming climate

Conference Paper Tundra
2007 Biodiversidad de insectos acuáticos y el funcionamiento de los ecosistemas
Ramírez, A. 2007. Biodiversidad De Insectos Acuáticos Y El Funcionamiento De Los Ecosistemas. In Simposio Internacional Entomología Acuática Mexicana: Estado Actual de Conocimiento y Aplicación, Simposio Internacional Entomología Acuática Mexicana: Estado Actual de Conocimiento y Aplicación, eds. R. N Gutiérrez and Lis, P. EAlonso-. ,Acapulco, Guerrero, México.: IMTA-SME.
Ramírez, A. Conference Paper
2014 Biodiversidad de Puerto Rico: Invertebrados / Serie de Historia Natural Joglar, R.L.; Santos-Flores, C.J.; Torres-Pérez, J.I.; González, G. Book
1996 Biodiversity and biogeochemical cycling
Silver, W. L, S. Brown, and A. E Lugo. 1996. Biodiversity And Biogeochemical Cycling. In Biodiversity and Ecosystem Processes in Tropical Forests, Biodiversity and Ecosystem Processes in Tropical Forests, eds. G. Orians, Dirzo, R., and Cushman, H. Springer-Verlag, Heidleberg, 49-67.
Silver, W.L.; Brown, S.; Lugo, A.E. Book Chapter tropical forest
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
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
1997 Biodiversity and ecosystem processes in freshwater sediments Palmer, M.A.; Covich, A.; Finlay, B.J.; Gilbert, J.; Hyde, K.D.; Johnson, A.H.; Kairesalo, T.; Lake, S.; Lovell, C.R.; Naiman, R.J.; Ricci, C.; Sabater, F.; Strayer, D. Journal Article tropical forests
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
2011 Biodiversity and Productivity Willig, M.R.

Researchers predict that human activities—especially landscape modification and climate change—will have a considerable impact on the distribution and abundance of species at local, regional, and global scales in the 21st century (1, 2). This is a concern for a number of reasons, including the potential loss of goods and services that biodiversity provides to people (3, 4). Exactly how biodiversity relates to ecosystem function and productivity, however, has been a widely studied and highly controversial issue over the past few decades. Initially, for example, many researchers believed that the relationship between species richness and net primary productivity (often expressed as the number of grams of carbon produced within a square meter of an ecosystem over a year) could be visualized as a hump-shaped or modal curve (5), with richness first rising and then declining with increasing productivity. However, subsequent theoretical and empirical research, including meta-analyses, seriously diminished acceptance of the modal pattern as a canonical relationship (611). On page 1750 of this issue, Adler et al. (12) carry the critique a step further. In a multiscale assessment of 48 plant communities on five continents, they demonstrate that the modal productivity-diversity pattern is quite rare in nature, rather than the dominant relationship. Their findings suggest that ecological understanding may advance more rapidly if investigators focus on exploring a range of topics that are germane to the productivity-diversity relationship in a changing world, rather than continue the search for a dominant pattern.

Journal Article Plants
1997 Biodiversity and the productivity and stability of ecosystems Johnson, A.H.; Vogt, D.; Clark, D.A.; Schmitz, O.J.; Vogt, D. Journal Article ecosytem diversity
2011 Biogeochemical cycling in tropical forests
McGroddy, M. E, and W. L Silver. 2011. Biogeochemical Cycling In Tropical Forests. In Tropical Rainforest Responses to Climatic Change, Tropical Rainforest Responses to Climatic Change, eds. M. Bush and Flenly, J. Verlag, Berlin: Praxis-Springer, 315-341.
McGroddy, M.E.; Silver, W.L.

Increased inputs of greenhouse gases have altered the composition of the atmosphere over the past 150 years (IPCC, 2001, 2007), resulting in shifts in temperature and precipitation around the globe. The scientific community has put an enormous effort into understanding the causes of these changes, and predicting future climate and the interactions between climate and the biosphere that may moderate or accelerate current trends. Most of the research on climate change has focused on boreal and north temperate ecosystems where temperature shifts are predicted to be the largest (IPCC, 2001, 2007). These ecosystems are often characterized by deep organic soils that present the potential for a strong positive feedback to climate change (Oechel et al., 1998; Vourlitis and Oechel, 1997; Hobbie et al., 2002).

Book Chapter
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
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
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
2011 Biogeography in the air: fungal diversity over land and oceans. Frohlich-Nowoisky, J.; Burrows, S.M.; Xie, Z.; Engling, G.; Solomon, P.A.; Fraser, T.; Mayol-Bracero, O.L.; Artaxo, P.; Begerow, D.; Conrad, R.; Andreae, M.O.; Despres, V.R.; Poschl, U.

Biogenic aerosols are relevant for the Earth system, climate, and public health on local, regional, and global scales. Up to now, however, little is known about the diversity and biogeography of airborne microorganisms. We present the first DNA-based analysis of airborne fungi on global scales, showing pronounced geographic patterns and boundaries. In particular we find that the ratio of species richness between Basidiomycota and Ascomycota is much higher in continental air than in marine air. This may be an important difference between the “blue ocean” and “green ocean” regimes in the formation of clouds and precipitation, for which fungal spores can act as nuclei. Our findings also suggest that air flow patterns and the global atmospheric circulation are important for the understanding of global changes in biodiversity.

Journal Article
2009 Biological Nitrogen Fixation in Two Tropical Forests: Ecosystem-Level Patterns and Effects of Nitrogen Fertilization Cusack, D.F.; Silver, W.L.; McDowell, W.H. Journal Article soil
1999 Biomasa y nutrientes en raices y brinzales de un bosque secundario en la zona cafetalera de Utuado Lugo, A.E.; Cristobal, D.; Irizarry, N.M. Journal Article secondary forests
1992 Biomass and nutrient accumulation in ten year old bryophyte communities inside a flood plain in the Luquillo Experimental Forest, Puerto Rico Frangi, J.L.; Lugo, A.E.

Ten year old bryophyte communities growing on wooden stakes along a microtopographic gradient in a flood plain forest at 750 m elevation accumulated between 210 and 1400 kg/ha of ash-free biomass and an average of 14.5, 0.8, 5.3, 2.7, 2.7, 18.5, and 22.0 kg/ha of N, P, K, Ca, Mg, Mn, Fe, and Al, respectively. This biomass and nutrient accumulation was in the same order of magnitude as the accumulation of biomass and nutrients in fine litter. Both biomass and nutrient accumulation were greater in communities on stream bank slopes or slopes of tree mounds. Less biomass and nutrient accumulated in depressions with long hydroperiods. Concentration of nutrients (except N), and annual rate of ash-free biomass accumulation (20-140 kg/ha$\cdot$yr) were low in comparison with other bryophyte communities. Bryophyte communities in tropical flood plains appear to be biotic filters of flood waters and help retain nutrients in the terrestrial biota.

Journal Article tropics
1993 Biomass and nutrient content of the Bisley Experimental Watersheds, Luquillo Experimental Forest, Puerto Rico before and after Hurricane Hugo, 1989 Scantena, F.N.; Silver, W.L.; Siccama, T.G.; Johnson, A.H.; de Leon, S. Journal Article watersheds
2004 Biomass and nutrient dynamics of restored neotropical forests Lugo, A.E.; Silver, W.L.; Molina, M. Journal Article tree plantations
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
2011 Biophysical and socioeconomic factors associated with forest transitions at multiple spatial and temporal scales Yackulic, C.B.; Fagan, M.; Jain, M.; Jina, A.; Lim, Y.; Marlier, M.; Muscarella, R.; Adame, P.; DeFries, R.; Uriarte, M.

Forest transitions (FT) occur when socioeconomic development leads to a shift from net deforestation to reforestation; these dynamics have been observed in multiple countries across the globe, including the island of Puerto Rico in the Caribbean. Starting in the 1950s, Puerto Rico transitioned from an agrarian to a manufacturing and service economy reliant on food imports, leading to extensive reforestation. In recent years, however, net reforestation has leveled off. Here we examine the drivers of forest transition in Puerto Rico from 1977 to 2000 at two subnational, nested spatial scales (municipality and barrio) and over two time periods (1977-1991 and 1991-2000). This study builds on previous work by considering the social and biophysical factors that influence both reforestation and deforestation at multiple spatial and temporal scales. By doing so within one analysis, this study offers a comprehensive understanding of the relative importance of various social and biophysical factors for forest transitions an the scales at which they are manifest. Biophysical factors considered in these analyses included slope, soil quality, and land-cover in the surrounding landscape. We also considered per capita income, population density, and the extent of protected areas as potential factors associated with forest change. Our results show that, in the 1977-1991 period, biophysical factors that exhibit variation at municipality scales (~100km²) were more important predictors of forest change than socioeconomic factors. In this period, forest dynamics were driven primarily by abandonment of less productive, steep agricultural land in the western,central part of the island. These factors had less predictive power at the smaller barrio scale (~10 km²) relative to the larger municipality scale during this time period. The relative importance of socioeconomic variables for deforestation, however, increased over time as development pressures on available land increased. From 1991-2000, changes in forest cover reflected influences from multiple factors, including increasing population densities, land development pressure from suburbanization, and the presence of protected areas. In contrast to the 1977-1991 period, drivers of deforestation and reforestation over this second interval were similar for the two spatial scales of analyses. Generally, our results suggest that although broader socioeconomic changes in a given region may drive the demand for land, biophysical factors ultimately mediate where development occurs. Although economic development may initially result in reforestation due to rural to urban migration and the abandonment of agricultural lands, increased economic development may lead to deforestation through increased suburbanization pressures.

Journal Article Agricultural abandonment; deforestation; Ecology; Forest transition; Forestry; Puerto Rico; Reforestation
2010 Biotic and abiotic controls on ecosystem significance of consumer excretion in two contrasting tropical streams Benstead, J.P.; Cross, W.F.; March, J.A.; McDowell, W.H.; Ramírez, A.; Covich, A.

Excretion of nitrogen (N) and phosphorus (P) is a direct and potentially important role for aquatic consumers in nutrient cycling that has recently garnered increased attention. The ecosystem-level significance of excreted nutrients depends on a suite of abiotic and biotic factors, however, and few studies have coupled measurements of excretion with consideration of its likely importance for whole-system nutrient fluxes. We measured rates and ratios of N and P excretion by shrimps (Xiphocaris elongata and Atya spp.) in two tropical streams that differed strongly in shrimp biomass because a waterfall excluded predatory fish from one site. We also made measurements of shrimp and basal resource carbon (C), N and P content and estimated shrimp densities and ecosystem-level N and P excretion and uptake. Finally, we used a 3-year record of discharge and NH4-N concentration in the high-biomass stream to estimate temporal variation in the distance required for excretion to turn over the ambient NH4-N pool. Per cent C, N, and P body content of Xiphocaris was significantly higher than that of Atya. Only per cent P body content showed significant negative relationships with body mass. C:N of Atya increased significantly with body mass and was higher than that of Xiphocaris. N : P of Xiphocaris was significantly higher than that of Atya. Excretion rates ranged from 0.16–3.80 μmol NH4-N shrimp−1 h−1, 0.23–5.76 μmol total dissolved nitrogen (TDN) shrimp−1 h−1 and 0.002–0.186 μmol total dissolved phosphorus (TDP) shrimp−1 h−1. Body size was generally a strong predictor of excretion rates in both taxa, differing between Xiphocaris and Atya for TDP but not NH4-N and TDN. Excretion rates showed statistically significant but weak relationships with body content stoichiometry. Large between-stream differences in shrimp biomass drove differences in total excretion by the two shrimp communities (22.3 versus 0.20 μmol NH4-N m−2 h−1, 37.5 versus 0.26 μmol TDN m−2 h−1 and 1.1 versus 0.015 μmol TDP m−2 h−1), equivalent to 21% and 0.5% of NH4-N uptake and 5% and <0.1% of P uptake measured in the high- and low-biomass stream, respectively. Distances required for excretion to turn over the ambient NH4-N pool varied more than a hundredfold over the 3-year record in the high-shrimp stream, driven by variability in discharge and NH4-N concentration. Our results underscore the importance of both biotic and abiotic factors in controlling consumer excretion and its significance for nutrient cycling in aquatic ecosystems. Differences in community-level excretion rates were related to spatial patterns in shrimp biomass dictated by geomorphology and the presence of predators. Abiotic factors also had important effects through temporal patterns in discharge and nutrient concentrations. Future excretion studies that focus on nutrient cycling should consider both biotic and abiotic factors in assessing the significance of consumer excretion in aquatic ecosystems.

Journal Article consumer-driven nutrient recycling; ecological stoichiometry; El Yunque; Luquillo experimental forest; Puerto Rico
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 Biotropica Issue Information Chazdon, R.L.; Uriarte, M. Journal Article
2002 Bird perches and soil amendments as revegetation techniques for landslides in Puerto Rico Shiels, A.B. Thesis seedlings
2003 Bird perches increase forest seeds on Puerto Rican landslide Shiels, A.B.; Walker, L.A. Journal Article seeds
1996 Birds
Waide, R. B. 1996. Birds. In The food web of a tropical rain forest, The food web of a tropical rain forest, eds. P.D. Reagan and Waide, R. B. Chicago, Illinois: University of Chicago Press, 363-398.
Waide, R.B. Book Chapter tropics
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
2014 Bromelia Invertebrate Communities on Saba, Netherlands Antilles Richardson, B.

We sampled tank bromeliads and censused their invertebrate fauna at four elevations on the small Caribbean island of Saba. We expected that invertebrate communities would show a strong response to the elevational gradient, as found on the larger island of Puerto Rico, but there was no difference in overall animal abundance, species richness, or biomass in bromeliads at the different sites. A weak rainfall gradient and relatively recent anthropogenic disturbance may be reasons for the lack of elevational response. The structure of the community in dry forest bromeliads was different from in the wetter forests, due to the dominance of the larvae of one particular species (Forcipomyoa antiguensis). The aquatic larvae of some bromeliad-specialist genera (e.g., Monopelopia, Corethrella, Wyeomyia, and Scirtes) common in the other Caribbean and mainland sites were absent from Saba. Their absence may be due to the target island effect, which reduces the chances of successful immigration and survival on small islands. 

Journal Article
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
2000 C and N dynamics in the riparian and hyporheic zones of a tropical stream, Luquillo Mountains, Puerto Rico Chesnut, T.J.; McDowell, W.H. Journal Article DOC; hydrologic characteristics; hyporheic zone; nitrogen; nutrient cycling; riparian zone; Tropical Rainforest
2009 Ca/Sr and 87Sr/86Sr ratios as tracers of Ca and Sr cycling in the Rio Icacos watershed, Luquillo Mountains, Puerto Rico Pett-Ridge, J.; Derry, L.A.; Barrows, J.K.

We investigated Ca and Sr cycling in a humid tropical forest by analyzing Ca/Sr ratios and 87Sr/86Sr ratios in soil minerals, soil exchangeable cations, soil porewater, and plant roots, wood and leaves, and calculating the relative contributions of Sr from atmospheric inputs and weathering of local bedrock. An unexpectedly large contribution of bedrock-derived Sr and presumably Ca is cycled through the vegetation, reflecting the important role of geological processes in controlling the cycling of base cation nutrients even in a system with intensely weathered soil. This is surprising because over 99% of the Ca and Sr that was originally in the bedrock is leached out of the soil and saprolite during early stages of weathering at this site, and because there are large atmospheric inputs to the site of both sea salt and Saharan dust. Substantial differences in Ca and Sr cycling are seen on small spatial scales between a ridgetop and an adjacent steep hillslope site. Measured Ca/Sr ratios reflect fractionation between these elements during biogeochemical cycling. Fractionation was particularly evident between wood and foliar tissue, but fractionation during soil exchange processes is also likely. In comparing the Ca/Sr ratios of plants, exchangeable cations, and bulk soils, we found that foliar Ca/Sr ratios were greater than exchangeable cation Ca/Sr ratios, which in turn were greater than soil Ca/Sr ratios, similar to patterns observed at other highly weathered tropical sites.

Journal Article strontium
1999 Calocybe cyanea - a rare and beautiful agaric is discovered in Puerto Rico Baroni, T.J.; Vilgalys, R.; Lodge, D.J.; Legon, N.V.

A rare find of Calocybe cyanea from Puerto Rico is described and illustrated. A discussion of all species of Calocybe found in the Caribbean is provided. Since nearly one-half of the described species of Calocybe can be found in the Neotropics (nine out of the 20 or so known taxa), a key to the species of Calocybe which are found in the Neotropics is included

Journal Article Calocybe cyanea; Caribbean; identification key; Neotropics
1991 Camillea: new combinations and a new species Rogers, J.D.; Laessøe, T.; Lodge, D.J. Journal Article Theaceae
2002 Can uptake length in streams be determined by nutrient addition experiments? Results from an inter-biome comparison study Mulholland, J.P.; Tank, J.; Webster, J.R.; Bowden, R.D.; Dodds, W.K.; Gregory, S.V.; Grimm, N.B.; Hamilton, L.S.; Johnson, A.H.; Marti, E.; McDowell, W.H.; Merriam, J.L.; Meyer, J.L.; Peterson, B.J.; Valett, H.M.; Wollheim, W.M. Journal Article uptake length
2002 Can we manage tropical landscapes? - an answer from the Caribbean perspective Lugo, A.E. Journal Article tropical landscapes
2013 Canopy arthropod responses to experimental canopy opening and debris deposition in a tropical rainforest subject to hurricanes Schowalter, T.D.; Willig, M.R.; Presley, S.J.

We analyzed responses of canopy arthropods on seven representative early and late successional overstory and understory tree species to a canopy trimming experiment designed to separate effects of canopy opening and debris pulse (resulting from hurricane disturbance) in a tropical rainforest ecosystem at the Luquillo Experimental Forest Long-Term Ecological Research (LTER) site in Puerto Rico. We expected that either canopy opening or added debris would result in increased abundances of certain scale insects and other hemipterans, and thereby affect arthropod diversity. Six of thirteen arthropod taxa tested showed significant responses to treatments as main effects or interactions. No taxon responded significantly to trim treatment alone. The red wax scale, Ceroplastes rubens (on Manilkara bidentata), was significantly less abundant in treatments with added debris than in treatments without added debris, and salticid spiders (on Sloanea berteriana) were significantly more abundant in treatments with added debris than in other treatments. Canopy trimming generally did not have a significant effect on assemblage diversity, whereas debris deposition significantly increased diversity on three late successional tree species. A number of significant treatment interactions were observed. Overall, the debris pulse had a greater effect on canopy arthropods than did canopy opening, suggesting that changes in plant condition resulting from nutrient availability associated with debris deposition have a greater effect on canopy arthropods than do the more direct and immediate changes in abiotic conditions resulting from canopy opening.

Journal Article Arthropod; Canopy opening; Debris pulse; disturbance; Red wax scale; tropical forest
2014 Canopy arthropod responses to experimental canopy opening and debris deposition in a tropical rainforest subject to hurricanes Schowalter, T.D.; Willig, M.R.; Presley, S.J.

We analyzed responses of canopy arthropods on seven representative early and late successional overstory and understory tree species to a canopy trimming experiment designed to separate effects of canopy opening and debris pulse (resulting from hurricane disturbance) in a tropical rainforest ecosystem at the Luquillo Experimental Forest Long-Term Ecological Research (LTER) site in Puerto Rico. We expected that either canopy opening or added debris would result in increased abundances of certain scale insects and other hemipterans, and thereby affect arthropod diversity. Six of thirteen arthropod taxa tested showed significant responses to treatments as main effects or interactions. No taxon responded significantly to trim treatment alone. The red wax scale, Ceroplastes rubens (on Manilkara bidentata), was significantly less abundant in treatments with added debris than in treatments without added debris, and salticid spiders (on Sloanea berteriana) were significantly more abundant in treatments with added debris than in other treatments. Canopy trimming generally did not have a significant effect on assemblage diversity, whereas debris deposition significantly increased diversity on three late successional tree species. A number of significant treatment interactions were observed. Overall, the debris pulse had a greater effect on canopy arthropods than did canopy opening, suggesting that changes in plant condition resulting from nutrient availability associated with debris deposition have a greater effect on canopy arthropods than do the more direct and immediate changes in abiotic conditions resulting from canopy opening.

Journal Article Arthropod; Canopy opening; Debris pulse; disturbance; Red wax scale; tropical forest
1995 Canopy invertebrate community response to disturbance and consequences of herbivory in temperate and tropical forests Schowalter, T.D. Journal Article tropical forests
2004 Carbon and nitrogen stoichiometry and nitrogen cycling rates in streams Dodds, W.K.; Marti, E.; Tank, J.; Pontius, J.; Hamilton, L.S.; Grimm, N.B.; Bowden, R.D.; McDowell, W.H.; Peterson, B.J.; Valett, H.M.; Webster, J.R.; Gregory, S.

Stoichiometric analyses can be used to investigate the linkages between N and C cycles and how these linkages influence biogeochemistry at many scales, from components of individual ecosystems up to the biosphere. N-specific NH4+ uptake rates were measured in eight streams using short-term 15N tracer additions, and C to N ratios (C:N) were determined from living and non-living organic matter collected from ten streams. These data were also compared to previously published data compiled from studies of lakes, ponds, wetlands, forests, and tundra. There was a significant negative relationship between C:N and N-specific uptake rate; C:N could account for 41% of the variance in N-specific uptake rate across all streams, and the relationship held in five of eight streams. Most of the variation in N-specific uptake rate was contributed by detrital and primary producer compartments with large values of C:N and small values for N-specific uptake rate. In streams, particulate materials are not as likely to move downstream as dissolved N, so if N is cycling in a particulate compartment, N retention is likely to be greater. Together, these data suggest that N retention may depend in part on C:N of living and non-living organic matter in streams. Factors that alter C:N of stream ecosystem compartments, such as removal of riparian vegetation or N fertilization, may influence the amount of retention attributed to these ecosystem compartments by causing shifts in stoichiometry. Our analysis suggests that C:N of ecosystem compartments can be used to link N-cycling models across streams.

Journal Article streams
1995 Carbon isotope characterization of vegetation and soil organic matter in subtropical forests in Luquillo, Puerto Rico von Fischer, J.C.; Tieszen, L.L. Journal Article soil organic matter
2006 Carbon isotope fractionation by methane-oxidizing bacteria in tropical rain forest soils Teh, Y.A.; Silver, W.L.; Conrad, M.E.; Borglin, S.E.; Carlson, C.M.

Humid tropical forests have the potential to be significant sources or sinks of atmospheric methane (CH4), a radiatively important trace gas. Methane oxidation can consume a large fraction of the CH4 produced in tropical soils, although controls on this process are poorly understood. Using soil incubation experiments, we investigated the effects of CH4 and oxygen (O2) concentrations on C isotope fractionation and CH4 oxidation in tropical rain forest soils. We also explored the effects of these environmental variables on the isotope fractionation factor for CH4 oxidation (α), which is widely used to evaluate the relative contributions of CH4 production and oxidation to the atmospheric CH4 pool. Methane oxidation was sensitive to CH4 at lower CH4 concentrations (<850 ppmv) and insensitive to O2 concentrations between 3 and 21%. Maximum rates of CH4 oxidation were between 8.2 ± 1.2 and 11.3 ± 1.5 nmol CH4 hour−1 g dry soil−1. Measured values for α were sensitive to both CH4 oxidation rate and CH4 concentration. Alpha was inversely proportional to CH4 oxidation rate (r2 = 0.86, P < 0.001) and positively correlated with CH4 concentration (r2 = 0.52, P < 0.01). A multiple regression model that included CH4 oxidation rate, CH4 concentration, and the interaction of the two terms explained a high proportion of the variability in α (r2 = 0.94, P < 0.0001). These data suggest that it is possible to accurately determine α, allowing for more precise estimates of CH4 oxidation by isotope mass balance.

Journal Article Rayleigh fractionation
2004 Carbon sequestration and plant community dynamics with reforestation of tropical pasture Silver, W.L.; Kueppers, L.; Lugo, A.E.; Ostertag, R.; Matzek, V. Journal Article tropical reforestation
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
2009 Carpe noctem: The importance of bats as bioindicators.
Willig, M. R. 2009. Carpe Noctem: The Importance Of Bats As Bioindicators.. Endangered Species Research 8: 93-115.
Willig, M.R. Journal Article Indicator species
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
2007 Cascading events in linked ecological and social-economic systems: Predicting change in an uncertain world Peters, D.P.C.; Sala, O.E.; Allen, C.D.; Covich, A.; Brunson, M. Journal Article human processes
2010 Case Studies of Ecological Integrative Information Systems: The Luquillo and Sevilleta Information Management Systems San Gil, I.; White, A.F.; Melendez-Colom, E.C.; Vanderbilt, K.

The thirty-year-old United States Long Term Ecological Research Network has developed extensive metadata to document their scientific data. Standard and interoperable metadata is a core component of the data-driven analytical solutions developed by this research network Content management systems offer an affordable solution for rapid deployment of metadata centered information management systems. We developed a customized integrative metadata management system based on the Drupal content management system technology. Building on knowledge and experience with the Sevilleta and Luquillo Long Term Ecological Research sites, we successfully deployed the first two medium-scale customized prototypes. In this paper, we describe the vision behind our Drupal based information management instances, and list the features offered through these Drupal based systems. We also outline the plans to expand the information services offered through these metadata centered management systems. We will conclude with the growing list of participants deploying similar instances.

Book Chapter Drupal Content Management System; Metadata Editor; Metadata Management Sytem
1993 Catastrophic and background disturbance of tropical ecosystems at the Luquillo Experimental Forest Lugo, A.E.; Waide, R.B. Journal Article tropical forest
1990 Cecropia peltata L. Yagrumo hembra, trumpet tree
Silander, S., and A. E Lugo. 1990. Cecropia Peltata L. Yagrumo Hembra, Trumpet Tree. eds. R. M Burns and Honkala, B. H. Washington, DC: USDA Forest Service.
Silander, S.; Lugo, A.E. Report yagrumo hembra
1998 Cecropia schreberiana in the Luquillo Mountains of Puerto Rico N. V. L. Brokaw

Cecropia schreberiana Miq. (Cecropiaceae) is a common tree in the Luquillo Mountains of Puerto Rico because it is a pioneer that establishes abundantly after recurrent hurricanes that damage Luquillo forests. In these forests C. schreberiana typically reaches about 20 m in height and 60 cm dbh and has few branches, these bearing large, deeply lobed leaves. The wood is light and weak. Unlike most of its congeners, C. schreberiana in Puerto Rico does not have symbiotic ants. It is dioecious and produces wind-pollinated flowers in spikes and abundant minute seeds broadly dispersed by birds and bats. Forest soils contain a high density of its seeds, which lie dormant until canopy opening stimulates germination. With adequate nutrients C. schreberiana grows fast in high light, while nondominant individuals suffer heavy mortality. An individual of the species is thought to live 30 to 50 years. Cecropia schreberiana is uncommon in abandoned pastures in the Luquillo Mountains. It colonizes road cuts, landslides, and infrequent, large treefall gaps. Yet these disturbances provide only a limited "background regeneration," which is not sufficient to maintain the species' observed high abundance in Luquillo forests. However, there is widespread and abundant C. schreberiana regeneration after hurricane damage opens the forest canopy. Despite high mortality among these post-hurricane colonizers, enough survive and grow so that C. schreberiana is generally among the ten most common canopy trees in the widespread "tabonuco" forest type. Post-hurricane colonizers mature, senesce, and decline in number, but C. schreberiana remains abundant as seeds in the soil ready to form tree cohorts after disturbance. The status of the C. schreberiana population indicates the developmental status of the forest as a whole. Moreover, C. schreberiana performs a key function in the reorganization of Luquillo forest ecosystems after disturbance, when its abundant regeneration and rapid growth capture and store nutrients. Also, its colonizing saplings may facilitate succession to mature forest by excluding grasses, herbs, and vines that hinder forest development. The biology of this species both reflects and helps drive the dynamics of forests in the Luquillo Mountains. /// Cecropia schreberiana Miq. (Cecropiaceae) es un árbol común en las Montañas Luquillo de Puerto Rico, porque es una especie pionera que se establece abundantamente despues de huracanes que dañan frecuentamente los bosques Luquillos. En estos bosques C. schreberiana normalamente alcanza 20 m de altura y 60 cm dap. Tiene pocas ramas, las que sostienen hojas grandes y lobadas. La madera es leve y débil. A diferencia de la mayoría de sus congeneros, C. schreberiana no tiene hormigas simbióticas. Es dioico y produce flores en espigas, polenados por el viento, y las semillas abundantes son dispersadas por aves y murciélagos. Los suelos en bosques contienen muchos de sus semillas, las que tienen germinación retardada hasta de que un claro del dosel la estimule. Con alimentos adecuados, C. schreberiana crece rapidamente en la luz alta; a la otra mano, los árboles que no se encuentran en luz alta sufren un nivel alto de mortalidad. Parece que vive hasta 30 a 50 años. Cecropia schreberiana es poco común en pastizales abandanados en las Montañas Luquillo. Coloniza los margenes de caminos, deslizamientos de tierra, y claros grandes aunque raros hechos por árboles caidos. Sin embargo, estos perturbaciones permiten solamente una "regeneración de transfondo" que está limitada y no suficiente sostenir la abundancia alta de la especie que se ve en los bosques Luquillos. Pero hay regeneración abundante y dispersa de C. schreberiana despues de los huracanes dañan el dosel del bosque. Luego, a pesar de la mortalidad alta, hay regeneración y sobrevivicencia suficiente para que C. schreberiana sea normalamente uno de los árboles más común en el bosque del tipo "taboncuo." Estes colonizadores maduran y disminuyen en abundancia, sin embargo hay semillas abundante de C. schreberiana en el suelo, listas para formar un población de árboles despues de una perturbación. El estado de la población de C. schreberiana indica el estado de desarrollo del bosque en general. Además, C. schreberiana realiza una función clave en la reorganización de la ecosistema en los bosques Luquillos despues de una perturbación, cuando su regeneración abundante, y su crecimiento rapido, capturan y guardan alimentos. Además, sus arbolitos colonizadores pueden facilitar la sucesión vegetal, por excluir lianas y hierbas que impeden el desarrollo de bosque. La biología de esta especie refleja y influye la dinámica de los bosques en las Montañas Luquillo. 

Journal Article post hurricane colonizers
2002 Challenges to understanding dynamics of biodiversity in time and space Willig, M.R. Journal Article organism speciation
2013 Changes in abiotic influences on seed plants and ferns during 18 years of primary succession on Puerto Rican landslides Walker, L.A.; Shiels, A.B.; Bellingham, P.J.; Sparrow, A.D.; Fetcher, N.; Landau, F.H.; Lodge, D.J.

1. Abiotic variables are critical drivers of succession in most primary seres, but how their inuence on biota changes over time is rarely examined. Landslides provide good model systems for examining abiotic inuences because they are spatially and temporally heterogeneous habitats with distinct abiotic and biotic gradients and post-landslide erosion. 2. In an 18-year study on 6 Puerto Rican landslides, we used structural equation models to interpret the changing effects of abiotic inuences (landslide dimensions, slope, aspect, elevation, parent material and related soil properties) on seed plants (density and diversity), tree fern density, scrambling fern cover, canopy openness and soil development (nitrogen, soil organic matter, pH and cation exchange capacity). 3. Seven years after landslide formation, catchment size (the landslide area above the point of measurement) was the key abiotic factor inuencing plants. The larger the catchment the greater was the diversity and density of seed plants. Conversely, the smaller the catchment the greater was the density of tree ferns and the cover of scrambling ferns. 4. Eighteen years after landslide formation, landslide slope was the key abiotic inuence. The greater the slope, the lower was the density and diversity of seed plants and the greater the scrambling fern cover. 5. Aspect, particularly east-facing slopes exposed to wind disturbances, positively inuenced tree fern densities at both 7 and 18 years and negatively inuenced seed plants and scrambling ferns after 18 years. Soils were least developed, that is, had lowest soil nitrogen and organic matter concentrations, after 18 years on steep slopes (like seed plants) and were most developed near landslide edges, on hurricane-exposed slopes (like tree ferns), and where there were high soil potassium concentrations. 6. Synthesis. Abiotic variables have important inuences on plant succession on landslides and the relative inuence of different abiotic variables changes with time. Improved predictability of temporal dynamics will rely not only on understanding the effects of initial disturbances and subsequent biological responses but also on the different and changing inuences exerted by each abiotic variable.

Journal Article catchment; determinants of plant community diversity and structure; disturbance; diversity; erosion; hurricane; scrambling fern; slope; structural equation modelling; tree fern; tropical forest
1997 Changes in earthworm density and community structure in abandoned tropical pastures Zou, X.M.; González, G. Journal Article tropical pastures
1991 Changes in light availability following Hurricane Hugo in a subtropical montane forest in Puerto Rico Fernandez, E.; Fetcher, N.

The changes in light availability in the understory of a subtropical wet forest (Luquillo Experimental Forest, Puerto Rico) were monitored after the passage of Hurricane Hugo on 18 September 1989 Gallium arsenide phosphide sensors were placed 1 m apart along a 32 m transect. Data were collected for periods of 7-10 d in October and December 1989, and in March, July, and November 1990. Daily histograms were generated for observations of photosynthetic photon flux density (PPFD) taken every two seconds. Mean total daily PPFD was calculated for each sensor in each data set. During the 14 mo after the passage of the hurricane, the PPFD showed a highly skewed distribution with most values <200 $\mu$ mol m$^{-2}$ s$^{-1}$ The maximum spatial heterogeneity was observed in July 1990 because of the shading of some sensors by the growing pioneer vegetation. Median values of total daily PPFD for ten months after the hurricane ranged from 7.7 to 10.8 mol m$^{-2}$ d$^{-1}$, which is similar to values previously observed for large (>400 m$^2$) treefall gaps. Median total daily PPFD fell to 0.8 mol m$^{-2}$ d$^{-1}$ in November 1990 because of almost complete coverage of the transect by a canopy of Cecropia schreberiana Miq. ex. C. peltata. An analysis of semivariance was used to discern patterns of autocorrelation in total daily PPFD along the transect. Through March 1990 patches of high and low light separated by distances of 10-12 m were detected. By July 1990 the patchiness was replaced by a pattern that showed no autocorrelation at distances of 1 m or greater.

Journal Article understory
2011 Changes in microbial community characteristics and soil organic matter with nitrogen additions in two tropical forests Cusack, D.F.; Silver, W.L.; Torn, M.S.; Burton, S.D.; Firestone, M.K.; McDowell, W.H.

Microbial communities and their associated enzyme activities affect the amount and chemical quality of carbon (C) in soils. Increasing nitrogen (N) deposition, particularly in N-rich tropical forests, is likely to change the composition and behavior of microbial communities and feed back on ecosystem structure and function. This study presents a novel assessment of mechanistic links between microbial responses to N deposition and shifts in soil organic matter (SOM) quality and quantity. We used phospholipid fatty acid (PLFA) analysis and microbial enzyme assays in soils to assess microbial community responses to long-term N additions in two distinct tropical rain forests. We used soil density fractionation and 13C nuclear magnetic resonance (NMR) spectroscopy to measure related changes in SOM pool sizes and chemical quality. Microbial biomass increased in response to N fertilization in both tropical forests and corresponded to declines in pools of low-density SOM. The chemical quality of this soil C pool reflected ecosystem-specific changes in microbial community composition. In the lower-elevation forest, there was an increase in gram-negative bacteria PLFA biomass, and there were significant losses of labile C chemical groups (O-alkyls). In contrast, the upper-elevation tropical forest had an increase in fungal PLFAs with N additions and declines in C groups associated with increased soil C storage (alkyls). The dynamics of microbial enzymatic activities with N addition provided a functional link between changes in microbial community structure and SOM chemistry. Ecosystem-specific changes in microbial community composition are likely to have far-reaching effects on soil carbon storage and cycling. This study indicates that microbial communities in N-rich tropical forests can be sensitive to added N, but we can expect significant variability in how ecosystem structure and function respond to N deposition among tropical forest types.

Journal Article 13C NMR; extracellular enzymes; fertilization; Luquillo experimental forest; nitrogen deposition; nuclear magnetic resonance; nutrient availability; phospholipid fatty acid analysis; PLFA; Puerto Rico
1996 Changes in nutrient cycling during tropical deforestation Garcia-Montiel, D. Thesis biogeochenistry; nutrient cycling; tropical deforestation; tropical forest
2004 Changes in patterns of understory leaf phenology and herbivory following hurricane damage Angulo-Sandoval, P.; Fernandez, E.; Zimmerman, J.K.; Aide, T.M.

Hurricanes are important disturbance events in many forested ecosystems. They can have strong effects on both forest structure and animal populations, and yet few studies have considered the impacts on plant—animal interactions. Reduction of canopy cover by severe winds increases light availability to understory plants, providing an opportunity for increased growth. An increase in light availability should cause an increase in annual production of leaves and a more even production throughout the year (i.e., less seasonality in production). This change will affect the availability of food resources to folivorous insects that feed primarily on young leaves; outbreaks of these insects could nullify the temporary advantage of increased understory light levels. On 21 September 1998, Hurricane Georges struck Puerto Rico, providing an excellent opportunity to determine the effect of the hurricane on leaf production and herbivory in the forest understory by comparing post-hurricane data with data obtained from a previous study conducted at the same site. Eight species were analyzed at El Verde Field Station, a wet forest site in eastern Puerto Rico. For the eight species combined, there was an increase in number of leaves produced after the hurricane and a more even seasonal pattern of leaf production, as predicted. Levels of herbivory were much lower (2.03%) after the hurricane compared with pre hurricane conditions (16.05%), indicating that increased light availability to understory plants was not offset by increased herbivory. Lower levels of herbivory were possibly due to herbivore satiation, changes in leaf chemistry, changes in herbivore populations, changes in herbivore predator populations, or a combination of two or more of these factors. /// Los huracanes son perturbaciones importantes en muchos ecosistemas forestales. Estos pueden tener fuertes efectos en la estructura de los bosques y en las poblaciones de animales, sin embargo pocos estudios han considerado su impacto en las interacciones planta-animal. La reducción de la cobertura del dosel, dada por fuertes vientos, aumenta la disponibilidad de luz para las plantas del sotobosque, dando una oportunidad de crecimiento para éstas. Un aumento en la disponibilidad de luz, podría causar un aumento en la producción anual de hojas al igual que una producción más continua a través del año. Este cambio afectaría la disponibilidad de alimento para insectos folívoros, que se alimentan principalmente de hojas jóvenes. Si el aumento en recursos se traduce en un gran aumento en las poblacionales de folívoros, esto podría anular la ventaja temporal dada por incrementos en niveles de luz. En 21 septiembre de 1998, el Huracán Georges azotó Puerto Rico, dando una oportunidad excelente para determinar el efecto de un huracán en la producción de hojas y herbivoría en el sotobosque, por medio de comparaciones con datos obtenidos antes del huracán. Ocho especies se analizaron en la Estación Biológica del Verde, en la parte Este de Puerto Rico. Para las ocho especies combinadas hubo un aumento en producción de hojas después del huracán, y un patrón de producción uniforme a lo largo del año. Los niveles de herbivoría fueron mucho menores (2.03%) después del huracán, comparados con las condiciones pre huracán (16.05%), indicando que el aumento en la disponibilidad de luz para las plantas del sotobosque no fue afectada por aumentos de herbivoría. Los bajos niveles de herbivoría pudieron darse posiblemente porque los herbívoros fueron saciados, cambios en la química de las hojas, cambios en las poblaciones de herbívoros, cambios en las poblaciones de depredadores de herbívoros o por la combinación de dos o más de estos factores.

Journal Article tropics
2010 Changes in Structure, Composition, and Nutrients During 15 Yr of Hurricane-Induced Succession in a Subtropical Wet Forest in Puerto Rico