|Title||Changes in abiotic influences on seed plants and ferns during 18 years of primary succession on Puerto Rican landslides|
|Publication Type||Journal Article|
|Year of Publication||2013|
|Authors||Walker, LA, Shiels, AB, Bellingham, PJ, Sparrow, AD, Fetcher, N, Landau, FH, Lodge, DJ|
|Journal||Journal of Ecology|
|Keywords||catchment, determinants of plant community diversity and structure, disturbance, diversity, erosion, hurricane, scrambling fern, slope, structural equation modelling, tree fern, tropical forest|
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.