Local and regional palm (Arecaceae) species richness patterns and their cross-scale determinants in the western Amazon

• Published in: The Journal of ecology Vol. 99; no. 4; pp. 1001 - 1015
• Main Authors: Kristiansen, Thea, Svenning, Jens-Christian, Pedersen, Dennis, Eiserhardt, Wolf L, Grández, César, Balslev, Henrik
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.07.2011; Blackwell Publishing; Blackwell
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Arecaceae; Biodiversity; Biological and medical sciences; Census; climate; climatic stability; data collection; Determinants of plant community diversity and structure; diversity; Ecology; Ecoregions; environmental factors; environmental filtering; Flowers & plants; Forest ecology; Forest habitats; Forestry; Fundamental and applied biological sciences. Psychology; General aspects; General forest ecology; Generalities. Production, biomass. Quality of wood and forest products. General forest ecology; Habitats; Human ecology; immigration; Neotropical rain forests; plant community ecology; Plants; Rainforests; soil; Soil fertility; spatial scale; Species; Species diversity; species pool effects; topography; Tropical rain forests; South America; America; Amazon Basin; South America, Amazon R; Monocotyledones; Climate; Stability; Plant community; Rain forest; Tropical zone; Diversity; Plant ecology; Spatial scale; Regional; plant community ecology; Climatic condition; species pool effects; climatic stability; Topography; Angiospermae; environmental filtering; Environment; Spermatophyta; Palmae; Neotropical Region; Species richness; Neotropical rain forests
• ISSN: 0022-0477; 1365-2745
• DOI: 10.1111/j.1365-2745.2011.01834.x

1. Local and regional patterns of plant species richness in tropical rain forests, as well as their possible drivers, remain largely unexplored. The main hypotheses for local species richness (alpha diversity) are (i) local environmental determinism with species-saturated communities, and (ii) regional control, in which the immigration of species from the regional species pool (gamma diversity) determines how many species coexist locally. The species pool hypothesis suggests a combined influence of local and regional drivers on alpha diversity. Differences in gamma diversity may arise from divergent environmental conditions or biogeographic histories. 2. We investigated the cross-scale determinants of palm alpha and gamma diversity across the western Amazon using a large field-based data set: a census of all palm individuals in 312 transects, totalling 98 species. We used regression-based variation partitioning to understand how habitat, topography and region influence alpha diversity, and correlations to assess the importance of the present environment (climate, soil, regional topography) and history (long-term habitat stability) for average regional alpha diversity and gamma diversity, including the link between these two diversity measures (species pool effect). 3. Variation in alpha diversity was primarily explained by region (36%) and habitat (18%), whereas the effect of topography was negligible (1%). Within habitats, region was even more important (up to 69% explained variation). Within regions, habitat and topography covaried and had a variable but an important influence. The pure effect of topography remained of minor importance (up to 13%). 4. Average regional alpha diversity was related to gamma diversity, precipitation seasonality and possibly long-term habitat stability. Gamma diversity was related to long-term habitat stability, and possibly current climate. 5. Synthesis. Gamma diversity strongly influenced alpha diversity, although a clear influence of local environment was also evident, notably habitat type, with a minor, more geographically variable effect of small-scale topography. Apart from gamma diversity, the factor most strongly related to regional alpha diversity was precipitation seasonality, while gamma diversity itself was strongly linked to long-term habitat stability. These results imply that plant species richness is contingent on both contemporary and historical factors with a strong link between local species richness and the regional species pool.