Commonness of Amazonian palm (Arecaceae) species: Cross-scale linksand potential determinants

摘要

The mechanisms that cause variation in commonness (abundances and range sizes) of species remaindebated in ecology, and a repeatedly observed pattern is the positive relation between local abundancesand larger scale range sizes. We used the Amazonian palm species (Arecaceae) to investigate the depep-dence between and potential determinants of commonness across three (local, landscape, continental)spatial scales. Commonness at the smaller scales (local abundance, landscape frequency) was estimatedusing data from 57 transects (5 × 500 m) in primary, non-inundated (terra firme) rainforest in a westernAmazonian landscape, while commonness at the largest scale (continental range size) was estimated fromdigitized distribution maps. Landscape frequency was positively related to both local abundance andcontinental range size, which, however, were not related to each other. Landscape frequency was positivelyrelated to topographic niche breadth. Stem height correlated with continental range size and was the onlyspecies life-history trait related to any commonness measure. Distance from the study area to a species'range centre did not influence any of the commonness measures. The factors determining commonness inthe Amazonian palm flora appear to be scale-dependent, with the unrelated local scale abundance andcontinental range size probably being controlled by different driving factors. Interestingly, commonness atthe intermediate, landscape scale seems linked to both the smaller and the larger scale. Our results pointtowards topographic niche breadth at the smaller scales and stem height, possibly reflecting species'dispersal potential, at the continental scale as important determinants of commonness.