Plant Functional Trait Diversity is Influenced by Spatial Scaling and Moisture

Abstract

Ecological communities are subsets of larger-scale species pools. Community assembly may be due to ecological drift, resulting in communities with a random set of species and functional traits. However, ecological selection processes can act as filters and reduce functional trait diversity to a narrow subset, especially where environmental stress is high (aka trait clustering). Alternatively, ecological selection processes such as competition can require resource partitioning and thereby cause communities to have greater than expected functional trait diversity (aka trait overdispersion), especially where environmental stress is. Trait-based community assembly may also be affected by scale. Competition between plants occurs over short distances, and so trait overdispersion should be most evident in small plots (i.e., small grain sizes). Environmental filtering should be most evident when comparing local communities to the largest spatial extent of the species pool and assembly should become increasingly random or over dispersed as the species pool extent is reduced in scale.