Plant-plant interactions influence phylogenetic diversity at multiple spatial scales in a semi-arid mountain rangeland.

Molecular phylogenies are increasingly used to understand how biotic interactions and environment shape phylogenetic community structure (PCS). However, we do not understand the effects of plant-plant interactions and environment on PCS and phylogenetic diversity across spatial scales, particularly in rangelands. Here, we ask: (1) do plant-plant interactions and environment affect PCS and phylogenetic diversity differently across the three spatial scales of the patch, the community, and the habitat? (2) What are the impacts of dominant cushion-nurse plants on the phylogenetic structure of plant communities? We assessed the PCS of semi-arid plant communities along an elevation gradient at the patch, community and habitat scales.

Spatial scale-dependent phylogenetic signal in species distributions along geographic and elevation gradients in a mountainous rangeland.

The mechanisms determining community phylogenetic structure range from local ecological mechanisms to broad biogeographical processes. How these community assembly processes determine phylogenetic structure and patterns in rangeland communities across multiple spatial scales is still poorly understood. We sought to determine whether the structure of herbaceous and shrub assemblages along local environmental gradients (elevation) and broad geography (latitude) exhibited phylogenetic signal at different spatial scales, across 2,500 ha of a mountainous rangeland.