Phylogenetic beta diversity in an upper montane Atlantic Forest along an altitudinal gradient

Abstract

Studying community phylogenies along elevation gradients can inform us about the influences of environmental conditions on the structuring communities, and therefore allow predictions on how future environmental changes may affect them. The aim of the work was to evaluate the processes that govern tree communities along an altitudinal gradient in an upper montane Atlantic Forest in the Mantiqueira Range, southeastern Brazil. To do so, we analyzed the phylogenetic structure of angiosperm tree communities in four elevations (ranging from 1500 to 2100 m) and verified if it varies significantly with altitude. We also analyzed the phylogenetic beta diversity among local angiosperm tree communities along the altitudinal gradient. Further, we evaluated the soil and temperature influences over these communities. The results showed tendency of increasing phylogenetic clustering with the elevation. We also verified that the phylogenetic lineages of the tree communities are replaced along the altitudinal gradient influenced by changes in temperature and soil, indicating phylogenetic niche conservatism. This suggest that these communities could move to higher altitudes in a global warming scenario, and that would change their species composition and abundance due to changes in soil along the altitudinal gradient. Thus, the highest areas would be threatened as they would not have higher altitude locations to migrate to. In addition, phylogenetic lineages which only occur, or occur in their large majority, at highest altitudes (i.e., Cunoniaceae and Winteraceae) would be locally extinct by the current (or future) climatic scenario.