MicroMic

To predict species distributions under climate change scenarios, modelers often use measures of climate at a coarse resolution. Most organisms, however, experience climate at smaller spatial scales. They experience fine-scale microclimatic variations, and these variations mediate their response to global climate change. The microorganisms living in tree canopies, for instance, experience microclimates that are highly variable in both space and time. Leaf surface temperature can indeed differ by several degrees between the canopies of two adjacent trees, between sun and shade leaves of the same tree, and even between the edge and the center of the same leaf. The aim of the present project is to predict the effects of climate change on microclimatic heterogeneity and microbial diversity within tree canopies. This is crucial to our understanding and management forest functioning because the impact of foliar microbial communities surpasses by far their microscale. Foliar microbial communities indeed influence tree performance (e.g. by modulating stomatal closure) and contribute to major ecosystem functions (e.g. litter decomposition). For the first time, we will combine metagenomics and state-of-the-art techniques of microclimate measurements (including drone flights). We will then use these data to calibrate canopy and community distribution models, and predict the response of foliar microbial communities to climate change. In addition, we will perform in situ manipulations of foliar microbial diversity to investigate its relationship with ecosystem function. The study will be performed in a riparian forest which is intensively monitored for conservation and restoration purposes. Our findings will therefore provide guidance to environment managers. The project will also provide new insight into the diversity and distribution of aquatic hyphomycetes, a group of foliar fungi involved in the functional coupling of terrestrial and aquatic ecosystems.