Warming in the Alps: impacts on soil microbiomes and microbial interactions

Alpine environments are disproportionately affected by anthropogenic climate warming, making them important environments for studying ecosystem responses to rising temperatures. Rising temperatures form feedback loops with soil microbiomes by altering microbial community dynamics, which in-turn impacts greenhouse gas (GHG) emissions and potential further warming. My research aims to identify underlying mechanisms driving microbial community dynamics and GHG fluxes under warming temperatures in the European Alps. More specifically, my research uses controlled laboratory experiments with a synthetic bacterial community to address 1) How does warming impact microbiome composition in alpine ecosystems? 2) How does warming shift the interactions between microbial community members? My work builds upon ongoing field experiments that employ miniature greenhouses, known as “open top chambers”, to locally heat soil at three alpine field sites in the Valais-Wallis region of the Swiss Alps. From these alpine soils, I isolated 12 bacterial strains, each representing a unique genus, to assemble a defined synthetic community. Under controlled laboratory conditions, I grew these strains in monocultures, paired co-cultures, and the full consortia at 10°C and 20°C to simulate a substantial warming scenario. Changes in both relative and absolute abundances will be used to quantify microbe-microbe interactions and assess how their strengths vary with temperature. A knowledge gap exists in studies that link GHG fluxes with genetic profiling of microbial communities in alpine regions, thus my laboratory findings will be also later compared to in-situ field sequencing data of microbial communities and GHG flux measurements. Shifts in microbial community compositions in response to warming will be compared in field and laboratory samples to test for parallel patterns; for example, if similar microbial taxa increase with warmer temperatures in both, this indicates taxa of interest for their GHG metabolisms. Co-occurrences and exclusions between species across temperatures in the natural versus simpler synthetic communities will also be assessed to identify keystone taxa. Understanding how microbial interactions and temperature together impact microbial community composition and associated GHG fluxes will improve predictions of whether alpine ecosystems are likely to act as future sources or sinks of greenhouse gases.