Soil Microbial Communities in the Boreal- Response to Disturbances.

Boreal forest soils are the single largest terrestrial carbon storehouse in the world. These soils are highly susceptible to global warming, and in the coming century are expected to face large increases in temperature and transformative vegetation shifts. In addition, boreal soils are subject to multiple recurrent natural and anthropogenic disturbances such as fire and harvesting. The overall objective of this research is to assess how these disturbances may be affecting boreal soil microbial communities, and their corresponding soil carbon fluxes.  We are taking advantage of several long-term experiments set up in the mixedwood boreal forest of Alberta, Canada to address this objective. In particular, we investigated the effects of fire, harvesting, and the compound disturbance of salvage logging on microbial communities 10-year post disturbance using phospholipid fatty acid (PLFA) analysis. In addition, we are following how different ¹³C-labelled substrates (glucose, leaves and roots) are processed by the microbial communities during a long-term laboratory incubation. Carbon assimilation by microbes is tracked by isotope probing of phospholipid fatty acids, while evolved ¹³C-CO₂ measurements allow us to quantify the percent of CO₂ coming from each added substrate.