Impacts of warming on boreal peatland microbial community structure and function

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NERC : Katy Faulkner : NE/L002493/1Peatlands contain a thick organic layer of partially decayed plant material and are huge carbon stocks, storing around 15-30% of soil carbon worldwide. Peatlands have acted as global carbon sinks for many millennia, but disturbance of these ecosystems from climate change factors such as increasing temperatures, rising CO2 levels and alterations of precipitation regimes could result in them becoming carbon sources. Northern regions, including peatlands found in Canada, are thought to be particularly vulnerable to climate warming. Warming and drying in peatlands could lower the water table and therefore increase the soil oxygen availability for microbial and mesofauna decomposers which break down the organic carbon to CO2. Peatlands will not be affected by warming alone, but in combination with other climate stressors such as extreme weather events. The effects of multiple environmental factors on peatland soil microbial structure and function is not currently known. In this project, we plan to investigate the impacts of warming on peatland ecosystems focussing on changes to soil microbial community structure and decomposition processes. We will link these changes in the soil microbiology to the changes in mesofauna communities and the wider soil food web dynamics. Finally, we will investigate how multiple climate change factors (e.g. CO2, temperature, precipitation) will impact peatland microbial community structure and function using unique, highly controlled but environmentally realistic biome chambers at Western University. We plan to use the BRACE (Biological Response to A Changing Planet) warming manipulation experiment (a collaborative project between Western University, Ontario Ministry of Natural Resources and Forestry-Ontario Forest Research Institute and the Canadian Forest Service Great Lakes Centre) where two peatland sites, located near White River, Ontario, have undergone experimental warming for the past three years and have 15 years of extensive monitoring data. This long-term field experiment allows us to determine how warming alters microbial community structure and function in peatland soils. The two sites differ in their vegetation type; one site is dominated by Sphagnum moss and the other is a Carex sedge dominated site, which are the most commonly found boreal peatland habitat types. We are therefore also able to address how aboveground community structure impacts the belowground response to warming. This project will enable us to understand how microbial communities and their functions (e.g. decomposition, greenhouse gas fluxes) will be impacted by climate change, the implications of this on soil food web stability and whether certain peatland habitats are more resilient to environmental change. This empirical data can be used to inform policymakers and mitigation strategies.