Fire and Ice: Impacts of peatland disturbances on carbon cycling and water quality in catchments on the Taiga Plains.

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Wildfire and permafrost thaw are two widespread disturbances that over the coming century are likely to significantly affect several functions of northern peatland-rich catchments, including carbon storage, methane emissions, runoff generation and water quality. The long term objectives of my research program are to further our understanding of the role of peatlands within catchments, in order to both assess vulnerability to climate change and to improve practices of peatland management and restoration. Over the next five year, this research program will focus on understanding the interactive effects on catchment functions from wildfire and permafrost in peatlands on the Taiga Plains of western Canada.***Northern peatlands within discontinuous permafrost zones, like the Taiga Plains, have since the end of the last glaciation accumulated a globally significant store of carbon in peat. A destabilization of this store due to climate change can cause substantial greenhouse gas emissions, constituting a feedback mechanism that would further accelerate climate change. The role of disturbances is a main obstacle for improving our projections of future peatland greenhouse gas emissions. ***The full impact of disturbances on catchment carbon cycling is however only understood once linkages between peatlands and downstream aquatic ecosystems also are considered. Peatlands are major sources of dissolved organic matter (DOM) to streams and lakes, where it in turn is partially degraded and emitted as greenhouse gases. Peatland DOM export also includes organic contaminants, including methylated metals. Altered peatland DOM export due to disturbances can therefore have cascading effects on both aquatic carbon cycling and water quality.***The research will be carried out at several peatland sites that represent sequences with regards to their time since permafrost thaw or fire. By studying changes along these sequences, we will discern long term disturbance effects. In particular, we will study I) how permafrost thaw affects greenhouse gas emissions and carbon storage in peatlands over decades to centuries; II) how fire affects permafrost stability and soil respiration in peatlands over years to decades; III) how fire and thaw in peatland-rich catchments alter catchment DOM export, including contaminants; and IV) how altered chemical composition of DOM due to disturbances alter its degradation in aquatic ecosystems.****This research will yield knowledge of how vulnerable the vast carbon stores in northern peatlands are to climate change, and how this could affect downstream aquatic ecosystems. The knowledge will inform and aid the development and implementation of policies at provincial, national and international levels that enhance climate change mitigation, and policies that protect and manage ecosystem services at the catchment scale.***