Wildfire, Degradation and Climate Change: A Triple Threat for the Northern Peatland Carbon Sink

The northern peatland carbon sink is critical for the regulation of the Earth’s climate, however, it is experiencing increasing stressors due to both anthropogenic and climate-mediated disturbances. This talk will discuss the impact of compounding disturbances on northern peatlands and present a large-scale modelling effort to quantify the effect on medium-term (100-yr) carbon dynamics. Direct, anthropogenic disturbance such as peatland drainage for horticultural, agricultural, forestry or development purposes, disrupts the ecohydrological feedbacks that promote the resilience of peatlands to other disturbances. Climate change stressors such as long-term drying and increased severity of drought can have similar or compounding effects. When degraded ecosystems are impacted by wildfire they tend to burn much more severely than their pristine counterparts, releasing around ten times more carbon into the atmosphere. There is considerable spatial variability in carbon losses due to variation in peat properties and ecohydrological conditions. Further, there is limited understanding of the post-fire carbon fluxes in degraded systems and the potential to exacerbate or dampen the initial carbon losses. To better understand the impact of these disturbance interactions on the globally-important northern peatland carbon stock, we collated empirical datasets from natural, degraded and restored peatlands in non-permafrost regions to model net ecosystem exchange and methane fluxes, integrating peatland degradation status, wildfire combustion severity and post-fire dynamics. Here, I present the results of our study including the likely impacts of climate change over the remainder of the century.