Assessing Vulnerability of Peatlands to Wildfire in Boreal Northwest Territories

Abstract:

Boreal Peatlands, which store most of their carbon belowground, cover more than 75% of southern Northwest Territories Canada and the effects of wildfire in these ecosystems is largely understudied. Under a grant from NASA's Arctic and Boreal Vulnerability Experiment, research was conducted over the past four years to understand the effects of widespread wildfire on peatlands and uplands that traverse the taiga shield and taiga plain ecozones and gradients of ecosystem types, severity of burn and seasons of fire. Field observations collected in 2015-2019 are being linked to remote sensing to scale our field-based observations to the landscape scale. To answer our research questions about controls on spatial and temporal variations in fire severity, we created two geospatial products for the study area, one of pre-fire land cover type (distinguishing bogs, treed and open fens, upland conifer and broadleaf) and the other of burn severity to the organic soil (peat) layers. Since peatlands store large amounts of carbon belowground, it is the susceptibility of these soil organic layers to burning that is critical for assessment. The intersection of the burn severity and ecotype maps for 142 2014-15 wildfires allowed us to study the patterns and controls of burn severity in peatlands across the ecological zones for assessment of the exposure and sensitivity of the landscape to wildfire. Recent changes in climate including earlier springs, longer summers and changes in moisture patterns across the landscape, are affecting wildfire regimes of the Arctic-boreal region including intensity, severity and frequency of wildfires. To answer the research questions about peatland resiliency: “How do pre-fire conditions and fire severity influence patterns of vegetation succession after fire? and; Under what conditions do we see vegetation recovering to its pre-fire composition vs. shifting to a new state?” we focused on our field-sampled data. Between 2015-2019 we sampled burn severity, pre-fire standing dead biomass, post-fire revegetation and tree recruitment in over 80 peatland and upland sites in the taiga shield, taiga plain and boreal shield. We will present on the results of fire effects from both the geospatial and field data.