Peatlands represent a globally significant carbon stock and wildfire is the largest disturbance affecting these ecosystems. Climate change scenarios suggest that increases in evapotranspiration are likely to exceed increases in precipitation in northern latitudes, raising concern that peatlands will experience substantial drying. Drying may increase peat burn severity and, when coupled with expected increases in total wildfire area burned, may exceed peatland resilience to wildfire. While previous studies have examined both peatland vulnerability to wildfire and post-fire recovery, these studies have not examined the driest peatlands on the landscape that are likely to be the most susceptible to the combined effects of climate change and wildfire. For this reason, this thesis examined the hydrogeological and ecohydrological controls on burn severity and post-fire recovery in peatlands in the Boreal Plains of Alberta, where peatlands exist at the limit of their climate tolerance.
High burn severity was prevalent at the margins of a small peatland isolated from groundwater flow, where average burn depths were five-fold greater than in the middle of the peatland. Deep burning was attributable to the effect of dynamic hydrological conditions on margin peat bulk density and moisture. Following wildfire, water availability was a key determinant of post-fire moss recovery. Both high and low burn severity can decrease post-fire water availability by altering peat hydrophysical properties. Post-fire recovery was also dependent on large-scale hydrological processes that influence peatland water tables, specifically, hydrogeological setting. Small peatlands isolated from groundwater flow systems had lower peatland moss recolonization rates at both their middles and margins due to drier conditions. This was important because the margins of these same peatlands were prone to deep burning. Therefore, deep burning is likely altering peatland margin ecohydrological function and may be facilitating a regime shift from peatland to mineral upland. / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/18107 |
| Date | 11 1900 |
| Creators | Lukenbach, Maxwell Curtis |
| Contributors | Waddington, James Michael, Geography and Earth Sciences |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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