Wetland ecohydrological sensitivity to ground ice conditions

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Wetlands that dominate the Western Boreal Forest (WBF) are particularly important due to their capacity to store water and carbon. The Boreal zone spans the transition from persistent seasonal ground ice to discontinuous permafrost and is expected to experience unprecedented warming. This warming is likely to cause a hydrological-ecological response, particularly in wetlands. The region is also stressed by increased industrial activity that may exacerbate the effects of climatic variability on wetland sustainability. These disturbances lead to changes in ground ice conditions (including permafrost degradation at the northern extent of this region) and surface cover, which directly affect the tenuous balance between evapotranspiration and precipitation, thereby posing serious challenges for sustainable water and natural resource management. The strong influence of ground ice on wetlands in the Boreal zone likely makes these ecosystems particularly susceptible to "hot" positive feedbacks, where disturbance may cause rapid non-linear responses in local climate, hydrology and biota. However, there remains a lack of understanding of the rates of frost layer degradation and the effects on surface cover and hydrological-ecological processes. Since the spatial and temporal patterns of both seasonal thaws and permafrost thaw are governed by ground thaw energy, it is hypothesized that the processes and patterns of seasonal thaw can be studied as a surrogate for permafrost thaw. This will aid in our understanding of the trajectory of permafrost systems in response to climate and human disturbance. This research will examine how hydrological and ecological processes interact and differ among wetland systems over a range in ice conditions (seasonal ice, permafrost and degraded permafrost). To accomplish this, I will build on previous work in the plains region of the WBF and initiate detailed process work in the northern reaches of the region (Scotty Creek, NWT) where discontinuous permafrost is found. This will establish a unique transect of simultaneous process work that will address the above knowledge gap at a range of scales, and will be useful to scientists as well as policy makers and managers.