Effects of Climate Change on Peatlands in the Far North of Ontario, Canada: A Synthesis

Abstract

The Hudson Bay Lowlands (HBL) is the largest peatland complex in North America. More than 75% of the HBL occurs in Ontario, where the provincial government mandates that ecosystem carbon storage and sequestration be considered in land-use planning. Accomplishing this task requires identifying carbon indicators and assessing their responses to changing ecosystem processes, such as succession, permafrost thaw, and evapotranspiration (ET). Therefore, we synthesized information on peat carbon indicators and ecosystem process from the literature. Findings indicate that the long-term carbon accumulation, carbon dioxide (CO2) sequestration, peat depth, and peatland age were similar (p > 0.10) between dry and wet peatland features. Furthermore, CO2 sequestration displayed the highest variability and ponds were net CO2 emitters. Recent carbon accumulation, CH4 emission, and ET were highest (p < 0.01) in wet features, with CH4 emission displaying wide variation. Increased active layer thickness (105 ± 92 cm per 100 years) in permafrost was the most variable ecosystem process analyzed in this study, while variation in permafrost loss (53 ± 23% per 100 years) was similar to that of carbon accumulation and ET rates. Processes creating wet and pond conditions may increase landscape-scale CO2 and CH4 emissions to the atmosphere, weakening peatland carbon sinks. Dry conditions may reduce CH4 emissions but potentially increase peatland susceptibility to fire. Knowledge of these changes should be useful for climate change vulnerability and adaptation assessments for large landscapes. However, better understanding of variability in CO2 sequestration, CH4 emission, and permafrost dynamics is required to design such assessments for small landscapes.