Master of Science (MSc)
Faculty of Science
Dr. Jennifer Baltzer
The current climate trends indicate amplified high latitude warming. Boreal peatlands can be found within those high latitudes and have important functions hydrologically, ecologically and also in terms of carbon cycling. Peatland’s are wetlands that have accumulated more than 40 cm of peat and can range from minerotrophic fens to ombrotrophic bogs. Naturally, a rich fen can be converted to a bog once groundwater sources are cut off by Sphagnum spp. In areas underlain by discontinuous permafrost, landscape changes are occurring particularly rapidly as the permafrost there is sensitive to both vertical and horizontal thaw. The purpose of this thesis is to determine whether permafrost thaw can lead to the reversal of successional pathways, converting a bog into a fen by increasing hydrological connectivity. The study was conducted in the northern boreal peatlands of the Northwest Territories sampling from rich fens, poor fens and collapse scar bogs, while examining how different levels of hydrological connections (isolated, ephemerally connected or fully connected) impacted species community. We concluded that bogs are resilient to increased connectivity due to permafrost thaw, as they did not increase in richness with increased connectivity. Fens meanwhile showed great variation in richness with increased connectivity. Although there were no whole sale differences in species community, rich fen species have begun encroaching into the fully connected collapse scar bog, providing support for the reversal of the normal autogenic pathway. If no whole scale changes could be found in species composition, pH and nitrate both increased with connectivity, which indicates that we are seeing differences in water chemistry. Finally, flooding simulations were used to determine whether frequency of inundation of a fully connected bog by fen water was predicting soil water chemistry ii and species composition. The data indicates that flooding alone cannot explain the presence of rich fen species and we speculate that nutrients are being released with permafrost thaw. Boreal peatlands are unique habitats and these changes in permafrost may eventually lead to the conversion of these wetlands and the loss of ecosystem functions.
Fafard, Mélissa M., "Musical chairs in a boreal peatland: how permafrost thaw reverses successional processes" (2014). Theses and Dissertations (Comprehensive). 1637.