Julie Loisel - Expanding peatlands in Alaska: Possible linkage with climatically induced glacier melting

Julie Loisel
Department of Earth and Environmental Sciences
Most mountain glaciers worldwide have been recording a negative balance over the last century due to global warming. This is particularly true around the Gulf of Alaska, where glacier recession has further accelerated since 1988. It is well known that glacier meltwater plays a critical role in the global sea level rise, but its effects on structure and functioning of lowland ecosystems remain poorly understood.
We have observed in the field that many peatlands are expanding in the Susitna Basin near Denali, AK. As high moisture levels are needed to promote peatland development and expansion, a regional change toward wetter conditions is likely responsible for the ongoing paludification of these sites. However, instrumental climatic data from this region show no increase in precipitation but an increase in temperature (and presumably evaporation) over the last decades. We hypothesize that climatically-induced glacier melting is modifying the local/regional air humidity, especially in summers, promoting the expansion of peatland systems. Our objectives are to document vertical accumulation and lateral expansion by dating and analyzing peat cores along a transect across an expanding peatland and to investigate a possible connection between hydroclimatic changes and documented glacier histories in the recent decades and during the Medieval Warm Period.
Preliminary paleohydrological reconstructions of two peat cores collected in 2008 near Talkeetna revealed a recent increase in the water table depth. This change coincides with a major increase in Sphagnum moss, a non-vascular plant capable of holding more than 20 times its weight in water. By acting as water sinks, peatlands located in glacierized watersheds may mediate the contribution of meltwater to present and future sea-level rise. Increases in peat accumulation rates due to favorable hydroclimatic conditions are also expected to promote carbon sequestration by these ecosystems.
Julie Loisel 's work as a paleoecologist focuses on the reconstruction of past environmental variability from peatland archives. She also interested in the effects of climate change on the carbon sink function of these ecosystems. She is a french Canadian who grew up in Montreal. She obtained my B.Sc. and M.Sc. degrees at the Department of Geography at University of Quebec in Montreal in 2006 and 2008, respectively. Her previous work focused on peatlands located along the St-Lawrence River (B.Sc.) as well as in the James Bay region (M.Sc.).