PARENT SESSION
Poster Session 5: Climate Dynamics
Tuesday, August 9, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Potential global warming effects on plant communities as simulated by drainage in two boreal peatlands.
St-Arnaud, Claudia1, Tuittila , Eeva2, Rochefort, Line 1, Waddington, J. Michael 3, 1 Université Laval, Québec, Québec, Canada2 University of Helsinki, Helsinki, Finland3 McMaster University, Hamilton, Ontario, Canada
ABSTRACT- Peatlands constitute an important natural resource of Canada (17 % of land surface) and accumulate more carbon that any other terrestrial ecosystem. It has been suggested that a rapid climate change will modify carbon cycling through changes in vegetation. The aim of this study was to analyse successional changes in plant communities after a short (1-2-3 years) and a long (8-9-10-11) period of water table lowering in a poor Canadian fen system as a simulation of future climatic change. We used an experimental approach to simulate the water table drawdown expected in a 2 X CO2 climate scenario. Between the summers 2001 and 2004, at the St-Charles peatland in Québec City (Canada), we analysed the changes in hydrology and vegetation before and after water level drawdown. Our sites included a control plot, an experimental plot with a water level drawdown treatment and a plot drained several years ago. We analysed changes along the water table gradient to determine which plant communities and species were disturbed, promoted, or remain unaffected. Moreover, we analysed changes in plant community diversity following the water level drawdown. We used Two Way Indicator Species Analysis to describe natural plant communities and Detrended Correspondence Analysis to follow their changes. Our preliminary results showed that control and experimental plots were similar in community structure and diversity before drainage. Following drainage, the lawn communities were invaded by species typical of drier habitats, like sedges. Similarly, species from the lawn level were found in the hollows. However, after the long term drainage, vegetation was suffering from dryness. Strong interannual variation that was observed both in pristine and successional communities was related to annual variation in weather conditions. These results and our final conclusions will be presented at the congress. This study will provide information that could be incorporated into regional and global climate models used for predicting future changes.
Key words: Climate changes, Peatland, Vegetation dynamic, Water table drawdown