CO_2 and CH_4 ecosystem exchange from peatlands: Eastmain-1 hydroelectric project, Quebec, Canada

摘要

Hydro-electric reservoirs cover approximately 1.5 million km~2 (Sr-Louis et al. 2000). The creation of these water bodies modifies the natural ecosystem dynamics from terrestrial to aquatic systems. In addition, large amounts of biomass are flooded, and greenhouse gas (GHG) budgets of the flooded areas are drastically changed. In boreal regions, GHG measurements tend to show that these fluxes go back to natural lakes levels within 10 years after impoundment (TREMBLAY et al. 2004). Small-scale studies have documented fluxes from before and after flooding in experimental reservoirs (e.g., KELLY et al. 1997), but none have been conducted for whole hydro-electric reservoirs. This study is part of the Eastmain-1 project: Reservoir net GHG emissions, which follows the recommendations from TREMBLAY et al. (2004) suggesting that "integration of fluxes at the landscape/catchment level prior to and after flooding" should be critically considered before drawing conclusions on the effect of hydro-electric reservoir on GHG production. This study is currently underway in the Eastmain-1 reservoir area, located 1200 km north of Montreal, Quebec, Canada (Fig. 1). The reservoir covers 603 km~2, 18 % of which is represented by peatlands, excluding lakes and rivers. Peatlands are long term carbon sinks through carbon dioxide (CO_2) absorption by surface vegetation and also emit important amounts of methane (CH_4; PELLETIER et al. 2007). The main objective of this research was to establish a GHG budget (CO_2 and CH_4) for the peatlands located inside and outside the Eastmain-1 reservoir prior to flooding.