SS4.12 Linking Science with Management of Freshwater Resources
Date: Thursday, June 13, 2002
Time: 4:30:00 PM
Location: Carson B
Pinel-Alloul, Bernadette, B, , Université de Montréal, Montréal, Canada,
PrepasEE, Lake head University, Thunder Bay, Ontario, Canada,
Carignan, R, , Université de Montréal, Montréal, Québec, Canada,
Planas, D, , Univ. Québec à Montréal, Montréal, Québec, Canada,
Steedman, R, , Ministry of Natural Resources, CNFER, Thunder Bay, Ontario, Canada,
Watershed impacts of logging and wildfire: Case studies in Canada
In Canada, clearing of boreal forests has increased due to expanding forestry and wildfires. A first attempt was made to link impacts of forest harvesting and wildfire to changes in water quality and biota of lakes. We present case studies in two major geological and climatic subregions of the boreal ecozone in Canada: the Boreal Plain and the Boreal Shield. Responses of lake ecosystems to wildfire and logging differed. Total phosphorus, inorganic N and algal biomass increased after wildfire, whereas, only total phosphorus and DOC increased after logging. Logging on the Boreal Shield and wildfire in wetland- and permafrost-dominated lakes on the Boreal Plain increased lake colour, causing light-limitation of algae and a decrease in calanoid biomass. The impacts of logging were the strongest in the oligotrophic ecosystems of the Boreal Shield. The nutrient response was strongly related to lake drainage ratios: lakes with high drainage ratios had the strongest response to disturbance. Effects were also dependent of climate, wetland coverage and regional lake characteristics. A series of indicators (morphological, chemical, biological) are recommended to monitor the impacts of natural and anthropogenic watershed disturbances on aquatic ecosystems in Canada’s Boreal Plain and Shield.