SS3.04 Biogeochemistry of DOC/DON in a Watershed Context
Date: Wednesday, June 12, 2002
Location: Poster Session - VCC
 
BERTOLOA, Univ. du Québec à Trois-Rivières, Trois-Rivières, Canada, bertolo@biologie.ens.fr
Magnan, P, , Univ. du Québec à Trois-Rivières, Trois-Rivières, Canada, 
Carignan, R, , Université de Montreal, Montreal, Canada, 
Pinel-Alloul, B, , Université de Montreal, Montreal, Canada, 
Planas, D, , Université du Québec à Montreal, Montreal, Canada, 
 
DOES BEAVERS AFFECT PHYSICO-CHEMICAL VARABLES IN LAKES ?
image
We used a spatial survey of physico-chemical variables in 38 lakes of the Canadian boreal forest (mean lake area: 0.50 km²) to determine the effects of lake and catchment morphometry, watershed disturbance (fire and logging) and the presence of beaver dams at the lake outlet on key limnological variables. Multivariate ordination techniques showed that the variation in DOC, light extinction and transparency were associated with (i) perturbation in the watershed (both fire and logging), ratio between the catchment area and the lake volume (CA/VOL), (iii) water residence time and (iv) presence of a beaver dam at the lake outlet. Fire, logging, CA/VOL and beaver dams were associated with higher concentrations of DOC and lower light penetration. The water residence time showed an inverse correlation with these variables. Despite the lack of direct observation on the activity of beavers and more precise measures of their distribution, our results suggest that their presence can affect the functioning of relatively large lakes.