The effect of low level forest harvesting on the water chemistry of boreal lakes in northeastern Ontario

Water chemistry was monitored in twenty-one headwater lakes located in Northeastern Ontario (49°38'N, 81°00'W) for three years prior to and three years after clearcut logging in 2005. Twelve of the twenty one lakes were left undisturbed to serve as a reference condition. The percentage of the catchments harvested ranged from 5 to 42%. Principal Component Analysis and Discriminant Function Analysis revealed that the lakes were grouped in a humic-intermediate-clear gradient. Two-way Analysis of Variance within these group designations revealed few significant (p<0.05) seasonal and annual differences in water chemistry that could be attributed to forest harvesting or any relationships between the percentage of a catchment harvested and the chemical response of lakes. The results of this study are consistent with other studies across the Boreal Shield and Boreal Plain that indicate that small watersheds within the boreal forest can withstand low level harvesting pressures with minimal impacts on water chemistry.