Large-scale Forest Disturbance Research Articles

The impact of large-scale forest harvesting on hydrology in the Willow watershed of Central British Columbia

Summary Availability of long-term hydrological and climatic data from 1953 to 2005, along with large-scale cumulative forest harvesting in the Willow watershed (2860 km2) situated in the central interior of British Columbia, Canada provided us a unique opportunity to study the impact of large-scale forest disturbance on hydrology. Various statistical techniques including time series analysis and non-parametric tests were applied to analyze the impacts of forest harvesting on peak, mean and low flows over annual and other periods (spring, summer and winter). The results showed that forest harvesting in the Willow watershed significantly increased mean and peak flows over annual and spring periods. However, the mean and peak flows in the summer and winter periods were not significantly affected. The impacts of forest harvesting on low flow for all studied periods were either not statistically significant or inconclusive. In addition, we specifically tested the relation between the spring peak flows and timber harvesting with consideration of climate variables by regression model analysis. Our regression analysis further confirmed that spring peak flows were significantly altered by forest harvesting in this large-scale watershed.

An analysis of future carbon budgets of Canadian boreal forests

The Canadian boreal forest covers over 300 Mha of land area. Its dynamics are largely influenced by fires and insect-induced stand mortality and to a much lesser extent by forest management. This paper analyses six scenarios of future (1990–2040) carbon (C) budgets of the Canadian boreal forest, each based on different assumptions about natural disturbances, rates of reforestation of disturbed land, and conversion of non-stocked to productive forest stands. The objective of these scenarios is to explore the range of responses to different management options. The results indicate an overall inertia of a system whose dynamics are strongly influenced by a recent 20-year period (1970–1989) of large-scale forest disturbances by fire and insects. The 50-year C budget of the six scenarios ranges from an estimated net source of 1.4 Pg C to a net sink of 9.2 Pg C. These estimates indicate the range of response to the management of the Canadian boreal forest. Although a full-scale implementation of the management activities examined here is not likely given ecological and economic realities in the Canadian boreal forest, the analyses explore the relative merits of reducing forest disturbance rates, regeneration delays, and the area of non-stocked forest land.