Canadian Forest Service Publications
Decadal soil and stand response to fire, harvest, and salvage logging disturbances in the western boreal mixedwood forest of Alberta, Canada. 2015. Kishchuk, B.; Thiffault, E.; Lorente, M.; Quideau, S.; Keddy, T.; Sidders, D. Canadian Journal of Forest Research 45(2):141-152.
Issued by: Northern Forestry Centre
Catalog ID: 35797
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Empirical knowledge of long-term ecosystem response to single and compound disturbances is essential for predicting disturbance effects and identifying management practices to maintain productive capacity of managed and restored landscapes. We report on soil, foliar nutrition, and regeneration growth response to wildfire, clearcut harvesting, and post-fire salvage-logging, as well as undisturbed control stands within the first year following disturbance and 10/11 years post-disturbance in trembling aspen-white spruce mixedwood forests near Lesser Slave Lake, north-central Alberta, Canada. The compound disturbance of salvage-logging resulted in greater long-term impacts on forest floor properties than either wildfire or harvesting alone. Changes in forest floor properties such as carbon and nitrogen pools and cation exchange capacity under salvage-logging have persisted for ten years, and exhibit a different recovery trajectory than fire or harvesting. Forest floor properties under harvesting including depth, carbon content, pH, extractable ammonium, and extractable sulphur were not different from the control condition ten years post-harvest. Effects on soil and foliar nutrition were not reflected in productivity (height and diameter) of regenerating vegetation. Our results show differences between short and long-term response to disturbance, among single natural and anthropogenic disturbances, and among single and compound disturbances.
Plain Language Summary
There is growing interest in managing forests to mimic natural disturbances such as wildfires. To maintain productivity in regenerating forests, we need to understand how forest ecosystems respond to such disturbances. There is also concern about the effects of salvaging standing timber after a wildfire for use in biofuels. This research compared the effects on soils and regenerating stands of three disturbances: salvage-logging after wildfire, wildfire alone, and conventional clearcut harvesting, as well as natural changes in undisturbed stands. This research was conducted in an area of boreal forest south of Lesser Slave Lake, in north-central Alberta, where an intense forest fire occurred in 2001. This study showed that post-fire salvage-logging had different long-term effects on soils, and a different pattern of soil recovery, than wildfire or logging alone. Clearcut harvesting did not result in long-term negative effects on these soils; in fact, properties of the forest floor in clearcut areas were similar to those in undisturbed stands at 10 years after harvest. By contrast, the forest floor recovered much more slowly after post-fire salvage-logging than after fire or logging alone. This new information on the long-term effects of multiple disturbances on western boreal forests is important for understanding ecological barriers to maintaining forest productivity and fibre supply.