Effects of partial post-fire salvage harvesting on vegetation communities in the boreal mixedwood forest region of northeastern Alberta, Canada.

Abstract: We examined forest structure and understory vascular plant communities of aspen (Populus tremuloides)-dominated mixedwood boreal forest in Alberta, Canada that had been burned by wildfire and then subjected to one of three treatments (salvage harvested with single-tree retention, salvage harvested with patch-retention, unsalvaged control). Both salvage harvesting treatments resulted in greater cover of regenerating aspen saplings, as compared to unsalvaged controls, but there were no significant effects on vascular plant richness per plot or β diversity. The salvage harvesting treatments differed from the unsalvaged control, but not from one another, in terms of vascular plant community composition. The significant indicators of the unsalvaged treatment were total moss cover and Geranium bicknellii, a fire specialist species. Another fire specialist, Corydalis sempervirens, was an indicator of the patch-retention treatment. Several environmental factors found to be significantly related to vascular plant composition reflected variation in burn severity, rather than the salvage-harvesting treatment. Burned-unsalvaged mixedwood forest was compared to three burned forest types that were unsalvaged because they are not considered merchantable [jack pine (Pinus banksiana), jack pine–black spruce (Picea mariana), black spruce]. The four types of forest were quite different in terms of their structure and vascular plant communities. Burned, non-merchantable forest will not serve as reserves of the post-fire plant communities typical of commercially desirable mixedwood forest, but they may harbor small populations of fire specialist species. Burn severity and pre-fire forest composition have an important influence on the post-fire community, perhaps even more than the salvage-harvesting treatments we examined. Partial salvage harvesting may be an effective way to mitigate some of the potentially negative impacts of post-fire salvaging. [Copyright &y& Elsevier]