Partial harvests in the boreal forest: response of the understory vegetation five years after harvest

Abstract

In the eastern boreal forest of Canada long fire cycles allow for a significant portion of stands to become old growth. Theseold-growth boreal forest stands are subjected to secondary disturbances that create uneven structure, which supports avariety of types of organisms. In order to maintain the proportion of stands with uneven structure on the landscape, partialcuts have been suggested as a management technique that could create or maintain these uneven structures. This studycompares the effects of partial and low-retention harvests and un-harvested control on understory plants in four sites fiveyears after harvest. The relative abundance of species was examined by a habitat group. While richness did not vary amongtreatments, increasing severity of harvest favoured pioneer species that prefer disturbed mineral soil and high light levels.Sites with thicker organic layers that were harvested in the winter were significantly less impacted by both partial and lowretentionharvest. Canopy opening alone had little impact in the three most northern sites. As old-growth black spruceforests are open by nature, this suggests that soil perturbation is a bigger driver of community change after harvest thanproportion of canopy removed for this forest type. Key words: Quebec, Picea mariana, harvest, variable retention, sustainable forest management, understory, structuralretention, vegetation