摘要 : Foresters must have knowledge of understorey vegetation responses to harvesting rehabilitation operations to manage competition effects on tree seedlings, protect species diversity, and reduce invasive weeds. In this study, unders... 展开 Foresters must have knowledge of understorey vegetation responses to harvesting rehabilitation operations to manage competition effects on tree seedlings, protect species diversity, and reduce invasive weeds. In this study, understory vegetation response to 6 post-harvest slash treatments was documented for 4 mixed coniferous forest sites in the eastern Cascade Mountains of Washington State, USA. The 6 residue treatments were 3 slash treatments where residues were burned (spring broadcast burning,fall broadcast burning, and piling and burning), and 3 treatments where residues were not burned (clearing, chopping, and pulling unmerchantable material), along with a no slash treatment control. Species abundance graphs were used to show the relative effects of the 6 slash-treatment disturbances on vegetation dominance and diversity. Harvest substantially reduced understorey cover, particularly among forbs. Shrub species persisted following harvest and in some treatments increased in cover. Slash treatments increased the abundance of weedy species that are not normally present in these forests. Treatments such as broadcast burning and pile/burn showed greater dominance by invader species. Overall, harvesting reduced species diversity but the responseamong slash treatments varied. After 3 growing seasons, species cover, richness, and diversity had no clear effect on seedling growth in the slash-treatment plots. The first (preceding) paper (Zabowski et al., pp. 25-34) reports the effect of residue treatment on seedlings, soils and microclimate. 收起