Effects on the flora in Norway spruce forests following clearcutting and shelterwood cutting

Clearcutting and shelterwood cutting of mature Norway spruce peatland forests were compared regarding the effects on the forest flora. Repeated observations of the field and bottom layer vegetation were made before and until 7 or 8 years after harvesting at four sites located along a gradient from southern to northern Sweden. Clearcutting resulted in a greater change of species composition compared with shelterwood cutting. Diversity, measured as Simpson's index, and species number per subplot were lower in the clearcut than in the shelterwood after 7 or 8 years. By applying Ellenberg's indicator values, it was concluded that shelterwood regimes may preserve species preferring shaded and moist conditions, whereas those species decreased after clearcutting. Species preferring high levels of nitrogen increased in the clearcut.According to both multivariate and univariate analyses, the vegetation changed in a similar direction at all sites, although the level of response differed considerably. Despite these similarities, there was a marked site effect, which was not surprising considering the large geographic variation between sites.It is concluded that shelterwood cutting might be a better alternative than clearcutting for forests on fertile peatland sites, with respect to conservation of vascular plants and bryophytes.