Abundance patterns in bird communities in old boreal forest in relation to stand structure and local habitat configuration

Abstrakti

In this sequel of a landscape level analysis (Edenius & Elmberg 1996) we relate abundance of species and functional groups ofbirds to stand structure and local habitat configuration in old naturally regenerated forests with a moderate but varying degree of human impact. Many species were rare, whereas the five most abundant comprised 54% of the total sample . No general pattern appeared among single-species regression models (abundance versus six habitat measures, N= 12), i.e . most were unique in their combination of variables and signs. Seven species produced models consistent with known habitat preferences, whereas the remaining were hard to interpret or contrary to expectation. Results for Anthus trivialis indicate that man-made and natural forest fragmentation affect abundance in opposite directions . Habitat configuration variables were more frequent than stand variables in single-species models, with `distance to clear-cut or plantation' being the single most common. We found no correlation between territory size and the spatial level at which response patterns were found. Models for functional groups were similarly diverse, habitat configuration variables again appearing more frequently than stand variables. Only a few examples of a consistent multi-level pattern emerge when the present study is combined with Edenius and Elmberg 1996; i .e . a negative effect on abundance in Turdus iliacus and in `Siberian species' on landscape as well as local habitat configuration level.