Trädlevande skalbaggars spridningsmöjligheter: En studie kring stadsträden som spridningselement i Lunds stad

Sammanfattning: Urban trees are of great value as habitat and as elements for dispersal of many biological organisms. Hence, tree inventories are an important step for local municipalities in the effort to promote urban biodiversity of organisms dependent of trees for dispersal and survival. Lund is one of the municipalities which have carried out a comprehensive tree inventory. The purpose of this study is, on basis of the tree inventories in Lund city, to provide an overview of the possibilities of dispersal for red-listed beetles dependent of living or dying trees in Lund city. The selection of tree species for the analysis was based on the habitat preferences of four red-listed tree living beetles, Quedicus truncicola, Ptenidium gressneri, Nosodendron fasciculare and Silusa rubiginosa, which have all been observed in Lund in previous inventories. Wounded trees with sap flows and hollow trees with mould are characteristics of special importance for the occurrence of the selected beetles in the city. This study shows that all four of the selected beetles can be regarded as relatively specialized in their habitat preferences. They are all dependent on specific types of microhabitats and more or less narrow in their selection of tree species. How specific they are in their selection of habitat may affect their possibilities of dispersal and local occurrence in Lund city. The less specific preferences, the more trees are available as choice for habitat and elements of dispersal. Unfortunately, the possibilities of dispersal in Lund city do not appear to be very promising for the beetles P. gressneri, N. fasciculare and S. rubiginosa. The situation appears to be a little bit better for the beetle Q. truncicola, which is slightly wider in its selection of trees, as long as they contain hollows with moist mould.