DEAD TREES LEFT IN CLEAR-CUTS BENEFIT SAPROXYLIC COLEOPTERA ADAPTED TO NATURAL DISTURBANCES IN BOREAL FOREST

Forest management alters the pattern of forest dynamics from that in n atural conditions in the boreal region. In order to examine how certai n forestry measures matching natural dynamics affect forest insects, w e compared assemblages of saproxylic Coleoptera on dead, standing birc h trunks left behind in eight clear-cut areas with corresponding assem blages in seven mature forests in southern and eastern Finland. We use d trunk-window traps for sampling. Distinct beetle assemblages were as sociated with the different habitats. Median numbers of species or spe cimens caught did not differ between closed forests and clear-cuts, bu t individual beetle species occurred unevenly among the habitats. Seve ral beetle species associated with open forest habitat, e.g. burned fo rests or storm-damage areas, including species regarded as threatened in Finland, were found almost exclusively, in clear-cuts. Correspondin gly, a number of beetle species occurring frequently in closed forests were not found in clear-cuts. We conclude that dead trunks left in th e clear-cut areas may host not only generalist saproxylic species but also many beetle species specialized to warm, sun-exposed environments , and such species may not be able to survive in closed forests. Manag ement measures matching suppressed natural disturbances are found usef ul in preserving diversity in managed forests.