%0 Articles
%T Green-tree retention and controlled burning in restoration and conservation of beetle diversity in boreal forests
%A Hyvärinen, Esko
%D 2006
%J Dissertationes Forestales
%V 2006
%N 21
%R doi:10.14214/df.21
%U http://dissertationesforestales.fi/article/1804
%X This thesis demonstrates the effects of green-tree retention and controlled burning on beetles (Coleoptera) and aims to provide information applicable to the restoration and conservation of beetle species diversity in boreal forests. A methodological aspect is also included, in the form of an examination of the sampling of forest beetle communities. A large-scale field experiment involving 24 forest sites was established in eastern Finland, where harvesting intensity was manipulated together with burning treatments. The beetle data collected during one pre-treatment year and two post-treatment years covered altogether 201 501 individuals representing 1235 species. Different ecological groups of beetles showed varying responses to harvesting with different levels of green-tree retention and burning in terms of species richness, abundance and changes in species assemblages. Many species colonized especially the burned sites effectively after the treatments. The richness of red-listed and rare saproxylic (deadwood-dependent) species was higher at burned than unburned sites and higher levels of green-tree retention seemed to promote the richness of saproxylics. In the second post-treatment year the richness often decreased in the unburned sites but continued to increase in the burned ones. Higher tree retention levels maintained the assemblages closer to the pre-treatment structure. The results show that the negative effects of timber harvesting on beetle diversity in boreal forests can be alleviated by increasing the green-tree retention volumes and by controlled burning. Many red-listed and rare saproxylic species benefit particularly from the burning of harvested sites with retained trees. Unharvested burned sites support rather different species assemblages from harvested ones, however, emphasizing the importance of fire as a restoration tool in conservation areas. Controlled burning and green-tree retention do not solve all the problems related to commercial forest management, but they will clearly benefit a significant part of the ecosystem, including some species of perhaps the most species rich and one of the most endangered groups, the saproxylic beetles.