Effects of logging residue removal on ground-active beetles in temperate forests

Abstract

Logging residue (“slash”) left on clear-cuttings may affect the microhabitat complexity, and thereby indirectly the beetle (Coleoptera) populations. In three regions (West, North and East) of south and central Sweden, we studied short-term effects of slash removal on species richness and abundance of beetles, collected by pitfall trapping in 16 clear-cuttings (<1 year old) in coniferous and mixed forests. The sites were managed in two alternative ways, either slash was removed (SR), or slash was left (SL). Overall, the number of morphospecies per trap was significantly higher on SL sites than on SR sites. Species richness differed significantly between the regions, the Western region being the poorest in number of species per trap. Rarefaction plots of species richness in four sites suggested that accumulation rate of species differed between two SR sites but rates were similar for two SL sites. Microhabitat structure was measured by aboveground height of slash heaps. Slash height was positively correlated with the number of sticks in slash heap and fractal dimension, respectively. There was a positive relationship between the number of individuals per trap and slash height in SR sites in the Western and Eastern regions, but not in the Northern one. We concluded that extensive slash removal leads to impoverish species richness of Coleoptera at a local scale. Slash heaps left on site may provide important refuges for ground-active beetles. Moreover, our results supported the general theory that microhabitat structure affects arthropod abundance and diversity.