Short-term responses of soil decomposer communities to forest management: clear felling versus alternative forest harvesting methods

Abstract

We studied the short-term responses of decomposers to different forest harvesting methods in a boreal spruce forest (Picea abies (L.) Karst.). We hypothesised that the less intensive the forest harvesting method is, the fewer changes occur in the decomposer community. The treatments, in addition to untreated controls, were (1) selection felling (30% of the stand volume removed), (2) retention felling (tree patches retained), (3) clear felling, (4) gap felling without and (5) with harrowing. Microbial community structure (phospholipid fatty acids (PLFA) pattern) changed in the first year, microbial biomass and basal respiration decreased in the second year, and density of the enchytraeid worm Cognettia sphagnetorum (Vejd.) increased in the third year after the clear felling. The community of collembolans did not respond to forest harvestings. Although there were changes in the microbial community, the invertebrates at higher trophic levels did not parallelly respond to these changes. The selection felling had no influence on the decomposers, while the gap fellings induced an increase in the numbers of enchytraeids in harvested gaps. We conclude that the decomposers of the coniferous forest soils are well buffered against initial environmental changes resulting from forest harvesting, and also that the PLFA pattern is a sensitive indicator of changes in the microbial community induced by forest harvesting.