Effects of stump removal on soil decomposer communities in undisturbed patches of the forest floor

Soil preparation after clear-cutting leads to fragmentation of forest floor and, consequently, changes the habitat of decomposers. Stump removal for bioenergy is further increasing the disturbance in the soil. We studied responses of decomposers to stump removal in boreal spruce forests during the first 4 years after clear felling in relation to mounding. Samples for each decomposer organism group were taken from undisturbed forest floor patches that are the main habitat for decomposers after forest regeneration and whose amount and size obviously differ between the treatments. Microbial biomasses and community structure, and the abundance of enchytraeids, were not found to be affected by the stump removal. The abundance of nematodes and the total numbers of collembolans were lower in the stump harvesting plots compared with the mounded plots 3 years after the regeneration. In addition, microbivorous macroarthropods had higher abundances in the mounded plots. Together, decomposer community in the fragments of undisturbed forest floor only slightly differed between the mounded and stump removal areas. However, more data are urgently needed to also find out the longer-term effects of stump removal on the forest soil decomposers and their functioning and the development of decomposer community in exposed mineral soil.