LONG-TERM EFFECTS OF LOGGING RESIDUE ADDITION AND REMOVAL ON MACROARTHROPODS AND ENCHYTRAEIDS

1, The long-term effects of logging residue addition and removal on so il macro-arthropods and enchytraeids were examined in a Scots pine Pin us sylvestris L, stand in central Sweden. The study was performed 15-1 8 years after the treatments had been applied after clear-cutting in 1 976, 2, In comparison with plots receiving roughly twice the normal am ount of residues, removal of logging residues (above-ground whole-tree harvesting) resulted in decreases in the total numbers of Collembola (springtails), gamasid mites, spiders, predatory insects and dipterous larvae, whereas no significant effects On enchytraeids and diplopods could be detected. Few effects on single species of Collembola and Gam asida were found, The composition of the soil fauna community, as well as food web structure. were significantly affected by whole tree harv esting, but the effects were quantitative rather than qualitative-most organism groups decreased, but the relative importance of different g roups did not change markedly. 3, Over the 4 years studied, community predictability (specifically, constancy) at the levels of higher taxa, functional groups and species did not differ substantially between th e treatments. Predictabilities of higher taxa and functional groups we re higher than predictability of species of Collembola and gamasid mir es, Values of community predictability were similar to those found in other studies of forest soil fauna. 4, It is concluded that whole tree harvesting may result in long-term decreases in the abundances of man y soil animal groups, The possible impact of decreased abundances of f ungivores and predatory arthropods on nutrient cycling and site produc tivity is discussed. It is argued that the direct effects of these cha nges on nitrogen mineralization are likely to be small. However, the p ossibility that the soil fauna may be involved in a positive feedback loop towards lower sire productivity means that the observed long-term decreases in several organism groups should be of concern, at least o n sites dominated by internal nutrient dynamics.