Effects of water level and nutrients on spatial distribution of soil mesofauna in peatlands drained for forestry in Finland

We investigated the within-site distribution of Enchytraeidae, Collembola, Oribatida, Mesostigmata and Prostigmata relative to varying water level and substrate quality on pine mire sites forming a drainage succession continu um. Collembolans were most intolerant of wetness, favoring drier locations at all stages of the drainage succession. In general, the effect of water l evel variation on the within-site distribution of the soil fauna was strong est when the site was at an early stage of either progressive or regressive water level change. When the average water level was below 20 cm, it no lo nger had a significant effect on the distribution of mites, but still affec ted that of Enchytraeidae and Collembola. Boron was positively correlated w ith faunal density in several cases, and thus may be the growth limiting nu trient affecting substrate quality for decomposers in these sites. The over all changes in the soil mesofauna in drained peatlands depicted here show t hat these peatland forests are converging ecologically on upland forests wh ere decomposition in general is much faster than in pristine peatlands. The change caused by restoration shows how labile these ecosystems are also wi th respect to the mesofaunal community. (C) 2001 Elsevier Science B.V. All rights reserved.