Influence of modern soil restoration techniques on litter decomposition in forest soils

Abstract

The study assesses the influence of various soil preparation techniques for afforestation on litter decomposition in replanted forest soils. Techniques were compared in three different study areas in the western part of Germany on gleyic, dystric cambisol and gleyic luvisol soil types. The mechanical soil preparation techniques compared was part of a comprehensive restoration of acidic and partially compacted forest soils on previously wind-blown sites which includes soil loosening, mixing and liming of the top horizons up to a depth of 40 to 50 cm. Litter decomposition studies were done using the minicontainer method of Eisenbeis (1993, 1994)and Eisenbeis et al. (1995). Minicontainers with mesh sizes of 25, 250 and 2500 μm were implanted vertically into the soil up to a depth of 25 cm and were collected after 2, 6, 12, 24 and 48 weeks. Mesh sizes were so chosen to selectively include the litter decomposition activity of the microflora and the meso- and macrofauna, respectively over time and at different soil depths. Distinct differences in litter decomposition rates were found between study areas, soil preparation techniques, soil depth and mesh sizes. The decomposition rate increased in the order gleyic luvisol, dystric cambisol and gleyic cambisol. Litter decomposition was greater as a result of mechanical soil preparation and liming. In mechanically prepared soils, the extent of litter decomposition was less in the top horizon (0–6 cm) than in unprepared soil and greater at 6–24 cm soil depth. The greatest rates of litter decomposition occured when the total ground area was mechanically mixed compared with soil preparations restricted to loosened strips. After soil milling, soil properties as well as litter decomposition were more homogeneous as compared with soil loosening treatments. We conclude that, nearly two years after the total soil restoration process, all functional groups of soil organisms have been re-established. The minicontainer-test proved to be a valuable tool in studying litter mass loss in the soil profile.