Restoration of forest soils on reforested abandoned agricultural lands

Restoration of forest soil character after the change of agricultural land use has not been studied yet despite the large areas reforested since the late 40ies of the last century. This process takes place throughout Europe to an increasing extent at present. The reformation of forest soils was studied in the area of Český Rudolec town: Natural Forest Area 16 - Czech-Moravian Uplands, altitude 600-630 m a.s.l., bedrock is built of granites and gneisses, soil type is Cambisol, forest site type 5K1. The process of restoration of a new humus form was analysed in plantations of American red oak (Quercus rubra), Swedish birch (Betula pendula), European larch (Larix europea) and Norway spruce (Picea abies), the site was homogeneous. The particular tree species accumulated 12.81, 13.81, 46.57 and 44.76 t/ha of surface organic matter during the last 30-40 years, these values are typical of forest sites at lower and middle altitudes and corresponding tree species composition. The effect of broadleaved species and conifers was markedly different, in the first case pH in KCl ranged 3.8-3.9 (mineral soil) and 3.5-5.2 (holorganic horizons), being 3.5-3.8 (mineral soil) and 3.1-5.1 (holorganic layers) for the conifers. Visible effects of the particular tree species were also evident in the soil adsorption complex and in the contents of plant available and total nutrients. The results can be summarised and generalised: - the forest soil character is reformed at lower and middle altitudes in a relatively short time from the aspect of surface humus accumulation and basic soil chemistry (30-40 years), - birch exhibited the best revitalisation effect among the studied species, - American red oak and Norway spruce humus accumulation potentials were different although the soil chemistry was comparable, - Norway spruce did not show a remarkable degradation effect until now, - on the contrary, European larch appeared as a site degrading species.