Tree species effect on soils in central Stara Planina Mountains

The results form investigations on the effects of different tree species on soil properties have implications for the sustainable management of environmentally sensitive areas. This study addressed the effects of three different tree species on some physical and chemical properties of brown forest soils in Beklemeto region, the central part of Stara Planina Mountains. At each site: Fagus sylvatica L., Picea abies Karst., and Pinus silvestris L., five representative soil profiles were opened and described giving a total 45 samples from the soil layers respectively at 0-10, 10-30 and 30-50 cm depth. Soil texture, bulk density, soil pH, SOC, total N, exchangeable K, Ca, and Na were analysed and interpreted. The textural fractions clay and silt, the soil pH and exchangeable Ca were increased under the Scot's pine, while the common beech and Norway spruce characterized with higher SOC stock, total N and exchangeable Na. The analyses of variance were applied and with the exception of a few cases, all considered soil properties showed influence by the tree species. The effect of tree vegetation on soils is clearer expressed in the upper 0-10 cm of soils. We suggest that in use of the short-term small-scale research investigations on the effects of tree species on soils it will be possible and more appropriate changes in SOC quantity to be monitored.