The Effect of Different Land Uses on New Indices of Soil Quality in Central Alborz Region

Different land uses have various effects on the changes of soil properties. The purpose of this study was to evaluate the effects of natural forest, needle-leaved plantation and rangelands of central Alborz on new indices of soil quality (i.e. organic matter stratification, carbon management index and soil biological activities). For this purpose, eight samples from organic layer (litter) and mineral soil (0-15 cm depth and 25 cm × 25 cm surface area) from each of the natural forest (beech mixed with hornbeam), picea plantation, pine plantation and rangeland were taken in the Javaherdeh region, Ramsar city, and then they transferred to the laboratory. According to the results, the minimum amount of organic matter stratification (1.45) and the highest amount of fine root biomass (91.03 g m-2), the earthworms density and biomass (1.75 n m-2 and 22.84 mg m-2), total nematode (595.13 in 100 gr dry soil) and microbial biomass of nitrogen (24.94 mg kg-1) were found in natural forests. The highest and lowest levels of microbial respiration were observed in rangelands and natural forests (0.20 and 0.10 mg CO2 in gr day-1), respectively. The highest amount of microbial biomass of carbon (242.22 mg kg-1) belonged to rangeland and the highest amount of nitrogen mineralization (27.03 mg kg-1) detected in natural forest. The carbon management index did not show significant statistical differences among the different land uses. According to the PCA output, changes in the characteristics of organic matter stratification, carbon management index and soil biological activities is directly related to the changes of soil physico-chemical properties under the influence of different land uses. The results of this study indicate the high importance of protecting broad-leaved mixed natural forests in order to maintain soil quality.