نقش جنگل تراشی، قرق و تخریب مراتع بر شاخص‌های کیفیت خاک در اراضی لسی استان گلستان

To investigate the degree of forest degradation and the effect of land use change on selected soil quality attributes in loess-derived landforms, samples were taken from different land uses including forest, rangeland, degradated rangeland and farmland in Pasang watershed located in the Galikesh area of Golestan province (37°16'N, 55°30'E). The annual average temperature and mean precipitation of study area were 15°C and 730 mm respectively. Organic matter, pH, EC, CaCO3 and nutrients (N, P, K) as chemical indicators, hydraulic conductivity, bulk density and porosity as physical indicators and soil respiration as biological indicator were measured. The results showed that the amount of organic matter decreased three percent when it was turned from forest to farmland, and increased two percent from farmland to rangeland. The amount of CaCO3 in surface layer of deforested area was more than in the forest soils. The amount of soil N in forest and soil P and K in rangeland were higher than in other land uses. Bulk density and porosity in forest and MWD in rangeland were higher than in other land uses because of the decrease in organic matter due to farming activities. Soil respiration in forest was highest as compared to in other land uses. Difference of enzymes activities (L-asparaginase and Dehydrogenase) compared to microbial respiration indicates that enzymes activity is related to specific biological processes while soil microbial respiration basically depends on the general activity of soil microbial population. It could be concluded that amount of organic matter, soil N, bulk density, porosity, MWD, soil respiration and enzymes activities are suitable indicators for soil quality evaluation in this area.