from economic and environmental perspectives. Mountainous landforms in central Zagros are mainly used as pasture and are heavily degraded due to overgrazing. There is no detailed information on the impact of such practices on soil C stocks, soil properties and quality. The objective of this study was to assess the effect of climate, vegetation type and long-term grazing exclusion on soil ltr" Inceptisols are the most widely occurring soils in studied regions and Mollisols is only observed in protected plots of Pishkuh and Poshtkuh regions with higher precipitation and higher plant production. Although grazed soils in these regions have enough organic carbon to fulfill the criteria of Mollic epipedon, but they are not qualified for Mollic epipedon due to lack of color and thickness criteria of this epipedon. Pishkuh and Chadegan regions have the highest and lowest C and N stocks, respectively. Long term grazing exclusion caused an increase in C and N storage in soils, but grazed soils had the highest amount of inorganic C due to soil surface erosion and the exposure of highly calcareous subsoil. Comparison of protected and grazed plots showed that the rate of organic C increase due to long term exclusion in Chadegan, Pishkuh and Poshtkuh regions are 0.3 to 1 and 1 to 2.5 Mg ha -1 y -1 for 0-30 cm and 0-100 cm, respectively. The highest biochemical, biological and aggregates degradation occurred in Chadegan region due to low fresh materials input and a dryer climate. The above parameters in Pishkuh and Poshtkuh regions are 2.5 to 3 times greater than those in Chadegan area. Pishkuh and Poshtkuh regions have the higher plant production, soil organic C and, consequently, higher microbial activity due to their more humid climate. Grazing intensity in Pishkuh is less than that in Poshtkuh region and that is possibly the reason why no significant difference between grazed and protected sites in Pishkuh was found. There is more labile C for microbial activity and better quality of organic matter in Poshtkuh and Pishkuh regions. Soil organic C was identified by factor analysis as the most sensitive indicator of soil quality in studied regions. Factor analysis and soil quality indices suggested the highest and lowest soil quality for protected plots of Poshtkuh and both grazed and protected plots of Chadegan regions, respectively. In conclusion, highly degraded rangelands in Pishkuh and Poshtkuh seem to be able to recover very quickly with proper management, while Chadegan region needs a much longer period to restore
