effects of topographic factors on carbon sequestration in astragalus gossypinus (case study of bazan region, kermanshah province)

increasing the concentration of atmospheric carbon dioxide is the main factor for the climatic change having some harmful consequences for the human health while there is no considerable effort for decreasing this accelerated global problem, yet. kermanshah province located in the west of iran has about 1,200,000 ha rangeland which is dominated by astragalus sppas the more frequent shrub beingable for the carbon sequestration and more than 80%, its biomass has a key role in the carbon sinking into the soil layers. in order to investigate the effects of topographic factors on carbon sequestration, this study was conducted in the bazan rangeland of kermanshah province as the representative site. this site is characterized by the indigenous vegetation of rangeland. the maps including topography, vegetation and date layers were digitized by gis (arc gis 9.1). in each homogeneous area of representative site, two or three linear parallel 30 m intervals were randomly established along the slope length and plant sampling for biomass was doneusing a quadrate plot (1×1 m) with 10 m plotting intervals. in addition, the highest rate (118.68 kg/ha) of sequestered carbon was observed in the altitude of 1900-2100 m above sea level in the northern direction while the lowest stored rate (39.13 kg/ha) was found in 1100-1300 m in the southern direction.