Effects of physiographic factors on soil Carbon sequestration potential of two types of Astragalus (Case study: Mountain Rangelands of Kermanshah Province)

Increased concentration of carbon dioxide in the atmosphere is the main cause of climate change, having harmful effects for human beings. Reducing the amount of this gas by inhibiting industrial development and the use of artificial methods is not suitable due to the lack of economic justification. Therefore, taking advantage of carbon storage potential in plant tissue and soil has attracted much attention in recent decades. According to the different climatic zones in the country, studying the carbon sequestration in each of these areas should be taken into consideration. Therefore, the potential of soil carbon sequestration in the mountain rangelands of Kermanshah Province was studied in three height classes and four aspects. Then, soil samples were taken from two depths of 0-30 cm and 30-60 cm in the habitats of Astragalus gossypinus and Astragalu sparrowianus. Soil organic carbon, bulk density, electrical conductivity, pH, moisture content and soil texture were measured in both soil depths. Stepwise regression results showed that soil parameters including texture, bulk density and pH, were the most important factors, affecting soil organic carbon. Based on the results of data analysis in a completely randomized factorial design, significant differences were observed for soil carbon sequestration among height classes and aspects at 1% level of significance. According to the results of mean comparisons based on SNK test, the highest amount of carbon sequestration was observed in the third height class and north aspect. Our results clearly showed that Astragalus parrowianus had a higher potential in soil carbon sequestration as compared to Astragalus gossypinus.