A Comparative Study of Soil Carbon Sequestration between a Deteriorated Rangeland and Pinus eldarica and Fraxinus rotundifolia Stands

Abstract

Tehran as the capital city of Iran is one of the most populous cities that overpopulation and industrial improvement there have caused the great diffusion of greenhouse gases. However, forestation in deteriorated rangelands of this city can have a high potential to decrease the density of atmospheric CO2. This research was done in two stands of Pinus eldarica and Fraxinus rotundifolia and the adjacent deteriorated rangeland as control (blank), in Chitgar forest park of Tehran and soil carbon sequestration content was measured. In addition, the relationship between soil organic carbon (SOC) and some physicochemical factors of soil was determined. Results indicated that Pinus eldarica and Fraxinus rotundifolia stands caused the increment of soil carbon sequestration around 46.18 and 37.2 tons per hectare, respectively in comparison with adjacent deteriorated rangeland. The content of SOC in two mentioned stands was more in the first layer than that of the second layer but it was opposite in blank (control). The result of stepwise regression showed that sand was the most important factor, affecting SOC. According to the results of correlation analysis, there was a positive significant relationship between SOC and % silt and % sand and a negative significant relation between SOC and %clay and %gravel. The economic values of carbon sequestration increment in mentioned stands were calculated to be 13.9 and 2.5 million dollars, respectively. Our study showed that forestation is an effective land-use option to restore deteriorated lands of this area and have a high potential to alleviate global warming and climate change.