Effects of Afforestation on Soil Carbon Sequestration Rates in Pardisan Park of Tehran

Increase in greenhouse gases causes climate change and global warming and has been adverse effects on the earth. The aim of this study is to survey the effects of afforestation on soil carbon sequestration. This Project was done as completely randomized design in a factorial experiment in Robinia-Fraxinus, Robinia and Cupressus stands with the surrounding arid lands (control). The study was done at Forest Pardisan Park in Tehran and it measured the amount of carbon sequestration in soil. It also investigated relationship between physical and chemical soil factors and with soil organic carbon. The results show carbon sequestration is the highest significant value (p< 0.01) in Robinia-Fraxinus stand soil (18.96 ton per ha). Also, carbon sequestration in Robinia and Cupressus is (14.86 and 9.69 ton per ha) and barren land (6/97 ton per ha) respectively. The economic value of carbon sequestration was calculated for these species, 3792, 2972 and 1938 dollars respectively. Organic carbon in 0-15 cm soil depth of afforest stand more than 15-30 cm depth but was observed reverse in the arid lands. Also stepwise regression showed that clay and nitrogen are the most important components affecting soil organic carbon. Generally the process of carbon sequestration leads to improvement of soil and water quality; it improves soil hydrology, prevents erosion and reduces the loss of nutrients. Thus, the optimal management of ecosystems should increase the potential of soil carbon sequestration.