Effects of agroforestry system on properties of soil surface layer (case study
Semnan- Biarjomand)

This study is carried out in two sites under agroforestry system (under tree canopy and between tree rows) and in a farmland without tree plantation for determination soil carbon storage in South Biarjomand region، Semnan province، Iran. Soil samples were taken through systematic-random method from two depths (0-25 and 25-50 cm) in three different places including under tree canopy، between trees and control area. Relationship between some physical and chemical properties of soil and its organic carbon content was also studied. Results showed that carbon storage (sequestration) under tree canopy
was 31 ton. ha-1 higher than that in between tree rows (42 ton. ha-1). Also، total carbon storage in between tree rows was significantly higher than that in the control (7. 4 ton. ha-1). Besides، carbon sequestration was higher in the first soil surface layer (0-25 cm) in under tree canopy and between tree rows. Stepwise regression analysis also showed that pH was the most effective factor in carbon sequestration and soil nitrogen and sand were placed in the second class with 13. 4 and 5. 6 % lmpact، respectively.