effect of converting forest to rainfed lands on spatial variability of soil chemical properties in the zagros forest, western iran

the control of biological, hydrological and geochemical cycles of soil is the key part of the earth system. the objective of this research was to evaluate changes in soil chemical properties due to deforestation occurred in the gazafolya village, merek watershed, kermanshah province, iran. toward this attempt, 35 soil samples were collected from top soil layer using auger in early june, 2013. soil analysis including ph, carbonate content, electrical conductivity (ec) and exchangeable sodium (na), soil organic carbon (soc) and cation exchange capacity (cec) were made. the results showed that there were no significant differences between soil ph, carbonate content, ec and na in the forest and rainfed areas while there was significant difference (p> 0.005) between soc in the forest (2.10%) and rainfed (1.35%) areas. the semi-variance analysis also revealed that the spatial dependence class of soc in the forest was strong, while it was mainly moderate in the rainfed areas due to improper plowing practices in the rainfed area there was moderate. in addition, the results showed the soil cec in the forest and rainfed areas were 33.3 and 25.1 cmolckg-1, respectively, indicating significant higher level in the forest area. semi-variance analysis also revealed a strong spatial variation for cec in the forest. finally, there were no significant differences for ec and na with moderate spatial variation in both areas. it was concluded that soc and cec significantly reduced by severe deforestation phenomenon of zagros forest.