Effect of fire severity on organic carbon, total nitrogen and available phosphorus of forest soils (case study: Marivan)

Fire is natural feature of most of ecosystems، including Mediterranean region and the site study in this research. In order to evaluate effect of fire intensity on dynamic of organic carbon، nitrogen and phosphorus of soil، 56 samples were selected from two depths (0-5 and 5-15 cm) in two areas of burned and unburned. Then، some unburned soil samples were burned in the laboratory by furnace at five temperature levels including of 95، 150، 220، 350 and 490 °C for 30 minutes. The amount of organic carbon، total nitrogen and available phosphorus were measured by Walkley-Black method، Kjeltec method and Olsen method، respectively. Maximum organic carbon and total nitrogen were measured 4. 44% and 0. 89% in soil depth 0-5 cm burned at 150 ˚C، respectively. Also، maximum available phosphorus was measured 14. 99 (mg/kg) in soil depth 0-5 cm burned at 350 ˚C. Overall it might be concluded that although increase in fire intensity، decreased total amount of organic carbon and total nitrogen، but increased amount of available phosphorus.