Effect of Forest Fire Disturbance on Soil Physical and Chemical Properties

With field researching and laboratory determinating，analyzing the effect of forest fire disturbance on Soil physical and chemical properties of Pinus armandii and Cupressus plantation，in Yunnan Forest Nature Center on the outskrits of Kunming. After forest fire, soil density of Pinus armandii has increased by 1148%, while soil noncapillary porosity, saturation moisture capacity, capillary water holding capacity, total soil porosity, and capillary porosity in soil have decreased by 3238%, 1621%, 1871%, 994%, 2244%, respectively. In Cupressus plantation, after forest fire, soil density has increased by 10.38%, while soil noncapillary porosity, saturation moisture capacity, capillary water holding capacity, total soil porosity, and capillary porosity in soil have decreased by 2355%, 1077%, 2322%, 538%, 1291%, respectively. Moreover, compared to control, soil pH and available P in Pinus armandii have increased by 581%, 13025%, respectively, while soil organic materials, total N, total P, total K, hydrolysable N and rapidly available K have reduced by 5330%, 2830%, 2260%, 3974%, 2532%, respectively．After forest fire, soil pH and available P have increased by 1233%, 17634%, respectively. And the soil organic materials，total N, total P，total K，hydrolysable N and rapidly available K have reduced by 3128%, 3125%, 6709%, 4066%, 5121%, respectively. Forest fire would result in soil hardening, decrease soil nutrient content, reduce improve soil fertility.