Abstract:

By using the space substitution of time method,the forest soil physical and chemical properties in the burned areas, which burned from 1982 to 2007, were investigated. The unburned nearby areas served as the control. This study was conducted in Betula platyphylla-Larix gmelinii mixed forests in Daxing'anling area. The results showed that: soil bulk density increased after being burned, soil porosity and soil water content reduced after being burned. But the variation gradually reduced with time, and the parameters eventually returned to close to the level of the unburned in 20 years; Soil organic matter in A and B layer in the burned area had a descending trend, and the decrease rate in A layer gradually slowed down with time until the 20^th year by which the soil organic matter was more than the level of the unburned. Soil total phosphorous content in A and B layer in the burned area basically showed an increasing trend, and soil total nitrogen in A layer had the same variation trend, while the nitrogen in B layer fluctuated over the years after being burned, without any apparent regulation. Soil effective phosphorous basically showed an increasing trend, but the change rate in A layer with time gradually reduced, and that in B layer had no obvious regulation. Soil hydrolysis nitrogen content in A layer increased, but its variation in B layer had no regulation. Soil available potassium did not show any regulation. The purpose of this study is to find out the change pattern of the soil physical and chemical properties with time after being burned. This study would provide a scientific basis on ecological restoration and land reclamation in burned areas.

Key words: fire disturbance, burned area, forest soil, physical and chemical properties