Abstract: In southern areas of Yunnan, slash-and-burn cultivation have damaged tropical rain forest and environment. We investigated soil microorganisms and soil fertility of recently burned areas and plots in different regeneration years at Bubon vaUage,Mengla county in Xishuangbanna. The aim was to explore degradation and recovery process of soils after forest being burned and to show the impact of burning on forest, the results were as follows: 1. The amount of microorganisms and soil fertility in 0～60cm depth of recently burned soils were higher than that in unburned soils. Except for fungi,the amount of microorganisms in surface soils(0～10cm)recently burned was higher than that of tropical rain forest,but in soils of 10～60cm depth ,it was lower than that of tropical rain forest. 2. The amount of microorganisms and soil fertility were decreased remarkably from recently burned soils to the area regenerated for a year. The amount of bacteria was decreased the largest in microorganisms. 3. The amount of soil microorganisms and soil fertility in the plot regenerated for five years were the lowest among the soils investigated ,but it was close to that of tropical rain forest after 15 years of regeneration. 4. After burning, the amount of microorganisms was decreased with the increase of soil depth(0～60cm).

Key words: species diversity, soil microbe, soil enzyme activity, vegetation restoration, purple soil.