Abstract: Rainfall is a main factor affecting soil erosion. Its erosivity is usually estimated by the product of rain kinetic energy times the biggest rain density during a certain period, and also, can be determined by the daily rainfall amount. With the daily rainfall data collected from four meteorological stations (Mengla, Menglun, Jinghong and Simao) and from tropical seasonal rain forest and rubber forest, this paper analyzed the rainfall erosivity and its seasonal variation in Xishuangbanna, and studied the effects of deforestation on the rainfall erosivity. The results showed that the rainfall erosivity in Xishuangbanna was smaller in dry season (November-April), but increased gradually in rainy season and got its maximum in July and August. The rainfall erosivity was bigger in four meteorological stations than in tropical seasonal rain forest and rubber forest, and bigger in rubber forest than in tropical season rain forest, which was more notable in rainy season than in dry season. The results obtained in this study could be served as the scientific basis for the further research on water and soil loss due to deforestation.

Key words: Cotton bollworm, Flight capacity, Migration, Facultative migration