Abstract: As a common pioneer species in the tropics, Trema orientalis dominates the early stage of secondary succession after slash and burn agriculture in Xishuangbanna. This study deals with the impact of slash and burn agriculture on soil seed bank of a 4-year Trema orientalis for-est.The results show that seed storage is significantly reduced from 65 355 seeds /m2 to 1 070 seeds/ m2 by slash-and-burn agriculture. There were 60 species in soil seed bank before slash-and-burn and 29 specise after that. Fire leads to an increase of burning-resistant seeds in the proportion in soil seed bank. The succession of forest is retarded by slash-and-burn agricul-ture.

Key words: Soil seed bank