Abstract: Based on the 1996-2006 daily runoff data of tropicalseasonal rainforest catchments in Xishuangbanna, the annual base flow index (BFI) values of the catchments were calculated, and by using these BFI values to partition the daily runoff data according as the hypothesis of dual water source, the total base flow of these catchments was calculated with the help of BFI software. The annual BFI values of the catchments varied from 0.24 to 0.45, withan average of 0322 and changed less among years, and the monthly BFI values were 0.31-0.34, being higher in dry season than in wet season The variation pattern of the total base flow was similar with that of rainfall, and the former lagged behind the latter. The findings of this study could provide basic data for the research of tropical forest ecohydrological functioningand the management of water resources in tropical area.

Key words: Houhe Nature Reserve, Rare plant community, Population structure, Distribution pattern