REGENERATION STUDY ON THE SEASONAL RAINFOREST IN XISHUANGBANNA OF YUNNAN
西双版纳季节雨林更新的研究

This paper deals with the regeneration of seasonal rainforest based on permanent research and ecological requevalence of floristic composition. The result showed that tbe rainforest has higher annual output of seed and a sto- rage pool of seed from mid-below layer of litter to the upper layer of soil at 2--4cm in depth. The seed germination,seedling growth is good in rainy se- ason, death of seedling is caused by dry drought, rainy rot die and insect rat-bit, foggy leaf rust respectively. One or two year seedlings die easier than old seedlings. The cyclical seed germination, seedling growth, suppre- ssiving, dying, survive and recruitment year after year are charateristics of local rainforest regeneration. It can gradually increase seed germination, see- dling growth when removing the litter and fern (Pleocnemia) layers, retaining fern and turn up soil 30cm or remove fern, litter and turn it up 30cm and is bencficial to regeneration. Above mentioned result indicates that the three layers are main ecological factors. Many extreme shade tolerant species appear to regenerate without forest gaps, those light demanding species are absolutely dependent on gaps for the- ir regeneration these seedlings need to pass drought and suppressive phases and then, develope into climax or pioneer real regenerative seedlings and sa- plings, among them seedlings of climax species are playing an important ro- le in regeneration, are common features of rainforest. The seedlings and sa- plings of dominant species rare, and the seedlings and saplings of frequent species relative more,this forest will be replacing those frequent species with small relative abundance, it has been formating cyclical mosaic regenera tion.