西双版纳季节雨林更新的研究

 根据定位试验研究和组成森林树种的生态习性，对季节雨林的更新进行了研究。结果表明雨林种子年产量高。残落物中、下层至表土2—4cm处是种子，特别优势种种子的贮存库。一年中，种子萌发，幼苗生长是雨季>雾季>干季，死亡则是干季>雨季>雾季。1—2龄苗易死，多龄苗不易死，雨季腐烂，干季干旱缺水致死，雾季叶锈病是致死的主因。年复一年的种子萌发、幼苗生长、抑制、死亡、残存、补充是该雨林更新的特征。如果除去残落物层或羽蕨层，保羽蕨层翻土，除蕨层、残落物层翻土可促进种子萌发，幼苗生长，减少死亡，由此可反映出蕨层，残落物层，表土层是影响森林更新的主要生态因子。借助乔木死亡形成林窗而繁衍的种和无须林窗繁衍的种，其幼苗经干旱后残存，可发育成顶极种及先锋种的更新苗和小树，其中顶极种更新苗在更新中起主要作用，是本雨林与典型雨林共有的特点。根据优势顶极种的更新苗和小树罕见，而常见顶极种的更新苗和小树相对地多来看，当优势顶极种消亡后，整个森林或森林片段将被那些相对多度小的常见顶极种替换，从而形成循环镶嵌更新。

REGENERATION STUDY ON THE SEASONAL RAINFOREST IN XISHUANGBANNA OF YUNNAN

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.