西双版纳热带雨林次生林的生物养分循环

BIOLOGICAL NUTRIENT CYCLING OF SECONDARY FORESTS IN XISHUANGBANNA

本文获得了西双版纳热带雨林，砍伐后2块处于恢复演替阶段不同年代的次生林的生物量、生长量、年凋落物量及它们的主要营养元素含量、对土壤养分状况的影响、以及土壤微生物状况和土壤生化活性等一系列资料。阐明了次生林生物物质和养分吸收、积累和归还的特点及对土壤养分状况的影响，研究了土壤微生物对凋落物的分解作用，从而对热带雨林次生林的生物养分循环作了一个初步的探讨，为热带森林生态系统研究奠定了基础。研究表明：1．热带雨林次生林植物生长旺盛，营养元素吸收量较大，归还／吸收率在0．5左右，随林龄增大，营养元素大量贮存于植物体中，土壤养分相对贫乏。2．次生林随林龄增大，营养元素的吸收、贮存、归还量增大，土壤微生物对凋落物的分解强度增强，物质循环速度加快。

The biomass, growth, annual litter fall, main nutrient contents, and the influences on soil nutrients, soil microbes and soil biochemial activities of secondary forests in Xishuangbarina were studied. Results showed the characteristics of uptake, accumulation and return of biological materials and nutrients in secondary forests, and their effects on soil nutrients. Microbe decomposition of litter fall and biological nutrient cycling of secondary forests were also dealt with. The study provided a basis for further research of tropical forest ecosystem. The plants grew quickly in the tropical secondary forests. The uptake of nutrient elements was large and its proportion of return to uptake was about 0.5. A great quantity of nutrient elements was accumulated in plants with increasing age of trees, and soil nutrient content was low. With increasing age of secondary forests, uptake,accumulation and return of nutrient elements increased, the intensity of litter fall decomposition increased and the speed of material cycling was quick.