【摘要】 土壤养分和土壤微生物生长代谢水平的衰退是热带山地退化的重要表现形式 ,二者的变化基本是一致的 ,即从热带雨林→ 33a次生林→ 6a轮歇地→ 4a轮歇地→旱谷地→橡胶林→荒草坡呈降低趋势 ;相对于热带雨林而言 ,不同利用方式土壤微生物和土壤养分状况均有不同程度的下降 ,且随退化程度增高减幅增大 ,土壤微生物衰减的速率比土壤养分的衰减更快。说明山地的退化严重影响着土壤微生物的生长代谢水平以及它们之间的协同作用 ,从而影响土壤碳氮循环代谢途径 ,降低土壤肥力水平。更多还原

【Abstract】 The studied area is located at the tropical area in Xishuangbanna where biological diversity is very rich but ecosystem is weak and Swidden agriculture is popular. With population growing, extensive cultivation and overuse of soil resources has resulted soil and environmental degradation, and restricted continuous development of countryside. It is necessary that the study on reason and process of degraded hillslope soil forming. The swidden system and plantation system are the two main using types in the area. Race land, four years and six years swidden land are different periods in swidden agriculture. Rubber plantation represents an important type of plantation system. Rain forest and wasteland represent original land use and degraded soil respectively, being contrast. The soil samples were collected in September 1997. Microbial quantity, respiration, microbial biomass and nutrient content in the soils were determined, and their variation in soils of different land uses was analysed. The results indicate that the variation pattern of soil microbe is almost same as that of soil nutrient content. The soil microbial quantity, respiration, microbial biomass and nutrient content are all decreased from rain forest→3 years of secondary forest→ix years of swidden land our years of swidden land ace land ubber plantation asteland. The values of soil microbe and nutrient content of different land uses show different degrees of decreasing compared with that of rain forest, and the decreasing extent increased with the increasing degraded extent. It is revealed that the soil microbial growth and metabolism decreased significantly with the increasing of soil degraded extent, and its decreasing speed is rapider than that of soil nutrient. The result show that the change of vegetation and environment and reduce of amount or nutrition of litter fall damage the level of microbial metabolism and nutrient content in soil significantly. The degradation of soil nutrition and microbial metabolism are the main aspects of tropical land degradation in Xishuanbanna. Burning and cultivating again in short time is an important reason resulting tropical land degradation, at the same time, the soil microbe and nutrient content in plantation are low too.更多还原