【摘要】 以自然林为对照 ,研究了云南省西双版纳热带地区刀耕火种农业 (旱稻 )和林下种植砂仁 ( Amomumvillosum) 2种不同土地利用方式对土壤弹尾、螨和线虫 3类土壤动物个体数量的影响。通过 2 4个月的取样分离 ,获得土壤动物个体 49,91 2个。结果表明 :不同土地利用方式导致了土壤理化性质不同程度的改变 ,例如土壤容重的增加、肥力下降、土壤水分蒸发加快等 ,这些土壤指标的变化是影响土壤动物个体数量的决定性因素。动物的个体数量在 3个样地中以自然林最多 ,砂仁地次之 ,刀耕火种地最少 ;在季节分布上以雾冷季最多 ,干热季最少。各样地的动物个体数量以刀耕火种与自然林之间的差异最显著 ,刀耕火种样地与砂仁样地或砂仁样地与自然林样地之间的差异有时达到显著水平 ,但在不同季节中各类型样地间的差异有所不同。土壤动物的季节变化不但受气候条件变化的影响 ,同时受到人类土地利用活动的影响 ,在人为干扰样地中高峰与低谷之间的变化幅度较大。某些土地利用的行为不但杀死了动物本身 ,而且破坏了动物的营养源 ,因此土壤动物个体数量随着土地利用强度的增加而下降。更多还原

【Abstract】 The impact of different land use practices on the number of individuals of three groups of soil animals (Acrina , Collembola [Springtails] and Nematoda ) were studied in the tropical ecosystems of Xishuangbanna (location, 21°54′41″~21°59′50″N, 101°00′06″~101°13′02″E; annual precipitation, 1600 mm), Yunnan, China. This study focused on two types of land use practices: shifting cultivation and cardamom (Amomum villosum) plantation under the native rainforest. Undisturbed nearby rainforest was sampled for comparison.In each land use type, three 30×30m+2 plots were sampled, each plot divided into four 15×15m+2 subplots. Soil cores (30mm diameter) were collected to a depth of 100 mm every month from June 1999 to May 2000. Five evenly-distributed samples were taken from each of two subplots, alternating with the other two subplots monthly. Animals were extracted from the cores by Tullgren funnel trapping for springtails and mites, and Bearmann funnel trapping for nematodes. Soil organic matter, unit weight and water content were measured seasonally (four times per year) on a subset of the cores from each plot. In Xishuangbanna, the seasons are dry and hot (Mar.to May), rainy (Jun.to Sept.), foggy and cool (Oct. to Nov.) and foggy and cold (Dec. to Feb.).The results show that:(1)A total of 49,912 individuals were isolated from the study period of 24 months. (2)Differences in numbers of soil animal individuals between shifting cultivation and undisturbed rainforest were, in all cases, significant. Numbers of individuals were typically higher in cardamom compared to shifting cultivation plots, though this difference appears significant only for nematodes. Differences between cardamom and rainforest plots were rarely significant for separate seasons, but were significant in the annual totals of all animal groups. (3)In all plots for all three land use types the number of the soil animals tends to be lowest in the dry-hot season (Mar.～May) and highest in the foggy-cool and foggy-cold season (Oct.～Feb.). However, plots impacted by shifting cultivation and cardamom planting exhibited greater seasonal variability compared to rainforest plots, due to plowing, weeding and burning. (4)Organic matter and nutrient content of soils decreased with increasing intensity of land use. We believe that this pattern in soil quality critically influences the number of soil fauna individuals. The abundances of animal distribution in the three land use types declined with increasing soil bulk density and decreasing soil fertility. Soils under shifting cultivation were most affected by agricultural activities. The number of soil animal individuals in this land use type was the lowest compared to the other two land use types. It seems that activities of farming killed or suppressed the growth of the soil fauna. (5)In the cardamom sites, the canopy trees were left shade, so the overstory environment was similar to the natural forest, but most of the understory plants were removed. Other management activities, such as yearly fruit collection, likely have significant impacts on soil quality and soil fauna community structure. Since the intensity of land use in cardamom plantation was less then that of shifting cultivation, the number of soil fauna individuals in former land use type was higher then in the latter, but lower then that of natural forest.更多还原