片断化热带雨林植物水分利用效率的边缘效应

利用样线设置取样法和稳定性同位素分析技术研究西双版纳片断化热带雨林林下幼树生长期水分利用效率的边缘效应，为片断化森林生态系统的管理、恢复以及生物多样性的保护提供科学的理论依据。同时比较不同科、属、种和不同生活型植物长期水分利用效率的差异，为揭示森林生态系统片断化与植物物种局域灭绝的关系和内在机理提供新的佐证和依据。

The foliar δ13C values of 226 plant species sampled from 7 transcets belonging to two types of rainforests (Chengzi and Bubeng sites) in Xishuangbanna of Yunnan Province, China, were analyzed. Using foliar δ13C value as an indicaor of plant water use efficiency (WUE), the characteristics of foliar δ13C values and WUE of plants indicated by δ13C values in this region, and the effects of exposure at forest edges facing different aspects on evergreen tree seedling leaves in two fragmented rainforests there were also determined. The results indicated that, (1) the foliar δ13C value in Xishuangbanna, ranging from -36.85‰~-27.60‰, was similar to those from other types of rainforests of the world; (2) there were significant difference between Chengzi and Bubeng in average foliar δ13C values, with the later being lower than that of the former; (3) the average foliar δ13C value of evergreen plants was significantly lower than that of deciduous plants, and there also existed significant difference among different life forms implying that the WUE of these plant species was also quite different; (4) in the edge effects, foliar δ13C value ranged from -35.32‰ to -27.60‰ averaging at -31.6‰±0.15‰. Significant difference can also be found between the average of foliarδ13C values of the four aspects in a forest fragment, with the western aspect higher than those of the northern and eastern aspects. The distance between 0 to 10m from the edge of the fragment, the foliarδ13C value differed significantly among the four aspects, but insignificantly within the ranges of 20 to 30m, 55 to 65m and 95 to 105m from the edge. These indicated that the effect of forest edge on plant WUE was the largest in the western and the distance of edge effects on plant WUE can extend to at least 10m from the edge. Thus the influence of aspect should not be neglected when investigating the edge effects on plant species in fragmented forests.Fragmented rainforest