西双版纳片断化热带雨林常绿乔木幼树水分利用效率的边缘效应研究

以植物叶片δ

EDGE EFFECTS OF PLANT WATER USE EFFICIENCY INDICATED BY FOLIAR

Using foliar δ13C value as an indicator of plant water use efficiency (WUE), we tested the effects of exposure at forest edges facing each of four different aspects on evergreen tree seedling leaves in a fragmented rainforest in Xishuangbanna, Yunnan. In the edge transects, foliar δ13C value ranged from -35.32‰ to -27.6‰, averaging -31.6‰±0.15‰. There were significant differences between the average foliar δ13C values of the four aspects, with the western aspect higher than those of the northern and eastern aspects of the forest. At sampling areas 0-10 m from the forest edge, the foliar δ13C value differed significantly among the four aspects, however at distances of 20-30 m, 55-65 m and 95-105 m from the edge differences were no longer significant. These results indicate that the effect of forest edges on WUE was the largest in the western and the smallest in the northern aspects and that the distance of edge effects on plant water use efficiency was at least 10 m in from physical edges. Therefore we conclude that the influence of aspect should not be neglected when investigating the edge effects on plant species in fragmented forests.