增强UV-B辐射对暖温带落叶阔叶林土庄绣线菊水分利用效率、气孔导度、叶氮素含量及形态特性的影响  

EFFECTS OF ENHANCED UV-B RADIATION ON WATER USE EFFICIENCY, STOMATAL CONDUCTANCE, LEAF NITROGEN CONTENT AND MORPHOLOGICAL CHARACTERISTICS OF SPIRAEA PUBESCENS IN A WARM-TEMPERATE DECIDUOUS BROAD-LEAF FOREST

作　　者：陈兰[1] 张守仁[1] 

机构地区：[1]中国科学院植物研究所植被数量生态学重点实验室

出　　处：《植物生态学报》2006年第1期47-56,共10页Chinese Journal of Plant Ecology

基　　金：国家自然科学基金资助项目(30270237);中国科学院"十五"预研项目

摘　　要：在北京东灵山暖温带森林生态系统中，选择常见灌丛土庄绣线菊（Spiraea pubescens），建立UV-B控制实验。连续3个生长季每天增补9．4kJ·m^-2的辐射剂量，模拟臭氧衰减17％时近地表面uv_B辐射的增强。该实验的目的是在野外环境下观测，长时间人工增强UV-B辐射对土庄绣线菊叶片的气孔导度、碳同位素比率（δ^13C）、叶含水量、叶面积、特别是水分利用效率（WUE）和叶片全氮含量等指标的影响。实验结果表明，增强UV-B辐射显著减少了土庄绣线菊的叶面积（50．1％），提高了叶片全氮含量（102％）。同时，UV-B辐射还在一定程度上（尽管统计显示不显著）降低了气孔导度（16．1％）、胞间CO2浓度与大气CO2浓度之比（Ci／Ca）（4．0％）、提高了碳同位素比率（δ^13C）（20．5‰）、叶含水量（3．1％）及比叶重（乩形）（5．2％），从而导致WUE的增加（4．1％）和植物的抗旱能力增强。值得注意的是，深层土壤（30—40cm）含水量变化会影响气孔导度、δ^13C和WUE对紫外辐射的响应程度：在土壤干旱的季节（6月和9月），气孔导度、δ^13C、WUE这些指标处理和对照的差异很小，但是当土壤水分充足时（7月和8月），处理和对照的差异就较为显著。另外，随着实验处理时间的延长，UV—B的效应变得不显著。相关分析表明，UV—B辐射降低了土壤含水量（30—40cm）与土庄绣线菊叶含水量、δ^13C、Ci／Ca和气孔导度的相关系数，增强了WUE与土壤含水量的相关性，这也许是由于UV-B辐射增强了WUE对土壤水分变化的敏感性。该研究的结果表明UV—B辐射对土庄绣线菊的形态和生长有显著的影响，但对主要水分生理指标影响不显著。Spiraea pubescens, a common shrub in the warm-temperate deciduous forest zone, is distributed in the Dongling Mountain area of Beijing, was exposed to ambient and enhanced uhraviolet-B （UV-B, 280- 520 mn） radiation by artificially supplying a daily dose of 9.4 kJ· m^- 2 for three growing seasons, a level that simulated a 17% depletion in stratospheric ozone. The objective of this study was to explore the effects of long-term UV-B enhancement on stomatal conductance, leaf tissue δ^13C, leaf water content, and leaf area. Particular attention was paid to the effects of UV-B radiation on water use efficiency （WUE） and leaf total nitrogen content. Enhanced UV-B radiation significantly reduced leaf area （50.1% ） but increased leaf total nitrogen content （ 102% ）. These changes were associated with a decrease in stomatal conductance （ 16.1% ） and intercellular CO2 concentration/air CO2 concentration （Ci/Ca） （4. 0%）, and an increase in leaf tissue δ^13C （20.5%）, leaf water content （3.1% ）, specific leaf weight （SLW） （5.2%）, and WUE （4.1% ）. The effects of UV-B on the plant were greatly affected by the water content of the deep soil （30 - 40 cm）. During the dry season, differences in the stomata1 conductance, δ^13C, and WUE between the control and UV-B treated shrubs were very small, whereas differences became much greater when soil water stress disappeared. Furthermore, the effects of UV-B became much less significant as the treatment period progressed over the three growing seasons. Correlation analysis showed that enhanced UV-B radiation decreased the strength of the correlation between soil water content and leaf water content, δ^13C, Ci/Ca, stomatal conductance, with the exception of WUE that had a significant correlation coefficient with soil water content. These results suggest that WUE would become more sensitive to soil water variation due to UV-B radiation. Based on this experiment, it was found that enhanced UV-B radiation had much more significant effect

关 键 词：暖温带落叶阔叶林 土庄绣线菊 UV-B辐射 碳同位素分差 水分利用效率 营养含量 

分 类 号：S718.43[农业科学—林学]