林冠环境对亚高山针叶林下缺苞箭竹生物量分配和克隆形态的影响

Effect of different canopy conditions on biomass allocation and clonal morphology of Fargesia denudata in a subalpine coniferous forest in southwestern China

通过对亚高山针叶林的林下、小林窗(130m2)、中林窗(300m2)和大林窗(500m2)4种林冠环境中缺苞箭竹(Fargesia denudata)分株种群特征进行调查,研究其生物量分配格局和克隆形态可塑性。研究结果表明:(1)分株生物量、基径、高度以及分株各构件生物量随林冠郁闭度减小均表现为先增加后减小的趋势,在小林窗中达到最大值;(2)大林窗中,根生物量分配和数量显著高于其他林冠环境,随林冠郁闭度增大,分株不断增大叶生物量分配、比叶面积和分枝百分比等地上部分投资,以适应低光环境;(3)比茎长和比地下茎长随林冠郁闭度增大表现为先减小后增加的趋势,在小林窗值最低,分枝强度在小林窗和中林窗中显著高于林下和大林窗环境。结果显示,缺苞箭竹在不同林冠环境中具有生物量分配和克隆形态的可塑性,以利于种群对光资源的有效利用。小林窗环境是缺苞箭竹较适宜的生境,生物量积累最多,长势最好。

Aims The bamboo Fargesia denudata is one of the Giant Panda＇s main food sources and also affects the structure and dynamics of Giant panda habitat in the subalpine coniferous forests of southwestern China. Bamboos are thought to influence forest regeneration by suppressing tree recruitment. Our objectives were to examine the clonal plastic response of F. denudata by studying （1） biomass allocation and clonal morphological plasticity under different canopy conditions and （2） environmental conditions most conducive for growth and survival. Methods In September 2007 and July-August 2008,we measured population density,biomass of ramets and modules,and clonal morphological features of F. denudata in four canopy conditions,i.e.,forest understory （Fu）,small gap （Sg）,middle gap （Mg）,and large gap （Lg）,in an Abies faxoniana forest in Wanglang National Nature Reserve in northwestern Sichuan,China. The data were analyzed statistically by One-Way ANOVA using SPSS13.0. Important findings The biomass,height,and basal diameter of ramets and biomass of modules were highest in the Sg canopy condition. With the increase of canopy cover,there were increases in biomass allocation to leaves,specific leaf area and percentage of branching and decreases in biomass allocation to roots and number of roots. Specific stem length and specific rhizome length were significantly lowest in the Sg canopy condition. Branching intensity of rhizomes was significantly higher in Sg and Mg. These results indicated that biomass allocation and morphological features of F. denudata are significantly different under different canopy conditions,for efficient utilization of light. Sg is the most suitable canopy condition for growth of F. denudata.