天目山近自然毛竹纯林的竹秆空间结构特征

近自然毛竹Phyllostachys pubescens纯林是浙江省天目山国家级自然保护区内特殊的植被保护类型。研究近自然毛竹纯林的竹秆空间结构特征，可正确认识近自然毛竹纯林地上部分的结构与功能关系。在浙江天目山国家级自然保护区内，选择近自然毛竹纯林设置样地（样地大小为100 m × 100 m），用全站仪测定每株毛竹坐标（x，y，z），采用8邻域边缘校正方法，利用角尺度、大小比数和秆龄混交度3个林分空间结构指数,分析近自然毛竹纯林的竹秆空间结构特征。结果表明：近自然状态的毛竹纯林活立竹、枯死竹和整个毛竹林的角尺度均值分别为0.554，0.556和0.553，均为聚集分布；活立竹的平均大小比数为0.511，表明参照竹和相邻竹在胸径因子上优势不明显，竞争能力相当；整个毛竹林的秆龄混交度均值为0.713，接近于强度混交，表明毛竹林具有秆龄多样性和较高的秆龄相互隔离程度。图6表1参28

Spatial structure of bamboo culm of an almost natural,pure Phyllostachys pubescens forest in Mount Tianmu

An almost natural Phyllostachys pubescens pure forest is a special vegetation type in the National Nature Reserve of Mount Tianmu,Zhejiang Province.Study of this bamboo forest was done to help understand the relationship of the structure and function of the ground part.A typical plot of 100 m × 100 m was surveyed in the reserve.Each Ph.pubescens stem was located in terms of x-,y-,and z-coordinates using a total station method with eight neighborhood edge corrections.Then the spatial structure of the stand was analyzed with the uniform angle index,by a neighborhood comparison,and by mingling of culm age.Results showed that the average uniform angle index of living Ph.pubescens was 0.554,for dead stems was 0.556,and for the entire stand was 0.553,which meant a clumped distribution.The average neighborhood comparison of living stems was 0.511 meaning there was no apparent trend of relative dominance.The mean mingling of culm age was 0.713 closing which showed strong mingling.Therefore,this Ph.pubescens stand had both diversity and a high degree of segregation with culm age.