【作者】 倪静；

【导师】 宋西德；

【作者基本信息】 西北农林科技大学 ， 森林培育， 2010， 硕士

【摘要】 林分结构是林分功能的基础和表现,对森林经营管理和健康评价有重要的参考意义。本研究以渭北黄土高原刺槐人工林为研究对象,基于33块标准地的每木调查数据,系统分析了林分的直径结构和树高分布规律,并采用聚集度指标法和距离法分析了林木的空间分布格局,然后以最小结构单元为基础,利用胸径大小比数、树高大小比数以及角尺度等空间结构参数具体分析了刺槐的空间结构。研究结果表明：(1)刺槐人工林的直径分布遵从于近似正态分布,林分密度愈大,直径左偏程度愈大,小径阶林木愈多；林龄越大,分布曲线的偏度和峰度愈小；阴坡正态分布曲线偏度小于阳坡,峰度大于阳坡。树高分布和直径分布规律大体相同,处于中间高度的林木分布最多,两端株数逐渐减少,小径阶的株数略多于大径阶。刺槐胸径越大,林木也越高,即树高与胸径之间存在着正相关关系。经X2检验知,正态分布函数拟合刺槐的直径结构和树高分布效果较好。(2)采用聚集度指标法分析各龄级刺槐的林木空间分布格局,结果表明：刺槐幼龄林、中龄林和成熟林为聚集分布；近熟林和过熟林为均匀分布。应用距离法分析林分空间分布结局的结果与聚集度指标法得到的结论略有差异。(3)在参照树与四株最近相邻木组成的最小结构单元中,结构单元的平均距离尺度为单峰型分布状态。(4)在最小结构单元的基础上,树高大小比数在反映参照树与相邻木的生长优势上和胸径大小比数具有较强的一致性。根据角尺度判断标准可以得出：刺槐幼龄林、中龄林和近熟林为聚集分布,成熟林和过熟林为均匀分布,且过熟林有随机分布的趋势。此外,本研究以样地1为例,根据采伐木选择的基本原则进行了林分的模拟采伐,并对伐后的林分空间结构进行分析。结果表明,伐后的林木趋于随机分布,这对调整林木水平分布格局,改善林木竞争关系有一定的理论和现实意义。更多还原

【Abstract】 The indicator of stand structure which is the foundation and manifestation of stand functions is an important frame of reference which includes forest management and forest health assessment.This thesis choose the Robinia pseudoacacia in Weibei Loess Plateau as the study object,analyzing forest basis structure like diameter and height in 33 sample plots,and with the help of the method of distribution type index and method of distance to describe the forest spacing structure.Then to the smallest structural unit based on,using the spatial structure of the parameters,analyzing spacing structure from the diameter and tree height and angle scale.The results indicated that:(1) The diameter distribution of Robinia pseudoacacia forest is near to normal distribution. With the increasing of the stand density more,the skew of stand distribution decreases and the kurtosis increases. With the increasing of the stand age bigger,the skew and kurtosis of the diameter distribution decreases.The skew of the shady slope distribution is smaller than the sunny slope,but the kurtosis is bigger.The law of stand height structure indicate that the tree’s height increased with the accretion of tree’s diameter,then decreased dissymmetrical to the two poles;the most wood is near to the average diameter and the average height;the tree’s number of small diameter class is more than big one’s and the similar regulation is displayed roughly in the same tree’s diameter class.And inspected byχ2,normal distribution function can precisely imitate the diameter and the height distribution.(2) The result of integrated analysis with method assemble index which related with distance shows that the young forest,middle-age forest and mature forest of Robinia pseudoacacia are aggregated distribution;nearly mature forest and over mature forest are randomized distribution.Application of the method of distribution type index that the results obtained with the method of distance slightly different rules.(3) The distribution of distanceses consistent was single-kurtosis distribution in minimum composition structure cell.(4) Based on the minimum composition structure cell,the average diameter of each age grade is not too different for the diameter.The distribution between height neighood comparison and DBH neighood comparison has a strong advantage of consistency,which has reflected the reference tree and the adjacent tree on the growth advantage.The result of angle analysis shows that the young forest,half aged forest and nearly mature forest are aggregated distribution;mature forest and over mature forest are randomized distribution.In addition,according to the basic selection principles of cutting wood,this paper took the first plot to simulated cutting as an example,then analysised the stand spatial structure after cutting.The result showed that,stand distribution is prone to random distribution after felled.It has some theoretic and practical significance for adjusting the horizontal distribution pattern of plantation stand and improving forest competition relations.更多还原