泰森多边形与传统四株树法的天然红树林空间结构比较研究

目的]以漳江口红树林为研究对象,利用泰森多边形和四株树法划分天然红树林林木平面空间分布结构,确定对象木的最邻近竞争木,计算林分空间结构指数,对比分析两种方法的异同,探讨泰森多边形法应用红树林林分空间结构量化的适用性.方法]设置20 m×20 m样地,每木调查时用钢尺测量横纵坐标,在坐标纸上标记调查木的位置和编号,同...

Comparative study on natural mangrove forest stand spatial structure by Tyson polygon and traditional four trees method

【Objective】Taking natural mangrove forest in Zhangjiang river Estuary as research object,the possibility was evaluated to calculate the indexes of mangrove forest stand spatial structure by Tyson polygon and traditional four trees method which divided spatial distribution structure of natural mangrove trees.Comparative analysis the results of the similarities and differences between the two methods and determine the target’s nearest neighbor competitive trees.【Method】The sample plot was 20 m×20 m.In the field survey,the horizontal and vertical coordinates of each tree were measured with a steel ruler,the locations and sequence number of the investigated trees were marked on the coordinate paper.At the same time,forest stand factors such as species,height and DBH were recorded on the questionnaire.The investigated tree locations marked on the coordinate paper were digitized to form points layer of sample trees by ArcGIS software,the forest stand factor questionnaires were imported into the attribute table of sample trees,and the Tyson polygons were generated from the points layer of survey trees.The spatial structure indexes of forest stand such as mingling,neighborhood comparison and uniform angle index were calculated by VBA program.【Result】With testing in the plot in Fujian Zhangjiangkou mangrove nation natural reserve,the paper gives a contrastive analysis of the outcomes of calculating the spatial structure indexes based on Tyson polygon method and the outcomes of traditional four trees algorithms.The result,showed:1)The forest stand spatial structure unit determined by Tyson polygon method is made up of 1 target tree and 3-12 competitive trees,with an average of 6.2)The correlation coefficient of mingling calculated based on the two methods is 0.828,0.881 for neighborhood comparison,and 0.225 for uniform angle index.The outcomes of mingling and neighborhood comparison have significantly correlation and agreement between the two methods,but the outcomes exist remarkably difference when calculating uniform angle index.3)The calculation of forest stand spatial structure index of different species are very close based on Tyson polygon method and traditional four trees algorithms.The maximum difference of mingling is 0.05,neighborhood comparison’s is 0.02,while it’s an obvious maximum difference at uniform angle index with 0.11.The results of mingling calculated by Tyson polygon method is slightly larger than those calculated by four trees algorithms,but neighborhood comparison and uniform angle index are slightly smaller.【Conclusion】No matter from the individual plant or the whole investigation sample trees,there is a little difference and high correlation and consistency in the calculation of mingling and neighborhood comparison based on Tyson polygon method or traditional four trees algorithms,but quite an obvious difference at uniform angle index.Compared with the four tree method,there is slightly larger at mingling and slightly smaller at neighborhood comparison based on Tyson polygon method.The difference comes from the fluctuation of competitive wood quantity determined by Tyson polygon method.Tyson polygon method divides planar space by principle of nearest neighbor,so it is reasonable and effective for quantitatively describing spatial competition relationship of trees.At the same time,it does not need to judge the nearest competing tree of the target tree,distance measurement and angle measurement in field investigation,which greatly reduces the workloads of field investigation,and is suitable for forest stand spatial structure research of natural mangrove forest.