The secondary forest of Mt. Longhu in the south Dongting Lake is chosen as the research object in this paper which tries to establish a stand model based on Voronoi diagram. This diagarm is applied here to illustrates the stand spatial structure and extract forest spatial quantitative information. Based on this, coefficient of variation (CV) is used to quantify the change rate of Voronoi polygon area, transferring the analytic results of stand spatial pattern to the calculation of the CV based on Voronoi diagram, and comparing the calculation results with uniform angle index. The result shows that the stand model of Voronoi diagram can accurately display some important spatial information, such as the correlation, distance and angle between adjacent trees as well as spatial density, etc. When sampling large scale(above 76m) , CV tends to remain stable, and the overall stand spatial pattern shows mild aggregation which is close to random distribution. The CV of Voronoi diagram and uniform angle index have notable positive correlation, which further proves the feasibility and effectiveness of the analytical methods applied in this paper.The spatial pattern of main tree species of abor layer in different development stages shows a distinct temporal and spatial dynamic characteristics due to many factors. The small鄄diameter wood belongs to aggregated distribution, while the large鄄diameter belongs to mild aggregation or random distribution. The stand spatial model and its pattern analytical method, both based on Voronoi diagram, charaterize the tree growth feature, intraspecific and interspecific relationship, characteristics of resources and enviornment distribution from the perspective of spatial structure, providing a new way of thinking for stand spatial management by applying computational geometry method.

The spatial structure rationality evaluation and ideal spatial structure of forest ecosystem is an important and difficult problem in forest management at home and abroad. In order to reveal the reasons why the community structure is simple and the stability of ecosystem is poor, and to take the regulation mechanism of structure in Dongting Lake forest, the research is targeted at East, South, West Dongting Lake area including Junshan Island, Longshan, Longhu forest farm on Chishan Island, Minglang mountain, Changde forest farm, Hefu Forest farm and natural secondary forest of Taoyuan County. Utilizing the ecosystem internal balance and homogenizing principle of the ecology, in the forest ecological system (plaque) scale, it analyses the spatial structure of mixed, competed and spatial distribution pattern. And then the heterogeneity goal of optimized stand spatial structure is proposed, which has multiple sub鄄goals in mixed, competed and spatial distribution pattern. Meanwhile the heterogeneity index of single tree and stand spatial structure is also defined, and the evaluation index, evaluation method and evaluation standard of stand spatial structure heterogeneity is determined. By applying the proposed evaluation method to the Dongting Lake area secondary forest heterogeneity evaluation, the results show that: in the fifteen Dongting Lake wetlands under investigation, the forest stand average homogeneity evaluation index is 0. 2517. There are 12 stands in the grade 1 and grade 2 which is accounted for 80% , and only 3 stands in the 3 grade accounted for only 20% in the five grades of homogeneity index. However, it lacks of the grade 4 and grade 5 ideal stand

收稿日期：２０１５• ０９• １５； 网络出版日期：２０１６• ０７• １３ * 通讯作者 Ｃｏｒｒｅｓｐｏｎｄｉｎｇ ａｕｔｈｏｒ．Ｅ•ｍａｉｌ： ｗｘｈｅ１９６８＠ １６３．ｃｏｍ ＤＯＩ： １０．５８４６ ／ ｓｔｘｂ２０１５０９１５１８９８ 曹永昌，杨瑞，刘帅，王紫泉，和文祥，耿增超．秦岭典型林分夏秋两季根际与非根际土壤微生物群落结构．生态学报，２０１７，３７(５) ：１６６７• １６７６． Ｃａｏ Ｙ Ｃ，Ｙａｎｇ Ｒ，Ｌｉｕ Ｓ，Ｗａｎｇ Ｚ Ｑ，Ｈｅ Ｗ Ｘ，Ｇｅｎｇ Ｚ Ｃ．Ｃｈａｒａｃｔｅｒｉｓｔｉｃｓ ｏｆ ｍｉｃｒｏｂｉａｌ ｃｏｍｍｕｎｉｔｙ ｉｎ ｆｏｒｅｓｔ ｓｏｉｌ ｂｅｔｗｅｅｎ ｒｈｉｚｏｓｐｈｅｒｅ ａｎｄ ｎｏｎ•ｒｈｉｚｏｓｐｈｅｒｅ ｉｎ ｓｕｍｍｅｒ ａｎｄ ａｕｔｕｍｎ ｉｎ Ｑｉｎｌｉｎｇ Ｍｏｕｎｔａｉｎｓ， Ｃｈｉｎａ．Ａｃｔａ Ｅｃｏｌｏｇｉｃａ Ｓｉｎｉｃａ，２０１７，３７(５) ：１６６７• １６７６．

No abstract

No abstract