Studies On Spatial Structure Quantification Of The Mixed Forest Of Masson Pine And Broad-leaved Trees

Forest is the subject of the land ecosystem,it can not only satisfy the need for material products and environmental services of human existence and development,but aslo may play an important role in maintaining global ecological balance and protecting biological diversity.The world forestry in the 21st Century is changing from traditional forestry into modern forestry. Modern forestry takes sustainable development theory as instruct, and takes ecological environment as the key,has changed the used forestry position ,which took wood harvest utilization as instruct,only as the important material product department of national economy. The construction of modern forestry not only has to undertake the need for forest products because of the rapid economic development,but aslo has to undertake the important historical mission of improving ecological environment and advancing harmonious between man and nature. Forest structure determines function,the spatial structure characteristics of forest is the most important information in identifing the health and stability of forest ecosystem. The sustainable development of modern forestry should be established in understanding the spatial structure characteristics of forest,and according the information of the forest spatial structure,using the reasonable management measure,to control and optimized the forest structures,in order to realize the forest sustainable utilization.This paper elaborated types of the forest spatial strueture distribution and its mathematieal model,and deseribed several indexes to realize quantitative analysis of the forests patial structure, including mingling degree, neighbhood comparison, uniform angle index and storey level rate. Based on the mixed forest of masson pine and broad-leaved trees in Yanping District of Nanping City ,selected three plots from the forest management inventory data, analysised and studied the forest characteristics,especially the quantization parameters of the spatial strueture,which could provide the theoretical and technical support for sustainable management of the mixed forest of masson pine and broad-leaved trees.The result showed that in the first plot the value of assembling index R was 1.09,the average mingling degree was 0.42, the average DBH neighbhood comparison was 0.66, the average uniform angle index was 0.470,and the average storey level rate was 0.522. In the second plot the value of assembling index R was 0.88,the average mingling degree was 0.47, the average DBH neighbhood comparison was 0.51, the average uniform angle index was 0.569,and the average storey level rate was 0.409. In the third plot the value of assembling index R was 0.86,the average mingling degree was 0.72, the average DBH neighbhood comparison was 0.48, the average uniform angle index was 0.556,and the average storey level rate was 0.528.The spatial distribution of the first plot was uniform distribution,and the second and third plot were both aggregation distribution.And the mingling degree of the third plot was the hightest,which showed that the average mingling degree was relatively high when the stand had not to bear the artificial disturbance.The stands of three plots were all at the earlier growth stage, as intolerant tree species, the masson pine grew faster,it was obviously predominant at the stand. Analysised from different trees,the uniform angle index of broad-leaved trees was relatively high,which showed that the trees around the broad-leaved trees were generally aggregation distribution,and the uniform angle index of masson pine was relatively high,so trees around the masson pine were more uniform than the broad-leaved trees.In addition, This paper used the parameters of the spatial strueture to select the cutting wood, established the basic selection principles of cutting wood,and made the program of optimizing forest spatial structure which took uniform angle index as the main regulated object.Took the third plot to simulated cutting as example, firstly selected the structural unit of selective cutting, on this basis determined the wood that need selective cutting through comprehensive analysis,then analysised the stand spatial strueture after cutting.The result showed that,the cutting based on the stand spatial strueture has improved the whole stand quality, optimized the stand spatial strueture,it is suitable for the ecological forest management and some commercial forest with important ecological significance.