| Forest is a complex system whose health situation is closely related to its structure, it has many impact factors, involves a wide range of aspects, and it has multi-dimensionality.Researches on theories, methods and techniques of forest health management based on forest structure that contains spatial information and its optimal adjustment are the hot spots and difficult points of forestry and ecology at home and abroad. In southern China, especially south of Yangtze River, for many years in the past, in those forest communities surrounding freshwater lakes, lakes and forest area were unceasingly shrinking, biological recourses decreased sharply and invasive exotic tree species increased. forest types are changing quickly from primitive organisms’ communities to artificial ones, forest ecosystem services in this area have suffered severe damage, even economic and social sustainable development along Yangtze River has been affected. Therefore, based on relationship between structure and function of systems engineering principles, studying southern forest health and management through forest spatial structure; recovering forest ecosystem function and maintain forest’s health and stability by adjusting forest’s spatial structure has important theoretical and practical significance for Improving the level of forest management in the study area, and building a "two-oriented society" and low-carbon economic society. Forest health has many impact factors and variety of management measures, it is actually a nonlinear multi-objective programming problem. International and domestic researches on it are not very systematic or scientific. Typical forest type in Changsha has been taken as an example in this paper, according to theories of forest health, ecology and system engineering, impact factors that affect forest health and the health situation and problems of Changsha have been analyzed at the level of forest ecosystem through the relationship between forest’s structure, function and its health. Studying ecosystem health management spatial structure control strategy by the application of Data-mining and intelligent Evolutionary Algorithms, based on Intelligent evolutionary algorithm solving multi-objective programming problem, studying forest health management multi-objective spatial structure optimization problem, determining the target spatial structure, establishing healthy management spatial structure optimization model of typical forest type in Changsha. Based on this study, corresponding improving measures have been proposed to adjust forest ecosystem spatial structure and formulate correct management thought, target and measures. The main contents and conclusions are as follows:(1).Study on pattern analysis method of stand spatial structure based on Voronoi maps, natural secondary forests in Dawei Mountain Nature Reserve, Liuyang Lake state-owned forest farm, Heimi Mountain forest park in Wangcheng district and Hunan forest botanical garden have been taken as objects, pattern analysis method of stand spatial structure based on Voronoi maps has been posed. The results show that pattern analysis method based on Voronoi maps can also describe trees spatial distribution, and it can describe main tree species dynamic spatial pattern at different time.(2).Analysis of spatial structure of Changsha typical forest types, using mingling, neighborhood comparison, neighborhood pattern and spatial density, stand spatial structure of typical natural secondary forest in Dawei Mountain Nature Reserve has been analyzed The results show that the objective stand’s average mingling is0.35, its average neighborhood pattern is0.47, and the average spatial density is0.65. There are not many species in the stand, the community is simple, spatial pattern is close to natural community’s distribution, the ecosystem is not very stable, and it is related by Artificial or natural disturbances.(3).Rationality evaluation of Changsha forest structure. Using ecosystem homogeneous internal balance principle in ecology, at the scale of forest ecosystem (patch), the target, index, evaluation method and standard of homogeneity of spatial optimization have been posed from the aspects of mixing, competition and distribution of spatial structure. The results show that the average spatial structure homogeneity evaluation index of the13typical secondary stand is only0.25which is far from the ideal spatial structure (1.0), homogeneity has5levels, there12stands are on Level1and Level2, which takes77percent of total, and only3stands are on Level3, only takes23percent. This tells there are many irrational factors exist in forest structure that involves spatial information in the study area. This conclusion truly reflects the secondary forest recourse current situation in the study area, stand spatial structure homogeneity increases gradually according to different altitudes. It is closely related to natural and anthropogenic disturbances and lack of protect and recover in a long time. The propose of homogeneity target and index of forest ecosystem spatial optimization is a expansion of spatial pathway for forest sustainable management, it discovers a new way for forest management’s ideal spatial structure and its expression.(4).Structure control method of forest health management based on intelligent algorithms. Considering trees’horizontal distribution pattern, tree species, intraspecific and interspecific competition, and multi-layered vertical structure, multi-objective optimization management model of natural secondary uneven-aged forest’s spatial structure based on system theory and structured forest management has been put forward; using Powerful parallel computing capabilities of intelligent PSO algorithm to find weaknesses of stand space, subtly transfer the problem from stands’ multi-objective spatial programming to Particle populations iterative optimization. The results show that through the model’s application in water conservation forest in Dongting Lake wetland, using PSO algorithm solving multi-objective optimization of spatial structure has obvious effects, the optimization model management example shows that the model breakthrough traditional forest management pattern, with non-spatial structure factors like tree species, diameter grades and age class distribution being kept the same, stand spatial structure indexes (except canopy index) are all improved. Enhancing the overall spatial structure of homogeneous target has important practical significance for promoting health stability and recovering of ecosystem, it provides new ideas for intelligent information techniques’application in forest spatial management.(5).Health assessment of Changsha’s typical forest ecosystem. Determination of forest ecosystem health by analyzing typical forest type’s stand structure and function characteristics and its health definition and health assessment practice is not a simple linear relationship. Forest health assessment index system has been established according to assessment index system establish principle. Learning from inventory survey of Hunan province, typical plot invitation and Hunan forest recourse management information system,25indexes (DBH, height, standing volume stock per unit, natural forest updating status, community layer structure, stand canopy density, natural closeness, soil thickness, soil organic matter, content of N, P, K in soil, forest fires and plant diseases and insect pests) are selected to build forest health assessment model which based on ecosystem(sub compartment). Weights of indexes are determined by Variance contribution rates in factor analysis method. Stand health scores and levels can be calculated. Among the selected110forest sub compartments, there are4high quality ones,4healthy ones,71sub-healthy ones and4unhealthy ones, they take1.8%,22.7%,64.5%,7.3%,3.6%. The overall forest ecosystem in the study area is at an unhealthy status.(6).Forest health assessment and structure control intelligent decision support system. Taking typical forest types in studying area as an object, on the basis of analyzing forest health assessment and structure optimization intelligent decision support system characteristics, forest health assessment and structure optimization intelligent decision support system based intelligent evolutionary algorithm has been developed by using HWME technology. Mainly including design of intelligent system development platform, system architecture, software architecture; Development of key technologies of assessment and control system architecture and modular decomposition. Models and methods have been analyzed and evaluated comprehensively through qualitative and quantitative ways. Through testing, the system turns out running well, and has higher degree of intelligent decision support.Trees’spatial pattern analysis method based on Voronoi maps aimed at forest health management spatial ways is put forward for the first time in this paper, This provides theoretical foundation for evaluating irrationality in forest spatial characteristics and determining right management measures, meanwhile, intelligent evolutionary algorithm spatial search function’s application into locating of forest spatial structure control brought new breakthrough for forest spatial structure multi-objective optimization. The debugging and running of forest health assessment and structure optimization intelligent decision support system based intelligent evolutionary algorithm shows it works well and can prospectively provide intelligent system support platform for forest health management. |
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