Study On The Nonlinear Models Of Forest Biomass And Optimal Felling

Because of the diversity and complexity of forest systems, made the forest resources management and forecasting often need a series of effective mathematical methods, and simple linear models can not properly simulate the complex dynamics of the forest changes So this paper research in the theory of nonlinear applications in fitting models for optimal harvesting model and the forest biomass. The data used in this paper is observation use three dimensional laser scanner,GPS,the entire station meter and so on the advanced instrument obtains. mainly consider cut down small-scale trees, fully utilize the indirect observation data to perform the biomass model instead.In the fitting biomass models, focusing on two aspects.: First, the preferred return factor, to choose a suitable return variables, and enhance the accuracy of the model, the methods used gradually opted contribution method in the model building, finally use the height, age and diameter breast height as return variables. Second, aims at the least-squares method, in view of it has weakness on adjustment, which means if the data includes gross errors, least squares method is weak.The robust estimate method has the ability to resists the gross errors, it is the principle which discards individual data, thus the models use robust estimate method has the commensurability. Although in the individual data fitting effect, possibly exists the instance that inferior to least squares method, but attention to the whole fitting, that the robust estimate has the preponderances. It is more reasonable and more optimized to robust estimate when the fitting computation, compares with tradition least squares method.Generally there is more non-linear problems in the forest system, Peoples can control and manage the forest system by change the parameter values. Intensity of fell is the main means that people control forest. This paper starting from felling rate, fully utilize the optimize principle, consider restraint and extreme value in the forest, employ the differential equation method and real variable function theory. Establish the model and analyze the fell intensity coefficient and the transformation for the area of woods change under fell influence. Concluded the optimum forest fell value existence and a method to calculate that value , can utilize apt to examine factor of trees, combine with modern forest manager means, cipher out the optimum point to fell intensity , offer the theoretical foundation and practical approach for the forest forever utilize and for the health stability of the forest system.Taking these aspects, the paper study the nonlinear theory applications in the fitting biomass model and in harvesting optimize. Basically achieved on the study of nonlinear models from the regression to optimize, from static to dynamic and from artificial selection factor to the computer selection, such important issues to explore, to do research variety and dynamic forest have an important role.