Study On Stand Structure And Growth Model Of The Quercus Variabilis Secondary

Oak secondary forest as a kind of typical secondary forest community types in the subtropical region of our country, It has a variety of functions. How to optimize the space structure and recover the function to perform the function of disaster prevention and reduction in protecting and restoring the secondary forest becomes one of the most urgent problem to address at present.This study to the oak secondary forest of Hebei Qing Yazhai Provincial Natural Reserve as the research object, begin with the structure characteristic and growth rule to aim at giving advice on better efficient operation using the forest. The main research contents and research conclusions are as follows:(1) The research in the diameter structure and tree height structure rules of quercus variabilis secondary forest. Using Weibull distribution function, the power function, index function and Richard function of the four distribution models to fitting the DBH and tree stand, and the fitting results are through a chi-square test. Results show that the diameter distribution rules of quercus variabilis secondary forest using Weibull distribution function is best fitting, F value is 1170.61, correlation coefficient is 0.998. Its optimal equation is N=130.6404×(1-EXP (-((D-2.2329)/5.9979)(?)(-1.9721))). The tree height structure rules using curve equation is best fitting, optimal equation is h=-3.022+2.091×(d)-0.065 (d2). Conform to the trend of oak secondary forest succession.(2) The study of the space structure of oak secondary forest. In stands, classify and choose the space factors which most influent ecological system management goal, analyze from their mixed, competition, space distribution pattern, tree species advantage status and forest tree growth status. The analysis reveals:①The forest tree species composition is simple, the diversity is low, the overall perform a transition from moderation to advantage state;②The distribution pattern whole shows random distribution bias to non-uniform distribution (turn round state distribution);③The whole competition strength stands no obvious difference, and decreases along with trees'diameter level grows.(3) The research based on support vector machine (SVM) model to study the growth of quercus variabilis secondary forest. According to the above analysis results using support vector machine for single tree diameter and tree height growth model of quercus variabilis secondary forest, through learning and training and testing data for inspection, got a very good prediction effect.