| Tree crown was important components of trees, directly affects the growth of trees, and it was closely related to production, quality, photosynthesis, how to improve the output of artificial forest was a big problem that facing under sustainable management of forest. Taiwania cryptomerioides plantation in State owned Forest Farm of Dehua city was chosen as the object of the study in this paper. Based on the data of the Sample-plot survey, Crown parsing, and standard to each wood positioning, the paper used related mathematics models and mathematical statistics methods to conduct a research on crown structure and the tree model of Taiwania cryptomerioides plantation, combined with variety built die methods. It could be some of reference and application value to estimate the growth of trees, health status, forest of optimization operating and scientific management in our country. Meanwhile, it has an important significance in forestry production. According to the content of this article, the main conclusions were summarized below:(1) The depth of the largest crown width was significantly related to diameter at breast height, tree high, under branch height, crown width and crown length. Through multiple linear stepwise, the optimum equation was made up of diameter at breast height and tree height, with a 94.5% of forecast accuracy. The crown contour model that consist of the allometric growth equation with 3 parameter was fitting better, all kinds of test indicators (E1, E2, E3) were less than 3%, and achieved a good results.(2) According to the Sample-plot survey data in artificial forest of Taiwania cryptomerioides,, the main-axis cutting method is used to calculate volume and surface area of Taiwania flousiana, by analyzing the correlation between independent variables and the dependent variable, choose the optimal factor, then combined with the allometric growth equation to build volume and surface area of Taiwania flousiana crown model. The results showed that Crown volume and surface area of Taiwania flousiana and forest factors such as tree diameter, height, Crown width, and Crown length were significantly correlated, and diameter at breast height, tree height, Crown length, Crown lies in the power function, and increases with the increase factor of forest trees. Crown volume and surface area of crown model with power function equation was the best, Crown volume and Crown surface area ratio increases with the increase of diameter at breast height, Crown volume and surface area of quadratic equations to simulate. Upon inspection, better constructed models, prediction accuracy of 86% or more, can provide estimates of stand growth and reasonable management provided some reference value.(3) Crown ratio and forest factors such as diameter at breast height, tree height, Crown width were significant positively correlated, and was a significant negative correlation correlated with H/D, basal area per hectare, while the dominant height had no significant effect on the crown rate. The paper used diameter at breast height, tree height, Breast Height per Hectare, crown width and H/D as Exponential model to build the crown ratio model of Taiwania cryptomerioides were more ideal.(4) Under branch height had close relationship with tree height, and it was significant positively correlated with tree height, diameter at breast height, Breast Height per Hectare. While it was a significant negative correlated with H/D and stand density. During the multiple linear stepwise, the result showed that if the numbers of regression model variables added to 3, the correlation index tended to be stable. The model which used diameter at breast height, tree height was the best variable combination, and the residual was more evenly distributed from top to bottom, there was no obvious deviation and the fitting was good with high precision in the model.(5) Crown width showed the normal distribution, and mainly distributed among 2 centimeters and 6 centimeters, even distributed in the two sides. The crown width of Taiwania cryptomerioides had close relationship with diameter at breast height, and it was significant positively correlated with DBH, tree height, Breast Height per Hectare, dominant height, while it was a significant negatively correlated with H/D and stand density.The crown width model which used diameter at breast height, tree height, dominant height, Breast Height per Hectare was the best variable combination and there was no obvious deviation, and the residual was more evenly distributed from top to bottom.The volume increases with the increase of the crown width showed a positive correlation with it. The model is best by the quadratic equation fitting, and the model of correlation index reached up to 91% which had high precision.(6) Based on the Sample-plot survey data in artificial forest of Taiwania cryptomerioides, Richards equation was used as the basic equation, and method of dummy variable of site quality factor was introduced. Tree height curve model of artificial forest of Taiwania cryptomerioides with the dummy variable of site quality was built and combined with the binary volume table to calculate standard volume. After cross modeling examination, the estimated accuracy of the established tree high curve model was close to the binary volume table. The work of the field survey would be largely reduced and more efficiency, it could be some of reference and application value to forest resources survey in our country.(7) The paper used multi model optimization method in order to select Nakajima as the best one variable volume equation of Taiwania cryptomerioides, with a 99.7% of forecast accuracy, there was no obvious deviation and the residual was more evenly distributed from top to bottom, meanwhile one-way volume table was organized; The paper selected Yamamoto as the best bivariate volume equation, and the model of correlation index reached up to 98.835% which had high precision.(8) Based on the 23 Standard two issue of survey data in artificial forest in State owned Forest Farm of Dehua city, this paper selected diameter at breast height as competition index that has nothing to do with the distance, and used the multiple linear stepwise method to construct individual diameter at breast height growth model which has nothing to do with the distance, and the model of correlation index reached up to 92.25% which had high precision. At the same time, there was no obvious deviation and the residual was more evenly distributed from top to bottom and the model is suitable; On the basis of Korf equation, the paper also selected simple competition index as competition index, using growth quantity correction method built diameter at breast height of potential growth model, also built individual diameter at breast height growth model which be connected with the distance. |
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