Visual Simulation Research On The Effect Of Crown On The Tree Growth For Cunninghamia Lanceolata

Stand Growth is a complex process with physiological and ecological characteristics, which is influenced by climate, topography and other environmental factors. The perfect growth models have a great significance to predict changes of the forest and build stand structure and growth visualization system. Furthermore, it finally can provide theoretical basis, operation standards, and quantitative information for forest management.The object of research was Chinese fir of Huangfengqiao state-owned forest in You country, Zhuzhou city, Hunan Province. In this study, the tree growth model considering the influence of the environment, tree crown and neighborhood competition was built to study the physiological process of plant growth, and expressing tree growth in the visualization by stand growth visual module. It can present true performance of real growth conditions, providing an intuitive and accurate criterion for studying the crown dynamics and its mechanism of the influence on the growth of tree.The following three respects are the main research contents of the paper.(1)In order to simulate the real shape of the tree, this study built the crown prediction models through the establishment of crown curve equation and canopy size equations:The canopy contour curve was set based on piecewise power function, and the crown index prediction models were involved. The crown size equations mainly included the prediction models for crown width, crown length and the height of the largest crown width. These equations took the tree size factors, diameter at breast height(DBH), tree height(H) and tree competition factors, tree competition index(CI), open Comparison(OP) as variables. Finally, the determination coefficient(R2) of the three optimal models were 0.799、0.805、0.710.(2)The biomass production model and distribution model were improved based on 3-PG model theory for the single tree level to study the physiological process of plant growth under the environment interactions. The improved model considered the the effects of crown shape and crown competition on tree growthinfluences. This study selected the DBH and H to evaluate the model simulation results. It showed that DBH and H average analog precision of the improved model were respectively 95.57% and 91.16%, significantly higher than the 3-PG model, which precision were 89.4% and 85.18%. It improved simulation accuracy significantly and simulated better.(3)In view of the interaction mechanism between the environment and tree crown structure, the individual tree growth dynamic simulation was achieved with the using of established models. Using the bottom-up method which was from individual tree to stand level, stand growth visualization module was developed by Direct X technology. Finally, with the Chinese fir artificial stand in Huangfengqiao Forest Farm, Hunan as the research object, and taking the visualization simulation experiment as an example.