The Research Of Visual Simulation Of Morphological Structure Change Of Cunninghamia Lanceolata Based On Physiological And Ecological Model

With the development of computer and information technologies, the application of thecomputer for three-dimensional visual simulation of tree's morphological structure has beengot more and more attention. The visual simulation technology of trees has become an effectivemethod. It is a new approach and have some advantages in the expression of tree'smorphological structure and growth of process. The ultimate goal of the technology is todevelop a model which is consistent with the real trees on the external morphological structureand internal function, and display the visual simulation results. Tree life activities are theinteractive results between the morphological structure, physiological and ecological processesand the environment. The parallel simulation of three-dimensional morphology structure andphysiological functions has become the major trend of the current tree simulation.Cunninghamia lanceolata as an unique timber species in China plays an important role inthe national economy. In this study, based on the Cunninghamia lanceolata, we achieved thequantitative simulation of the growth by selecting the environmental factors which have a greatimpact on tree growth as the driving variable and built the physiological and ecological modelwith the photosynthesis production and allocation of the roots, trunk, branches and leaves. Byanalyzing the relationship between model and physiological and ecological model, the processof production and allocation of the biomass with different environment factors was achieved,and the morphological structure was depended on the biomass allocation. With the analyzedrelationship between environment factors and morphological structure, it simplified theresearch of tree three-dimensional visual simulation, and provided a new method for theresearch of impact of the environment on tree growth. Main contents and results are listed asfollows:(1) The physiological and ecological model was developed by analyzing photosynthesis,respiration, biomass production and allocation, water balance, environmental response. Basedon the model, the biomass changed with different environments. It provided a basis forquantitative growth of Cunninghamia lanceolata. (2) The morphological structure of Cunninghamia lanceolata was analyzed based on thetheory of plant architecture. Results indicated that the bifurcation ratios increased with the age;the branching angles of primary branches and secondary branches obeyd to normal distribution,and they mainly disributed from50°to80°and50°to100°, respectively; the azimuth ofprimary branches also obeyed to normal distribution, whereas the secondary branches mostlydistributed in horizontal direction.(3) Morphological structure model was established by iterative function system(IFS)based on the characteristics of morphological structure of Cunninghamia lanceolata.According to the growth space of crown, tree's crown shape function taking Height(H), Heightunder branch(Hb), Crown width(Cr) and Height of crown(Hc) as independent variables was alsoestablished by power function. The independent vairbles values were calculated with growthcurves. Using the tree crown shapes in different years through IFS method, we achieved thesimulation of the dynamic growth and established its control module. The above method couldbe used to analyze the common tree crown and provided a method to simulate themorphological of other species.(4) The relationship between the biomass and structure was also established based on thebiomass of different components and the morphological structure model. Shape parameters ofthe trunk were abtained based on establishing the relationship between tree volume andbiomass with trunk allometry equation. Based on the survay data, the branche changes werealso analyzed, including the number of branch round, branch location and number of deaths peryear. Branch biomass and crown shape were applied in determining the branches. Leaf amountwere obtained by the function of leaf areas and the leaf biomass, and distribution of leaves wasalso discussed.(5) The3D visual simulation system of morphological structure and growth ofCunninghamia lanceolata was developed with computer programming languages andcomputer graphics based on the above theory and method. The visual results with differentmorphological structure parameters and environment were displayed using the system.The application of visual simulation technology of trees provides a intuitionistic platformand a convenient tool for forest informationization development, and havs a wide range of practical value. It promotes the forest management and scientific research for making theforestry science research and production practice from the time-consuming observation transferto convenient, direct, lifelike environment of3D visualization. The previous researches on thesimulation of the trees emphasized the vision and ignored tree characteristics, and had somelimitations in practical applications, which lacked theoretical support. In this study, we buildedthe mechanism of Cunninghamia lanceolata responsed to environment, and showed the resultsby visualization. In the future, we need to improve the physiological and ecology model,account for the interactive feedback between the internal growth mechanism and environment,strengthen the combination of the theory and practice, optimize the parameters of the modeland test the reliability of the model.