Abstract:In recent years, the phenomenon of the landscape degradation in the river basin has been more and more serious because of over ecotourism, and the forestry visualization technology provides important reference for ecosystem restoration and landscape optimization decision, therefore, it is necessary and practically significant to research the visual simulation of vegetation growth in the river basin. This paper presented the case of pterocarya stenoptera in aquatic-terrestrial ecotones in Lijiang River, and found that total nitrogen content of soil plays a critical role during its growth after analyzing the correlation between soil sample and growth data. Based on this finding, the modified Hegyi’s simple competition index model with added nitrogen factors was adopted to the single tree growth model for pterocarya stenoptera stands built in Lijiang River, then diameter distribution model and random algorithm were applied to whole stand model. In the process of simulation, the information of location and diameter at breast height distribution of pterocarya stenoptera in the plot was confirmed by the trees distribution model first; the next step, the height and the crown of each pterocarya stenoptera were simulated according to the fitting relationship between tree height and diameter at breast height, crowns with diameter at breast height and the diameter at breast height of each pterocarya stenoptera were measured, and then, the growth of pterocarya stenoptera was simulated by iterative execution of the growth model using the data got before; after that twodimensional simulation with different soil nitrogen contents was achieved by implementing C# programming language and GDI+ technology, and then the dot and the circle in twodimensional simulation would be mapped into specific pterocarya stenoptera model on 3D Max; finally the threedimensional visual simulation of the growth of pterocarya stenoptera in Virtools platform was achieved. The result showed that a significantly positively relationship existed between diameter at breast height growth and soil total nitrogen content of pterocarya stenoptera, and the correlation coefficient was 0.749; a significantly negative relationship exists between competition index and diameter at breast height growth, and the correlation coefficient improved from -0.621 to -0.657 with the competition index model improved; the error rates were 6.25% and 11.9% respectively when fitting the diameter distribution of pterocarya stenoptera in the simulation and the decision coefficient of diameter at breast height growth model reached 0734. It’s found that adopting modified Hegyi’s simple competition index model and random algorithm had strong applicability and higher fidelity for pterocarya stenoptera growth simulation in aquatic-terrestrial ecotone. The originality of this paper is to adopte modified Hegyi’s simple competition index model with added nitrogen factors, with the help of Virtools platform, to lay the foundation for further development of humancomputer interaction and real time walkthrough. In this article, it provides theoretical basis and reference for the vegetation restoration and succession simulation in Lijiang River watershed, and presents a feasible research idea and implementation method for the forestry visualization research by visualization simulation of pterocarya stenoptera growth in the Lijiang River watershed.
