Objective Based on simulated annealing algorithm, a multi-objective forest management method considering the health status of stand structure and average diameter of stand was studied. The individual tree growth equation was used to realize the dynamic visualization of the stand management based on the Unity3D visualization engine.

Method Based on 2012-2017 survey data of 5 Chinese fir (Cunninghamia lanceolata) sample stands located in Huangfengqiao State-owned Forest Farm of You County, Hunan Province, considering the distribution status, competition degree and nutrient space of the stand, the spatial structure function was established by three structural parameters: average angular scale, average size ratio and forest congestion degree. On the basis of spatial structure function, taking the healthy forest structure and the average diameter as management objectives, taking the results of a combinatorial permutation of thinned trees as the set of management planning with competition index as reference, the simulated annealing algorithm was used to select the optimal thinning mangement planning. Finally, by establishing a individual trees growth equation considering the variable growth rate of Hegyi competition index, the structural analysis-management-growth method was continuously iterated and the dynamic visualization of the forest management based on Unity3D rendering engine was realized.

Result The dynamic visualization of the management dynamics was carried out on the plot 5 (initial stand of 230 trees, 16-years-old, average diameter 20.21 cm) with the healthy stand structure and average diameter of 30 cm as target. The stand was simulated thinned in the 21st, 26th, and 31st years. When the forest was 31 years old (after thinning), the average diameter reached 30.10 cm, the average angular scale of the forest was 0.65, and the forest congestion was 0.74, which showed a health level.

Conclusion The dynamic visual simulation method of forest multi-objective management based on simulated annealing algorithm proposed in this paper can simulate forest dynamics and meet the multi-objective management demand. The image is intuitive, and can support research and production.