A Simulated Comparisons of Thinning Effects Using SIBYLA Program

บทคัดย่อ

Thinning effects comparisons were undertaken based on two selective thinning options-thinning from below (TB) and thinning from above (TA)-and no thinning (NT). Growth and tree characteristics were investigated using the SIBYLA growth simulation program (originally designed for Czech forests) that was adapted to simulate the growth characteristics of tree species available in Thailand. Specifically, Carpinus viminea (Betulaceae) was chosen as a representative Thai species. The study investigated the effects of TB, TA, and NT on tree productivity (mean height, mean diameter, volume per stem, volume per hectare), biomass, and biodiversity. Pairwise comparisons and statistical analysis were applied. Based on the results, TB could increase the growth potential of trees after thinning more than TA and NT. Although there were similar results for TB and TA in each period, the TB data were slightly higher. However, TA and TB were not significantly different in productivity yields (p>0.05). Therefore, both TA and TB would be effective in increase production yields.

Based on the study, selective thinning model of growth using the SIBYLA program substantially reduced the computational and practical workload. This opens possibilities for further exploration of thinning algorithms and their integration into the SIBYLA program, for application in forestry simulations or the management of Thailand’s diverse plantation forests.