Distribution of Tree Height and DBH of Four Coniferous Mixed Near-mature Forests

In 2022, a study was conducted on the mixed near-mature coniferous forests of four coniferous tree species (Chamaecyparis formosensis, Calocedrus macrolepis, Cunninghamia lanceolata, and Fokienia hodginsii) in the Yangkou Forestry Farm in Fujian Province.The study used the plot method to investigate tree height and diameter at breast height (DBH).Eleven representative and biologically significant curve models were selected to fit the DBH-tree height relationship in coniferous forests.The reliability of the models was tested using the T-test.The results showed that all eleven models achieved a certain degree of fitting.The S-function model was found to be the best fit, based on the determination coefficient (R²) and fitting accuracy, and could be used to estimate tree height in coniferous forests using DBH.The optimal model formulas for each species were as follows:C.formosensis H=exp(2.951-8.097/D)(R²=0.583), C.macrolepis H=exp(2.954-7.993/D)(R²=0.627), F.hodginsii H=exp(3.108-7.231/D)(R²=0.756), and C.lanceolata H=exp(3.337-13.497/D)(R²=0.632).The results of this study can provide a reference for predicting the growth patterns and timber accumulation of coniferous forests in the region, as well as the formulation of conservation measures and rational development strategies for the populations of C.formosensis, C.macrolepis, C.lanceolata, and F.hodginsii.