Growth Responses of Middle-aged Altingia excelsa Plantation to Slope Direction and Density

In order to understand the growth process of Altingia excelsa plantation, individual log scaling of 21-year-old A. excelsa plantation were conducted in 2021. Using diameter as the criterion for selecting standard trees, 1 tree was selected from each planting density in the southwest slope, while 3 trees were selected from each planting density in the south slope. Standard trees were chosen as analytical trees to analyze the differences in forest growth among different slope aspects and planting densities. The results showed that mean diameters at the breast height(DBHs), tree heights(THs) and volume of TCs consisted with different slope directions and planting densities for the 21-year-old stand trees were 17.60–20.78 cm, 25.73–28.51 m and 0.3186–0.4293 m³, respectively, and the trees were still in vigorous growth stage; there were significant differences of all above parameters between the TCs. The fast-growing periods of the DBH, TH and volume were presented in the ages for 1–9, 1–10 and 8–16 years old with the maximum current growth of which 2.19 cm/year, 2.74 m/year and 4.3966 × 10⁻² m³/year, respectively. Slope direction, density and their interaction significantly affected the growth of A. excelsa stand trees. A. excelsa belongs to tree species of the long-lived and large-diameter timber in the topical and south-subtropical area. Its fast-growing period lasts for a long time, and its growth is more sensitive to the site and density. It is should to select the most suitable site and planting density for establishing A. excelsa plantation with high-quality and high-efficiency, and dynamically regulate stand density on due time. Comprehensively, the initial planting density will ultimately affected the volume by affecting the growth of tree heights, and the south slope was selected to match 3 m × 2 m × 5 m uneven row spacing could achieved the maximum volume of individual tree, which suggested to be applied to site selection and density control of high-quality and efficient plantation establishment of A. excelsa in the production practice.