Study on the Growth Characteristics of Cunninghamia unica Artificial Forest in Southwest China and Its Relationship with Environmental Factors

To scientifically manage and operate the plantation of Cunninghamia unica, this study focused on its artificial forest in Jiangxijie Township, Huidong County, Liangshan Yi Autonomous Prefecture. Standard plot surveys, stem analysis, and local meteorological data were integrated to investigate the relationship between key environmental factors and the growth characteristics of Cunninghamia unica. The results demonstrated that a 36-year-old plantation exhibited total growth increments of 22.65 cm in diameter at breast height (DBH), 15.2 m in height, and 0.2828 m³ in volume. The DBH experienced rapid growth during years 1-6, peaking at year 6, and entered the maturation stage after year 9. The average height growth rate reached its maximum between years 6 and 12, while the annual increment peaked at year 9, suggesting tending and thinning should be implemented during years 9-12. The annual volume increment curve intersected with the average increment curve at year 36, indicating the optimal harvest age.Correlation analysis with environmental factors revealed that moisture was the dominant driver for DBH and height growth but inversely affected volume accumulation. High temperature and radiation promoted volume accumulation while suppressing both radial (DBH) and vertical (height) growth. During the fast-growing stage, management should prioritize water regulation and shading measures to mitigate growth inhibition caused by high temperatures and excessive evaporation. In the maturation stage, thinning practices should be intensified to enhance light penetration and soil temperature, thereby amplifying the thermal benefits for volume accumulation. These findings provide actionable strategies for balancing environmental constraints and growth optimization in Cunninghamia unica plantation management.