Abstract
Masson pine (Pinus massoniana Lamb.) and Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) are important coniferous species commonly found in southern China and play crucial ecological and economic roles. Understanding how regionally variable conditions influence their growth patterns can support effective forest management strategies and conservation efforts. Here, we used the Richards growth equation to comprehensively analyze their volumetric growth processes through multiple diverse regions in southern China, representing a pioneering large-scale application of unified modeling techniques. This work provides theoretical and technical knowledge to support the sustainable stewardship of these vital forest ecosystems. We found that: (1) The highest per-hectare volume accumulation occurs in southwestern China, at 97.455 m(3) hm(-2) for P. massoniana and 85.288 m(3) hm(-2) for C. lanceolata. These values are higher than in the southeastern (71.424 m(3) hm(-2) and 79.520 m(3) hm(-2), respectively) or south-central regions (70.697 m(3) hm(-2) and 65.647 m(3) hm(-2)), predominantly due to varying stand maturity across these regions. (2) Both species exhibit age-dependent growth patterns in the first 100 years of forest development, characterized by rapid early growth and transitioning into slower, stable phases. The highest total volume growth for P. massoniana occurred in the southwest, followed by the southeast and south-central regions. Conversely, C. lanceolata growth is highest in the southeast, followed by south-central and the southwest. (3) Quantitative maturity for P. massoniana ranges from 27 to 29 years (average: 30 years) whereas C. lanceolata matures earlier, between 16 to 19 years (average: 20 years). Climate and soil factors significantly influence their growth dynamics, with precipitation, temperature variation, and soil characteristics driving differences in suitability and growth potential across distinct regions in southern China. Tailored management practices that align with local climatic and environmental conditions are recommended to optimize growth and ensure sustainable management and development of P. massoniana and C. lanceolata forests.