Opposing effects of warming and increased precipitation on site productivity of planted larch (Larix spp.) forests in Northeast China

Climate conditions exhibit significantly greater susceptibility to change compared to relatively stable soil and topographic factors, underscoring the critical need to quantify the impacts of climate change on forest site productivity. This study aimed to develop a climate-sensitive dominant height/site index model using data from 389 larch plantation plots located in northeast China. The Mitscherlich and Schumacher equations were selected as the base models to describe dominant height growth as a function of stand age. The results indicated that the Mitscherlich-based site index models performed significantly better than those derived from the Schumacher equation. Among the 13 climatic variables examined, degree days above 5°C (DD5) and mean annual precipitation (MAP) were identified as the most influential factors affecting dominant height growth. Model simulations revealed significant reductions in site index across different climate change scenarios, namely 0.35 m under RCP2.6, 0.45 m under RCP4.5, and 0.82 m under RCP8.5 at a reference age of 30 years. These declines correspond to an estimated reduction in carbon sequestration capacity by approximately 1.30–3.12 Mg CO 2 per hectare. Sensitivity analysis further revealed that site index values decreased significantly with increasing DD5 but increased with higher MAP. The models developed in this study offer a valuable insight for updating stand growth and yield tables under changing climatic conditions, suggesting that a moderate increase in stand density can help maintain higher stand productivity for larch plantations in the future.