Dynamic Interactions of Stand Characteristics and Site on Quercus spp. Volume in China Under Climate Change

The impacts of global warming on species’ habitat suitability and consequent potential range shifts have attracted increasing scholarly attention. As keystone species in China’s climax communities, Quercus spp. are widely distributed across the country and play vital roles in ecological conservation, economic development, and recreational services. Current research primarily focuses on variations in biomass at regional/watershed scales or employs distribution modeling to predict population responses to climate change. This study investigates nationwide trends in stand volume of Quercus spp. across three elevation gradients, analyzing the impacts of forest age, origin, and temporal dynamics by integrating historical National Forest Inventory (NFI) datasets with meteorological records spanning 1948–2021. Our findings demonstrate a persistent warming trend throughout China from 1948 to 2021, exhibiting significant seasonal divergence in temperature variability patterns. The stand volume of Quercus spp. showed non-significant elevational variation (p > 0.05), but exhibited marked differences across temporal gradients and origins. Notably, natural forests demonstrated higher stand volume than plantations (p < 0.01). Moreover, significant interactive effects were observed among elevation, origin, and forest age (p < 0.05), particularly for natural Quercus spp. Their stand volume exhibited distinct age-dependent trajectories: (1) high-elevation stands (>3000 m) displayed a “decline-recovery” fluctuation during 41–80 years, (2) mid-elevation stands (500–3000 m) maintained steady increases, and (3) low-elevation stands (<500 m) followed parabolic patterns peaking at 61–80 years. Our work further validates differential migration patterns of Quercus spp. under global warming, providing novel mechanistic insights into their climate-responsive dynamics.