Constraining Mechanism of Lithological Differences in Ground Substrates on Vegetation Coverage in the Yanshan Mountain of Northern China

Abstract: Heterogeneity of ground substrates is a key controlling factor for vegetation differentiation in mountainous regions. However, the cascading regulatory mechanism involving lithological differences, substrate structure, water retention, and vegetation response remains unclear. This study focuses on three typical ground substrate areas in the Yanshan Mountains of northern China—granite, gneiss, and dolomite regions—located within the ecological barrier zone of the Beijing–Tianjin–Hebei region. By integrating multi‑source data from field trenching, shallow well excavation, in‑situ electrical detection, vegetation quadrat surveys, and remote sensing inversion, the regulatory mechanism of lithological differences on vegetation coverage was revealed. The results indicate that: (1) The development of bedrock fractures and the appropriate grain size composition of the substrate directly affect the water‑holding capacity of the ground substrate, influencing root distribution and plant water‑use strategies, thereby controlling the spatial distribution characteristics of vegetation. (2) Bedrock fracture density shows a significant positive correlation with vegetation coverage (r2= 0.79), with the order being granite > gneiss > dolomite. Ground substrate moisture content is positively correlated with the proportion of silt‑clay particles ( gneiss > granite. (3) The thickness of the bedrock weathering layer (granite > gneiss > dolomite) and fracture density jointly control vegetation root distribution, providing a scientific basis for differentiated vegetation restoration strategies based on lithological characteristics in mountainous regions of northern China.Keywords: lithological differences; vegetation type; vegetation coverage; constraining mechanism; Yanshan MountainFunding: This study was supported by the National Natural Science Foundation of China (Grant No. U2344227)