Abstract
Comprehending the role of stand density in soil properties and microbial communities is crucial for optimizing forest ecosystem functions. However, the relationship between them and how they respond to key environmental drivers at different planting densities remains unclear. In this study, we investigated the growth indices, soil properties, as well as soil microbial community composition and diversity of two Xanthoceras sorbifolium provenances (YC and KL) under three planting densities (low, medium, and high). Results indicated: (1) soil nutrient levels decreased with increasing stand density, while microbial community diversity was highest at medium density, followed by low and high density. Low planting density was more favorable for X. sorbifolium growth. (2) Microbial co-occurrence network stability was highest under medium and low densities. The assembly of bacterial communities was primarily governed by deterministic processes, whereas fungal community assembly was predominantly stochastic. (3) Soil total phosphorus (TP) and available potassium (AK) were the main drivers affecting microbial communities and their structures. (4) Compared with high-density soil, there were more abundant functional communities of bacteria and fungi in low- and medium-density soils, showing better adaptability to environmental changes and disturbances. These results will provide a scientific basis for the management optimization of X. sorbifolium plantations and are of great significance for the sustainable development of forest ecosystems.