Monoculture plantations of Eucalyptus in China have raised ecological concerns due to water depletion, soil degradation, and fire risk. Integrating Eucalyptus with Cupressus offers a sustainable approach to improving forest ecosystem health. In this study, we established five forest treatments, pure Eucalyptus (1:0), mixed Eucalyptus–Cupressus at three ratios (2:1, 1:1, and 1:2), and pure Cupressus (0:1), to assess their effects on soil properties, microbial diversity, and metabolomic profiles. Laboratory analyses revealed significant differences in physicochemical soil properties (such as water content (p < 0.05), pH (p < 0.001), organic carbon (p < 0.001), and nitrogen (p < 0.001)) among various groups within the mixed forests. Microbial community investigations highlighted a unique microbial signature in Eucalyptus–Cupressus mixed forests, especially when the tree ratio was 1:2, characterized by a rich (Chao1, p < 0.05) and diverse (Shannon, p < 0.05) array of bacterial taxa. The mixed Eucalyptus–Cupressus forest also exhibited an uplift in microbial communities, bacterial genera such as RB41, and fungal genera including Penicillium, Talaromyces, and Mortierella, which are associated with enhanced organic matter decomposition and nutrient cycling. Interactive networks within microbial communities were revealed through co-occurrence and Spearman correlation analyses, highlighting potential symbiotic relationships and ecological complexities. Metabolomic analysis, coupled with pathway analysis, further illuminated metabolic shifts in the mixed forests, emphasizing alterations in key metabolic pathways such as phenylpropanoid biosynthesis, tyrosine metabolism, arachidonic acid metabolism, and isoquinoline alkaloid biosynthesis. Collectively, these results show that moderately mixed Eucalyptus–Cupressus forests improve soil fertility and microbial multifunctionality, providing a practical model for sustainable and resilient forest management in subtropical regions.

The water-level-fluctuation zone of a reservoir is an important connection between land and water; due to counter-seasonal rhythmic water level changes, this area is more sensitive and vulnerable, whereas the assessment and management of heavy metal pollution are still elusive. This study selected the water-level-fluctuation zone in the hinterland of the Three Gorges Reservoir. Through a quadrats investigation, the soil pollution status of seven heavy metals and the composition of herbaceous plants were identified, and the potential of the dominant species for phytoremediation was assessed. The results showed that the overall pollution was at the alert level (P_N = 0.97) and a low ecological risk level (RI = 123.12). And the study area was primarily contaminated by a mixed source of traffic, agriculture, and industry. A total of 17 dominant species were calculated using importance values. Most dominant species had better phytoremediation potential for Cd and Cu. None of the 17 dominant species were hyperaccumulators, but they could still play an important role in phytoremediation due to their high adaptability to specific environments. The results have guiding significance for the management and remediation of soil heavy metal pollution in global reservoir areas, further promoting global ecological security and sustainable development.