Urban parks are key to urban ecosystems, where soil microbe-plant-soil interactions sustain ecosystem services. Using high-throughput sequencing and multivariate statistics, this study explored how plant species diversity affects soil microbial community structure, functional diversity, and environmental drivers. Results showed that fungal and bacterial OTUs differed across plant diversity gradients, with Ascomycota (fungi) and Actinobacteriota/Proteobacteria (bacteria) dominant. Soil organic carbon (SOC) was positively correlated with Verrucomicrobia, while Acidobacteriota increased with lower SOC. Fungi were more sensitive to pH than bacteria. Partial Least Squares Path Modeling (PLS-PM) indicated that plant diversity was significantly positively associated with fungal community structure and was indirectly associated with bacterial diversity via soil factors (e.g., SOC, pH), with fungal community variation more explained than bacterial. Higher plant diversity was associated with elevated SOC and a higher relative abundance of putative nutrient-cycling taxa (e.g., Rhizobium), suggesting a potential enhancement of soil nutrient cycling capacity. This study demonstrates that plant diversity shapes microbial communities directly and via soil properties, highlighting synergistic effects. We propose arbor-shrub-herb composite vegetation in urban forest management to optimize microbial habitats and ecological services.

Continuous paddy reclamation is a promising strategy for restoring sodic lands, yet the exact mechanisms driving soil organic carbon (SOC) stabilization remain insufficiently quantified. Here, we investigated SOC dynamics across a 12-year rice cultivation chronosequence (0, 2, 5, 10, and 12 years) at 0–20 cm and 20–40 cm depths in western Jilin Province, China. Successive rice cultivation progressively alleviated saline–alkaline stress, with electrical conductivity (EC) decreasing by 70.11% in topsoil after 12 years, establishing a stabilized soil environment by years 10–12. Concurrently, topsoil SOC and total nitrogen (TN) increased by 63.09% and 26.02%, respectively. This physicochemical amelioration triggered a directional carbon transformation: while particulate organic carbon (POC) accumulated in early stages, mineral-associated organic carbon (MAOC) dominated medium-term storage, expanding by 147.12% in topsoil and elevating its share of SOC. Fourier transform infrared (FTIR) spectroscopy confirmed a shift toward molecular structural persistence, marked by increased aromaticity and hydrophobicity. Partial least squares path modeling (PLS-PM) demonstrated that cultivation duration directly drove soil stability (β = 0.94, p < 0.001), operating through a hierarchical cascade where management-induced stress reduction enhanced soil enzyme activity and microbial processing, thereby accelerating the conversion of labile plant inputs into mineral-protected MAOC. Overall, this study quantifies the pivotal role of paddy management in driving organo-mineral protection and chemical persistence, providing a mechanistic framework for carbon sequestration in degraded agroecosystems.

Saline–alkali soils are important reserve resources for agricultural production. In western Jilin Province, China, large areas of saline–alkali land have been reclaimed as paddy fields; however, their carbon cycling responses to long-term rice cultivation and warming remain unclear. Using a space-for-time chronosequence approach, a laboratory incubation experiment was conducted at 15 °C and 25 °C using soils collected from two soil layers (0–20 and 20–40 cm) in fields with 2, 5, 10, and 12 years of rice cultivation, together with an uncultivated reference field (CK). The results showed that cumulative potential soil carbon dioxide (CO₂) production was generally higher in cultivated soils than in CK, peaking at 5 years under 15 °C and at 10 years under 25 °C. It subsequently declined in the 10- and 12-year treatments at 15 °C and decreased slightly at 12 years at 25 °C. Soils with longer rice cultivation histories generally exhibited relatively high apparent temperature sensitivity (Q₁₀) at several stages of incubation, particularly in the 0–20 cm soil layer. Hydrolytic enzyme activities generally increased along the rice cultivation chronosequence, whereas polyphenol oxidase activity showed an overall declining trend, reflecting differences in potential enzymatic capacity for carbon transformation among cultivation duration treatments. Bacterial and fungal alpha diversity was generally higher in cultivated soils, particularly from the 5-year stage onward, and they also differed significantly among rice cultivation duration groups in both soil layers, although the fungal pattern in the 20–40 cm layer was partly influenced by heterogeneous within-group dispersion. Partial least squares path modeling showed that enzyme activity was strongly associated with cumulative potential soil CO₂ production at 25 °C and Q₁₀. These findings indicate that potential SOC mineralization across the rice cultivation chronosequence showed clear temperature-dependent patterns. This study provides insights into carbon cycling and its temperature response in reclaimed saline–alkali paddy soils and may inform their sustainable management under changing temperature conditions.