Understanding the characteristics of urban plant multidimensional diversity and urban green spaces (UGSs) landscape patterns is the central theme of urban ecology, providing theoretical support for UGSs management and biodiversity conservation. Taking Changchun, a provincial city, as an example, a total of 240 plots were surveyed using the stratified random sampling method. We studied the effects of the urban park construction period on plant multidimensional diversities, landscape patterns of green spaces, and their associations in Changchun City, Northeast China. The results indicated that total woody species and tree species diversity attributes were both the highest in the construction period of 2001–2020 and lowest in the construction period before 1940. However, shrub species diversity attributes were completely the opposite. Diameter at the breast height (DBH) diversity index (H_d) was the highest in the construction period before 1940 and lowest in the construction period of 2001–2020. However, the height diversity index (H_h) showed the opposite trend. Phylogenetic structures of total woody species and tree species showed divergent patterns in parks constructed before 1940 and 1940–2000 period, while that in 2001–2020 period could not be determined. In contrast, the phylogenetic structure of the shrub species clustered across all construction periods. Landscape pattern metrics varied significantly among different construction periods. Total Area (TA) was the highest in the construction period of 2001–2020. The structural equation model (SEM) revealed that construction periods exerted significant direct effects on both multidimensional diversities and landscape patterns of green spaces. Specifically, construction periods indirectly affected tree species diversity through structural diversity and influenced shrub species’ phylogenetic diversity through shrub species diversity. What is more, Patch Density (PD), Edge Density (ED), and Aggregation Index (AI) correlated with H_h, which had a direct effect on the Shannon–Wiener diversity index of tree species (H′_t). Overall, the results indicated that species diversity can be enhanced through regulating landscape patterns, rationally selecting tree species, and optimizing plant configuration. These above results can provide scientific references for the configuration of plant communities and selection of tree species in urban parks, and offer important guidance for urban biodiversity conservation and enhancement.

Urban parks, as vital components of urban green infrastructure, can improve urban ecological environments, showcase urban culture, and offer spaces for human recreation and exercise. However, human activities in these parks also produce severe disruption to soil ecosystems. Studying the effects of recreational disturbances on soil properties and microbial communities is crucial for conserving urban biodiversity and maintaining ecosystem services. This study investigated the effects of human recreational disturbances (HRDs) on soil physicochemical properties and bacterial communities in four forest stands (Phellodendron amurense Rupr (Phe amu), Salix matsudana Koidz. (Sal mat), Pinus tabuliformis var. mukdensis (Pin tab), and Picea asperata Mast. (Pie asp)) in Changchun’s South Lake Park. The results showed that HRD significantly reduced soil water content (SWC) and total phosphorus (TP) while increasing soil bulk density (SBD) and pH. Soil organic carbon (SOC) and total nitrogen (TN) increased in Phe amu and Pie asp soils but decreased in Sal mat and Pin tab soils (p < 0.05). Electrical conductivity (EC) changes were inversely related to SOC and TN trends. Dominant bacterial phyla included Actinobacteriota, Proteobacteria, Acidobacteriota, and Chloroflexi. HRD reduced bacterial species richness and diversity by 5.3% and 7.6%, respectively. SWC and SBD were key factors influencing bacterial community dynamics, with SBD affecting Bacteroidota, Proteobacteria, and Myxococcota, and SWC impacting Proteobacteria, Bacteroidota, and Actinobacteriota. These findings provide insights for urban park management, supporting soil microbial diversity and sustainable urban ecosystem development.

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.