Impacts of Human Recreational Disturbances on Soil Bacterial Community Composition and Diversity in Urban Forest in Changchun, Northeast China

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.