Urban forest soil is often disturbed by frequent human activity. Organic mulching is effective for improving soil quality; however, the effects of organic mulching on soil bacterial communities in urban forests are still largely unexplored. This study evaluated how organic mulching changed the urban forest soil bacterial community through an incubation experiment. Four treatments were applied: (1) no organic mulch (CK); (2) wood chips alone (5 g, Mw); (3) wood compost alone (5 g, Mc); and (4) wood chips + wood compost (This mulch was divided into two layers, i.e., the upper layer of wood chips (2.5 g) and the lower layer wood compost (2.5 g, Mw+c).) We found significant differences in the soil physicochemical properties under organic mulching after incubation. Overall, organic mulching can alter soil bacterial community structure. Soil alkali-hydrolyzable nitrogen, soil organic carbon, soil total nitrogen, and carbon-nitrogen ratio were the main factors affecting soil microbial community structures. Soil bacterial groups under organic mulching treatments mainly acted on the C and N cycling of functional pathways in soil. This study suggests that organic mulching could maintain the development of soil bacteria, which establishes a theoretical foundation for enhancing the microbiological environment of urban forest soils.

Understanding how different land-use types shape soil bacterial communities and functions is critical for promoting sustainable land management and ecological restoration in fragile karst regions. This study evaluated the effects of different land-use types (pitaya [HF], maize [MF], sugarcane [SF], and paddy [PF] fields, forestland [FL], and grassland [AF]) on soil bacterial diversity, community composition, functional potentials, and co-occurrence networks in karst regions. The results showed that HF, MF, and PF exhibited the highest bacterial diversity (Shannon index), whereas SF had the lowest possibly because of continuous cropping and fertilization. Variance partitioning analysis revealed that soil bacterial community composition and functional potential were largely explained by the combined effects of land-use type and soil properties (34.8% for composition and 59.7% for functional potential), suggesting that land-use effects on bacterial communities are mainly mediated through changes in soil physicochemical properties. Hierarchical partitioning analysis further identified that soil texture, particularly silt and sand, and pH were the primary factors shaping bacterial community composition, whereas pH was the dominant driver of functional potential. Functional analysis indicated that HF enhanced nitrogen cycling processes, such as nitrification, aerobic nitrite oxidation, and aerobic ammonia oxidation; SF promoted carbon-related functions, including chemoheterotrophy, aerobic chemoheterotrophy, and cellulolysis; and PF favored iron and sulfur respiration. Co-occurrence network analysis demonstrated that HF had the most complex microbial interactions, likely attributable to no-tillage practices and favorable soil conditions, whereas PF showed the lowest network connectivity. Core bacterial groups such as Acidobacteria, Proteobacteria, Chloroflexi, and Actinobacteria, dominated in abundance but also functioned as keystone taxa, suggesting their critical roles in driving nutrient cycling and maintaining ecological stability. These findings suggest that no-till pitaya cultivation may help improve soil microbial diversity, functional potential, and ecological stability in fragile karst ecosystems, indicating its potential as a sustainable agricultural land-use practice. However, long-term monitoring and adaptive management are necessary to ensure sustained soil health.

The order of affiliations 1 and 2 in the original published version of the above article was incorrect. The affiliations of the first author, Dan Chen, should include "Guangxi Key