Abstract:

The study aims to explore the effects of different thicknesses of garden waste branches and leaves on the composition and diversity of soil bacterial communities, and to provide a scientific basis for the resource utilization of urban garden waste and soil ecological management. A controlled experimental design was adopted, with bare soil without garden waste branches and leaves as the control group (S), and four treatment groups with different coverage thicknesses were set up, including 3 cm (A), 5 cm (B), 10 cm (C) and 15 cm (D). High-throughput sequencing technology was used to sequence and analyze the bacterial communities in soil samples from different treatment groups, comparing the differences in bacterial structure, basic functions, and composition distribution among the groups. The results showed that compared with the control group (S), the soil pH value, organic matter content, total nitrogen, available potassium and available phosphorus content increased in all four treatment groups (A to D), indicating that branch and leaf coverage had a significant impact on soil physicochemical properties. With increasing coverage thickness, the number of bacterial species classifications and sequence counts showed an overall increasing trend, demonstrating relatively rich bacterial diversity. Across all treatment levels, the Shannon index increased over time, while the Simpson index initially increased and then decreased. The gene abundance of various bacterial phyla in all treatment groups was higher than that in the control group. Significant differences were observed in both the quantity of bacterial species and the composition of dominant species under different coverage thicknesses. The treatment group with 10 cm coverage (C) showed the highest Shannon and Simpson indices, with the most stable dominant species in the soil bacterial community. At 15 cm coverage (D), the gene abundance of all bacterial phyla reached maximum levels, exceeding 2.0×10⁵. In the control group (S), Pseudomonas was the dominant genus, while in groups with thicker coverage (B, C and D), bacteria such as Streptomyces and Rhizobium gradually became dominant. The study demonstrates that moderate garden waste coverage (5-10 cm) effectively promotes soil bacterial community richness and diversity, whereas excessive coverage may adversely affect bacterial survival.

Key words: gardens, abandoned branches and leaves, coverage thickness, soil bacterial community, physical and chemical properties