Characteristics and Seasonal Variations of Soil Bacterial Diversity and Life Strategies in Natural Vegetation and Different Ecological Restoration Sites on a Sea Island

Abstract

Abstract While bacterial communities in ecologically restored soils have been extensively studied, the diversity and life strategies of those inhabiting soil environments formed by new restoration techniques like aggregate spray-seeding (ASS) remain unclear. To address this research gap, we compared the ASS restoration area (SRA) and AAS forest conversion area (FCA) with the natural vegetation area (NVA) and traditional afforestation area (TAA) on Triangle Island, China. Environmental DNA sequencing was employed to investigate diversity and life strategies of soil bacterial communities during summer and winter seasons. Results showed that (1) SRA and FCA exhibit significantly higher Chao1 index and relative abundance of r-strategy bacteria compared to NVA and TAA, accompanied lower DNA guanine-cytosine (GC) content. (2) The soil bacterial communities of NVA and TAA were similar, while those of SRA and FCA were also similar to each other. (3) Proteobacteria and Acidobacteriota were the dominant phyla in our studied soils, accounting for 67.83–76.54% of the total relative abundance. (4) The relative abundance of Proteobacteria was higher in summer, while that of Acidobacteriota was higher in winter. (5) GC content showed a negative correlation (p < 0.0001) with the relative abundance r-strategy bacteria and a positive correlation (p < 0.01) with the relative abundance K-strategy bacteria. In summary, our study demonstrates the impact of ASS application on soil bacterial community diversity and life strategy, while confirming the correlation between the bacterial GC content and life strategy. These findings provide a foundation for regulating soil microbial communities in ecological restoration projects.