Abstract: Forest secondary succession closely relates with the dynamics of ecosystem structure and function. Previous studies have reported the changes of plant community and soil organic carbon (SOC) during forest succession, with limited understanding of the responses of soil microbial community. Here, we explored the changes of soil microbial community structure (represented by phospholipid fatty acid) across secondary forest succession (20, 80, 120, 200, and ≥300 years) and soil depth (topsoil and subsoil). We demonstrated that the changes in microbial community structure among forest successional stages were ascribed to the specific microbial functional groups. Soil microbial community was dominated by Gram-negative bacteria and saprotrophic fungi at earlysuccessional stages, and by Gram-positive bacteria and arbuscular mycorrhizal fungi at late-successional stages. Quantity and quality of soil organic matter (SOM) were the predominant factors driving soil microbial community structure and biomass. The increase in SOC contents at early and middle successional stages stimulated microbial biomass, and the increase in soil aromatic compounds suppressed microbial biomass at late-successional stages. Soil microbial community was affected by the varied soil physicochemical properties between topsoil and subsoil, e.g., high SOC content in topsoil correlated with microbial biomass. Our findings suggest that changed soil microbial community and its driving factors in temporal and spatial scales reflect the response of ecosystem structure and function to environmental change.

Key words: controlled release nitrogen fertilizer, double cropping paddy field;surface water, nitrogen, runoff loss, rainwater interception, extensive green roof, hot and humid region, Guangzhou.