Effects of cultivation duration on soil organic carbon components, bacterial communities, metabolites and bamboo growth in the Phyllostachys edulis- Ganoderma lucidum agroforestry systems.

Agroforestry systems are a production mode in bamboo forest management that balance ecological and economic benefits. Soil carbon (C) pools form the most important and stable C sinks. However, there is limited information on soil C pool components, bacterial communities, metabolites and bamboo growth in agroforestry systems. Here, Phyllostachys edulis-Ganoderma lucidum agroforestry systems with cultivation durations of 1, 2, and 3 years were selected, and pure Moso bamboo forest as the control (CK). We examined the variation in soil organic C components, related enzyme activities, bacterial community structure and diversity, metabolites and bamboo aboveground biomass in response to different cultivation years of G. lucidum, and explored their interrelationships. The results showed that cultivation of G. lucidum significantly enhanced bamboo aboveground biomass by 30.2%-40.2%, and concurrently increased soil total organic carbon (SOC) and mineral-associated organic carbon (MOC) by 14.23%-34.73% and 27.13%-120.71%, respectively, along with the extension of cultivation duration. Cultivation of G. lucidum for more than 2 years enhanced soil catalase activity, bacterial community diversity and richness, and the relative abundances of Proteobacteria, Actinobacteriota, and Verrucomicrobiota. Six significantly upregulated differential metabolites were shared between different cultivation durations and belonged to the categories of amino acids and their derivatives, organic acids, and benzene and its derivatives. Structural equation modeling analysis revealed that cultivation durations exerted a direct positive impact on changes in the soil bacterial Actinobacteriota, Verrucomicrobiota, and indirect positive impact on MOC, thereby indirectly promoting bamboo aboveground biomass. In conclusion, agroforestry promotes soil C and bamboo productivity, providing a theoretical basis for enhancing bamboo biomass through the targeted regulation of soil bacterial and metabolite profiles, thus supporting the sustainable management of Moso bamboo forests.