Contribution of Arbuscular Mycorrhizal Fungal Communities to Soil Carbon Accumulation during the Development of Cunninghamia lanceolata Plantations

Arbuscular mycorrhizal (AM) fungi can establish mutual association with most land plants, and impact a series of important ecological processes, including plant productivity, ecological succession and soil carbon (C) accumulation. Understanding the AM fungal diversity and community assembly, and their associated soil C sequestration, could be a crucial interest for the forest ecologist. In this study, the AM fungal abundances and community structure as well as glomalin-related soil protein (GRSP) concentrations were investigated in typical development stages (young, middle and mature) of Cunninghamia lanceolate plantations, which are widely distributed species in subtropical regions. The mycorrhizal colonization, spore density, AM fungal biomass and diversity were higher in mature than younger stands. The development of C. lanceolata also increased soil GRSP concentrations, and enhanced their C contribution to soil organic C. Soil difficulty extractable (DE) GRSP demonstrated a greater C contribution to soil organic C relative to easily extractable (EE) GRSP. Linkage analyses found that AM fungal biomass demonstrated a positive correlation with GRSP concentrations, and soil organic C positively related to DE-GRSP and total (T) GRSP. Soil AM fungal community structure differed dramatically across all studied C. lanceolata plantations with a decrease in Gigasporaceae and increase in Acaulosporaceae. Soil AM fungal community assembly was more phylogenetic clustering than expected by chance and primarily shaped by deterministic processes, with a non-shift during the development of C. lanceolata. Collectively, C. lanceolata development shaped the AM fungal communities and enhanced their biomass and GRSP contents, which might, in turn, partially contribute to soil C accumulation.