Effects of vegetation succession on soil microbial stoichiometry in Phyllstachys edulis stands following abandonment

Moso bamboo (Phyllostachys edulis) is China's most important economic bamboo species. With a continuous decline in the value of its shoots and timber and an increase in affiliated labor and production costs, many of these stands have been abandoned, resulting in the occurrence of vegetation succession. Currently, our understanding on changes in soil microbial stoichiometric and entropic effects and associated imbalances following stand abandonment is limited. Accordingly, this study explores three timescales of Ph. edulis stand abandonment (i.e., 0, 9, and 21 years) to investigate soil-microbial carbon (C), nitrogen (N), and phosphorus (P) dynamics within a 30 cm soil profile. Results showed that (1) following abandonment, vegetation succession significantly influenced soil carbon (Csoil), nitrogen (Nsoil), and phosphorus (Psoil), microbial biomass (Cmic), nitrogen (Nmic), and phosphorus (Pmic), and Csoil:Nsoil:Psoil and Cmic:Nmic:Pmic ratios. Additionally, Csoil, Nsoil, Psoil, Cmic, Nmic, Pmic all increased significantly over time following abandonment. Moreover, Csoil:Nsoil, Cmic:Pmic, and Nmic:Pmic ratios clearly increased while Csoil:Psoil, Nsoil:Psoil, and Cmic:Nmic ratios all significantly decreased. (2) Soil microbial entropy nitrogen (qMBN) and soil microbial imbalances in Cimb:Nimb increased while soil microbial entropy carbon (qMBC), soil microbial entropy phosphorus (qMBP), and soil microbial imbalances in Cimb:Pimb and Nimb:Pimb decreased over time following abandonment. (3) Redundancy analysis (RDA) indicated that Csoil:Nsoil and Cmic:Pmic ratios were key influencing factors of microbial quotient (qMB), explaining 55.35 % and 24.39 % of variation, respectively. Following abandonment, positive or negative successional impacts on Csoil:Nsoil:Psoil, microbial C, N, P stoichiometric imbalances (Cimb:Nimb:Pimb), and Csoil:Nsoil:Psoil ratios had a positive effect on qMB. Collectively, these findings highlight the importance of Csoil:Nsoil:Psoil and Cimb:Nimb:Pimb ratios in regulating qMB induced by vegetation succession following Ph. edulis abandonment, and provide valuable information for vegetation restoration and establishment of bamboo mixed forest.