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 (C), nitrogen (N), and phosphorus (P), microbial biomass (C), nitrogen (N), and phosphorus (P), and C:N:P and C:N:P ratios. Additionally, C, N, P, C, N, P all increased significantly over time following abandonment. Moreover, C:N, C:P, and N:P ratios clearly increased while C:P, N:P, and C:N ratios all significantly decreased. (2) Soil microbial entropy nitrogen (qMBN) and soil microbial imbalances in C:N increased while soil microbial entropy carbon (qMBC), soil microbial entropy phosphorus (qMBP), and soil microbial imbalances in C:P and N:P decreased over time following abandonment. (3) Redundancy analysis (RDA) indicated that C:N and C:P 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 C:N:P, microbial C, N, P stoichiometric imbalances (C:N:P), and C:N:P ratios had a positive effect on qMB. Collectively, these findings highlight the importance of C:N:P and C:N:P 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.