How Does the Mulching Management of Phyllostachys Praecox Affect Soil Enzyme Activity and Microbial Nutrient Limitation in Karst Bamboo Forest Ecosystems?

Phyllostachys praecox is a valuable tree species in karst ecosystems, but improper mulching practices can worsen soil degradation. Understanding soil nutrient limitations is crucial for successful restoration and sustainable development. However, it remains unclear whether and how mulching management of Phyllostachys praecox affects soil enzyme stoichiometry and nutrient limitation in karst areas. Here, we conducted a field experiment in Chongqing karst bamboo forest ecosystems with four mulching treatments: 1-year (T1), 2-years (T2), 1-year and recovery and 1-year (T3), and no mulching (CK). We investigated the activities of the C-acquiring enzyme β-1,4-glucosidase (BG), N-acquiring enzymes L-leucine aminopeptidase (LAP) and β-1,4-N-acetylglucosaminidase (BNA), as well as P-acquiring enzyme phosphatase activity (AP), to assess the limitations of C, N or P and identify the main factors influencing soil microbial nutrient limitation. Compared with the CK treatment, both the T2 and T3 management treatments significantly increased the SOC, TN, MBC, and MBN. Furthermore, the soil enzyme stoichiometric ratio in the karst bamboo forests deviated from the global ecosystem ratio of 1:1:1. T1 > T3 > CK > T2 presented higher values of C/(C + N) and C/(C + P), with T1 having values that were 1.10 and 1.12 greater than those of T2, respectively. Additionally, there was a significant negative correlation between microbial C and N limitations and total nutrients, but a positive correlation with microbial biomass ratios. In conclusion, changes in mulching management of Phyllostachys praecox affect soil enzyme stoichiometry activities and their ratios by influencing total nutrients and microbial biomass ratios. This study suggests an alternate year cover pattern (mulching in one year and resting in the next) as a scientific management approach for bamboo forests, contributing to a better understanding of nutrient limitation mechanisms in karst bamboo forest ecosystems.