Abstract
<title>Abstract</title> <p>Purpose Wetland soils are critical hotspots for biogeochemical cycling mediated by microbial extracellular enzymes, yet they are severely affected by ongoing wetland degradation. However, the patterns of extracellular enzyme activities, the associated microbial metabolic limitation, and their key drivers along wetland degradation gradients remain unclear. Methods We quantified extracellular enzyme activities associated with carbon (C), nitrogen (N), and phosphorus (P) acquisition, together with plant community attributes and environmental variables, across a wetland degradation gradient in the lower Yellow River wetlands, China, to investigate the response of microbial metabolism to habitat degradation. Results Wetland degradation significantly decreased the activities of C-, N-, and P-acquiring enzymes, and increased enzymatic C:N and C:P ratios. The enzymatic stoichiometry modeling further revealed a coupled C and P limitation for microbial metabolism in degraded wetlands, which intensified along the degradation gradient. These changes were primarily driven by plant community characteristics (e.g., plant density), soil environment (pH and electrical conductivity), and nutrient availability. Structural equation modeling showed that wetland degradation resulted in C and P limitation primarily via altering soil electrical conductivity and nutrient availability. Conclusion Our results suggest that degradation-induced changes in plant community and soil factors jointly drive C and P co‑limitation of microbial metabolism in wetland ecosystems. This understanding highlights the importance of integrating plant–soil interactions and their effects on microbial functions and ecosystem processes in the restoration and management of degraded wetlands.</p>