Soil enzyme activity and its stoichiometry characteristics in peatlands with different nutrient types

Peatlands are important terrestrial carbon reservoirs, and their ecological functions are deeply influenced by nutrient sources and hydrological conditions. However, the characteristics of soil enzyme activity and its driving mechanisms between different types of peatlands are still unclear. We compared soil enzyme activity, enzyme chemical stoichiometric characteristics, and soil physicochemical properties between ombrotrophic and minerotrophic peatlands which differed in nutrient sources and moisture conditions, and further analyzed the main factors driving the differences. The results showed that, in comparison with minerotrophic peatland, ombrotrophic peatland exhibited significantly higher soil water content (SWC), total carbon (TC), total nitrogen, C/P, and N/P ratios, by 715.0%, 42.8%, 38.9%, 84.2%, and 83.2%, respectively. Conversely, soil pH, total phosphorus, and microbial biomass nitrogen (MBN) in ombrotrophic peatland were significantly lower than those in minerotrophic peatland by 25.9%, 25.0%, and 68.5%, respectively. Furthermore, the activities of acid phosphatase, β-1,4-glucosidase, β-1,4-N-acetylglucosaminidase, leucine aminopeptidase, and peroxidase in ombrotrophic peatland were all more than 1.2 times higher than those in minerotrophic peatland. However, phenol oxidase activity was significantly lower by 50%. Soil enzyme activity and stoichiometric ratios were significantly affected by SWC, pH, TC, C/P, N/P, MBN, and mineral-associated organic carbon. Both peatland types exhibited phosphorus limitation, which was more severe in ombrotrophic peatland. The study has yielded fundamental data on nutrient resource limitations in different nutritional types of peatlands and provided a scientific basis for maintaining the long-term stable deve-lopment of peatlands.