Altitudinal variation of soil extracellular enzyme activity in a subtropical evergreen broad-leaved forest

Background Soil extracellular enzymes play pivotal roles in driving biogeochemical cycling within forest ecosystems, with altitude being a significant predictor for the response of ecosystem function to climate change. However, soil extracellular enzyme stoichiometry and its variations along altitudinal gradients in mountains are still not well-investigated. In this study, we analyzed the variations of soil extracellular enzyme activities (EEA) across six different altitudes (700 m, 800 m, 900 m, 1000 m, 1100 m, and 1200 m) within evergreen broadleaf forests in Wuyi Mountain, Fujian Province, China. Results Carbon (C)-acquiring (BG: beta-1,4-glucosidase) enzyme activities increased linearly with altitude, while phosphorus (P)-acquiring (AP: alkaline phosphatase) activity exhibited a bimodal pattern, peaking at 1100 m. Conversely, nitrogen (N)-acquiring activities (NAG + LAP: beta-1,4-N-acetylglucosaminidase + L-leucine aminopeptidase) showed no significant linear trend but reached their highest levels at 1000 m. Vector analysis revealed that there is a consistent N limitation of soil microbes across all altitudes. Soil nutrient content, altitudes, and soil microbial biomass of C and N were identified as key drivers of soil enzyme stoichiometry in Wuyi Mountain. Conclusion Altitude significantly affect soil enzyme activities due to changes in microenvironment. This provides essential information for predicting ecosystem function in response to climate change in the subtropical mountains.