Longitudinal dependency of soil extracellular enzyme activities across alpine grasslands, Tibetan Plateau

Abstract

This study investigated the geographical patterns and controlling factors of soil extracellular enzyme activities in the alpine grasslands of the Tibetan Plateau, using data from 135 sample sites collected in 2020. The activities of four essential soil extracellular enzymes, namely β-glucosidase (BG), leucine aminopeptidase (LAP), N-Acetyl-β-D-Glucosaminidase (NAG), and alkaline phosphatase (AP), were analyzed through partial correlation and structural equation modeling (SEM), incorporating climatic and geographic variables. The main findings are as follows: Soil BG activity (cv:0.69) showed more significant spatial variation, followed by soil LAP (cv: 0.66), NAG (cv: 0.57), and AP (cv: 0.55) activities. Furthermore, the longitudinal dependency of BG, AP, and NAG activities was mainly governed by the soil organic carbon, soil total nitrogen, and soil total phosphorus. Interestingly, soil LAP activity was uncorrelated with soil properties, community traits, and climatic elements. Specifically, precipitation has a significant positive impact on plant community characteristics and soil properties, increasing the substrates available (e.g., soil organic carbon) for soil extracellular enzyme decomposition. In conclusion, the study confirmed that there is a longitudinal dependency of soil extracellular enzyme activities across alpine grasslands, presenting a reduced tendency from east to west over the Tibetan Plateau. Besides, the main findings highlighted the cascade effect of precipitation on the above-mentioned pattern via altering soil properties.