摘要
Background and aims Understanding the impacts of ever more severe and widespread drought events has become a central focus of recent ecological research. Accordingly, the objective of this study is to investigate fundamental mechanisms that control drought effects on climate sensitive ecosystems by regulating soil-plant interactions. Methods Field experiments were conducted in high altitudinal grasslands of the Tibetan Plateau. Based on historical records, we simulated extreme drought events, intercepting water inputs in early (spring), mid (summer), and late (autumn) periods of the plant-growing season (PGS). We measured vegetation responses to changes in soil physical, chemical, and biological properties, examining how the interplay of abiotic and biotic processes regulate the impacts of drought above and below ground. Results Decreasing water input resulted in proportional increases in summer and autumn soil temperature, but reduced soil temperature during the spring drought. As a result, soil microbial biomass and available N and P concentrations remained stable during the early-PGS drought, while enzymatic activity, decomposition of organic materials, and nutrient release increased during the mid- and late-PGS. Concerted changes in microbial and plant activity determined seasonal fluctuations in carbon assimilation, microbial activity and nutrient dynamics, with varying degrees of resistance and resilience to drought stress observed at different PGS periods. Conclusions Significant interactions were observed between plant productivity and microbial activity in response to moisture variability and associated changes in soil temperature, with the largest deleterious drought effects registered during the summer, when competition for limiting resources between plants and microorganisms was strongest.