A study of soil-dynamics based on a simulated drought in an alpine meadow on the Tibetan Plateau

Extreme weather events have played an important role in driving the ecosystem dynamics in high altitude areas, but the underlying mechanism remains unclear. To understand if and how the soil processes of an ecosystem react to extreme drought, we manipulated a once-in-a-century meteorological extreme drought in an alpine meadow on the Tibetan Plateau, which is also known as the “forerunner of global weather changes”. The extremity was determined by statistical extreme weather events with respect to a historical reference period from April to September during 1962–2004, where the local historical precipitation data was calculated and intensified to 100-year recurrent drought event with Gumbel I distribution. The indicators we measured included soil microbial biomass C/N/P and soil enzymatic activities of phosphatase (AP) disbounding organic phosphate, cellobiohydrolase (CBH), β-glucocidase (BG), N-releasing enzyme N-acetylglucosaminidase (NAG) as well as soil respirations, during and after the treatments. It was found that the manipulated event induced a rapid shift in microbial biomass and activities, indicating a lower resistance of the underground process. However, the microbial and biochemical parameters saw rapid recovery after the event, which meant the soil processes enjoyed high resilience. The high responsiveness and lag-time effects of the soil indicators rendered new horizons for us to evaluate the interaction between the extremes and the ecosystem stability. Our study indicated that the once-in-a-century extreme drought induced very short term response in the soil biotic process, and the soil processes worked to buffer against such events under the observation period.