A research team from the Xinjiang Institute of Ecology and Geography (XIEG) of the Chinese Academy of Sciences has pinpointed soil moisture as the principal water stress factor for vegetation across Central Asia. The study, led by Prof. Guli Jiapaer from XIEG, has been recently published in Agricultural and Forest Meteorology.

The researchers used three indices to quantify vegetation sensitivity to each type of water stress: the Standardized Precipitation Index (SPI) for precipitation, the Standardized Soil Moisture Index (SSMI) for soil moisture, and the Standardized Vapor Pressure Deficit Index (SVDI) for atmospheric moisture. They then combined these indices with data on vegetation structure, greenness, and photosynthesis.

Vegetation across all land-cover types in Central Asia is most sensitive to soil moisture, according to the results. What's more, from 1982 to 2020, that sensitivity has increased significantly. Looking ahead, projections show that soil moisture stress will remain the dominant factor for vegetation in the future.

In cultivated lands, irrigation made a clear difference. It notably reduced crops' sensitivity to soil moisture, and this mitigating effect grew stronger with higher irrigation intensity.

This study deepens our understanding of how Central Asian vegetation responds to different water stresses and offers a theoretical foundation for designing measures to ease the adverse impacts of water stress.