Plant drought adaptation strategies regulate alpine grassland water yield in the Qinghai Lake Basin, northeastern Qinghai-Tibet Plateau

Abstract

Study region: The Qinghai Lake Basin, northeast Qinghai-Tibetan Plateau. Study focus: Vegetation dynamic induced change on catchment water yield (including surface runoff and groundwater runoff) is one of the research hotspots in the field of hydrology and ecology. However, few studies have explored the underlying biological mechanism by which plant regulate water yield. In this study, we examined the impact of different plant drought adaptation strategies on watershed water yield in the Qinghai Lake Basin, using both the ecohydrological model, water balance method and surface runoff experiments. New hydrological insights: we defined two type of plant drought adaptation strategies: drought-avoiding strategy can maximize the soil moisture and therefore minimize vegetation water stress, while drought-tolerating strategy tends to increase productivity by tolerating a certain degree of water stress. The result shows that plants employing drought-avoiding strategy have significantly higher water yield and water yield coefficient (the ratio of water yield to precipitation) than plants adopting drought-tolerating strategy, regardless of meadow or steppe species. Meanwhile, for all grassland species in the study region, plants with drought-avoiding strategy have less vegetation cover and net primary productivity than plants with drought-tolerating strategy, which reflect the trade-off between avoiding water stress and achieving competitive advantages. Our findings offer insights into the biological mechanism by which vegetation regulates water yield, and provide vital guidance for watershed management.

Keywords

• Plant drought adaptation
• Basin water yield
• Eagleson’s ecohydrological model