Enhanced water-depleted westerly wind strongly degrades alpine vegetation in monsoon-dominated East Asia

Although dozens of studies have examined the sensitivity of alpine vegetation to recent climate warming, few have accounted for upper-atmosphere wind-systems. We first report that a westerly influence can dominate the alpine vegetation of Taibai Mountain (3767 m a.s.l.) in the monsoon-dominated regions of China. Proxies of vegetation productivity and soil conservation from a high-resolution alpine lacustrine record dated to the mid-Holocene show that westerly winds limit the extension of the East Asian summer monsoon (EASM) into the high altitudes of inland continental East Asia (Taibai Mountain region), resulting in lower precipitation, which have contributed to the decreased vegetation productivity and subsequently increased soil erosion from 5850 to 4000 calibrated years before present (1950 CE, cal. yr BP). An opposite phenomenon prevailed from 4000 cal. yr BP to present. Based on the relationship between the reconstructed circulations and vegetation productivity, strengthening westerly winds in the future projections of CMIP5 (Coupled Model Intercomparison Project Phase 5) climate models may offset the warming-induced enhancement of vegetation productivity in temperature-limited mountain areas of the studied region. Our results highlight the importance of contrasting westerlies and monsoon impacts on the alpine climate and ecosystems in East Asia, which may have implications for other alpine regions in the world.