ABSTRACT Shrubs growing at higher latitudes and altitudes are considered to be highly sensitive to climate warming. In particular, alpine shrubs are potential climate proxies for understanding responses of high-elevation treeless ecosystems to warmer conditions. However, little is known about how alpine shrub radial growth responds to climate variables, specifically temperature and precipitation. This lack of knowledge is particularly notable in the Himalayas where shrubs reach some of their worldwide uppermost limits. Herein, we investigated the climatic response of alpine juniper shrub (Juniperus indica) to climate in two areas (dry Manang valley; wet Everest valley) situated in the central Himalayas. In spite of different sites and elevations, the radial growth of juniper shrub is positively correlated with spring precipitation in both areas, and also with summer precipitation in the dry area. Juniper shrub shares common climatic responses with Himalayan treeline tree populations, whose growth dynamics are also controlled by moisture availability. Thus, radial growth of juniper in the central Himalayas may experience drought stress if climate warming leads to drier conditions. We conclude that alpine shrubs are crucial indicators of the responses of alpine ecosystem to global climate warming.

中文翻译：

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生长季早期降水推动喜马拉雅中部高山杜松灌木径向生长

摘要 生长在较高纬度和海拔高度的灌木被认为对气候变暖高度敏感。特别是，高山灌木是了解高海拔无树生态系统对温暖条件的反应的潜在气候代理。然而，关于高山灌木径向生长如何响应气候变量，特别是温度和降水，我们知之甚少。这种知识的缺乏在喜马拉雅山尤为明显，那里的灌木达到了它们在世界范围内的一些最高极限。在此，我们调查了位于喜马拉雅山脉中部的两个地区（干燥的马南山谷；潮湿的珠穆朗玛峰山谷）高山杜松灌木（Juniperus indica）对气候的气候响应。尽管地点和海拔不同，杜松灌木的径向生长与两地春季降水呈正相关，干旱地区也有夏季降水。杜松灌木与喜马拉雅树线树种群具有共同的气候反应，其生长动态也受水分可用性控制。因此，如果气候变暖导致更干燥的条件，喜马拉雅中部杜松的径向生长可能会遭受干旱压力。我们得出结论，高山灌木是高山生态系统对全球气候变暖反应的重要指标。