The high sensitivity of Nothofagus pumilio growth to climate variations at upper treelines provides a unique opportunity to document changes in tree responses to a warmer climate in the Patagonian Andes. In the context of significant recent temperature and precipitation changes across Patagonia, we conducted a study along the precipitation gradient in the Río de las Vueltas basin, southern Patagonian Andes, to: (1) document differences in N. pumilio growth trends at upper treelines, (2) determine changes in climate-growth relationships along the precipitation gradient, and (3) estimate future growth responses to simulated 21^st century warming. For the past 100 years, mean tree-ring width increases progressively from wet to dry treelines in response to less abundant precipitation and less persistent snow cover into the growing season. Mountain aspect regulates snow cover duration and hence growing season length, thereby also influencing tree-ring width. On interannual scale, temperature directly modulates tree-growth variations in wet and mesic treelines, but is inversely related to growth in dry sites. Growth trends show that the approximate 0.56°C temperature increment since the mid-1970’s in the Patagonian Andes dramatically enhanced the recorded long-term increasing growth rates at mesic, but to a lesser extent at humid treelines, suggesting nonlinear interactions between temperature and snow persistence on tree growth. Contrarily, growth rates at dry treelines decreased over the past 100 years. Our predictive statistical models indicate sustained decadal increases in current radial growth rates at wet and mesic sites and decreases at dry treelines towards the end of the 21^st century under the simulated future warming scenarios for the southern Andes. However, the nonlinear relationships between warming, snow cover and tree growth, combined with unreliable estimates of precipitation for the region during the 21^st century, suggest that these simulated changes in tree growth should be viewed with caution.

Nothofagus pumilio生长对上部林线气候变化的高度敏感性为记录巴塔哥尼亚安第斯山脉气候变暖的树木响应变化提供了独特的机会。在巴塔哥尼亚近期气温和降水量显着变化的背景下，我们沿着巴塔哥尼亚安第斯山脉南部的 Río de las Vueltas 盆地的降水梯度进行了一项研究，以：（1）记录上部树线处 Pumilio N. pumilio生长趋势的差异， (2) 确定沿降水梯度的气候-增长关系的变化，以及 (3) 估计未来对模拟 21^{日的增长响应}世纪变暖。在过去的 100 年里，平均树轮宽度从湿润到干燥的树线逐渐增加，以应对生长季节降水量减少和积雪持续时间减少。山坡调节积雪持续时间，从而调节生长季节长度，从而影响树木年轮宽度。在年际尺度上，温度直接调节湿润和中等林线中的树木生长变化，但与干燥地区的生长成反比。增长趋势表明，自 1970 年代中期以来，巴塔哥尼亚安第斯山脉约 0.56°C 的温度增量显着提高了中速记录的长期增长速率，但在潮湿的林线中幅度较小，这表明温度和积雪持久性之间存在非线性相互作用关于树的生长。相反，在过去的 100 年里，干旱林线的增长率下降了。我们的预测统计模型表明，在 21 世纪末，湿润和中干地的当前径向增长率持续十年增长，而干燥的树线则下降。在模拟的安第斯山脉南部未来变暖情景下的世纪^。然而，变暖、积雪和树木生长之间的非线性关系，再加上对该地区 21 世纪降水量的不可靠估计^，表明应谨慎看待树木生长的这些模拟变化。