20世纪以来美国树木生长响应气候变化敏感度的时空差异

树木生长响应气候变化的敏感度是全球变化研究的重要内容。利用20世纪以来美国本土1058个样本点的树轮宽度指数和温度、降水数据,通过相关分析,揭示了树木生长速率年际变化响应气候变化敏感度的时空差异。研究发现：① 美国树木径向生长速率与温度普遍负相关、与降水普遍正相关,绝大多数地区树木生长受水分条件限制。② 径向生长速率对温度和降水响应敏感度呈现一定的季节差异,最敏感的季节因地区而异,这主要与不同月份温度、降水条件差异导致的水分条件变化有关。同时,径向生长速率对温度、降水响应敏感度还随着气候条件变化而变化,随着年平均温度升高（降低）,径向生长速率与温度的负相关逐渐增强（减弱）,随着年降水增加（减少）,与降水的正相关强度逐渐减弱（增强）。

Spatiotemporal variation of the response of tree radial growth and its sensitivities to climate changes in the United States since the 20th century

The response of tree radial growth and its sensitivity to climate change is an important topic in the global environmental research community. Using tree-ring width index data from 1058 sample sites in the United States and instrumental temperature and precipitation data since the 20th century, correlation analysis was carried out to reveal the spatiotemporal variation of tree radial growth's response and its sensitivity to climate changes. Results show that in the United States radial growth rates of trees were mostly negative correlated with temperature and positive correlated with precipitation. Moisture may be dominant limiting factor of tree growth in most of regions of the United States. Response sensitivity of tree radial growth rate to temperature and precipitation changes exhibited seasonal variations. The most sensitive season varies with regions. The spatial variability of most sensitive seasons was mainly resulted from seasonal variations of moisture conditions due to local seasonal cycles of temperature and precipitation. Moreover, the response sensitivities of tree radial growth rate to temperature and precipitation changes along with climate changes. The negative correlation between tree radial growth rate with temperature would be strengthened (weakened) along with the climate warming (cooling). The positive correlation between tree radial growth rate with precipitation would be strengthened (weakened) along with precipitation decrease (increase).