Aim: Previous work demonstrated the global variability of synchrony in tree growth within populations, that is, the covariance of the year-to-year variability in growth of individual neighbouring trees. However, there is a lack of knowledge about the causes of this variability and its trajectories through time. Here, we examine whether climate can explain variation in within-population synchrony (WPS) across space but also through time and we develop models capable of explaining this variation. These models can be applied to the global tree cover under current and future climate change scenarios. Location: Global. Time period: 1901–2012. Major taxa studied: Trees. Methods: We estimated WPS values from a global tree-ring width database consisting of annual growth increment measurements from multiple trees at 3,579 sites. We used generalized linear mixed effects models to infer the drivers of WPS variability and temporal trends of global WPS. We then predicted WPS values across the global extent of tree cover. Finally, we applied our model to predict future WPS based on the RCP 8.5 (2045–2065 period) emission scenario. Results: Areas with the highest WPS are characterized by a combination of environments with both high mean annual temperature (>10°C) and low precipitation (<300 mm). Average WPS across all temperate forests has decreased historically and will continue to decrease. Potential implications of these patterns include changes in forest dynamics, such as higher tree growth and productivity and an increase in carbon sequestration. In contrast, the WPS of tropical forests of Central and South America will increase in the near future owing to reduced annual precipitation. Main conclusions: Climate explains WPS variability in space and time. We suggest that WPS might have value as an integrative ecological measure of the level of environmental stress to which forests are subjected and therefore holds potential for diagnosing effects of global climate change on tree growth.

中文翻译：

---

气候驱动的邻近树木生长同步性的全球视角

目的：先前的工作证明了种群内树木生长同步的全球变异性，即个体相邻树木生长的逐年变异性的协方差。然而，人们对这种可变性的原因及其随时间变化的轨迹缺乏了解。在这里，我们检查气候是否可以解释跨空间以及跨时间的种群内同步 (WPS) 变化，我们开发了能够解释这种变化的模型。这些模型可以应用于当前和未来气候变化情景下的全球树木覆盖率。地点：全球。时间段：1901-2012。研究的主要分类群：树木。方法：我们从全球树轮宽度数据库中估计 WPS 值，该数据库由 3,579 个地点的多棵树的年生长增量测量值组成。我们使用广义线性混合效应模型来推断 WPS 变异性和全球 WPS 时间趋势的驱动因素。然后，我们预测了全球树木覆盖范围内的 WPS 值。最后，我们应用我们的模型来预测基于 RCP 8.5（2045-2065 年）排放情景的未来 WPS。结果：WPS 最高的地区的特点是年平均气温高 (>10°C) 和降水量低 (<300 mm) 的环境组合。所有温带森林的平均 WPS 在历史上都有所下降，并将继续下降。这些模式的潜在影响包括森林动态的变化，例如更高的树木生长和生产力以及碳固存的增加。相比之下，由于年降水量减少，中南美洲热带森林的 WPS 将在不久的将来增加。主要结论：气候解释了 WPS 在空间和时间上的变化。我们认为 WPS 可能作为衡量森林所受环境压力水平的综合生态指标具有价值，因此具有诊断全球气候变化对树木生长影响的潜力。