Dry and warm climate conditions in southern Europe represent clear limits for European beech (Fagus sylvatica) growth near the species southern distribution limit, but it is unclear how aridification and changes in seasonal precipitation regimes will affect these forests at the individual level. We explored climate-growth relationships and the seasonality of peak climate signals in European beech using daily climate data and a large collection of tree-ring width series from southern and southeastern Europe through Generalised Linear Mixed Models (GLMMs). In most cases we found a positive and significant influence of precipitation on tree growth, and a significant negative effect of maximum temperature. Predictions from the GLMMs revealed a positive impact of precipitation during an 88 day window from spring to early summer (mid-April to mid-July), for an average tree across our network. This critical growing time window ranged from 75 days in warmer and drier conditions, and extended up to 100 days in areas with mild temperatures and moderate summer precipitation. Maximum temperatures negatively affected trees for an average of 27 day window in summer (June-July). This period was reduced to <10 days in locations with wetter and colder summers, rising up to 45 days in sites with drier and warmer summers. The positive effect of precipitation on growth was stronger and commenced earlier in larger trees. Similarly, the negative effects of maximum temperatures were more pronounced for larger trees. The use of daily climate data and a tree-centred approach allowed for capturing critical temporal dynamics in climate-growth relationships that are often overlooked by conventional methods. These insights significantly enhance our understanding of climatic factors influencing individual beech growth at the edge of its distribution range and their seasonal variations.

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一种单树方法确定欧洲山毛榉的气候生长模式及其在物种南部分布区的季节性

南欧干燥和温暖的气候条件代表了欧洲山毛榉 （Fagus sylvatica） 生长的明显限制，接近物种南部分布限制，但尚不清楚干旱化和季节性降水机制的变化将如何在个体层面影响这些森林。我们使用每日气候数据以及通过广义线性混合模型 （GLMM） 从南欧和东南欧收集的大量树木年轮宽度序列，探讨了欧洲山毛榉的气候-生长关系和峰值气候信号的季节性。在大多数情况下，我们发现降水对树木生长有积极和显着的影响，而最高温度则有显着的负面影响。GLMM 的预测显示，从春季到初夏（4 月中旬到 7 月中旬）的 88 天窗口内，降水对我们网络中的平均树木产生了积极影响。这个关键的生长时间窗口从温暖和干燥条件下的 75 天不等，在温度温和和、夏季降水适中的地区长达 100 天。最高温度在夏季（6 月至 7 月）平均 27 天对树木产生负面影响。在夏季较潮湿和较冷的地区，这一时期减少到 <10 天，在夏季较干燥和较温暖的地区增加到 45 天。降水对生长的积极影响更强，并且在较大的树木中开始得更早。同样，最高温度的负面影响对于较大的树木更为明显。使用每日气候数据和以树木为中心的方法可以捕捉传统方法经常忽视的气候-生长关系中的关键时间动态。 这些见解极大地增强了我们对影响山毛榉分布范围边缘个体生长及其季节性变化的气候因素的理解。