AimTo quantify the intra‐community variability of leaf‐out (ICVLo) among dominant trees in temperate deciduous forests, assess its links with specific and phylogenetic diversity, identify its environmental drivers and deduce its ecological consequences with regard to radiation received and exposure to late frost.LocationEastern North America (ENA) and Europe (EUR).Time Period2009–2022.Major Taxa StudiedTemperate deciduous forest trees.MethodsWe developed an approach to quantify ICVLo through the analysis of RGB images taken from phenological cameras. We related ICVLo to species richness, phylogenetic diversity and environmental conditions. We quantified the intra‐community variability of the amount of radiation received and of exposure to late frost.ResultsLeaf‐out occurred over a longer time interval in ENA than in EUR. The sensitivity of leaf‐out to temperature was identical in both regions (−3.4 days per °C). The distributions of ICVLo were similar in EUR and ENA forests, despite the latter being more species‐rich and phylogenetically diverse. In both regions, cooler conditions and an earlier occurrence of leaf‐out resulted in higher ICVLo. ICVLo resulted in ca. 8% difference of radiation received from leaf‐out to September among individual trees. Forest communities in ENA had shorter safety margins as regards the exposure to late frosts, and were actually more frequently exposed to late frosts.Main ConclusionsWe conducted the first intercontinental analysis of the variability of leaf‐out at the scale of tree communities. North American and European forests showed similar ICVLo, in spite of their differences in terms of species richness and phylogenetic diversity, highlighting the relevance of environmental controls on ICVLo. We quantified two ecological implications of ICVLo (difference in terms of radiation received and exposure to late frost), which should be explored in the context of ongoing climate change, which affects trees differently according to their phenological niche.

中文翻译：

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跨尺度的物候学：温带落叶乔木群落叶期的洲际分析


目的量化温带落叶林中优势树木的落叶群落内部变异性（ICVLo），评估其与特定和系统发育多样性的联系，确定其环境驱动因素，并推断其在接受辐射和晚霜暴露方面的生态后果地点北美东部 (ENA) 和欧洲 (EUR)。时间段 2009–2022。研究温带落叶林树木的主要分类群。方法我们开发了一种通过分析物候相机拍摄的 RGB 图像来量化 ICVLo 的方法。我们将 ICVLo 与物种丰富度、系统发育多样性和环境条件联系起来。我们量化了社区内接受的辐射量和晚霜暴露量的变异性。结果 ENA 发生叶子脱落的时间间隔比 EUR 更长。两个地区的落叶对温度的敏感性是相同的（每°C-3.4天）。 ICVLo 在 EUR 和 ENA 森林中的分布相似，尽管后者物种更加丰富且系统发育更加多样化。在这两个地区，较凉爽的条件和较早出现的落叶导致了较高的 ICVLo。 ICVLo 导致约。从落叶到 9 月份，各树所接收到的辐射有 8% 的差异。 ENA 的森林群落在暴露于晚霜方面的安全裕度较短，并且实际上更频繁地暴露于晚霜。主要结论我们对树木群落规模的落叶变异性进行了首次洲际分析。尽管北美和欧洲森林在物种丰富度和系统发育多样性方面存在差异，但表现出相似的 ICVLo，这凸显了环境控制对 ICVLo 的相关性。 我们量化了 ICVLo 的两个生态影响（接收辐射和晚霜暴露的差异），这应该在持续的气候变化的背景下进行探索，气候变化根据树木的物候生态位对其产生不同的影响。