Abstract Climate change is predicted to affect tree growth due to increased frequency and intensity of extreme events such as ice storms, droughts and heatwaves. Yet, there is still a lot of uncertainty on how trees respond to an increase in frequency of extreme events. Use of both ground-based wood increment (i.e. ring width) and remotely sensed data (i.e. vegetation indices) can be used to scale-up ground measurements, where there is a link between the two, but this has only been demonstrated in a few studies. We used tree-ring data together with crown features derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) to assess the effect of extreme climate events on the growth of beech (Fagus sylvatica L.) in Slovenia. We found evidence that years with climate extremes during the growing season (drought, high temperatures) had a lower ring width index (RWI) but we could not find such evidence for the remotely sensed EVI (Enhanced Vegetation Index). However, when assessing specific events where leaf burning or wilting has been reported (e.g. August 2011) we did see large EVI anomalies. This implies that the impact of drought or heatwave events cannot be captured by EVI anomalies until physical damage on the canopy is caused. This also means that upscaling the effect of climate extremes on RWI by using EVI anomalies is not straightforward. An exception is the 2014 ice storm that caused a large decline in both RWI and EVI. Extreme climatic parameters explained just a small part of the variation in both RWI and EVI by, which could indicate an effect of other climate variables (e.g. late frost) or biotic stressors such as insect outbreaks. Furthermore, we found that RWI was lower in the year after a climate extreme occurred in the late summer. Most likely due to the gradual increase in temperature and more frequent drought we found negative trends in RWI and EVI. EVI maps could indicate where beech is sensitive to climate changes and could be used for planning mitigation interventions. Logical next steps should focus on a tree-based understanding of the short -and long-term effects of climate extremes on tree growth and survival, taking into account differential carbon allocation to the crown (EVI) and to wood-based variables. This research highlights the value of an integrated approach for upscaling tree-based knowledge to the forest level.

中文翻译：

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斯洛文尼亚与极端气候相关的山毛榉生长的时空评估——使用遥感和树轮数据的综合方法

摘要 由于冰暴、干旱和热浪等极端事件的频率和强度增加，预计气候变化将影响树木的生长。然而，树木如何应对极端事件频率增加的问题仍然存在很多不确定性。使用基于地面的木材增量（即环宽）和遥感数据（即植被指数）可用于扩大地面测量，这两者之间存在联系，但这仅在少数情况下得到证明学习。我们将年轮数据与中分辨率成像光谱仪 (MODIS) 的树冠特征一起使用，以评估极端气候事件对斯洛文尼亚山毛榉 (Fagus sylvatica L.) 生长的影响。我们发现证据表明，在生长季节（干旱、高温）具有较低的环宽指数（RWI），但我们找不到遥感 EVI（增强植被指数）的证据。然而，在评估报告了叶片燃烧或枯萎的特定事件时（例如 2011 年 8 月），我们确实看到了大量的 EVI 异常。这意味着在对冠层造成物理损坏之前，EVI 异常无法捕捉干旱或热浪事件的影响。这也意味着通过使用 EVI 异常来放大气候极端事件对 RWI 的影响并不简单。一个例外是 2014 年的冰暴，导致 RWI 和 EVI 大幅下降。极端气候参数仅解释了 RWI 和 EVI 变化的一小部分，这可能表明其他气候变量（例如晚霜）或昆虫爆发等生物压力因素的影响。此外，我们发现，在夏末气候极端事件发生后的那一年，RWI 较低。最有可能是由于温度逐渐升高和更频繁的干旱，我们发现 RWI 和 EVI 呈负趋势。EVI 地图可以指示山毛榉对气候变化敏感的地方，并可用于规划缓解干预措施。合乎逻辑的下一步应该侧重于对极端气候对树木生长和生存的短期和长期影响的基于树木的理解，同时考虑到树冠 (EVI) 和木材变量的差异碳分配。这项研究强调了将基于树木的知识升级到森林级别的综合方法的价值。最有可能是由于温度逐渐升高和更频繁的干旱，我们发现 RWI 和 EVI 呈负趋势。EVI 地图可以指示山毛榉对气候变化敏感的地方，并可用于规划缓解干预措施。合乎逻辑的下一步应该侧重于对极端气候对树木生长和生存的短期和长期影响的基于树木的理解，同时考虑到树冠 (EVI) 和木材变量的差异碳分配。这项研究强调了将基于树木的知识升级到森林级别的综合方法的价值。最有可能是由于温度逐渐升高和更频繁的干旱，我们发现 RWI 和 EVI 呈负趋势。EVI 地图可以指示山毛榉对气候变化敏感的地方，并可用于规划缓解干预措施。合乎逻辑的下一步应该侧重于对极端气候对树木生长和生存的短期和长期影响的基于树木的理解，同时考虑到树冠 (EVI) 和木材变量的差异碳分配。这项研究强调了将基于树木的知识升级到森林级别的综合方法的价值。合乎逻辑的下一步应该侧重于对极端气候对树木生长和生存的短期和长期影响的基于树木的理解，同时考虑到树冠 (EVI) 和木材变量的差异碳分配。这项研究强调了将基于树木的知识升级到森林级别的综合方法的价值。合乎逻辑的下一步应该侧重于对极端气候对树木生长和生存的短期和长期影响的基于树木的理解，同时考虑到树冠 (EVI) 和木材变量的差异碳分配。这项研究强调了将基于树木的知识升级到森林级别的综合方法的价值。