Helfenstein Isabelle S, Sturm Joan T, Schmid Bernhard, Damm Alexander, Schuman Meredith C, Morsdorf Felix
Remote Sensing Laboratories, Department of Geography, University of Zurich, Zurich, Switzerland.
Eawag, Swiss Federal Institute of Aquatic Science and Technology, Surface Waters - Research and Management, Duebendorf, Switzerland.
Glob Chang Biol. 2025 Feb;31(2):e70059. doi: 10.1111/gcb.70059.
Climate extremes such as droughts are expected to increase in frequency and intensity with global change. Therefore, it is important to map and predict ecosystem responses to such extreme events to maintain ecosystem functions and services. Alongside abiotic factors, biotic factors such as the proportion of needle and broadleaf trees were found to affect forest drought responses, corroborating results from biodiversity-ecosystem functioning (BEF) experiments. Yet it remains unclear to what extent the behavior of non-experimental systems at large scales corresponds to the relationships discovered in BEF experiments. Using remote sensing, the trait-based functional diversity of forest ecosystems can be directly quantified. We investigated the relationship between remotely sensed functional richness and evenness and forest drought responses using data from temperate mixed forests in Switzerland, which experienced an extremely hot and dry summer in 2018. We used Sentinel-2 satellite data to assess aspects of functional diversity and quantified drought response in terms of resistance, recovery, and resilience from 2017 to 2020 in a scalable approach. We then analyzed the BEF relationship between functional diversity measures and drought response for different aggregation levels of richness and evenness of three physiological canopy traits (chlorophyll, carotenoid/chlorophyll ratio, and equivalent water thickness). Forest stands with greater trait richness were more resistant and resilient to the drought event, and the relationship of trait evenness with resistance or resilience was hump-shaped or negative, respectively. These results suggest forest functional diversity can support forests in such drought responses via a mixture of complementarity and dominance effects, the first indicated by positive richness effects and the second by negative evenness effects. Our results link ecosystem functioning and biodiversity at large scales and provide new insights into the BEF relationships in non-experimental forest ecosystems.
随着全球气候变化，诸如干旱等极端气候事件的频率和强度预计将会增加。因此，绘制并预测生态系统对这类极端事件的响应，对于维持生态系统功能和服务而言至关重要。除了非生物因素外，针叶树和阔叶树的比例等生物因素也被发现会影响森林对干旱的响应，这进一步证实了生物多样性与生态系统功能（BEF）实验的结果。然而，尚不清楚非实验性系统在大尺度上的行为在多大程度上与BEF实验中发现的关系相符。利用遥感技术，可以直接量化森林生态系统基于性状的功能多样性。我们利用瑞士温带混交林的数据，研究了遥感功能丰富度和均匀度与森林干旱响应之间的关系，该地区在2018年经历了极其炎热干燥的夏季。我们使用哨兵-2卫星数据评估功能多样性的各个方面，并以一种可扩展的方法，从2017年到2020年，根据抗性、恢复力和弹性对干旱响应进行了量化。然后，我们分析了三种生理冠层性状（叶绿素、类胡萝卜素/叶绿素比率和等效水厚度）的丰富度和均匀度的不同聚合水平下，功能多样性指标与干旱响应之间的BEF关系。具有更高性状丰富度的林分对干旱事件具有更强的抗性和恢复力，而性状均匀度与抗性或恢复力的关系分别呈驼峰状或负相关。这些结果表明，森林功能多样性可以通过互补效应和优势效应的混合，在这类干旱响应中支持森林，前者表现为正的丰富度效应，后者表现为负的均匀度效应。我们的结果在大尺度上连接了生态系统功能和生物多样性，并为非实验性森林生态系统中的BEF关系提供了新的见解。
