Centre of Excellence PLECO (Plants and Ecosystems), Department of Biology, University of Antwerp, 2160, Wilrijk, Belgium.
CSIC, Global Ecology Unit, CREAF-CSIC-UAB, Cerdanyola del Vallès, 08193, Barcelona, Catalonia, Spain.
New Phytol. 2019 Oct;224(1):166-176. doi: 10.1111/nph.15991. Epub 2019 Jul 23.
Information on the onset of leaf senescence in temperate deciduous trees and comparisons on its assessment methods are limited, hampering our understanding of autumn dynamics. We compare five field proxies, five remote sensing proxies and two data analysis approaches to assess leaf senescence onset at one main beech stand, two stands of oak and birch, and three ancillary stands of the same species in Belgium during 2017 and 2018. Across species and sites, onset of leaf senescence was not significantly different for the field proxies based on Chl leaf content and canopy coloration, except for an advanced canopy coloration during the extremely dry and warm 2018. Two remote sensing indices provided results fully consistent with the field data. A significant lag emerged between leaf senescence onset and leaf fall, and when a threshold of 50% change in the seasonal variable under study (e.g. Chl content) was used to derive the leaf senescence onset. Our results provide unprecedented information on the quality and applicability of different proxies to assess leaf senescence onset in temperate deciduous trees. In addition, a sound base is offered to select the most suited methods for the different disciplines that need this type of data.
有关温带落叶树叶片衰老开始的信息以及对其评估方法的比较有限，这阻碍了我们对秋季动态的理解。我们比较了 2017 年和 2018 年在比利时一个山毛榉主要林分、两个栎树和桦树林分以及三个相同树种的辅助林分中使用的五种野外探针、五种遥感探针和两种数据分析方法来评估叶片衰老的开始。在物种和地点方面，基于叶片叶绿素含量和冠层颜色的野外探针的叶片衰老开始没有明显差异，除了在极其干燥和温暖的 2018 年，冠层颜色出现了提前。两种遥感指数的结果与野外数据完全一致。叶片衰老开始和落叶之间出现了显著的滞后，当研究中季节性变量（如叶绿素含量）的变化阈值为 50%时，用于确定叶片衰老开始的时间。我们的研究结果为评估温带落叶树叶片衰老开始的不同探针的质量和适用性提供了前所未有的信息。此外，为需要此类数据的不同学科选择最合适的方法提供了坚实的基础。
