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Hyperspectral solar-induced chlorophyll fluorescence of urban tree leaves: Analyses and applications.

机译：城市树木叶片的高光谱太阳诱导叶绿素荧光分析和应用。

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摘要

Solar energy is the primary energy source for life on Earth which is converted into chemical energy through photosynthesis by plants, algae and cyanobacteria, releasing fuel for the organisms' activities. To dissipate excess of absorbed light energy, plants emit chlorophyll (Chl) fluorescence (650-850 nm) from the same location where photosynthesis takes place. Hence, it provides information on the efficiency of primary energy conversion. From this knowledge, many applications on vegetation and crop stress monitoring could be developed, a necessity for our planet under threat of a changing global climate.;Even though the Chl fluorescence signal is weak against the intense reflected radiation background, methods for retrieving the solar-induced Chl fluorescence have been refined over the last years, both at leaf and airborne scale. However, a lack of studies on solar-induced Chl fluorescence gives difficulties for the interpretation of the signal. Within this thesis, hyperspectral upward and downward solar-induced Chl fluorescence is measured at leaf level. Fluorescence yield (FY) is calculated as well as different ratios characterizing the emitted Chl fluorescence shape.;The research in this PhD dissertation illustrates the influence of several factors on the solar-induced Chl fluorescence signal. For instance, both the intensity of FY and its spectral shape of urban tree leaves are able to change under influence of stress factors such as traffic air pollution. This shows how solar-induced Chl fluorescence could function as an early stress indicator for vegetation. Further, it is shown that the signal contains information on the ultrastructure of the photosynthetic apparatus. Also, it is proven that the leaf anatomical structure and related light scattering properties play a role in the partitioning between upward and downward Chl fluorescence emission. All these findings indicate how the Chl fluorescence spectrum is influenced by factors which also influence photosynthesis.;From this we conclude that solar-induced Chl fluorescence emitted by vegetation is a meaningful signal affected by several environmental and plant specific factors. It is important to define these factors in order to obtain a better interpretation of the signal, especially regarding the current and future remote sensing mapping possibilities of the signal.
机译：太阳能是地球上生命的主要能源，通过植物，藻类和蓝细菌的光合作用转化为化学能，从而为生物的活动释放燃料。为了消散多余的吸收光能，植物从发生光合作用的同一位置发出叶绿素（Chl）荧光（650-850 nm）。因此，它提供了有关一次能源转换效率的信息。据此，可以开发出许多在植被和作物压力监测方面的应用，这是地球面临全球气候变化威胁的必要条件。即使Chl荧光信号在强烈的反射辐射背景下仍然微弱，但采用太阳能的方法在过去的几年中，无论是在叶片还是在空气传播的尺度上，诱导的Ch1荧光都得到了改进。然而，缺乏对太阳诱导的Chl荧光的研究给信号的解释带来了困难。在本论文中，在叶片水平上测量了高光谱向上和向下的太阳诱导的Chl荧光。计算了荧光产率（FY）以及表征所发射的Chl荧光形状的不同比率。;本博士论文的研究阐明了多种因素对太阳诱导的Chl荧光信号的影响。例如，FY的强度及其城市树叶的光谱形状都能够在压力因素（如交通空气污染）的影响下发生变化。这显示了太阳诱导的Ch1荧光如何充当植被的早期胁迫指标。此外，表明该信号包含有关光合装置超微结构的信息。而且，已经证明，叶片解剖结构和相关的光散射特性在向上和向下Chl荧光发射之间的分配中起作用。所有这些发现表明，Ch1荧光光谱如何受到也影响光合作用的因素的影响。；由此我们得出结论，植被释放的太阳诱导的Chl荧光是受多种环境和植物特定因素影响的有意义的信号。重要的是定义这些因素，以便更好地理解信号，尤其是关于信号的当前和未来遥感映射的可能性。

著录项

  • 作者

    Van Wittenberghe, Shari.;

  • 作者单位

    Universiteit Antwerpen (Belgium).;

  • 授予单位 Universiteit Antwerpen (Belgium).;
  • 学科 Physiology.;Environmental science.;Remote sensing.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 200 p.
  • 总页数 200
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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