Complex Systems Research Center, Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH 03824, USA.
New Phytol. 2011 Jan;189(2):375-94. doi: 10.1111/j.1469-8137.2010.03536.x. Epub 2010 Nov 16.
How plants interact with sunlight is central to the existence of life and provides a window to the functioning of ecosystems. Although the basic properties of leaf spectra have been known for decades, interpreting canopy-level spectra is more challenging because leaf-level effects are complicated by a host of stem- and canopy-level traits. Progress has been made through empirical analyses and models, although both methods have been hampered by a series of persistent challenges. Here, I review current understanding of plant spectral properties with respect to sources of uncertainty at leaf to canopy scales. I also discuss the role of evolutionary convergence in plant functioning and the difficulty of identifying individual properties among a suite of interrelated traits. A pattern that emerges suggests a synergy among the scattering effects of leaf-, stem- and canopy-level traits that becomes most apparent in the near-infrared (NIR) region. This explains the widespread and well-known importance of the NIR region in vegetation remote sensing, but presents an interesting paradox that has yet to be fully explored: that we can often gain more insight about the functioning of plants by examining wavelengths that are not used in photosynthesis than by examining those that are.
植物与阳光的相互作用是生命存在的核心，为生态系统的功能提供了一个窗口。尽管几十年来人们已经了解了叶片光谱的基本特性，但解释冠层光谱更具挑战性，因为叶片层面的影响因一系列茎和冠层层面的特征而变得复杂。尽管这两种方法都受到一系列持续挑战的阻碍，但通过实证分析和模型已经取得了进展。在这里，我回顾了当前对叶片到冠层尺度不确定性来源的植物光谱特性的理解。我还讨论了进化趋同在植物功能中的作用以及在一系列相关特征中识别单个特征的困难。一个明显的模式表明，叶片、茎和冠层层面特征的散射效应之间存在协同作用，这种协同作用在近红外（NIR）区域最为明显。这解释了近红外（NIR）区域在植被遥感中广泛而众所周知的重要性，但提出了一个有趣的悖论，尚未得到充分探索：我们通常可以通过检查光合作用中不使用的波长来更好地了解植物的功能，而不是检查那些用于光合作用的波长。
