Castro-Esau Karen L, Sánchez-Azofeifa G Arturo, Rivard Benoit, Wright S Joseph, Quesada Mauricio
Earth Observation Systems Laboratory, Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada, T6G 2E3;
Am J Bot. 2006 Apr;93(4):517-30. doi: 10.3732/ajb.93.4.517.
Leaf traits and physiological performance govern the amount of light reflected from leaves at visible and infrared wavebands. Information on leaf optical properties of tropical trees is scarce. Here, we examine leaf reflectance of Mesoamerican trees for three applications: (1) to compare the magnitude of within- and between-species variability in leaf reflectance, (2) to determine the potential for species identification based on leaf reflectance, and (3) to test the strength of relationships between leaf traits (chlorophyll content, mesophyll attributes, thickness) and leaf spectral reflectance. Within species, shape and amplitude differences between spectra were compared within single leaves, between leaves of a single tree, and between trees. We also investigated the variation in a species' leaf reflectance across sites and seasons. Using forward feature selection and pattern recognition tools, species classification within a single site and season was successful, while classification between sites or seasons was not. The implications of variability in leaf spectral reflectance were considered in light of potential tree crown classifications from remote airborne or satellite-borne sensors. Species classification is an emerging field with broad applications to tropical biologists and ecologists, including tree demographic studies and habitat diversity assessments.
叶片性状和生理性能决定了叶片在可见光和红外波段反射的光量。关于热带树木叶片光学特性的信息匮乏。在此，我们研究了中美洲树木的叶片反射率，用于三个方面：（1）比较物种内和物种间叶片反射率的变异性大小，（2）确定基于叶片反射率进行物种识别的潜力，（3）测试叶片性状（叶绿素含量、叶肉属性、厚度）与叶片光谱反射率之间关系的强度。在物种内部，比较了单叶内、单棵树的叶片之间以及不同树木之间光谱的形状和幅度差异。我们还研究了一个物种的叶片反射率在不同地点和季节的变化。使用前向特征选择和模式识别工具，在单个地点和季节内的物种分类是成功的，而不同地点或季节之间的分类则不成功。鉴于从机载或卫星遥感传感器进行潜在树冠分类的情况，考虑了叶片光谱反射率变异性的影响。物种分类是一个新兴领域，在热带生物学家和生态学家中有广泛应用，包括树木种群统计学研究和栖息地多样性评估。
