Senescence and spectral reflectance in leaves of northern pin oak (Quercus palustris Muenchh.)

The effect of seasonal spectral variation on species classification in the Panamanian tropical forest

“…3a and b for the wet and dry seasons, respectively. Spectral features in the visible region (400-700 nm) are reflective of leaf chemistry and pigment content, specifically chlorophyll content, which results in strong absorption features both above and below the 550 nm green peak (Boyer et al, 1988). Features in the near-infrared (700-1100 nm) range most related to leaf structure (Woolley, 1971), with weak water absorption features at~1000 and 1200 nm (Gao and Goetz, 1995).…”

Remote sensing in food production and #8211; a review

“…Because of the importance of leaves, variations in their condition may offer important information regarding the whole plant status. The reflectance curve of leaves in the visible spectral region, as earlier detailed, shows two minima: one in the blue region and the other in the red region, due to the intense absorption of sunlight by photosynthetic pigments, essentially by chlorophylls (Hoffer, 1978;Boyer et al, 1988). Besides, in the NIR spectral region healthy green vegetation is characterized by high reflectance values.…”

“…High reflectance in the near infrared is due to multiple scattering of light at the air-cell interfaces in the spongy mesophyll cells located in the interior or back of leaves. In the mid-infrared spectral region the vegetation behavior is mainly determined by the water content of the leaf tissues (Sinclair et al, 1971;Hoffer, 1978;Barrett and Curtis, 1982;Boyer et al, 1988).…”

“…It is comprehensible, therefore, that many studies of vegetation using remote sensing data use the spectral regions of the red and near infrared (Pinter et al, 2003). In the spectral signature of green leaves there is a sharp increase in reflectance values in the transition zone from the visible to the near infrared region, between about 0.7 and 0.75 µm (Hoffer, 1978;Boyer et al, 1988). This abrupt variation in reflectance is generally referred to as the ``red edge" and is due to a change of processes: from the absorption of visible light by photosynthetic pigments to the diffusion of near infrared radiation in the internal structure of the leaves.…”

“…However, they are less influenced by atmospheric effects and background noise (Mauser andBach, 1995 in Broge andLeblanc, 2000). For example, it has been found that due to situations of nutrients deficiency this inflection point of the spectral curve can oscillate towards higher or lower wavelengths (Boyer et al, 1988). …”