Soil-dependent spectral response in a developing plant canopy

American Society of Agronomy, Inc
Publication Type:
Journal Article
Agronomy Journal, 1987, 79 (1), pp. 31 - 68
Issue Date:
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Amajor problem in the use of remote sensing techniques to assess plant biomass and condition over incomplete canopies concerns the soil background contribution toward measured spectral response. An understanding of this soil signal is essential 10 better relate canopy spectra with plant properties. An interactive, plant-soil radiant flux model was developed to separate spectral variations associated with soil background from those attrlbutable to vegetation. Field measured spectra taken over It developing cotton (Gossypinm hirsutum L.) canopy with four soil types (Cumnlic Cryoboroll, Typic TorriHuvent, Ustollic Haplargid, and Typic Calciorthid) alternately inserted underneath were decomposed into soil and vegetation spectra by utilizing the model in It principal component analysis. The soil component included all radiation penetrating the canopy and inter~ acting with the underlying soil. The vegetation compOnent repre· seoted all radiation reflected directly from the plant tover with no soil interaction. The soil component was found to resemble the spectral response of green vegetation due to the scattering and trans-mittance properties of the overlying plant canopy. Results show how the soil signal mixes into various vegetation indices inhibiting reliable vegetation discrimination. The potential improvements in veg· etation analysis that can result from filtering soil background response from planHanopy spectra are also discussed.
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