A modelling approach to the biochemical assay of vegetation canopies from remote sensing
A modelling approach to the biochemical assay of vegetation canopies from remote sensing
Understanding the interaction of radiation with vegetation canopies requires a knowledge of the spectral properties of individual leaves. Leaves are an important component of forest canopies and it is their biochemical constituents, namely pigments, water, nitrogen, cellulose and lignin, together with canopy structure that shapes the absorption features of remotely sensed reflectance spectra. Absorption features in the near infrared region of the spectrum (900 - 2500 nm) are a function of the bending and stretching vibrations of biochemical bonds together with their harmonics and overtones. In the visible region (400 - 700 nm), chlorophyll and carotenoid pigments have strong absorption due to electron energy transitions.
Fine spectral resolution remotely sensed data can be analysed statically using multiple linear regression to estimate the concentration of biochemicals in forest canopies. Such information has been used to drive ecosystem simulation models and estimate photosynthetic efficiency, rate of nutrient cycling and degree of vegetation stress. However, wavebands selected by multiple linear regression of canopy spectra using biochemical assay data are often not consistent with the absorption features of the biochemicals within the leaves. Significantly, statistical relationships between canopy spectra and biochemical concentrations are highly site-specific and are not robust. Reports have suggested that these problems might be attributable to spectral variation in canopy architecture and atmosphere.
This thesis presents a new leaf model, LIBERTY, which has been designed to simulate the reflectance and transmittance spectra of conifer needles. The analysis and coupling of LIBERTY and a hybrid Monte Carlo ray-tracing canopy model was investigated to see if the absorption features of the key foliar biochemicals visible in the leaf spectrum are preserved in the canopy reflectance spectrum. The potential for estimating biochemical concentrations from leaf and canopy spectra was then assessed using a variety of inverted model and empirical techniques.
University of Southampton
1997
Dawson, Terence Peter
(1997)
A modelling approach to the biochemical assay of vegetation canopies from remote sensing.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Understanding the interaction of radiation with vegetation canopies requires a knowledge of the spectral properties of individual leaves. Leaves are an important component of forest canopies and it is their biochemical constituents, namely pigments, water, nitrogen, cellulose and lignin, together with canopy structure that shapes the absorption features of remotely sensed reflectance spectra. Absorption features in the near infrared region of the spectrum (900 - 2500 nm) are a function of the bending and stretching vibrations of biochemical bonds together with their harmonics and overtones. In the visible region (400 - 700 nm), chlorophyll and carotenoid pigments have strong absorption due to electron energy transitions.
Fine spectral resolution remotely sensed data can be analysed statically using multiple linear regression to estimate the concentration of biochemicals in forest canopies. Such information has been used to drive ecosystem simulation models and estimate photosynthetic efficiency, rate of nutrient cycling and degree of vegetation stress. However, wavebands selected by multiple linear regression of canopy spectra using biochemical assay data are often not consistent with the absorption features of the biochemicals within the leaves. Significantly, statistical relationships between canopy spectra and biochemical concentrations are highly site-specific and are not robust. Reports have suggested that these problems might be attributable to spectral variation in canopy architecture and atmosphere.
This thesis presents a new leaf model, LIBERTY, which has been designed to simulate the reflectance and transmittance spectra of conifer needles. The analysis and coupling of LIBERTY and a hybrid Monte Carlo ray-tracing canopy model was investigated to see if the absorption features of the key foliar biochemicals visible in the leaf spectrum are preserved in the canopy reflectance spectrum. The potential for estimating biochemical concentrations from leaf and canopy spectra was then assessed using a variety of inverted model and empirical techniques.
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Published date: 1997
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Local EPrints ID: 463170
URI: http://eprints.soton.ac.uk/id/eprint/463170
PURE UUID: cc4ec813-c2d1-4dc3-aabb-ffeff4fbfc53
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Date deposited: 04 Jul 2022 20:46
Last modified: 04 Jul 2022 20:46
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Author:
Terence Peter Dawson
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