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Title: Relationships between forest biophysical properties and polarimetric radar backscatter
Author: Green, R. M.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1995
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Accurate quantitative biophysical estimates derived from remotely sensed data are required for effective forest monitoring and to enhance the understanding of biospheric processes at regional and global scales. The aim of this thesis was to examine relationships between forest biophysical properties and polarimetric synthetic aperture radar (SAR) backscatter. Multiwaveband polarimetric SAR data were acquired by the NASA/JPL. AIRSAR over coniferous plantations in Thetford Forest, East Anglia and the Tywi forest, central Wales. Thetford Forest was located on relatively flat terrain and the Tywi forest was an upland plantation with variable topography. A simple classification of the Thetford Forest SAR data showed that species and age classes could be distinguished to a high level of separability when using data from all wavebands. Backscatter, represented by mean amplitude, increased with compartment age until 20 years, with the strongest relationships evident using long wavelength P- and L-band data. The strength of relationships, especially in C-band, were improved when variables representing changes in scattering behaviour (e.g. polarization ratios) were used. Backscatter from the Tywi forest was found to be highly dependent on viewing geometry; a function of radar look angle and topography. Relationships between mean amplitude and estimates of forest biophysical properties related to above-ground biomass (e.g. stem biomass) were significant only for stands situated at high incidence angles and with little topographic variability. Mean percentage canopy closure was significantly related to polarization ratios and coefficients of variation, but not to single wavebank/polarization mean amplitude. It was found that canopy gaps formed by windthrow could be identified and that the remotely sensed response was related to geometric properties of the gaps (e.g. area, perimeter). In conclusion, the research highlighted the potential for deriving quantitative estimates of a range of forest biophysical properties when multidimensional SAR data is available.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available