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Estimating the biophysical properties of tropical forests : the role of middle infrared radiation (1.5-5.0 um)

Estimating the biophysical properties of tropical forests : the role of middle infrared radiation (1.5-5.0 um)
Estimating the biophysical properties of tropical forests : the role of middle infrared radiation (1.5-5.0 um)

The concentration of carbon dioxide in the atmosphere is increasing, but the amount and rate of increase is still less than expected given our current knowledge of atmospheric carbon sources and sinks. It has been hypothesised that the terrestrial biosphere in general and tropical forests in particular are acting as major and underestimated sinks of atmospheric carbon. A possible mechanism for these sinks is the rapid regeneration of forests following the abandonment of previously cleared land, with the strength of the sinks being a function of regeneration stage. Regeneration stages can be characterised by biophysical properties, such as leaf and wood biomass, which influence the radiance emitted and/or reflected from the forest canopy. Remotely sensed data may therefore be used to estimate these biophysical properties and thereby determine forest regeneration stage. Previous studies conducted in temperate forests have related biophysical properties successfully with visible and near infrared (NIR) radiation, on their own or combined within vegetation indices (e.g. the Normalised Difference Vegetation Index (NDVI)). However, only weak correlations have generally been observed for tropical forests and therefore an alternative approach must be sought.

This thesis investigated the potential of using middle infrared (MIR) radiation for the estimation of biophysical properties of tropical forests. More specifically, the thesis proposed that strong relationships exist between MIR radiation and biophysical properties of tropical forests and that these relationships are stronger than those derived with visible and NIR radiation. This proposal was explored at three sites located throughout the forested tropics (the Brazilian Amazon, south west Ghana and southern Cameroon). In general, the proposal was corroborated with strong relationships attained between measured biophysical properties (e.g. mean basal area) or surrogates for these (e.g. forest age) and MIR radiation at each site. Moreover, vegetation indices containing data acquired in MIR wavelengths were more strongly related to the biophysical properties than was the NDVI.

University of Southampton
Boyd, Doreen Sandra
8fd8f688-355f-40db-98bd-3ed3150c93e1
Boyd, Doreen Sandra
8fd8f688-355f-40db-98bd-3ed3150c93e1

Boyd, Doreen Sandra (1996) Estimating the biophysical properties of tropical forests : the role of middle infrared radiation (1.5-5.0 um). University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

The concentration of carbon dioxide in the atmosphere is increasing, but the amount and rate of increase is still less than expected given our current knowledge of atmospheric carbon sources and sinks. It has been hypothesised that the terrestrial biosphere in general and tropical forests in particular are acting as major and underestimated sinks of atmospheric carbon. A possible mechanism for these sinks is the rapid regeneration of forests following the abandonment of previously cleared land, with the strength of the sinks being a function of regeneration stage. Regeneration stages can be characterised by biophysical properties, such as leaf and wood biomass, which influence the radiance emitted and/or reflected from the forest canopy. Remotely sensed data may therefore be used to estimate these biophysical properties and thereby determine forest regeneration stage. Previous studies conducted in temperate forests have related biophysical properties successfully with visible and near infrared (NIR) radiation, on their own or combined within vegetation indices (e.g. the Normalised Difference Vegetation Index (NDVI)). However, only weak correlations have generally been observed for tropical forests and therefore an alternative approach must be sought.

This thesis investigated the potential of using middle infrared (MIR) radiation for the estimation of biophysical properties of tropical forests. More specifically, the thesis proposed that strong relationships exist between MIR radiation and biophysical properties of tropical forests and that these relationships are stronger than those derived with visible and NIR radiation. This proposal was explored at three sites located throughout the forested tropics (the Brazilian Amazon, south west Ghana and southern Cameroon). In general, the proposal was corroborated with strong relationships attained between measured biophysical properties (e.g. mean basal area) or surrogates for these (e.g. forest age) and MIR radiation at each site. Moreover, vegetation indices containing data acquired in MIR wavelengths were more strongly related to the biophysical properties than was the NDVI.

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Published date: 1996

Identifiers

Local EPrints ID: 460218
URI: http://eprints.soton.ac.uk/id/eprint/460218
PURE UUID: d5131db0-beaa-4bd3-9b92-0676cdb244c2

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Date deposited: 04 Jul 2022 18:13
Last modified: 23 Jul 2022 00:58

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Author: Doreen Sandra Boyd

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