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Monitoring land degradation in South...

Wessels, Konrad J.

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Monitoring land degradation in Southern Africa by assessing changes in primary productivity.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Monitoring land degradation in Southern Africa by assessing changes in primary productivity./
Author:	Wessels, Konrad J.
Description:	160 p.
Notes:	Source: Dissertation Abstracts International, Volume: 66-05, Section: A, page: 1909.
Contained By:	Dissertation Abstracts International66-05A.
Subject:	Geography. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3175149
ISBN:	9780542130366

Monitoring land degradation in Southern Africa by assessing changes in primary productivity.
Wessels, Konrad J.

Monitoring land degradation in Southern Africa by assessing changes in primary productivity. - 160 p.

Source: Dissertation Abstracts International, Volume: 66-05, Section: A, page: 1909.

Thesis (Ph.D.)--University of Maryland, College Park, 2005.

Land degradation is one of the most serious environmental problems of our time. Land degradation describes circumstances of reduced biological productivity. The fundamental goal of this thesis was to develop land degradation monitoring approaches based on remotely sensed estimates of vegetation production, which are capable of distinguishing human impacts from the effects of natural climatic and spatial variability. Communal homelands in South Africa (SA) are widely regarded to be severely degraded and the existence adjacent, non-degraded areas with the same soils and climate, provides a unique opportunity to test regional land degradation monitoring methods.

ISBN: 9780542130366Subjects--Topical Terms:

524010
Geography.

Monitoring land degradation in Southern Africa by assessing changes in primary productivity.
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100 1 $a Wessels, Konrad J. $3 1912569
245 1 0 $a Monitoring land degradation in Southern Africa by assessing changes in primary productivity.
300 $a 160 p.
500 $a Source: Dissertation Abstracts International, Volume: 66-05, Section: A, page: 1909.
500 $a Chair: Stephen D. Prince.
502 $a Thesis (Ph.D.)--University of Maryland, College Park, 2005.
520 $a Land degradation is one of the most serious environmental problems of our time. Land degradation describes circumstances of reduced biological productivity. The fundamental goal of this thesis was to develop land degradation monitoring approaches based on remotely sensed estimates of vegetation production, which are capable of distinguishing human impacts from the effects of natural climatic and spatial variability. Communal homelands in South Africa (SA) are widely regarded to be severely degraded and the existence adjacent, non-degraded areas with the same soils and climate, provides a unique opportunity to test regional land degradation monitoring methods.
520 $a The relationship between 1km2 AVHRR, growth season SigmaNDVI and herbaceous biomass measurements (1989--2003) was firstly tested in Kruger National Park, SA. The relationship was moderately strong, but weaker than expected. This was attributed to the fact that the small areas sampled at field sites were not representative of the spatial variability within 1km 2. The SigmaNDVI adequately estimated inter-annual changes in vegetation production and should therefore be useful for monitoring land degradation.
520 $a Degraded areas mapped by the National-Land-Cover in north-eastern SA were compared to non-degraded areas in the same land capability units. The SigmaNDVI of the degraded areas was consistently lower, regardless of large variations in rainfall. However, the ecological stability and resilience of the degraded areas, as measured by the annual deviations from each pixel's mean SigmaNDVI were no different to those of non-degraded areas. This suggests that the degraded areas may be in an alternative, but stable ecological state.
520 $a To monitor human-induced land degradation it is essential to control for the effects of rainfall on vegetation production. Two methods were tested (i) Rain-Use Efficiency (RUE = NPP/Rainfall) and (ii) negative trends in the differences between the observed SigmaNDVI and the SigmaNDVI predicted by the rainfall using regressions calculated for each pixel (RESTREND). RUE had a strong negative correlation with rainfall and did not provide a reliable index of degradation. The RESTREND method identified areas in and around the degraded communal lands that exhibit negative trends in production per unit rainfall. This research made a significant contribution to the development of remote sensing based land degradation monitoring methods.
590 $a School code: 0117.
650 4 $a Geography. $3 524010
650 4 $a Biology, Plant Physiology. $3 1017865
650 4 $a Agriculture, Range Management. $3 1022885
690 $a 0366
690 $a 0817
690 $a 0777
710 2 0 $a University of Maryland, College Park. $3 657686
773 0 $t Dissertation Abstracts International $g 66-05A.
790 1 0 $a Prince, Stephen D., $e advisor
790 $a 0117
791 $a Ph.D.
792 $a 2005
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3175149