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Patchiness in semi‐arid dwarf shrublands: Evidence from satellite‐derived indices for elevated CO2 assimilation rates on a geochemical mound in the Karoo National Park, South Africa

Patchiness in semi‐arid dwarf shrublands: Evidence from satellite‐derived indices for elevated... Abstract Satellite‐derived vegetation indices were used to identify a geochemical mound of higher active greenness in the Karoo National Park, Beaufort West, South Africa. We determined whether this mound was occupied by plants with higher CO2 assimilation rate. Plant cover on and off the mound was determined. Three woody species with high cover were selected for further investigation. Two deep‐rooted species, Rhigozum obovatum Burch. and Eriocephalus ericoides (L.f.) Druce, showed greater net CO2 assimilation rates on the mound. Net CO2 assimilation rates for the third species, Pentzia incana (Thunb.) Kuntze were similar both on and off the mound. In an attempt to find a mechanistic basis for the elevated CO2 assimilation rates, the relationships between soil factors, foliar nutrients and CO2 assimilation capacity were also examined. Our results suggest that the elevated net CO2 assimilation was not mediated via improved soil or plant water relations on the actively greening mound, nor through a difference in nitrogen levels in the soil or plant material, but possibly by way of the higher sub‐soil phosphorus levels measured from the geochemical mound. Genotype and cover cannot alone be used for rangeland condition assessment since localized elevated soil nutrient status (patchiness) contributes to greater photosynthetic carbon gain which may confer superior browsing responses to plants occurring on these mounds. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png African Journal of Range & Forage Science Taylor & Francis

Patchiness in semi‐arid dwarf shrublands: Evidence from satellite‐derived indices for elevated CO2 assimilation rates on a geochemical mound in the Karoo National Park, South Africa

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Patchiness in semi‐arid dwarf shrublands: Evidence from satellite‐derived indices for elevated CO2 assimilation rates on a geochemical mound in the Karoo National Park, South Africa

Abstract

Abstract Satellite‐derived vegetation indices were used to identify a geochemical mound of higher active greenness in the Karoo National Park, Beaufort West, South Africa. We determined whether this mound was occupied by plants with higher CO2 assimilation rate. Plant cover on and off the mound was determined. Three woody species with high cover were selected for further investigation. Two deep‐rooted species, Rhigozum obovatum Burch. and Eriocephalus ericoides (L.f.) Druce,...
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Publisher
Taylor & Francis
Copyright
Copyright Taylor & Francis Group, LLC
ISSN
1727-9380
eISSN
1022-0119
DOI
10.1080/10220119.1997.9647925
Publisher site
See Article on Publisher Site

Abstract

Abstract Satellite‐derived vegetation indices were used to identify a geochemical mound of higher active greenness in the Karoo National Park, Beaufort West, South Africa. We determined whether this mound was occupied by plants with higher CO2 assimilation rate. Plant cover on and off the mound was determined. Three woody species with high cover were selected for further investigation. Two deep‐rooted species, Rhigozum obovatum Burch. and Eriocephalus ericoides (L.f.) Druce, showed greater net CO2 assimilation rates on the mound. Net CO2 assimilation rates for the third species, Pentzia incana (Thunb.) Kuntze were similar both on and off the mound. In an attempt to find a mechanistic basis for the elevated CO2 assimilation rates, the relationships between soil factors, foliar nutrients and CO2 assimilation capacity were also examined. Our results suggest that the elevated net CO2 assimilation was not mediated via improved soil or plant water relations on the actively greening mound, nor through a difference in nitrogen levels in the soil or plant material, but possibly by way of the higher sub‐soil phosphorus levels measured from the geochemical mound. Genotype and cover cannot alone be used for rangeland condition assessment since localized elevated soil nutrient status (patchiness) contributes to greater photosynthetic carbon gain which may confer superior browsing responses to plants occurring on these mounds.

Journal

African Journal of Range & Forage Science – Taylor & Francis

Published: Dec 1, 1997

Keywords: NDVI; nutrients

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