David C Le Maitre | Council for Scientific and Industrial Research (CSIR) (original) (raw)
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Papers by David C Le Maitre
South African Journal of Science, Oct 1, 2007
... Important issues identified in these studies. ... This study was funded by the CSIR from the ... more ... Important issues identified in these studies. ... This study was funded by the CSIR from the Strategic Research Panel budget under the project 'The flow of benefits to people provided by ecosystems at multiple scales: a spatial ... Sustainability science: the emerging research program. ...
Ecological Economics, Aug 31, 1997
Water S a, Oct 1, 2008
... Those with evenly distributed and relatively low rainfall and low BFI - J25D, J35A, J35D in t... more ... Those with evenly distributed and relatively low rainfall and low BFI - J25D, J35A, J35D in the Little Karoo, H90E in the ... CHEVALIER L, GIBSON LA, NHLEKO LO, WOODFORD AC, NOMQUPHU W AND KIPPIE I (2004) Hydrogeology of fractured-rock aquifers and related ...
South African Journal of Botany, 2009
Restoration Ecology, 2015
Water S.A
... TABLE 2 RELATIVE WATER INFILTRATION RATES IN RELATION TO SOIL TEXTURE AND PRESENCE OF A WOODY... more ... TABLE 2 RELATIVE WATER INFILTRATION RATES IN RELATION TO SOIL TEXTURE AND PRESENCE OF A WOODY ... Soil water, groundwater extraction and root depths ... 100% (or more in situations where plants are tapping stored water) but generally ranges between 45 and ...
Copyright: 2009 Botanical Society of South Africa With enhanced global warming predicted to have ... more Copyright: 2009 Botanical Society of South Africa With enhanced global warming predicted to have major impacts on our flora and fauna, environmentalists are on the lookout for any signs of our flora responding to climate change. So it was with alarm that Nick Helme reported mass mortality on the north slopes of the Cradocksberg in July 2008. Further investigation by Di and Bill Turner showed that the dead patches extended from George to Engelseberg (near Robinson Pass) and in some areas were quite bad.
The impacts of the widespread invasions by alien plants in South Africa are increasingly recognis... more The impacts of the widespread invasions by alien plants in South Africa are increasingly recognised. Most of the past concern has been about the impacts on conservation areas, other areas of natural vegetation and on agricultural productivity. The potential impact of invading alien woody plants on water resources was known to be serious but there has been no information available to evaluate the significance of these water losses across the whole country. This paper reports on the results of a preliminary survey aimed at obtaining an overview of the extent, impacts and implications of alien plant invasions at a national and regional level for South Africa and Lesotho. Data on the extent and location of the invaded areas were obtained from a variety of sources including detailed field mapping, mainly at a 1:250 000 scale with some at 1:50 000 and 1:10 000, and generalised information on species and densities. The density class of each species in each polygon was mapped and used to de...
Diversity and Distributions
Data on the nutrient pool sizes in fynbos vegetation and estimates of nutrients released followin... more Data on the nutrient pool sizes in fynbos vegetation and estimates of nutrients released following actual or hypothetical fires at three fynbos sites are presented. Nutrient pool sizes vary between the sites, but they reflect the very low levels of essential nutrients typical of fynbos sites. Nutrients released by fire will vary with individual fires and sites. There are some
AoB PLANTS, 2015
ABSTRACT There have been many studies of the diverse impacts of invasions by alien plants but few... more ABSTRACT There have been many studies of the diverse impacts of invasions by alien plants but few have assessed impacts on water resources. We reviewed the information on the impacts of invasions on surface runoff and groundwater resources at stand to catchment scales and covering a full annual cycle. Most of the research is South African so the emphasis is on South Africa's major invaders with data from commercial forest plantations where relevant. Catchment studies worldwide have shown that changes in vegetation structure and the physiology of the dominant plant species result in changes in surface runoff and groundwater discharge, whether they involve native or alien plant species. Where there is little change in vegetation structure (e.g. leaf area [index], height, rooting depth and seasonality) the effects of invasions generally are small or undetectable. In South Africa, the most important woody invaders typically are taller and deeper rooted than the native species. The impacts of changes in evaporation (and thus runoff) in dryland settings are constrained by water availability to the plants and, thus, by rainfall. Where the dryland invaders are evergreen and the native vegetation (grass) is seasonal the increases can reach 300-400 mm/yr. Where the native vegetation is evergreen (shrublands) the increases are about 200-300 mm/yr. Where water availability is greater (riparian settings or shallow water tables), invading tree water-use can reach 1.5-2.0 times that of the same species in a dryland setting. So riparian invasions have a much greater impact per unit area invaded than dryland invasions. The available data are scattered and incomplete, and there are many gaps and issues that must be addressed before a thorough understanding of the impacts at the site scale can be gained and used in extrapolating to watershed scales, and in converting changes in flows to water supply system yields. Published by Oxford University Press on behalf of the Annals of Botany Company.
South African Journal of Botany, 2015
ABSTRACT Many Prosopis species have been introduced to South Africa; some taxa and their hybrids ... more ABSTRACT Many Prosopis species have been introduced to South Africa; some taxa and their hybrids have naturalised and become widespread invasive trees. These invasions have detrimental effects on biodiversity, ecosystem services and human livelihoods. Although several studies have documented these impacts, the studies have been limited to single sites or restricted areas. This study assessed the Prosopis population across the full invasive range of the genus in South Africa, and quantified the effects of invasions on native woody and herbaceous species. Basal areas of invasive Prosopis stands reached 9 m2/ha, and were on average higher along perennial rivers than along ephemeral rivers (mean basal areas of 3.2 vs. 1.4 m2/ha). Native woody species density, basal area, richness and diversity all decreased significantly as the basal area of Prosopis stands increased. For example, up to eight native woody species occurred at basal area of < 2 m2/ha, this decreased to three native species or fewer at basal areas of > 4 m2/ha. The cover of native perennial grasses and herbaceous plants declined from 15–20% where the basal area of Prosopis was < 2 m2/ha to zero where the basal area of Prosopis was > 4.5 m2/ha. The results highlight the widespread nature of the impacts across all invaded biomes. Current control of Prosopis has had limited success, and alternative, potentially more effective, options are controversial. In the light of the widespread impacts, we recommend that a thorough assessment of the problem be undertaken to inform policy.
Journal of Arid Environments, 2015
Trends in ecology & evolution, 1998
South African Journal of Science, Oct 1, 2007
... Important issues identified in these studies. ... This study was funded by the CSIR from the ... more ... Important issues identified in these studies. ... This study was funded by the CSIR from the Strategic Research Panel budget under the project &#x27;The flow of benefits to people provided by ecosystems at multiple scales: a spatial ... Sustainability science: the emerging research program. ...
Ecological Economics, Aug 31, 1997
Water S a, Oct 1, 2008
... Those with evenly distributed and relatively low rainfall and low BFI - J25D, J35A, J35D in t... more ... Those with evenly distributed and relatively low rainfall and low BFI - J25D, J35A, J35D in the Little Karoo, H90E in the ... CHEVALIER L, GIBSON LA, NHLEKO LO, WOODFORD AC, NOMQUPHU W AND KIPPIE I (2004) Hydrogeology of fractured-rock aquifers and related ...
South African Journal of Botany, 2009
Restoration Ecology, 2015
Water S.A
... TABLE 2 RELATIVE WATER INFILTRATION RATES IN RELATION TO SOIL TEXTURE AND PRESENCE OF A WOODY... more ... TABLE 2 RELATIVE WATER INFILTRATION RATES IN RELATION TO SOIL TEXTURE AND PRESENCE OF A WOODY ... Soil water, groundwater extraction and root depths ... 100% (or more in situations where plants are tapping stored water) but generally ranges between 45 and ...
Copyright: 2009 Botanical Society of South Africa With enhanced global warming predicted to have ... more Copyright: 2009 Botanical Society of South Africa With enhanced global warming predicted to have major impacts on our flora and fauna, environmentalists are on the lookout for any signs of our flora responding to climate change. So it was with alarm that Nick Helme reported mass mortality on the north slopes of the Cradocksberg in July 2008. Further investigation by Di and Bill Turner showed that the dead patches extended from George to Engelseberg (near Robinson Pass) and in some areas were quite bad.
The impacts of the widespread invasions by alien plants in South Africa are increasingly recognis... more The impacts of the widespread invasions by alien plants in South Africa are increasingly recognised. Most of the past concern has been about the impacts on conservation areas, other areas of natural vegetation and on agricultural productivity. The potential impact of invading alien woody plants on water resources was known to be serious but there has been no information available to evaluate the significance of these water losses across the whole country. This paper reports on the results of a preliminary survey aimed at obtaining an overview of the extent, impacts and implications of alien plant invasions at a national and regional level for South Africa and Lesotho. Data on the extent and location of the invaded areas were obtained from a variety of sources including detailed field mapping, mainly at a 1:250 000 scale with some at 1:50 000 and 1:10 000, and generalised information on species and densities. The density class of each species in each polygon was mapped and used to de...
Diversity and Distributions
Data on the nutrient pool sizes in fynbos vegetation and estimates of nutrients released followin... more Data on the nutrient pool sizes in fynbos vegetation and estimates of nutrients released following actual or hypothetical fires at three fynbos sites are presented. Nutrient pool sizes vary between the sites, but they reflect the very low levels of essential nutrients typical of fynbos sites. Nutrients released by fire will vary with individual fires and sites. There are some
AoB PLANTS, 2015
ABSTRACT There have been many studies of the diverse impacts of invasions by alien plants but few... more ABSTRACT There have been many studies of the diverse impacts of invasions by alien plants but few have assessed impacts on water resources. We reviewed the information on the impacts of invasions on surface runoff and groundwater resources at stand to catchment scales and covering a full annual cycle. Most of the research is South African so the emphasis is on South Africa's major invaders with data from commercial forest plantations where relevant. Catchment studies worldwide have shown that changes in vegetation structure and the physiology of the dominant plant species result in changes in surface runoff and groundwater discharge, whether they involve native or alien plant species. Where there is little change in vegetation structure (e.g. leaf area [index], height, rooting depth and seasonality) the effects of invasions generally are small or undetectable. In South Africa, the most important woody invaders typically are taller and deeper rooted than the native species. The impacts of changes in evaporation (and thus runoff) in dryland settings are constrained by water availability to the plants and, thus, by rainfall. Where the dryland invaders are evergreen and the native vegetation (grass) is seasonal the increases can reach 300-400 mm/yr. Where the native vegetation is evergreen (shrublands) the increases are about 200-300 mm/yr. Where water availability is greater (riparian settings or shallow water tables), invading tree water-use can reach 1.5-2.0 times that of the same species in a dryland setting. So riparian invasions have a much greater impact per unit area invaded than dryland invasions. The available data are scattered and incomplete, and there are many gaps and issues that must be addressed before a thorough understanding of the impacts at the site scale can be gained and used in extrapolating to watershed scales, and in converting changes in flows to water supply system yields. Published by Oxford University Press on behalf of the Annals of Botany Company.
South African Journal of Botany, 2015
ABSTRACT Many Prosopis species have been introduced to South Africa; some taxa and their hybrids ... more ABSTRACT Many Prosopis species have been introduced to South Africa; some taxa and their hybrids have naturalised and become widespread invasive trees. These invasions have detrimental effects on biodiversity, ecosystem services and human livelihoods. Although several studies have documented these impacts, the studies have been limited to single sites or restricted areas. This study assessed the Prosopis population across the full invasive range of the genus in South Africa, and quantified the effects of invasions on native woody and herbaceous species. Basal areas of invasive Prosopis stands reached 9 m2/ha, and were on average higher along perennial rivers than along ephemeral rivers (mean basal areas of 3.2 vs. 1.4 m2/ha). Native woody species density, basal area, richness and diversity all decreased significantly as the basal area of Prosopis stands increased. For example, up to eight native woody species occurred at basal area of < 2 m2/ha, this decreased to three native species or fewer at basal areas of > 4 m2/ha. The cover of native perennial grasses and herbaceous plants declined from 15–20% where the basal area of Prosopis was < 2 m2/ha to zero where the basal area of Prosopis was > 4.5 m2/ha. The results highlight the widespread nature of the impacts across all invaded biomes. Current control of Prosopis has had limited success, and alternative, potentially more effective, options are controversial. In the light of the widespread impacts, we recommend that a thorough assessment of the problem be undertaken to inform policy.
Journal of Arid Environments, 2015
Trends in ecology & evolution, 1998