Nicky Allsopp - Academia.edu (original) (raw)
Papers by Nicky Allsopp
Ecology, Evolution, and Conservation of a Megadiverse Region, 2014
Ecology, Evolution, and Conservation of a Megadiverse Region, 2014
Journal of Arid Environments, 2007
... Lee Simons Corresponding Author Contact Information , a , E-mail The Corresponding Author and... more ... Lee Simons Corresponding Author Contact Information , a , E-mail The Corresponding Author and Nicky Allsopp a , E-mail The Corresponding Author. ... shading and competition for water with the adult plant can also reduce the growth of associated seedlings (Franco and Nobel ...
ABSTRACT Anthropogenic nitrogen (N) emissions have increased dramatically since the agricultural ... more ABSTRACT Anthropogenic nitrogen (N) emissions have increased dramatically since the agricultural and industrial revolutions leading to N deposition in the northern hemisphere that is estimated to be an order of magnitude greater than preindustrial fluxes. N deposition rates of 5-15 kg N ha-1 yr-1 in Europe and N. America decrease plant species diversity, increase invasive species, and lead to eutrophication of surface waters. The southern hemisphere is home to over 50% of the world's biodiversity hotspots, including the 90,000 km2 Cape Floristic Region which houses 9,030 vascular plant species, 69% of which are endemic. However, to date, N deposition rates in the southern hemisphere are highly uncertain, with global models of N deposition based upon sparse datasets at best. Many terrestrial systems, such as fynbos shrublands, are adapted to low N availability and exhibit high species diversity and endemism, rendering them susceptible to ecological changes from N deposition. In this research, we quantified the spatial and temporal distribution of wet and dry N deposition across 30 protected fynbos ecosystems within the urban airshed of Cape Town, South Africa. We predicted that 1) total inorganic N deposition varies predictably along the urban-rural gradient (highest near the city centre), 2) N deposition varies seasonally, with higher fluxes in the winter months when atmospheric stability causes a build-up of N gases in and around the city, and 3) total inorganic N deposition will exceed the critical load of 10-15 kg N ha-1 yr-1 for Mediterranean shrublands, past which negative ecosystem effects have been shown to occur. Estimates of N deposition based on NO2 concentrations within the city suggest that total N deposition ranges from 8-13 kg N ha-1 yr-1 . However, we show that N deposition measured by ion-exchange resin collectors is far less than expected, averaging less than 2 kg N ha-1 yr-1 (range 0.5 - 5.5 kg N ha-1 yr-1 ), and is is dominated by NO3-, suggesting combustion sources. Despite low rates compared to northern hemisphere studies, throughfall N fluxes are lower on average than bulk N fluxes, suggesting significant N uptake through the canopy. Preliminary analyses of cloud water + dry deposition show concentrations of N up to an order of magnitude higher than rainfall. These results suggest that dry and cloud water deposition may contribute high N loads to fynbos shrublands, but these areas may be localized to mountain tops near the city center.
Revue Tiers Monde, 2009
Au début des années 1990, les approches d'« evidencebased medicine » ont commencé à être formalis... more Au début des années 1990, les approches d'« evidencebased medicine » ont commencé à être formalisées pour permettre l'usage le plus judicieux possible des connaissances disponibles par les praticiens, le mot « evidence » renvoyant à la fois aux idées de corroboration empirique et de preuve. Ces approches se sont étendues à d'autres sphères de la décision publique (lutte contre la pauvreté, éducation, justice, environnement...), donnant naissance à la notion d'« evidence-based policy » (EBP). Dans le monde francophone, ces approches sont souvent assimilées à un simple effet de rhétorique ou à une tentative de dépolitiser les débats. L'analyse de leur genèse invite à plus de nuances et montre plutôt la volonté de renouveler les démarches positives d'aide à la décision publique en proposant des méthodes ad hoc offrant une alternative au recours croissant à des modèles de connaissances reposant trop exclusivement sur des opinions ou des simulations qui s'exonèrent de tests de validation empiriques.
South African Journal of Science, 2012
Plant Ecology, 2011
Nearest-neighbour analysis was used to examine the competitive interactions between Stipagrostis ... more Nearest-neighbour analysis was used to examine the competitive interactions between Stipagrostis brevifolia, a C 4 perennial grass, and two leaf succulent shrubs, Ruschia robusta and Leipoldtia pauciflora, at the ecotone between semi-arid grassland and succulent shrubland in the Karoo. The root distribution in the soil was also compared to assess the degree of overlap in the potential use of soil resources. Regressions between the combined sizes of interspecific, nearest-neighbour species and the distance between them showed significant positive correlations for S. brevifolia and R. robusta, which suggest the presence of competition. We infer from individual species regressions that the grass exerted a stronger competitive force on the shrub R. robusta than R. robusta on the grass. There was also evidence for strong intraspecific competitive relationships within S. brevifolia and R. robusta. There was no evidence of competition between S. brevifolia and L. pauciflora or among L. pauciflora individuals. S. brevifolia had the deepest root system, and was recorded at depths of 70 cm. Most of this root mass occurred between 10 and 40 cm. Ruschia robusta roots were recorded as deep as 55 cm, but more than 90% was found in the top 20 cm of the soil, creating a degree of overlap with the vertical root distribution of S. brevifolia. A clear separation in rooting depths occurred between S. brevifolia, and L. pauciflora which had only 3% of the total root mass below 10 cm. The partial overlap in the vertical root distribution between S. brevifolia and R. robusta may account for the observed competitive relationship, but each species dominates in a different layer, potentially minimising the net competition between S. brevifolia and R. robusta. Our findings demonstrate the possibility of a two-layer water-obtaining strategy in a semi-desert ecosystem, where the succulent shrubs seem to be playing the typical ''grass'' role described in most models of water partitioning between grass and woody plants. The stronger competitive effect of S. brevifolia on R. robusta at all the sites is of significance to species dynamics, and might be related to winter/summer rainfall dynamics at the climatic transition.
Plant Ecology, 2005
We describe the long-term effects of a CO 2 exhalation, created more than 70 years ago, on a natu... more We describe the long-term effects of a CO 2 exhalation, created more than 70 years ago, on a natural C 4 dominated sub-tropical grassland in terms of ecosystem structure and functioning. We tested whether longterm CO 2 enrichment changes the competitive balance between plants with C 3 and C 4 photosynthetic pathways and how CO 2 enrichment has affected species composition, plant growth responses, leaf properties and soil nutrient, carbon and water dynamics. Long-term effects of elevated CO 2 on plant community composition and system processes in this sub-tropical grassland indicate very subtle changes in ecosystem functioning and no changes in species composition and dominance which could be ascribed to elevated CO 2 alone. Species compositional data and soil d 13 C isotopic evidence suggest no detectable effect of CO 2 enrichment on C 3 :C 4 plant mixtures and individual species dominance. Contrary to many general predictions C 3 grasses did not become more abundant and C 3 shrubs and trees did not invade the site. No season length stimulation of plant growth was found even after 5 years of exposure to CO 2 concentrations averaging 610 lmol mol À1 . Leaf properties such as total N decreased in the C 3 but not C 4 grass under elevated CO 2 while total non-structural carbohydrate accumulation was not affected. Elevated CO 2 possibly lead to increased end-of-season soil water contents and this result agrees with earlier studies despite the topographic water gradient being a confounding problem at our research site. Long-term CO 2 enrichment also had little effect on soil carbon storage with no detectable changes in soil organic matter found. There were indications that potential soil respiration and N mineralization rates could be higher in soils close to the CO 2 source. The conservative response of this grassland suggests that many of the reported effects of elevated CO 2 on similar ecosystems could be short duration experimental artefacts that disappear under long-term elevated CO 2 conditions.
Plant and Soil, 2011
Here we aim to demonstrate that in arid environments the competitive balance between species can ... more Here we aim to demonstrate that in arid environments the competitive balance between species can be determined by niche separation with either nitrogen or water as the relevant niche axis. To do this we sampled roots <2 mm in diameter for 5 soil pits equidistant between two coexisting species, a shrub and a grass. Using stable carbon and nitrogen isotope ratios of fine roots we determine both photosynthetic pathway and rooting depth. We also examine the distribution of soil moisture and nitrogen relative to root biomass. Our results for root biomass and stable isotope ratios of fine roots demonstrate both niche separation and competition for resources. Root biomass is highest at the top of the profile where soil nitrogen is highest and soil moisture is lowest. We conclude that while there is competition for resources in the middle of the profile, competition is mitigated by photosynthetic pathway. The facultative CAM shrub grows whenever the soil at the surface is wet enough. The C 4 photosynthetic pathway of the grass is more nitrogen and water use efficient making it better adapted to the low nitrogen in the middle of the profile and low summer rainfall.
Nomadic Peoples, 2008
... On the communal farms livestock graze in paddocks that are rented out to individuals or group... more ... On the communal farms livestock graze in paddocks that are rented out to individuals or groups of pastoralists from Leliefontein. Livestock on the communal area are managed by herders who have developed several herding strategies as a response to environmental and ...
Journal of Arid Environments, 2007
... Funding in terms of the Franco/South African Science and Technology Agreement is acknowledged... more ... Funding in terms of the Franco/South African Science and Technology Agreement is acknowledged. Financial support from GEF and UNEP through the Desert Margins Programme is also acknowledged. We thank the two anonymous reviewers for their comments. References. ...
Journal of Arid Environments, 2007
... allocated ownership rights to large farms during the C19th, these pastoralists were forced on... more ... allocated ownership rights to large farms during the C19th, these pastoralists were forced onto ... Their nomadic strategies for coping with environmental variability became constrained and seasonal ... and Hoffman, 2006), but none have specifically looked at herding patterns during ...
Environmental Science & Policy, 2006
Biological Reviews of the Cambridge Philosophical Society, 2000
Many introduced plant species rely on mutualisms in their new habitats to overcome barriers to es... more Many introduced plant species rely on mutualisms in their new habitats to overcome barriers to establishment and to become naturalized and, in some cases, invasive. Mutualisms involving animalmediated pollination and seed dispersal, and symbioses between plant roots and microbiota often facilitate invasions. The spread of many alien plants, particularly woody ones, depends on pollinator mutualisms. Most alien plants are well served by generalist pollinators (insects and birds), and pollinator limitation does not appear to be a major barrier for the spread of introduced plants (special conditions relating to Ficus and orchids are described). Seeds of many of the most notorious plant invaders are dispersed by animals, mainly birds and mammals. Our review supports the view that tightly coevolved, plant-vertebrate seed dispersal systems are extremely rare. Vertebrate-dispersed plants are generally not limited reproductively by the lack of dispersers. Most mycorrhizal plants form associations with arbuscular mycorrhizal fungi which, because of their low specificity, do not seem to play a major role in facilitating or hindering plant invasions (except possibly on remote islands such as the Galapagos which are poor in arbuscular mycorrhizal fungi). The lack of symbionts has, however, been a major barrier for many ectomycorrhizal plants, notably for Pinus spp. in parts of the southern hemisphere. The roles of nitrogen-fixing associations between legumes and rhizobia and between actinorhizal plants and Frankia spp. in promoting or hindering invasions have been virtually ignored in the invasions literature. Symbionts required to induce nitrogen fixation in many plants are extremely widespread, but intentional introductions of symbionts have altered the invasibility of many, if not most, systems. Some of the world's worst invasive alien species only invaded after the introduction of symbionts. Mutualisms in the new environment sometimes re-unite the same species that form partnerships in the native range of the plant. Very often, however, different species are involved, emphasizing the diffuse nature of many (most) mutualisms. Mutualisms in new habitats usually duplicate functions or strategies that exist in the natural range of the plant. Occasionally, mutualisms forge totally novel combinations, with profound implications for the behaviour of the introduced plant in the new environment (examples are seed dispersal mutualisms involving wind-dispersed pines and cockatoos in Australia ; and mycorrhizal associations involving plant roots and fungi). Many ecosystems are becoming more susceptible to invasion by introduced plants because : (a) they contain an increasing array of potential mutualistic partners (e.g. generalist frugivores and pollinators, mycorrhizal fungi with wide host ranges, rhizobia strains with infectivity across genera) ; and (b) conditions conducive for the establishment of various alien\alien synergisms are becoming more abundant. Incorporating perspectives on mutualisms in screening protocols will improve (but not perfect) our ability to predict whether a given plant species could invade a particular habitat.
Biological Conservation, 2008
Mining Oral histories Succulent Karoo Semi-arid Wind erosion control Windbreaks Wind-nets A B S T... more Mining Oral histories Succulent Karoo Semi-arid Wind erosion control Windbreaks Wind-nets A B S T R A C T
African Journal of Range & Forage Science, 2013
Questions: What are the effects of root competition from mature plants and soil type on the survi... more Questions: What are the effects of root competition from mature plants and soil type on the survival and growth of dominant grass and succulent shrub seedlings at an ecotonal site between arid grassland and succulent shrubland? Do these factors explain the occurrence of separate grass-dominated and shrubdominated communities along the ecotone?
Ecology, Evolution, and Conservation of a Megadiverse Region, 2014
Ecology, Evolution, and Conservation of a Megadiverse Region, 2014
Journal of Arid Environments, 2007
... Lee Simons Corresponding Author Contact Information , a , E-mail The Corresponding Author and... more ... Lee Simons Corresponding Author Contact Information , a , E-mail The Corresponding Author and Nicky Allsopp a , E-mail The Corresponding Author. ... shading and competition for water with the adult plant can also reduce the growth of associated seedlings (Franco and Nobel ...
ABSTRACT Anthropogenic nitrogen (N) emissions have increased dramatically since the agricultural ... more ABSTRACT Anthropogenic nitrogen (N) emissions have increased dramatically since the agricultural and industrial revolutions leading to N deposition in the northern hemisphere that is estimated to be an order of magnitude greater than preindustrial fluxes. N deposition rates of 5-15 kg N ha-1 yr-1 in Europe and N. America decrease plant species diversity, increase invasive species, and lead to eutrophication of surface waters. The southern hemisphere is home to over 50% of the world's biodiversity hotspots, including the 90,000 km2 Cape Floristic Region which houses 9,030 vascular plant species, 69% of which are endemic. However, to date, N deposition rates in the southern hemisphere are highly uncertain, with global models of N deposition based upon sparse datasets at best. Many terrestrial systems, such as fynbos shrublands, are adapted to low N availability and exhibit high species diversity and endemism, rendering them susceptible to ecological changes from N deposition. In this research, we quantified the spatial and temporal distribution of wet and dry N deposition across 30 protected fynbos ecosystems within the urban airshed of Cape Town, South Africa. We predicted that 1) total inorganic N deposition varies predictably along the urban-rural gradient (highest near the city centre), 2) N deposition varies seasonally, with higher fluxes in the winter months when atmospheric stability causes a build-up of N gases in and around the city, and 3) total inorganic N deposition will exceed the critical load of 10-15 kg N ha-1 yr-1 for Mediterranean shrublands, past which negative ecosystem effects have been shown to occur. Estimates of N deposition based on NO2 concentrations within the city suggest that total N deposition ranges from 8-13 kg N ha-1 yr-1 . However, we show that N deposition measured by ion-exchange resin collectors is far less than expected, averaging less than 2 kg N ha-1 yr-1 (range 0.5 - 5.5 kg N ha-1 yr-1 ), and is is dominated by NO3-, suggesting combustion sources. Despite low rates compared to northern hemisphere studies, throughfall N fluxes are lower on average than bulk N fluxes, suggesting significant N uptake through the canopy. Preliminary analyses of cloud water + dry deposition show concentrations of N up to an order of magnitude higher than rainfall. These results suggest that dry and cloud water deposition may contribute high N loads to fynbos shrublands, but these areas may be localized to mountain tops near the city center.
Revue Tiers Monde, 2009
Au début des années 1990, les approches d'« evidencebased medicine » ont commencé à être formalis... more Au début des années 1990, les approches d'« evidencebased medicine » ont commencé à être formalisées pour permettre l'usage le plus judicieux possible des connaissances disponibles par les praticiens, le mot « evidence » renvoyant à la fois aux idées de corroboration empirique et de preuve. Ces approches se sont étendues à d'autres sphères de la décision publique (lutte contre la pauvreté, éducation, justice, environnement...), donnant naissance à la notion d'« evidence-based policy » (EBP). Dans le monde francophone, ces approches sont souvent assimilées à un simple effet de rhétorique ou à une tentative de dépolitiser les débats. L'analyse de leur genèse invite à plus de nuances et montre plutôt la volonté de renouveler les démarches positives d'aide à la décision publique en proposant des méthodes ad hoc offrant une alternative au recours croissant à des modèles de connaissances reposant trop exclusivement sur des opinions ou des simulations qui s'exonèrent de tests de validation empiriques.
South African Journal of Science, 2012
Plant Ecology, 2011
Nearest-neighbour analysis was used to examine the competitive interactions between Stipagrostis ... more Nearest-neighbour analysis was used to examine the competitive interactions between Stipagrostis brevifolia, a C 4 perennial grass, and two leaf succulent shrubs, Ruschia robusta and Leipoldtia pauciflora, at the ecotone between semi-arid grassland and succulent shrubland in the Karoo. The root distribution in the soil was also compared to assess the degree of overlap in the potential use of soil resources. Regressions between the combined sizes of interspecific, nearest-neighbour species and the distance between them showed significant positive correlations for S. brevifolia and R. robusta, which suggest the presence of competition. We infer from individual species regressions that the grass exerted a stronger competitive force on the shrub R. robusta than R. robusta on the grass. There was also evidence for strong intraspecific competitive relationships within S. brevifolia and R. robusta. There was no evidence of competition between S. brevifolia and L. pauciflora or among L. pauciflora individuals. S. brevifolia had the deepest root system, and was recorded at depths of 70 cm. Most of this root mass occurred between 10 and 40 cm. Ruschia robusta roots were recorded as deep as 55 cm, but more than 90% was found in the top 20 cm of the soil, creating a degree of overlap with the vertical root distribution of S. brevifolia. A clear separation in rooting depths occurred between S. brevifolia, and L. pauciflora which had only 3% of the total root mass below 10 cm. The partial overlap in the vertical root distribution between S. brevifolia and R. robusta may account for the observed competitive relationship, but each species dominates in a different layer, potentially minimising the net competition between S. brevifolia and R. robusta. Our findings demonstrate the possibility of a two-layer water-obtaining strategy in a semi-desert ecosystem, where the succulent shrubs seem to be playing the typical ''grass'' role described in most models of water partitioning between grass and woody plants. The stronger competitive effect of S. brevifolia on R. robusta at all the sites is of significance to species dynamics, and might be related to winter/summer rainfall dynamics at the climatic transition.
Plant Ecology, 2005
We describe the long-term effects of a CO 2 exhalation, created more than 70 years ago, on a natu... more We describe the long-term effects of a CO 2 exhalation, created more than 70 years ago, on a natural C 4 dominated sub-tropical grassland in terms of ecosystem structure and functioning. We tested whether longterm CO 2 enrichment changes the competitive balance between plants with C 3 and C 4 photosynthetic pathways and how CO 2 enrichment has affected species composition, plant growth responses, leaf properties and soil nutrient, carbon and water dynamics. Long-term effects of elevated CO 2 on plant community composition and system processes in this sub-tropical grassland indicate very subtle changes in ecosystem functioning and no changes in species composition and dominance which could be ascribed to elevated CO 2 alone. Species compositional data and soil d 13 C isotopic evidence suggest no detectable effect of CO 2 enrichment on C 3 :C 4 plant mixtures and individual species dominance. Contrary to many general predictions C 3 grasses did not become more abundant and C 3 shrubs and trees did not invade the site. No season length stimulation of plant growth was found even after 5 years of exposure to CO 2 concentrations averaging 610 lmol mol À1 . Leaf properties such as total N decreased in the C 3 but not C 4 grass under elevated CO 2 while total non-structural carbohydrate accumulation was not affected. Elevated CO 2 possibly lead to increased end-of-season soil water contents and this result agrees with earlier studies despite the topographic water gradient being a confounding problem at our research site. Long-term CO 2 enrichment also had little effect on soil carbon storage with no detectable changes in soil organic matter found. There were indications that potential soil respiration and N mineralization rates could be higher in soils close to the CO 2 source. The conservative response of this grassland suggests that many of the reported effects of elevated CO 2 on similar ecosystems could be short duration experimental artefacts that disappear under long-term elevated CO 2 conditions.
Plant and Soil, 2011
Here we aim to demonstrate that in arid environments the competitive balance between species can ... more Here we aim to demonstrate that in arid environments the competitive balance between species can be determined by niche separation with either nitrogen or water as the relevant niche axis. To do this we sampled roots <2 mm in diameter for 5 soil pits equidistant between two coexisting species, a shrub and a grass. Using stable carbon and nitrogen isotope ratios of fine roots we determine both photosynthetic pathway and rooting depth. We also examine the distribution of soil moisture and nitrogen relative to root biomass. Our results for root biomass and stable isotope ratios of fine roots demonstrate both niche separation and competition for resources. Root biomass is highest at the top of the profile where soil nitrogen is highest and soil moisture is lowest. We conclude that while there is competition for resources in the middle of the profile, competition is mitigated by photosynthetic pathway. The facultative CAM shrub grows whenever the soil at the surface is wet enough. The C 4 photosynthetic pathway of the grass is more nitrogen and water use efficient making it better adapted to the low nitrogen in the middle of the profile and low summer rainfall.
Nomadic Peoples, 2008
... On the communal farms livestock graze in paddocks that are rented out to individuals or group... more ... On the communal farms livestock graze in paddocks that are rented out to individuals or groups of pastoralists from Leliefontein. Livestock on the communal area are managed by herders who have developed several herding strategies as a response to environmental and ...
Journal of Arid Environments, 2007
... Funding in terms of the Franco/South African Science and Technology Agreement is acknowledged... more ... Funding in terms of the Franco/South African Science and Technology Agreement is acknowledged. Financial support from GEF and UNEP through the Desert Margins Programme is also acknowledged. We thank the two anonymous reviewers for their comments. References. ...
Journal of Arid Environments, 2007
... allocated ownership rights to large farms during the C19th, these pastoralists were forced on... more ... allocated ownership rights to large farms during the C19th, these pastoralists were forced onto ... Their nomadic strategies for coping with environmental variability became constrained and seasonal ... and Hoffman, 2006), but none have specifically looked at herding patterns during ...
Environmental Science & Policy, 2006
Biological Reviews of the Cambridge Philosophical Society, 2000
Many introduced plant species rely on mutualisms in their new habitats to overcome barriers to es... more Many introduced plant species rely on mutualisms in their new habitats to overcome barriers to establishment and to become naturalized and, in some cases, invasive. Mutualisms involving animalmediated pollination and seed dispersal, and symbioses between plant roots and microbiota often facilitate invasions. The spread of many alien plants, particularly woody ones, depends on pollinator mutualisms. Most alien plants are well served by generalist pollinators (insects and birds), and pollinator limitation does not appear to be a major barrier for the spread of introduced plants (special conditions relating to Ficus and orchids are described). Seeds of many of the most notorious plant invaders are dispersed by animals, mainly birds and mammals. Our review supports the view that tightly coevolved, plant-vertebrate seed dispersal systems are extremely rare. Vertebrate-dispersed plants are generally not limited reproductively by the lack of dispersers. Most mycorrhizal plants form associations with arbuscular mycorrhizal fungi which, because of their low specificity, do not seem to play a major role in facilitating or hindering plant invasions (except possibly on remote islands such as the Galapagos which are poor in arbuscular mycorrhizal fungi). The lack of symbionts has, however, been a major barrier for many ectomycorrhizal plants, notably for Pinus spp. in parts of the southern hemisphere. The roles of nitrogen-fixing associations between legumes and rhizobia and between actinorhizal plants and Frankia spp. in promoting or hindering invasions have been virtually ignored in the invasions literature. Symbionts required to induce nitrogen fixation in many plants are extremely widespread, but intentional introductions of symbionts have altered the invasibility of many, if not most, systems. Some of the world's worst invasive alien species only invaded after the introduction of symbionts. Mutualisms in the new environment sometimes re-unite the same species that form partnerships in the native range of the plant. Very often, however, different species are involved, emphasizing the diffuse nature of many (most) mutualisms. Mutualisms in new habitats usually duplicate functions or strategies that exist in the natural range of the plant. Occasionally, mutualisms forge totally novel combinations, with profound implications for the behaviour of the introduced plant in the new environment (examples are seed dispersal mutualisms involving wind-dispersed pines and cockatoos in Australia ; and mycorrhizal associations involving plant roots and fungi). Many ecosystems are becoming more susceptible to invasion by introduced plants because : (a) they contain an increasing array of potential mutualistic partners (e.g. generalist frugivores and pollinators, mycorrhizal fungi with wide host ranges, rhizobia strains with infectivity across genera) ; and (b) conditions conducive for the establishment of various alien\alien synergisms are becoming more abundant. Incorporating perspectives on mutualisms in screening protocols will improve (but not perfect) our ability to predict whether a given plant species could invade a particular habitat.
Biological Conservation, 2008
Mining Oral histories Succulent Karoo Semi-arid Wind erosion control Windbreaks Wind-nets A B S T... more Mining Oral histories Succulent Karoo Semi-arid Wind erosion control Windbreaks Wind-nets A B S T R A C T
African Journal of Range & Forage Science, 2013
Questions: What are the effects of root competition from mature plants and soil type on the survi... more Questions: What are the effects of root competition from mature plants and soil type on the survival and growth of dominant grass and succulent shrub seedlings at an ecotonal site between arid grassland and succulent shrubland? Do these factors explain the occurrence of separate grass-dominated and shrubdominated communities along the ecotone?