Figure 5. Development pathways since 1970 for selected key indicators of human-environment intera... more Figure 5. Development pathways since 1970 for selected key indicators of human-environment interactions, which show a large increase in the scale of global economic growth and its impacts on nature, with strong contrasts across developed, developing, and least developed countries. Countries are classified according to the UN World Economic Situation and Prospects (www.un.org). Global gross domestic product has risen 4-fold in real terms with the vast majority of growth occurring in developed and developing countries (A). Extraction of living biomass (e.g. crops, fisheries) to meet the demand for domestic consumption and for export is highest in developing countries and rising rapidly (B). Material consumption per capita within each country (from imports and domestic production), however, is highest in developed countries (C). Overall protection of Key Biodiversity
We modelled the future distribution in 2050 of 975 endemic plant species in southern Africa distr... more We modelled the future distribution in 2050 of 975 endemic plant species in southern Africa distributed among seven life forms, including new methodological insights improving the accuracy and ecological realism of predictions of global changes studies by:(i) using only endemic species as a way to capture the full realized niche of species,(ii) considering the direct impact of human pressure on landscape and biodiversity jointly with climate, and (iii) taking species' migration into account. Our analysis shows important ...
Corrections made as of 13 April 2007. Note: text, table and figures given here are final but subj... more Corrections made as of 13 April 2007. Note: text, table and figures given here are final but subject to checking and copy- editing and editorial adjustments to figures ... Drafting Authors: Neil Adger, Pramod Aggarwal, Shardul Agrawala, Joseph Alcamo, Abdelkader Allali, Oleg ...
The rate of future climate change is likely to exceed the migration rates of most plant species. ... more The rate of future climate change is likely to exceed the migration rates of most plant species. The replacement of dominant species by locally rare species may require decades, and extinctions may occur when plant species cannot migrate fast enough to escape the ...
ABSTRACT Boundaries between Fynbos and Succulent Karoo vegetation in the Greater Cape Floristic R... more ABSTRACT Boundaries between Fynbos and Succulent Karoo vegetation in the Greater Cape Floristic Region are frequently characterised by sharp transitions from sandy, dystrophic to loamy, mesotrophic soils, together with a more gradual climate transition from cooler, wetter conditions typical of Fynbos at higher elevations to warmer, drier conditions at lower elevations typical of Succulent Karoo. There is very high species turnover across these boundaries, providing an opportunity to disentangle the relative roles of climate and soil type in determining the biome boundary. A fully reciprocal transplant approach was employed here to investigate this question, using three species from each biome occurring naturally in close proximity at Jonaskop, Western Cape. Greenhouse-germinated and established seedlings of all species were planted into both sandy, dystrophic and loamy, mesotrophic soils typical of each biome at four sites along an elevational transect (elevations 545 m, 744 m, 953 m, 1303 m) at Jonaskop, and their growth and survivorship monitored for 7 months.
Shade cast by trees, which suppresses grass growth, and fire fuelled by grass biomass, which prev... more Shade cast by trees, which suppresses grass growth, and fire fuelled by grass biomass, which prevents tree sapling establishment, are mutually exclusive and self-reinforcing drivers of biome distribution in savanna-forest mosaics. We investigated how shade depth, represented by canopy leaf area index (LAI), is generated by adult trees across savanna-forest boundaries and how a shade gradient filters tree functioning, and grass composition and biomass. Forest trees exerted greater shading through increased stem density and greater light interception per unit biomass. A critical transition at LAI c. 1.5 was linked to tree shifts from savanna to forest species, functional shifts from fire-tolerant to light-competitive species, and grass composition shifts from C to C pathways. A second transition to grass fuel loads too low to support fires, occurred at a lower canopy density (LAI > 0.5), accompanied by shifts in C subtype dominance. This pattern suggests that shade suppression of g...
Abstract Potted individuals of two perennial shrub species of South Africa's arid region wer... more Abstract Potted individuals of two perennial shrub species of South Africa's arid region were subjected to a soil-drying cycle. Plant stomatal conductances and water-use efficiencies were related to soil water content. High, opportunistic stomatal conductance and low water ...
ABSTRACT Tree densities in tropical and sub-tropical vegetation have, until recently, long been u... more ABSTRACT Tree densities in tropical and sub-tropical vegetation have, until recently, long been understood as increasing proportionally in response to precipitation. Current understanding is that trees are organised into alternative states with divergent properties that are linked, in the case of savannas, to frequent grass-fuelled fires or the absence of fire in non-savannas. In this paper we explored the hypothesis of functional divergence in three biomes, defined structurally by their dominant growth forms: savannas, ‘thicket’ and forest, within the vegetation of a South African park (Hluhluwe-iMfolozi). Thicket and forest both lack a continuous C4 grassy layer and are therefore non-savannas. ‘Thicket’, as defined here, has shorter trees than forests (4–6 m vs. >10 m) and, often a dense understorey of sub-shrubs. We analysed tree species composition in 253 sites across these three biomes. We then compared herbivore use and fire frequency among the three biomes. Finally we characterised functional traits for 58 tree species including several linked to fire and herbivore responses. In support of the emerging alternative states paradigm for both tree density and phylogenetic composition,we found that the three structurally defined biomes had separate tree species assemblages. Differences in growth form, especially the presence or absence of C4 grasses had key consequences for consumers with high fire frequency in savannas, low in thickets and none in forest and high grazing in savannas, high browsing in thickets and very low herbivory in forests. Trait analysis was consistent with these differences among biomes. Consumers appear to be important environmental filters by admitting some tree species to a biome and excluding others, depending on their functional traits. Positive feedbacks between vegetation and consumers may explain the coexistence of biomes in areas with similar climate and geology.
Climate change adds an additional layer of complexity to existing sustainable development and bio... more Climate change adds an additional layer of complexity to existing sustainable development and biodiversity conservation challenges. The impacts of global climate change are felt locally, and thus local governance structures will increasingly be responsible for preparedness and local responses. Ecosystem-based adaptation (EbA) options are gaining prominence as relevant climate change solutions. Local government officials seldom have an appropriate understanding of the role of ecosystem functioning in sustainable development goals, or access to relevant climate information. Thus the use of ecosystems in helping people adapt to climate change is limited partially by the lack of information on where ecosystems have the highest potential to do so. To begin overcoming this barrier, Conservation South Africa in partnership with local government developed a socio-ecological approach for identifying spatial EbA priorities at the sub-national level. Using GIS-based multi-criteria analysis and...
Figure 5. Development pathways since 1970 for selected key indicators of human-environment intera... more Figure 5. Development pathways since 1970 for selected key indicators of human-environment interactions, which show a large increase in the scale of global economic growth and its impacts on nature, with strong contrasts across developed, developing, and least developed countries. Countries are classified according to the UN World Economic Situation and Prospects (www.un.org). Global gross domestic product has risen 4-fold in real terms with the vast majority of growth occurring in developed and developing countries (A). Extraction of living biomass (e.g. crops, fisheries) to meet the demand for domestic consumption and for export is highest in developing countries and rising rapidly (B). Material consumption per capita within each country (from imports and domestic production), however, is highest in developed countries (C). Overall protection of Key Biodiversity
We modelled the future distribution in 2050 of 975 endemic plant species in southern Africa distr... more We modelled the future distribution in 2050 of 975 endemic plant species in southern Africa distributed among seven life forms, including new methodological insights improving the accuracy and ecological realism of predictions of global changes studies by:(i) using only endemic species as a way to capture the full realized niche of species,(ii) considering the direct impact of human pressure on landscape and biodiversity jointly with climate, and (iii) taking species' migration into account. Our analysis shows important ...
Corrections made as of 13 April 2007. Note: text, table and figures given here are final but subj... more Corrections made as of 13 April 2007. Note: text, table and figures given here are final but subject to checking and copy- editing and editorial adjustments to figures ... Drafting Authors: Neil Adger, Pramod Aggarwal, Shardul Agrawala, Joseph Alcamo, Abdelkader Allali, Oleg ...
The rate of future climate change is likely to exceed the migration rates of most plant species. ... more The rate of future climate change is likely to exceed the migration rates of most plant species. The replacement of dominant species by locally rare species may require decades, and extinctions may occur when plant species cannot migrate fast enough to escape the ...
ABSTRACT Boundaries between Fynbos and Succulent Karoo vegetation in the Greater Cape Floristic R... more ABSTRACT Boundaries between Fynbos and Succulent Karoo vegetation in the Greater Cape Floristic Region are frequently characterised by sharp transitions from sandy, dystrophic to loamy, mesotrophic soils, together with a more gradual climate transition from cooler, wetter conditions typical of Fynbos at higher elevations to warmer, drier conditions at lower elevations typical of Succulent Karoo. There is very high species turnover across these boundaries, providing an opportunity to disentangle the relative roles of climate and soil type in determining the biome boundary. A fully reciprocal transplant approach was employed here to investigate this question, using three species from each biome occurring naturally in close proximity at Jonaskop, Western Cape. Greenhouse-germinated and established seedlings of all species were planted into both sandy, dystrophic and loamy, mesotrophic soils typical of each biome at four sites along an elevational transect (elevations 545 m, 744 m, 953 m, 1303 m) at Jonaskop, and their growth and survivorship monitored for 7 months.
Shade cast by trees, which suppresses grass growth, and fire fuelled by grass biomass, which prev... more Shade cast by trees, which suppresses grass growth, and fire fuelled by grass biomass, which prevents tree sapling establishment, are mutually exclusive and self-reinforcing drivers of biome distribution in savanna-forest mosaics. We investigated how shade depth, represented by canopy leaf area index (LAI), is generated by adult trees across savanna-forest boundaries and how a shade gradient filters tree functioning, and grass composition and biomass. Forest trees exerted greater shading through increased stem density and greater light interception per unit biomass. A critical transition at LAI c. 1.5 was linked to tree shifts from savanna to forest species, functional shifts from fire-tolerant to light-competitive species, and grass composition shifts from C to C pathways. A second transition to grass fuel loads too low to support fires, occurred at a lower canopy density (LAI > 0.5), accompanied by shifts in C subtype dominance. This pattern suggests that shade suppression of g...
Abstract Potted individuals of two perennial shrub species of South Africa's arid region wer... more Abstract Potted individuals of two perennial shrub species of South Africa's arid region were subjected to a soil-drying cycle. Plant stomatal conductances and water-use efficiencies were related to soil water content. High, opportunistic stomatal conductance and low water ...
ABSTRACT Tree densities in tropical and sub-tropical vegetation have, until recently, long been u... more ABSTRACT Tree densities in tropical and sub-tropical vegetation have, until recently, long been understood as increasing proportionally in response to precipitation. Current understanding is that trees are organised into alternative states with divergent properties that are linked, in the case of savannas, to frequent grass-fuelled fires or the absence of fire in non-savannas. In this paper we explored the hypothesis of functional divergence in three biomes, defined structurally by their dominant growth forms: savannas, ‘thicket’ and forest, within the vegetation of a South African park (Hluhluwe-iMfolozi). Thicket and forest both lack a continuous C4 grassy layer and are therefore non-savannas. ‘Thicket’, as defined here, has shorter trees than forests (4–6 m vs. >10 m) and, often a dense understorey of sub-shrubs. We analysed tree species composition in 253 sites across these three biomes. We then compared herbivore use and fire frequency among the three biomes. Finally we characterised functional traits for 58 tree species including several linked to fire and herbivore responses. In support of the emerging alternative states paradigm for both tree density and phylogenetic composition,we found that the three structurally defined biomes had separate tree species assemblages. Differences in growth form, especially the presence or absence of C4 grasses had key consequences for consumers with high fire frequency in savannas, low in thickets and none in forest and high grazing in savannas, high browsing in thickets and very low herbivory in forests. Trait analysis was consistent with these differences among biomes. Consumers appear to be important environmental filters by admitting some tree species to a biome and excluding others, depending on their functional traits. Positive feedbacks between vegetation and consumers may explain the coexistence of biomes in areas with similar climate and geology.
Climate change adds an additional layer of complexity to existing sustainable development and bio... more Climate change adds an additional layer of complexity to existing sustainable development and biodiversity conservation challenges. The impacts of global climate change are felt locally, and thus local governance structures will increasingly be responsible for preparedness and local responses. Ecosystem-based adaptation (EbA) options are gaining prominence as relevant climate change solutions. Local government officials seldom have an appropriate understanding of the role of ecosystem functioning in sustainable development goals, or access to relevant climate information. Thus the use of ecosystems in helping people adapt to climate change is limited partially by the lack of information on where ecosystems have the highest potential to do so. To begin overcoming this barrier, Conservation South Africa in partnership with local government developed a socio-ecological approach for identifying spatial EbA priorities at the sub-national level. Using GIS-based multi-criteria analysis and...
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Papers by Guy Midgley