Box 3.1. Direct Drivers: Example from Southern African Sub-global Assessment

(SG-SAfMA)

The direct drivers of biodiversity loss in southern Africa include the impacts of land use change, alien invasives, overgrazing, and overharvesting— all of which have already had a large impact on the region’s biodiversity, ecosystem services, and human well-being, and all of which are likely to spread in the absence of interventions.

The dominant direct driver of ecosystem change in southern Africa is considered to be widespread land use change that in some cases has led to degradation. Forests and woodlands are being converted to croplands and pastures at a rate somewhat slower than in Southeast Asia and the Amazon during the 1990s, but nevertheless sufficiently fast to endanger ecosystem services at a local scale. Half of the region consists of drylands, where overgrazing is the main cause of desertification.

In the first half of the twenty-first century, climate change is a real threat to water supplies, human health, and biodiversity in southern Africa. The threats arise partly because the projected warming may, over large areas, be accompanied by a drying trend, and partly because of the low state of human welfare and weak governance, which increases vulnerability of humans to climate change. Although some of these threats have slowed in some regions (afforestation with monocultures of alien species in South Africa has decreased, for example), some have accelerated elsewhere (afforestation with alien species in Mozambique has increased, for instance, due to favorable growing conditions and weak regulation). Thus, the region’s biodiversity remains vulnerable to land use change. In addition, the more subtle problem of land degradation is considered a bigger threat in the region.

Several studies indicate that the biodiversity of southern Africa is at risk. There is now evidence, for example, that it is declining in the northern part of its range, but stable in the southern part, as predicted by the global change models. In addition, there is experimental evidence that the recorded expansion of woody invasions into grasslands and savannas may be driven by rising global CO₂ concentrations. The ability of species to disperse and survive these pressures will be hampered by a fragmented landscape made inhospitable by human activities. The Assessments of Impacts and Adaptations to Climate Change in Multiple Regions and Sectors project is currently analyzing response options that may conserve biodiversity under future climate and land cover scenarios in southern Africa.

Source: Millennium Ecosystem Assessment
 Ecosystems and Human Well-being: Biodiversity Synthesis (2005),
Chapter 2, p.49

Biodiversity & Human Well-being

Direct cross-links to the Global Assessment Reports of the Millennium Assessment

Box 1. Biodiversity and Its Loss— Avoiding Conceptual Pitfalls

Box 1.1. Linkages among Biodiversity, Ecosystem Services, and Human Well-being

Box 1.2. Measuring and Estimating Biodiversity: More than Species Richness

Box 1.3. Ecological Indicators and Biodiversity

Box 1.4. Criteria for Effective Ecological Indicators

Box 2. MA Scenarios

Box 2.1. Social Consequences of Biodiversity Degradation (SG-SAfMA)

Box 2.2. Economic Costs and Benefits of Ecosystem Conversion

Box 2.3. Concepts and Measures of Poverty

Box 2.4. Conflicts Between the Mining Sector and Local Communities in Chile

Box 3.1. Direct Drivers: Example from Southern African Sub-global Assessment

Box 4.1. An Outline of the Four MA Scenarios

Box 5.1. Key Factors of Successful Responses to Biodiversity Loss

Figure 3.3. Species Extinction Rates

Figure 1.1. Estimates of Proportions and Numbers of Named Species in Groups of Eukaryote Species and Estimates of Proportions of the Total Number of Species in Groups of Eukaryotes

Figure 1.2. Comparisons for the 14 Terrestrial Biomes of the World in Terms of Species Richness, Family Richness, and Endemic Species

Figure 1.3. The 8 Biogeographical Realms and 14 Biomes Used in the MA

Figure 1.4. Biodiversity, Ecosystem Functioning, and Ecosystem Services

Figure 2. How Much Biodiversity Will Remain a Century from Now under Different Value Frameworks?

Figure 2.1. Efficiency Frontier Analysis of Species Persistence and Economic Returns

Figure 3. Main Direct Drivers

Figure 3.1. Percentage Change 1950–90 in Land Area of Biogeographic Realms Remaining in Natural Condition or under Cultivation and Pasture

Figure 3.2. Relationship between Native Habitat Loss by 1950 and Additional Losses between 1950 and 1990

Figure 3.3. Species Extinction Rates

Figure 3.4. Red List Indices for Birds, 1988–2004, in Different Biogeographic Realms

Figure 3.5. Density Distribution Map of Globally Threatened Bird Species Mapped at a Resolution of Quarter-degree Grid Cell

Figure 3.6. Threatened Vertebrates in the 14 Biomes, Ranked by the Amount of Their Habitat Converted by 1950

Figure 3.7. The Living Planet Index, 1970–2000

Figure 3.8. Illustration of Feedbacks and Interaction between Drivers in Portugal Sub-global Assessment

Figure 3.9. Summary of Interactions among Drivers Associated with the Overexploitation of Natural Resources

Figure 3.10. Main Direct Drivers

Figure 3.11. Effect of Increasing Land Use Intensity on the Fraction of Inferred Population 300 Years Ago of Different Taxa that Remain

Figure 3.12. Extent of Cultivated Systems, 2000

Figure 3.13. Decline in Trophic Level of Fisheries Catch since 1950

Figure 3.14. Estimated Global Marine Fish Catch, 1950–2001

Figure 3.15. Estimates of Forest Fragmentation due to Anthropogenic Causes

Figure 3.15. Estimates of Forest Fragmentation due to Anthropogenic Causes

Figure 3.15. Estimates of Forest Fragmentation due to Anthropogenic Causes

Figure 3.15. Estimates of Forest Fragmentation due to Anthropogenic Causes

Figure 3.15. Estimates of Forest Fragmentation due to Anthropogenic Causes

Figure 3.15. Estimates of Forest Fragmentation due to Anthropogenic Causes

Figure 3.16. Fragmentation and Flow in Major Rivers

Figure 3.17 Trends in Global Use of Nitrogen Fertilizer, 1961–2001 (million tons)

Figure 3.18 Trends in Global Use of Phosphate Fertilizer, 1961–2001 (million tons)

Figure 3.19. Estimated Total Reactive Nitrogen Deposition from the Atmosphere (Wet and Dry) in 1860, Early 1990s, and Projected for 2050

Figure 3.20. Historical and Projected Variations in Earth’s Surface Temperature

Figure 4. Trade-offs between Biodiversity and Human Well-being under the Four MA Scenarios

Figure 4.1. Losses of Habitat as a Result of Land Use Change between 1970 and 2050 and Reduction in the Equilibrium Number of Vascular Plant Species under the MA Scenarios

Figure 4.2. Relative Loss of Biodiversity of Vascular Plants between 1970 and 2050 as a Result of Land Use Change for Different Biomes and Realms in the Order from Strength Scenario

Figure 4.3. Land-cover Map for the Year 2000

Figure 4.4. Conversion of Terrestrial Biomes

Figure 4.5. Forest and Cropland/Pasture in Industrial and Developing Regions under the MA Scenarios

Figure 4.6. Changes in Annual Water Availability in Global Orchestration Scenario by 2100

Figure 4.7. Changes in Human Well-being and Socioecological Indicators by 2050 under the MA Scenarios

Figure 6.1. How Much Biodiversity Will Remain a Century from Now under Different Value Frameworks?

Figure 6.2. Trade-offs between Biodiversity and Human Well-being under the Four MA Scenarios

Table 1.1. Ecological Surprises Caused by Complex Interactions

Table 2.1. Percentage of Households Dependent on Indigenous Plant-based Coping Mechanisms at Kenyan and Tanzanian Site

Table 2.2. Trends in the Human Use of Ecosystem Services and Enhancement or Degradation of the Service Around the Year 2000 - Provisioning services

Table 2.2. Trends in the Human Use of Ecosystem Services and Enhancement or Degradation of the Service Around the Year 2000 - Regulating services

Table 2.2. Trends in the Human Use of Ecosystem Services and Enhancement or Degradation of the Service Around the Year 2000 - Cultural services

Table 2.2. Trends in the Human Use of Ecosystem Services and Enhancement or Degradation of the Service Around the Year 2000 - Supporting services

Table 6.1. Prospects for Attaining the 2010 Sub-targets Agreed to under the Convention on Biological Diversity