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Box 1. Biodiversity and Its Loss— Avoiding Conceptual PitfallsDifferent interpretations of several important attributes of the concept of biodiversity can lead to confusion in understanding both scientific findings and their policy implications. Specifically, the value of the diversity of genes, species, or ecosystems per se is often confused with the value of a particular component of that diversity. Species diversity in and of itself, for example, is valuable because the presence of a variety of species helps to increase the capability of an ecosystem to be resilient in the face of a changing environment. At the same time, an individual component of that diversity, such as a particular food plant species, may be valuable as a biological resource. The consequences of changes in biodiversity for people can stem both from a change in the diversity per se and a change in a particular component of biodiversity. Each of these aspects of biodiversity deserves its own attention from decision-makers, and each often requires its own (albeit connected) management goals and policies. Second, because biodiversity refers to diversity at multiple scales of biological organization (genes, populations, species, and ecosystems) and can be considered at any geographic scale (local, regional, or global), it is generally important to specify the specific level of organization and scale of concern. For example, the introduction of widespread weedy species to a continent such as Africa will increase the species diversity of Africa (more species present) while decreasing ecosystem diversity globally (since the ecosystems in Africa then become more similar in species composition to ecosystems elsewhere due to the presence of the cosmopolitan species). Because of the multiple levels of organization and multiple geographic scales involved, any single indicator, such as species diversity, is generally a poor indicator for many aspects of biodiversity that may be of concern for policy-makers. These two considerations are also helpful in interpreting the meaning of biodiversity “loss.” For the purposes of assessing progress toward the 2010 targets, the Convention on Biological Diversity defines biodiversity loss to be “the long-term or permanent qualitative or quantitative reduction in components of biodiversity and their potential to provide goods and services, to be measured at global, regional and national levels” (CBD COP VII/30). Under this definition, biodiversity can be lost either if the diversity per se is reduced (such as through the extinction of some species) or if the potential of the components of diversity to provide a particular service is diminished (such as through unsustainable harvest). The homogenization of biodiversity—that is, the spread of invasive alien species around the world—thus also represents a loss of biodiversity at a global scale (since once-distinct groups of species in different parts of the world become more similar) even though the diversity of species in particular regions may actually increase because of the arrival of new species. Source: Millennium Ecosystem Assessment Go to Facts on Biodiversity Related publication:
Other Figures & Tables on this publication: 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 2.1. 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 1.3. 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 3.3. Species Extinction Rates Figure 3.4. Red List Indices for Birds, 1988–2004, in Different Biogeographic Realms Figure 3.7. The Living Planet Index, 1970–2000 Figure 3.10. Main Direct Drivers 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 3.20. 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 4.3. 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 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 |
