1、Chapter 7Conserving BiologicalResourcesChapter 7 Conserving BiologicalResources7.1 Value of Wild Species7.2 Biodiversity About 1.75 million species of plants, animals, and microbes have been examined, named, and classified, but scientists estimate that between 4 million and 112 million additional sp
2、ecies have not yet been systematically explored . instrumental value: its existence or use benefits some other entityintrinsic value: it has value for its own sake Sources for agriculture, forestry, aquaculture, and animal husbandrySources for medicines, pharmaceuticalsRecreational, aesthetic, and s
3、cientific valueIntrinsic valueBiodiversity: the variety and variability among living organisms and the ecological complexes in which they occurSpecies diversity: the number of species that occur in an area Figure 7.1 Preserving 50% of total habitat area often leaves about 90% of the original species
4、 remaining alive 7.2.3 Extinction Species extinction:Ecological extinction: a species has become so rare that it has essentially no role or impact on its ecosystem a species has died out in a local areaChange physical environment:1.Habitat disruptionExamplesDrain swamp, toxic pollutionChange biologi
5、cal environment:2.Introduce new species3. Overhunting4. Secondary extinctionsNew predatorBig-game huntingLoss of food speciesTable 7.3 Four ways that humans cause population decline and species extinctionOne is that small populations may have breeding problems.The second cause is that small populati
6、ons are much more easily wiped out by random environmental fluctuationsPhysical Alteration of HabitatsThe Population Factor Exotic Species Overuse Adopt specific national biodiversity action plans and strategiesEstablish a system of protected areas and ecosystems within the countryEstablish policies
7、 that provide incentives to promote sus-tainable use of biological resources 7.2.5 Convention on Biological Diversity (1992 in Rio de Janeiro)Restore habitats that have been degraded.Protect threatened species.Respect and preserve knowledge and practices of indigenous peoples.Respect the ownership of genetic resources by countries, and share the technologies developed from those resources.
