Conservation Biology and Restoration Ecology保护生物学和恢复生态学.ppt

Conservation Biology and Restoration Ecology Chapter 55 LAST CHAPTER!!!!! Conservation Biology conserve biological diversity at all levels Restoration Ecology return degraded ecosystems to conditions as similar as possible to their natural, pre-degraded state Extinction is a natural phenomenon has been occurring almost since life first evolved current rate of extinction underlies the biodiversity crisis rate of species extinction is high largely as a result of escalating rate of ecosystem degradation by human beings Three Levels of Biodiversity genetic diversity species diversity ecosystem diversity Genetics individual genetic variation within a population genetic variation between populations one population becomes extinct, then a species may have lost some of the genetic diversity that makes microevolution possible Species Diversity Endangered species - “in danger of extinction throughout all or a significant portion of its range.” U.S. Endangered Species Act (ESA) Threatened species - considered likely to become endangered in the foreseeable future at current rates of extinction, more than half of all currently living plant and animal species will have disappeared by the end of the 21st century Ecosystem Diversity local extinction of one species can have a negative impact on the overall species richness of the community Keystone predator Foundation species Loss of species means the loss of genes Ecosystem Services Purification of air and water Reduction of the severity of droughts and floods Generation and preservation of fertile soils Detoxification and decomposition of wastes Pollination of crops and natural vegetation Dispersal of seeds Cycling of nutrients Control of many agricultural pests by natural enemies Protection of shorelines from erosion Protection from ultraviolet rays Moderation of weather extremes Provision of beauty and recreational opportunities ?? Major Threats to Biodiversity Habitat Destruction Introduced Species Overexplo