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Answers To Review Questions
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  1. We change ecosystems by replacing them with agricultural ecosystems, we alter species mixtures by introducing plants and animals, and we reduce populations by harvesting trees and animals for our use.


  2. The impact of humans is greater today because the population is greater than it has ever been, and our technology is more harmful to the environment.


  3. Mutations, migration, selective breeding, population size, and sexual reproduction.


  4. Habitat loss due to agriculture, urban development, logging and other activities. Over-exploitation of fish, wildlife, and forestry resources. Introduction of exotic species that reduce or eliminate native species, Campaigns against organisms considered to be pests


  5. Over-exploitation by fishers Destructive harvesting practices such as trawls.


  6. Recycling is generally more energy efficient than mining new raw materials because there are no costs for mining or refining new material, such as in the case of aluminum.


  7. Problems associated with forest exploitation are exposure of soil to increased erosion, loss of animal habitat and biodiversity, stream-bank erosion, stream siltation, increased water temperature, and a loss of scenery.


  8. Desertification is the process of converting arid and semiarid land to desert because of improper use by humans. It is caused by overgrazing, unsuccessful farming practices, and removal of vegetation for fuelwood.



  9. * Develop national strategies for the conservation and sustainable use of biological diversity.
    * Identify components of biological diversity important for its conservation.
    * Monitor biological diversity.
    * Identify activities, which have adverse impacts on the conservation and sustainable use of biological diversity.
    * Establish a system of protected areas.
    * Rehabilitate and restore degraded ecosystems and promote the recovery of threatened species.
    * Develop or maintain necessary legislation for the protection of threatened species and populations.
    * Integrate consideration of the conservation and sustainable use of biological resources into national decision-making.


  10. Six techniques used by wildlife managers include game and habitat analysis, population census methods, stocking areas with game species, predator control, establishing refuges, and habitat management.


  11. Special problems associated with waterfowl management include protection of summer nesting areas, prevention of pond and lake drainage, the development of refuges as havens from hunters, and the protection of food and shelter in the overwintering areas.


  12. Extinction is the death of a species or the elimination of all the individuals of a particular kind. Natural extinction can occur in areas where there is a low population density, a small habitat area, a specialized niche, and low reproductive rates. Human-accelerated extinctions occur wherever humans become the dominant organism.


  13. Production of food and raw materials
    Soil formation
    Recreation
    Nutrient cycling and waste treatment
    Water services
    Climate regulation
    Refuges for biodiversity
    Disturbance regulation and erosion control
    Genetic resources
    Atmospheric gas balance
    Pollination and pest control


  14. Actions that can be taken to prevent extinctions include legislation to protect species that are in danger of becoming extinct, the preservation of the habitat required by the endangered species, and education of the local population about the need to protect endangered species.









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