Across
- 2. when members of a species are held by people in zoos of other conservation facilities.
- 4. layer of the atmosphere that helps to protect living things on Earth's surface from damaging doses of ultraviolet radiation from the sun.
- 8. a species in which the number of individuals falls so low that extinction is possible.
- 10. rain, snow, sleet, or fog with a pH below 7; causes the deterioration of forests, lakes, and buildings.
- 11. damage to a habitat by air, water, and land pollution.
- 14. separation of wilderness areas from each other; may cause problems for organisms that need large areas for food or mating.
Down
- 1. nonnative species in an are; may take over niches of native species in an area and eventually replace them.
- 3. variety of life in an area; usually measured as the number of species in an area.
- 5. natural strips of land that allow the migration of organisms from one wilderness area to another.
- 6. philosophy that promotes letting people use resources in wilderness areas in that will not damage the ecosystem.
- 7. programs that release organisms into an area where their species once lived in hopes of reestablishing naturally reproducing populations.
- 9. field of biology that studies methods and implements plans to protect biodiversity.
- 12. species that have rapidly decreasing numbers of individuals.
- 13. when the last members of a species die
- 15. different environmental conditions that occur along the boundaries of an ecosystem.