Across
- 4. a species in which the number of individuals falls so low that extinction is possible
- 6. natural strips of land that allows the migration of organisms from one wilderness area to another
- 9. damage to a habitat by air, water, and land pollution
- 11. layer of the atmosphere that helps to protect living organisms on Earth's surface from getting damaged by ultraviolet radiation from the sun
- 12. separation of wilderness areas from each other
- 15. when members of a species are held by people in zoos or other conservation facilities
Down
- 1. different environmental conditions that occur along the boundaries of an ecosystem
- 2. programs that release organisms into an area where their species once lived in hopes of reestablishing naturally reproducing populations
- 3. species that have rapidly decreasing numbers of individuals
- 5. philosophy that promotes letting people use resources in wilderness areas in ways that will not damage the ecosystem
- 7. nonnative species in an area
- 8. field of biology that studies methods and implement plans to protect biodiversity
- 10. variety of life in an area
- 13. rain, snow, sleet or fog with a pH below 7
- 14. when the last members of a species dies