Saving the Planet

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Across
  1. 5. avoidance of the depletion of natural resources in order to maintain an ecological balance
  2. 6. a waterless, desolate area of land with little or no vegetation
  3. 9. the concentration of human population in discrete areas
  4. 10. the introduction of harmful materials into the environment
  5. 11. the process of replanting an area with trees
Down
  1. 1. a biological community of interacting organisms and their physical environment
  2. 2. prevention of wasteful use of a resource
  3. 3. the natural home or environment of an animal, plant, or other organism
  4. 4. an irregular rising and falling (example: of precipitation)
  5. 7. extremely large mass of ice
  6. 8. extreme scarcity of food