Lanni Guffey

3. Area that receives less than 25 centimeters of precipitation per year.
7. Leafy roof formed by tall trees in a forest.
9. Study of where organisms live.
10. Species that are carried to a new location by people.
11. Region of shallow ocean water over the continental shelf.
12. Tree that sheds its leaves and grows new ones each year.
14. Very slow motion of the continents.
16. Series of events in which one organism eats another and obtains energy.
17. Soil that is frozen all year.
18. An area populated by grasses and other nonwoody plants. Most grasslands get 25 to 75 centimeters of rain each year.
19. Layer of shorter plants that grow in the shade of a forest canopy.
20. Pattern of overlapping food chains in an ecosystem.

1. Group of land ecosystems with similar climates and organisms.
2. Organism that breaks down waste and dead organisms.
4. Habitat in which the fresh water of a river meets the salt water of the ocean.
5. Process of changing free nitrogen gas into a usable form.
6. Movement of organisms from one place to another.
8. Area between the highest high-tide line and lowest low-tide line.
13. Tree that produces its seeds in cones and that has needle-shaped leaves.
15. Diagram that shows the amount of energy that moves from one feeding level to another in a food web.