Ages 7 to 9 years. Earth has six major types of environments with different climates and containing complex communities of plants and animals that have adapted to the special conditions in each. These types of environments are called biomes. The main biomes are: freshwater, marine, desert, forest, tundra, and grassland. They are broken down into seventeen sub-categories. This easy-to-understand book explains this important subject and stresses the importance of conserving our precious biomes and the life forms that inhabit each one.