| A | B |
|---|
| biome | A large region that has a distinct combination of plants and animals |
| birth rate | The ratio of the number of births to the number of individuals in a population |
| canopy | The highest layer of trees in a forest |
| climate | The average weather in a region over a long period of time |
| climax community | The final, stable community in succession |
| coniferous forest | A biome made up of cone-bearing trees, or conifers, such as pines and spruces |
| death rate | The ratio of the number of deaths to the number of individuals in a population |
| deciduous forest | A biome made up of mainly broad-leaved trees that lose their leaves in the fall |
| desert | A biome that occurs in an area that receives less than 25cm of rainfall per year |
| grassland | A biome in which grasses are the main plants and in which rainfall is moderate |
| herb layer | Layer of plants with soft, green stems that grows closest to the ground in a forest |
| intertidal zone | Area of the marine biome along the ocean shore; it is a constantly changing environment |
| limiting factor | A factor that prevents a population from reaching its greatest possible size |
| near-shore zone | Area of the marine biome over the continental shelf that can support a wide variety of organisms |
| open-sea zone | Area of the marine biome that has the greatest number of plankton; the top 200 meters provide the greatest amount of food |
| permafrost | The layer of permanently frozen soil in a tundra |
| phytoplankton | Microscopic plants in the ocean that carry on photosynthesis |
| pioneers | The first organisms to grow in an area where primary succession is taking place |
| plankton | The many small organisms that float or swim near the surface of ocean water |
| population density | The number of individuals per unit of space |
| primary succession | When organisms start a community where none existed before |
| salinity | The amount of salt in water |
| secondary succession | The regrowth of a community that occurs after one has been destroyed |
| shrub layer | Layer of short, woody plants in a forest |
| succession | The orderly sequence of changes that occur in a community over time |
| taiga | The northern part of the coniferous forest |
| temperate rain forest | A biome in which the main trees are conifers, such as redwoods; it occurs along the western coast of North America |
| tropical rain forest | A warm, humid biome that has the greatest variety of living things |
| tundra | The northernmost land biome; a cold, dry region that has a limited variety of plants |
| turbidity | The number of particles suspended in water |
| understory | A layer of shorter trees and tall shrubs in a forest |
| zooplankton | Microscopic animals in the ocean that feed on phytoplankton and other microscopic animals |
