Biomes are the major regional groupings of plants and animals discernible at a global scale. Their distribution patterns are strongly correlated with regional climate patterns and identified according to the climax vegetation type. However, a biome is composed not only of the climax vegetation, but also of associated successional communities, persistent subclimax communities, fauna, and soils.
The biome concept embraces the idea of community, of interaction among vegetation, animal populations, and soil. A biome (also called a biotic area) may be defined as a major region of distinctive plant and animal groups well adapted to the physical environment of its distribution area.
To understand the nature of the earth’s major biomes, one needs to learn for each:
- The global distribution pattern: Where each biome is found and how each varies geographically. A given biome may be composed of different taxa on different continents. Continent-specific associations of species within a given biome are known as formations and often are known by different local names. For example, the temperate grassland biome is variously called prairie, steppe, pampa, or veld, depending on where it occurs (North America, Eurasia, South America, and southern Africa, respectively).
- The general characteristics of the regional climate and the limitations or requirements imposed upon life by specific temperature and/or precipitation patterns.
- Aspects of the physical environment that may exert a stronger influence than climate in determining common plant growthforms and/or subclimax vegetation. Usually these factors are conditions of the substrate (e.g., waterlogged; excessively droughty, nutrient-poor) or of disturbance (e.g., periodic flooding or burning).
- The soil order(s) that characterize the biome and those processes involved in soil development.
- The dominant, characteristic, and unique growthforms; vertical stratification; leaf shape, size, and habit; and special adaptations of the vegetation. Examples of the last are peculiar life histories or reproductive strategies, dispersal mechanisms, root structure, and so forth.
- The types of animals (especially vertebrates) characteristic of the biome and their typical morphological, physiological, and/or behavioral adaptations to the environment.