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The scheme of global terrestrial biomes presented here follows the traditional division of Earth’s land surface into major biotic regions that is found in American textbooks and taught in classrooms from K-12 through university undergraduate levels. The extent of each biome is generally determined by the spatial patterns of the Koeppen climate system and the structural and physiological responses of natural or potential vegetation to average climate conditions. A given biome may encompasses several long-term states that reflect such controlling factors as edaphic conditions or frequent burning. The term biome traces back to F.E. Clements, who introduced it in his 1916 opening address to the first meeting of the Ecological Society of America.¹  He equated it to “biotic community”. Clements is best known for his theory of succession leading to a climax community reflecting regional climate. The biome concept was later developed by Shelford and Olson (1939)² and used to refer to the vegetation climax. Initially the vegetation, in various stages of succession, that constituted a biome was delineated according to accumulated expert knowledge. Later modifications reflected an ecosystems approach and added typical and endemic animal life, soil types, disturbance regimes, and—most recently—human impacts. The concept has also been applied to aquatic environments, both fresh and salt water.A number of other schemes exist for recording the spatial patterns of life on the planet; and increasingly these are enhanced by remote sensing and model building as well as field studies. Among them are ecoregions, ecozones, bioclimatic realms, and land cover classifications. Each has specific criteria for establishing ecological regions and specific purposes.³

Biomes and the other schemes are relevant today in applied sciences such as conservation ecology, especially in the determination and assessment of future scenarios related to changing climate and land use practices.³

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INTRODUCTION TO BIOMES

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.