Ecozone (biogeographic realm)

Characteristics and how ecozones differ from biomes

Ecozones are defined by the deep-time distribution and relationships of species. Two locations in different ecozones may have similar climate and plant communities yet host very different species because their biotas came from separate evolutionary pools. In contrast, biomes classify areas by predominant life forms and climatic regimes (for example, tropical rainforest, tundra, or temperate grassland) and can occur within multiple ecozones. An ecozone can therefore contain several biomes, while a single biome can span multiple ecozones.

Origins and shaping forces

The pattern of ecozones has been shaped over geological time by plate tectonics, sea-level change, and the rise of mountain ranges. Continental drift separated once-connected landmasses, isolating plant and animal lineages and allowing independent evolution. Major physical barriers limited dispersal and created distinct faunas and floras. For discussion of the geological processes behind these distributions, see plate tectonics resources.

Typical classification and examples

Modern schemes generally recognize several principal terrestrial ecozones, such as the Nearctic (North America), Palearctic (Eurasia north of the tropics), Neotropical (Central and South America), Afrotropical (sub-Saharan Africa), Indomalayan (South and Southeast Asia), Australasian (Australia, New Guinea, nearby islands), Oceanian (remote Pacific islands), and Antarctic. Each of these realms contains distinctive lineages and many endemic genera and families. The concept aligns with older botanical floristic kingdoms and zoological regions used in mammal and bird biogeography; see a general biogeography overview at biogeographic resources.

Uses, importance, and conservation

Ecozones are useful for understanding large-scale biodiversity patterns and for setting conservation priorities at continental scales. They help scientists and planners identify regions with unique evolutionary heritage and high levels of endemism. Conservation strategies often consider ecozone boundaries to preserve representative samples of Earth's evolutionary history and ecological variation. For contrast between ecozone-based and habitat-based approaches, consult material on biomes and ecosystems.

Notable distinctions and practical notes

• Terminology varies: authors may use realm, kingdom, or region interchangeably.
• Ecozone boundaries are broad and sometimes gradual; transition zones (ecotones) can blur edges.
• Human activity—habitat change and species introductions—has altered natural distributions, complicating strictly historical classifications.

Understanding ecozones provides a framework for appreciating the planet's biological diversity at the largest scale and for recognizing how Earth's history has shaped the living world we see today.