The Nearctic is a major terrestrial ecozone that encompasses most of North America, including Greenland and the highlands of Mexico. In biogeographic schemes it is one of eight recognized terrestrial ecozones and is defined by a set of related ecosystems, climates, and distinctive lineages of plants and animals. The name Nearctic contrasts with the Neotropical ecozone to the south; their boundary lies roughly where tropical and subtropical biotas replace temperate and boreal communities. For a different use of the name, see Nearctic (horse).

Extent and boundaries

The Nearctic covers Canada, the United States, Greenland, the Arctic islands, and most of Mexico's highlands and plateaus. It excludes southern Florida, southern Mexico, the Caribbean islands, and Central America, which belong to the Neotropical ecozone. At its northern edge the Nearctic meets polar ice environments, while at its western and eastern margins it interfaces with marine realms. The Nearctic is often compared and sometimes grouped with the Palearctic (Eurasia) under the broader Holarctic concept because of shared faunal and floral elements and historical connections across the Bering land bridge.

Climate, habitats, and characteristic life

Climates across the Nearctic range from Arctic cold and tundra in the north, through the boreal forest (taiga) belt, into temperate broadleaf and mixed forests, prairie grasslands, desert basins, and montane zones. Typical vegetation includes northern conifers (spruce, fir, pine), temperate hardwoods (oak, maple), prairie grasses, and xeric shrubs in deserts. Characteristic fauna include mammals such as bison, pronghorn, deer, bears, wolves, and many migratory bird species; Arctic regions support polar bears and seals, while montane and desert areas host specialized endemic species.

Biogeographic history

The Nearctic's biota reflects a long history of geological and climatic change. During the Pleistocene glaciations species ranges shifted repeatedly, shaping modern distributions and endemism. Periodic land connections to Eurasia via Beringia allowed exchanges with Palearctic lineages, while isolation from South America since the early Neogene limited tropical interchange until the Isthmus of Panama formed. These events produced the distinctive mix of temperate, Arctic, and some Neotropical elements seen today.

Conservation and human significance

Much of the Nearctic supports productive agriculture, forestry, and urban development, placing pressure on native habitats. Prairie grasslands and some temperate forests have been especially reduced by conversion to farmland. Conservation efforts focus on protecting remaining large landscapes, restoring wetlands and grasslands, and maintaining connectivity for migratory species. International organizations and regional agencies recognize Nearctic diversity in planning and list priority ecoregions and reserves.

Division and references

The World Wide Fund for Nature (WWF) divides the Nearctic into four bioregions to help organize conservation priorities; these bioregions contain many ecoregions spanning tundra, boreal forest, temperate forest, grassland, and desert types. For general context on ecozones and related concepts, see resources on ecology and biogeography.

For more specialized treatments—such as floristic provinces, ecoregion maps, and lists of endemic taxa—consult regional field guides and conservation assessments. The Nearctic remains a central subject in studies of biogeography, climate change impacts, and continental-scale conservation planning.