Land

Etymology

Middle English, from Old English; akin to Old High German lant land, Middle Irish lann

• Date: before 12th century

Definitions

• 1 a : the solid part of the surface of the earth; also : a corresponding part of a celestial body (as the moon)

b : ground or soil of a specified situation, nature, or quality <dry land>

c : the surface of the earth and all its natural resources

• 2 : a portion of the earth's solid surface distinguishable by boundaries or ownership <bought land in the country>: as a : country <the finest cheese in all the land>

b : a rural area characterized by farming or ranching; also : farming or ranching as a way of life <wanted to move back to the land>

• 3 : realm, domain <in the land of dreams> —sometimes used in combination <TV-land>
• 4 : the people of a country <the land rose in rebellion>
• 5 : an area of a partly machined surface (as the inside of a gun barrel) that is left without machining

Description

Terrestrial ecoregions are land ecoregions, as distinct from freshwater and marine ecoregions. In this context, terrestrial is used to mean "of land" (soil and rock), rather than the more general sense "of Earth" (which includes land and oceans).

World Wildlife Fund ecologists currently divide the land surface of the Earth into 8 major ecozones containing 867 smaller terrestrial ecoregions. The WWF effort is a synthesis of many previous efforts to define and classify ecoregions. Many consider this classification to be quite decisive, and some propose these as stable borders for bioregional democracy initiatives.

The eight terrestrial ecozones follow the major floral and faunal boundaries, identified by botanists and zoologists, that separate the world's major plant and animal communities. Ecozone boundaries generally follow continental boundaries, or major barriers to plant and animal distribution, like the Himalayas and the Sahara. The boundaries of ecoregions are often not as decisive or well recognized, and are subject to greater disagreement.

Ecoregions are classified by biome type, which are the major global plant communities determined by rainfall and climate. Forests, grasslands (including savanna and shrubland), and deserts (including xeric shrublands) are distinguished by climate (tropical and subtropical vs. temperate and boreal climates) and, for forests, by whether the trees are predominantly conifers (gymnosperms), or whether they are predominantly broadleaf (Angiosperms) and mixed (broadleaf and conifer). Biome types like Mediterranean forests, woodlands, and scrub; tundra; and mangroves host very distinct ecological communities, and are recognized as distinct biome types as well.