Ecoregions or bioregions are geographical units with characteristic flora, fauna and ecosystems. They are a division of the larger "ecozones" or biogeographic regions. Political divisions of counties, states and countries do not respect ecological processes, so it is important to develop public policies that include appropriate spatial scales and that consider environmental dynamics. The ecoregional approach is important from several points of view.
Many species require large areas to maintain viable populations. For example, raptors and large predators have areas of activity of more than 20 km2. To keep populations of hundreds of individuals of these species, we need large areas.
Ecosystem processes, such as the cycles of water and nutrients, sometimes operate at large spatial and temporal scales, e.g. the composition of coastal lagoons is influenced by the ocean and by the supply of currents of fresh water that come from great distances.
Most human communities perform their economic and social activities within a regional environmental setting. A healthy environment provides goods and services of high quality to the populations within. By contrast, large cities go beyond their local or regional scope in order to satisfy the needs of their residents: water, food, materials and energy must be imported from distant places.