by David D. McClosky Cascadia Institute

Ecoregions are the rooms in the house of a bioregion. Ecoregion is short-hand for regional ecosystem. An ecoregion is a relatively similar area united by common geography, ecology, and culture. Ecoregions are distinct places which help articulate the internal diversity of a large and complex region such as Cascadia.

The purpose of ecoregional mapping is two-fold: one, to provide a common, integrative framework for management of natural resources, and two, for deeper social identification with the land and each other, and thus, better political organization.



An ecoregion is known in two ways: internally by its distinctive character (e.g. the Okanogan Highlands), and externally by its context in the region (e.g. Okanogan in relation to the Columbia Plateau and Coeur d'Alene-Spokane).

An ecoregion may be analyzed on physical, biological, and cultural levels. First, we map the landforms, geology, climate, and hydrology, and how these environmental factors work together to create a common template for life in that particular place. Second, we map the flora and fauna, especially the characteristic vegetative communities, and link them to their habitats. Third, we look at native peoples, western settlement, and current land-use patterns and problems, in interaction with the first two levels.

Each layer of information is brought together to represent the regional system. No one single factor (e.g. climate) explains everything. The inner structure of an ecoregion is organized as a series of intersecting gradients; temperature and precipitation changing with elevation, in alternating belts of vegetation along windward and leeward sides of a parallel series of mountain ranges, with biodiversity thinning toward the edges. Such flows of energy, matter, and information form a distinctive matrix. To understand the region, we must comprehend this system of relationships.

Boundaries are natural, and often found as soft transitional areas rather than hard-edged political lines on a map. The boundary is a convergent threshold where many layers intersect, located where several significant factors end and begin. Borders articulate the natural envelope of the place--its centers and bounds--and link this diversity into the larger world.

Since ecological systems are open and lack definite boundaries, in complex terrain, watersheds are often used to represent ecosystems on a landscape level. Here, ecoregions are often drawn as a series of contiguous watersheds with similar character and context. However, where other factors predominate--such as landforms, tectonic suites, regional rivers, vegetative breaks, or major cultural boundaries--then watershed lines may be crossed. In each case, the key is to be true to the land and its people.

In terms of size, an ecoregion is larger than a watershed and smaller than a bioregion; or in political terms, larger than a county and smaller than a state or province. There are over 75 ecoregions in the more than 750,000 square miles of Cascadia. Thus, they average about 10,000 square miles each, though ranging from 2,000 to over 30,000 square miles; again, size depends upon the unique character and context of the place itself. An ecoregion in Cascadia often covers several degrees of latitude and perhaps longitude.

No ecoregion is self-contained but rather is intertwined with others as houses within houses. The ecoregion is a mediating level linked to the habitat or neighborhood, and watershed, on smaller scales, and to the bioregion, continent, and planet, on larger scales in many complex ways. We seek to understand the structure, function, and evolution of each ecoregion in terms of this larger system of relationships.

As a practical matter, ecoregions may be flexibly combined and recombined in different configurations to fit changing condi-tions and special purposes. For instance, Okanogan could be linked to Mountain Valleys and the Selkirks-Pend Oreille for one application, and with the Columbia Plateau and Coeur d'Alene-Spokane for another task, or they could all be combined for a third purpose.

Ecoregions provide a general purpose map of the local world, as we seek to comprehend the life of the place as a whole.

© 1997 Cascadia Institute
