Since the late 1960s, governments, nongovernmental organizations, universities and industry have worked to develop a common, hierarchical ecosystem framework and terminology for Canada. In 1991, a collaborative project was undertaken by a number of federal agencies in cooperation with provincial and territorial governments, all under the auspices of the Ecological Stratification Working Group, to revise previous work and establish such a common ecological framework for Canada.

The underlying principle for the initiative was the commitment and need to think, plan, and act in terms of ecosystems. The principle required people to move away from an emphasis on individual elements that comprise an ecosystem to a perspective that is more comprehensive - a holistic approach. This required a consistent, national spatial context within which ecosystems at various levels of generalization can be described, monitored, and reported on. The use of such a framework of standard ecological units provides for common communication and reporting between different jurisdictions and disciplines.

The resulting report, A National Ecological Framework for Canada, released by the Ecological Stratification Working Group in 1996, describes the methods used to construct the ecological framework maps, the concepts of the hierarchical levels of generalization, narrative descriptions of each ecozone and ecoregion, their linkages to various data sources, examples of applications of the framework, and a list of contributors and collaborating agencies.

Ecological land classification

Ecological land classification is a process of delineating on a map and describing ecologically distinctive areas of the Earth's surface. Each area can be viewed as a discrete system which has resulted from the mesh and interaction of the geologic, landform, soil, vegetative, climatic, wildlife, water, and human factors which may be present. The dominance of any one or a number of these factors varies with the given ecological land unit. The holistic approach to land classification can be applied incrementally on a scale-related basis from site-specific ecosystems to very broad ecosystems.

The fundamental basis for delineating ecological units is to capture the major ecological composition and the linkages between the various components (e.g., landforms, soils, water, and vegetation) rather than treating each component as a separate characteristic of the landscape. Key points in the application of ecological land classification in delineating ecological map units are as follows:

• Ecological land classification is holistic, incorporating all major components of ecosystems - air, water, land, and biota, including humans.
• It involves an integrated of all these components and is not simply an overlay of them.
• It is based on a hierarchy, with ecosystems nested within ecosystems.
• The number and relative importance of factors helpful in delineating ecological units varies from one area to another, regardless of the level within the hierarchy.
• It recognizes that ecosystems are interactive and that characteristics of one ecosystem blend with those of another.
• It recognizes that map lines generally depict the location of areas of transition.

Some basic ecosystem concepts

Ecosystems are numerous and complex. The challenge is to make the ecological map units reflect this complexity. Ecological cycles, characteristics, and interactions are not always readily apparent or measured and therefore need to be interpreted from the development of vegetation, soil, and landform characteristics or other factors.

Ecosystems not only vary tremendously, but form part of a "nested hierarchy" at multiple scales, in which smaller ecosystems are encompassed within successively larger ones. A hierarchical system permits the choice of detail that suits management objectives and proposed uses. Because management and other decision-making deal at various levels, from local to regional to national and even to international, one of the prerequisites of ecological land classification is to portray ecosystems at a level, scale, and intensity appropriate to the need.

Although the ecosystem concept implies equality among components (soils, climate, vegetation, etc.), all components may not be equally significant throughout the hierarchy (i.e., some can be more determinant or enduring than others). The dominance or importance of any one factor may vary considerably in defining the spatial expression of an ecosystem at each level of generalization. Ideally, differentiating criteria are based on enduring components of the ecosystem and are those that do not change perceptibly over time, such as geology, surficial materials, landform, and water bodies. For any level of generalization the pattern of components may vary from one ecological unit to the next, as do their relationships and processes. For example, in northern Ontario, ecosystems are controlled by the bedrock of the Canadian Shield, shallow soils, and multiple lakes, whereas southern Ontario exhibits flat sedimentary bedrock, buried by deep soils and fewer lakes. These factors influence other conditions such as habitat, vegetation growth, and productivity.

Ecosystems can range from natural systems through to those heavily modified by human activity, such as urbanization and agricultural development. In some situations human activities have historically been pervasive, significantly influencing the ecological processes and character of a region (e.g., the permanent influence of agriculture on the grasslands of the Prairie Provinces or urban development and agriculture on the Carolinian forests of southern Ontario).

Enjoy learning more about this national spatial ecological framework for Canada!

• Read the Background and Methodology behind this report
• Access the table of contents
• View the map of Canada's ecozones and read the descriptions