Provisional versions of the Terrestrial Ecozones and Ecoregions of Canada map at 1:7.5 million scale were distributed to provincial collaborators for comment in December 1993 and a revised version was released in May 1994. Ecozone names remain from Wiken (1986). Ecoregion names are generally derived from a centrally located, prominent physiographic feature such as a mountain range, plateau, plain, basin, or lake, within the respective map unit. Ecodistricts are displayed on a separate series of 6 regional map coverages at map scales of 1:2 million in British Columbia and the Yukon, the Prairie Provinces, Ontario, Quebec, and Atlantic Provinces, and 1:3 million in the Northwest Territories. Each ecodistrict is identified by a unique number. It is intended that other levels of the hierarchy, particularly the ecoprovinces, will be revised in future framework developments.
Attributes and their referenced sources are documented for each revised level of the framework in Table 2. The names that appear on the 1:7.5 million map legend are stored as ecozone, ecoregion, and ecodistrict attributes within the framework data model. The hierarchical framework consists of 15 ecozones. Within these are 194 ecoregions, some of which contain more than one map polygon, so there are 217 ecoregion map polygons in total. For example, the Long Range Mountains ecoregion in Newfoundland is composed of three map polygons (108, 110 and 111). There are 1020 ecodistricts which are directly linked to the approximately 17 000 soil landscape polygons and their associated data stored in CanSIS. All polygons are physically nested and linked by unique polygon numbers at each level (Figure 3). In Alberta, revisions to the soil landscape polygons must first be completed before full nesting is achieved.
The national 1:7.5 million scale map has been produced for this package by digital files and conventional offset printing. Also available are a series of 1:2 and 1:3 million regional coverages showing ecozone, ecoregion, and ecodistrict lines. All maps are available from CanSIS in hard copy or digital form for a variety of GIS systems.
Brief narrative descriptions of each ecozone and ecoregion can be found in the Appendix. These descriptions represent a preliminary first version and provide a cursory overview of the principal attributes of each unit. Enhancements of the database and descriptions with additional biological, socioeconomic, and resource data will be ongoing.