The concepts and hierarchy set out by CCELC remained the overall guide for revising three priority levels (ecozone, ecoregion and ecodistrict) of the framework. Map delineations at each level were judged on a case by case basis within and between provinces and territories. These levels were deemed to be the most suitable to report on national issues and regional issues of national significance concerning the environment and sustainability of resources.
A range of stakeholders from federal, provincial, and territorial governments, environmental interest groups, and the private sector, were consulted to incorporate wherever possible, the most recent provincial ecological mapping products to provide seamless national coverage at each level. This involved correlating existing ecological maps and, where needed, revising maps. Regionalization was guided by the previous national terrestrial ecoregion map (Wiken et al. 1993), as well as by other published national map sources, such as the Ecoclimate Regions of Canada (Ecoregions Working Group 1989), and the Physiographic Regions of Canada (Bostock 1970). A pre-existing ecodistrict coverage (Environment Canada 1985), the Soil Landscapes of Canada series of 1:1 million scale soil maps (Shields et al. 1991), and the Northern Land Use Information Series of 1:250 000 scale maps (Environment Canada and Indian and Northern Affairs Canada 1978-1986) were used in delineating map units at the ecodistrict level of the framework. Finally, the process included the use of LANDSAT imagery as a broad correlation tool to ensure that the defined biological and physical patterns of the landscape were consistently captured across boundaries and between provinces and territories, particularly in northern Canada where detailed ecological information was less available.
Levels of Generalization
Map delineations of three levels of the CCELC hierarchy were refined during this project. They are listed in Table 1 and are also described below. Other levels in the hierarchy less suited to meeting the needs of environmental reporting and monitoring were not utilized.
Ecozones are areas of the earth's surface representative of large and very generalized units characterized by interactive and adjusting abiotic and biotic factors. Canada was first subdivided into 15 ecozones to meet reporting requirements of the first State of the Environment Report for Canada published in 1986 (Wiken 1986). The ecozone lies at the top of the ecological hierarchy as defined by the CCELC (Wiken 1979). In this context, the ecozone defines on a subcontinental scale, the broad mosaics formed by the interaction of macroscale climate, human activity, vegetation, soils, geological, and physiographic features of the country. The former Terrestrial Ecozones of Canada report is being updated and will also include descriptions for the recently developed marine ecozones (Wiken, personal communication 1995).
Modifications were introduced to several ecoregions which affected the boundaries of some parts of ecozones. For example, the Boreal Shield ecozone now includes Lake Melville and Paradise River ecoregions of Labrador in the east, and the Athabasca Plain ecoregion of northern Saskatchewan. The Atlantic Maritime ecozone has been extended to include the Appalachian Mountains of southeastern Quebec. The Boreal Plains ecozone has been revised to extend northward to Great Slave Lake along the Slave River valley. The Boreal Plains ecozone has been withdrawn from the Northwest Territories - Yukon - British Columbia boundary intersection. This area now belongs to the Boreal Cordillera ecozone in recognition of its mountainous condition. Many smaller adjustments have been made to all ecozone boundaries on the revised map (Figure 1), based on input from local Working Group members.
Ecoregions are subdivisions of the ecozone characterized by distinctive large order landforms or assemblages of regional landforms, small order macro- or mesoclimates, vegetation, soils, water, and regional human activity patterns/uses. In this compilation, ecoregion boundaries which already existed from previous work were refined to reflect more recent detailed provincial studies and knowledge. The ecoregions constitute the major bridge between the subcontinental scale ecozones and the more localized ecodistricts. The revisions to the ecoregions provided the principal basis for the refinement of the original ecozones delineated by Wiken (1986).
Provincial ecoregion maps were incorporated into the national map with only minor modification to original material in Newfoundland (Wiken et al. 1993; afterHirvonen 1984;Damman 1983), Prince Edward Island (Wiken et al. 1993; afterHirvonen 1984), Nova Scotia (Wiken et al. 1993; afterHirvonen 1984;Simmons and Muecke 1984), Labrador (Hirvonen 1984;Meades 1993), Manitoba (Eilers and Mills 1992), and British Columbia (Demarchi 1993). In New Brunswick the latest developments by Godin and Roberts (1994) were incorporated. In the Yukon, ecoregion boundaries were redrawn based on the earlier work of Oswald and Senyk (1977), Wiken et al. (1981), and Alberta Environmental Protection (1994) and modified to match a recent ecoregion map of Alaska (Gallant et al. 1995). In Alberta, a new map resulted through a consensus review and merger of two existing systems (Achuff et al. 1988;Strong 1992) incorporating concepts published by Pettapiece (1989). In Quebec, existing works of Gilbert et al. (1985) and Ducruc et al. (1994) at the Ministère de l'Environnement et de la Faune (1994) were modified and amalgamated. In Ontario, efforts by a federal/provincial working group modified the ecoregions of Wickware and Rubec (1989) and the site regions of Hills (1976). In Saskatchewan, a similar working group produced a new ecoregion map (Padbury and Acton 1994) incorporating the work of Harris et al. (1989), and Thorpe (1992). In the Northwest Territories, existing ecoregions (Wiken et al. 1993) and regional studies (Weatherall 1985;Wiken et al. 1985) were modified. Recent NOAA/AVHRR imagery provided by the Department of Renewable Resources, Government of the Northwest Territories (GNWT) and data from the recently completed Soil Landscapes of Canada map series were also used in preparing revised ecoregions.
Ecodistricts are subdivisions of ecoregions and are characterized by distinctive assemblages of landform, relief, surficial geologic material, soil, water bodies, vegetation, and land uses. The ecodistricts bring together various subregional units which had been defined by Environment Canada, Agriculture and Agri-Food Canada and provincial agencies. Under the sponsorship of the Northern Land Use Information Series (NLUIS) much of the Canadian Territories were mapped and classified according to ecodistricts by Environment Canada. These descriptions are contained on the individually published 1:250 000 NLUIS maps. These maps contain information on soils, landforms, vegetation, wildlife, and water resources in the context of ecodistricts. Another example, is the Centre for Land and Biological Resources Research's development of a subregional unit termed an "agroecological resource area" for land evaluation and modelling purposes. The agroecological resource areas were completed for the agricultural portions of the Prairie Provinces (Dumanski et al. 1993;Pettapiece 1989;Eilers and Mills 1990) and in Nova Scotia (Patterson and Langman 1992). The method of identifying significant separations at this level was, in large part, based on differences in parent material, topography, landform and soil development derived from the Soil Landscapes of Canada. The Soil Landscapes maps represented the most detailed level (1:1 000 000 scale) of national biophysical landscape information available for all of Canada during the compilation of the ecodistrict boundaries.
In addition to the agroecological resource areas, soil landscape units have been used as a basis to refine and define ecodistricts in some nonagricultural areas of Canada. In northern Quebec and the Northwest Territories, units that had been established under the first approximation of ecodistricts (Environment Canada 1985) and through the Northern Land Use Information Series (Environment Canada 1978-references.html1986) were evaluated, revised, correlated and combined to produce a uniform ecodistrict coverage depicted on the Soil Landscape polygon base.
In British Columbia, the province's subregional "ecosections" (Demarchi 1993) were equated to ecodistricts with only minor modifications. In British Columbia, ecoregions were mapped in relation to the biogeoclimatic ecosystem classification (Pojar et al. 1987). Due to the complex nature of climates and landforms within mountainous ecosystems, ecodistricts depict in greater detail the ecological assemblages that are found within the same macroclimatic and physiographic region (i.e. ecoregion). With the Cordilleran ecoregions, ecodistricts tend to contain a greater range of properties than are found in ecodistricts elsewhere in the country.
Digital coverages of ecozones, ecoregions and ecodistricts were compiled on the standard 1:1 million scale map bases of the Soil Landscapes of Canada database, and stored as discrete layers of map polygons within the Canadian Soil Information System (CanSIS) (MacDonald and Valentine 1992). CanSIS is run on an ARC/INFOTM version 6.10 geographic information system, based on Hewlett PackardTM Model 735,717 work stations operating under a UnixTM operating system.
All polygon boundaries of the ecological framework are matched to soil landscape polygons. Although not specifically a part of the Ecological Land Classification system of CCELC, the Soil Landscapes of Canada map series provided a suitably detailed digital cartographic information base upon which to aggregate the smaller scale products of ecological regionalization.
A data model has been designed to minimize redundancy and maximize data flexibility (Selby and Santry 1993). This relational data model is composed of an integrated application of seven dBase IV database files (Figure 2). The database files and their structures were designed to relate polygons and their attributes from one level within the framework with those of other levels. The data model was also designed to facilitate the linking of external databases to the framework.
Two categories of databases were established within the application. The first category of files contains the standard data codes, descriptions, and rules (data type definitions) for the entire application. The TYPE_DEF, ATT_CODE, MISC_DEF and RULE_SET files were designed to act as an on-line database manual. The second category of files was designed to contain the data specific to each polygon. These files provide descriptions of map codes (MAP_CODE.DBF), values for ecozone, ecoregion or ecodistrict attributes (MAP_ATT.DBF) and a link to the Soil Landscapes of Canada (SLC) polygons (POLYGON.DBF). Additional files (not shown in Figure 2) are generated by programs for the convenience of users. They are temporary in nature, serving very specific purposes. One of these programs was written to generate a flat file summary of data intended for use by GIS operators for plotting attributes of map polygons.