The Ecoregions of British Columbia
The British Columbia Ecoregion Classification
The understanding of British Columbia’s complex environment is essential for the management, utilization, and conservation of the province’s natural resources. The purpose of a regional ecosystem classification scheme is to organize the ecological mosaic into simple patterns and to provide a practical framework for managing natural resources (Bailey, and Hogg 1986). Several regional classification schemes exist for the stratification of parts of North America into ecosystem units (see; Munro and Cowan 1947; Krajina 1965; Omernik 1977; Bailey 1980, 1983, 1995; Brown and Lowe 1980; Brown 1982: Wiken 1986; Gallant et al. 1989; Marine Environmental Quality Advisory Group 1994; McNab and Avers 1994; Ecologial Stratification Working Group 1995). Each has its positive attributes, but each also has shortcomings for delineating regional ecosystems in a mountainous area such as British Columbia (Demarchi 1992a).
The British Columbia Ecoregion classification was developed to provide a systematic view of the small scale ecological relationships in the Province given its great ecological complexity (Demarchi 1988a, 1992). This classification is based on macroclimatic processes (Marsh 1988), and physiography (Holland 1964; Mathews 1986), which is a fundamental difference between this and all other regional ecosystem classifications. Macroclimatic processes are the physical and thermodynamic interaction between climatic controls, or the relatively permanent atmospheric and geographic factors that govern the general nature of specific climates (Marsh 1988).
Another concept that is unique to the British Columbia Ecoregion classification is the integration of the terrestrial and marine environments so as to describe one regional ecosystem classification. The stratification of the B.C. marine and oceanic environments into Ecoregions was first proposed by Demarchi et al. (1990), subsequently a National Marine Ecoregion classification was developed, with many of the same units as the B.C. Ecoregion classification (Marine Environmental Quality Advisory Group 1994). However, there are some notable exceptions, mainly that fjords, inter-island channels and small sounds are grouped in with adjacent continental shelf or strait units, whereas in the B.C. Ecoregion Classification, the large straits and sounds are placed into separate units from the fjords, inter-island channels and smaller sounds.
There is also another level of ecological complexity that occurs within mountainous regions, that of topo-climatic zonation. Within each terrestrial region bounded by climatic processes and landform parameters, there are climatic zones that are reflected by the plant and animal communities present. This level is best pursued through the Biogeoclimatic Ecosystem Classification (British Columbia Ministry of Forests 1992a; Krajina 1965; Meidinger and Pojar 1991; Pojar et al. 1987). At the biogeoclimatic subzone level, the climate interacts with land surface materials to create particular environments suitable for the development of specific plant and animal communities (Rowe 1984; Demarchi 1992b; Demarchi and Lea 1987). Oceanic Environments, however, are the products of temperature, salinity, sea-bed configuration, and water depth (Thomson 1981). Classification of marine biophysical zonation is best pursued through the British Columbia Marine Ecosystem Classification (Wainwright et al. 1995) and the report on the Oceanography of British Columbia (Thomson 1981).
The Ecoregion classification system of British Columbia divides the province into 184 units (Table 1). However, arranging them into a hierarchical classification simplifies the result and makes them a useful tool for managing the natural resources of the province. The hierarchical levels has been defined as follows:
- Ecodomain - an area of broad climatic uniformity, defined at the global level;
- Ecodivision - an area of broad climatic and physiographic uniformity, defined at the continental level;
- Ecoprovince - an area with consistent climatic processes or oceanography, and relief, defined at the sub-continental level;
- Ecoregion - an area with major physiographic and minor macroclimatic or oceanographic variation, defined at the regional level;
- Ecosection - an area with minor physiographic and macroclimatic or oceanographic variation, defined at the sub-regional level.
The Ecodomains and Ecodivisions are very broad and place British Columbia in a global context. Ecoprovinces, Ecoregions, and Ecosections are progressively more detailed and narrow in their scope and relate the province to other parts of North America or the Pacific Ocean, or segments of the province to each other. These lower three classes describe areas of similar climate, physiography, vegetation, and wildlife potential. In the terrestrial environment each Ecoregion or Ecosection class can be further subdivided by biogeoclimatic criteria to provide a basis for detailed interpretation of climate, topography, soil, and vegetation for the purposes of habitat and wildlife management. And in the marine environment each Ecoregion or Ecosection can be subdivided by biophysical criteria to provide a detailed interpretation of climate, bathymetry, water chemistry, and currents for the purposes of fisheries management.
Since the first Ecoregions of British Columbia map was prepared in 1988 (Demarchi 1988b) there have been a number of edits, corrections and changes, in fact as predicted by Demarchi et al. (1990) as a better understanding of the broad ecological relationships in the province is gathered by such means as mapping ecosystems in greater detail, the Ecoregions map will continue to be updated. The first Ecoregion map was based on 1:2,000,000 level macroclimatic, physiographic and geographical information (Demarchi 1988b). By 1993 the Ecoregion classification became integrated with the Biogeoclimatic Ecosystem Classification as was mapped at 1:250,000 (Demarchi 1993). In 1995, the Ecoregion classification was edited using the revised - 1995 Biogeoclimatic data base, in addition a number of changes suggested from mapping exercises coordinated by the Ecological Stratification Working Group (1995), and mapping the British Columbia Ecoregion Classification criteria in the United States (Demarchi and Lea 1992; Demarchi 1994a,b) were incorporated into the British Columbia Ecoregion map (Demarchi 1995).
While the central concept of the British Columbia Ecoregion classification remains the same, there has been a redefinition of all the boundaries. For example, 100 Ecoprovinces are still recognized, but the Southern Interior now incorporates the Southern Chilcotin Ranges Ecosection; the Central Interior incorporates the Quesnel Lowland Ecosection, but not the Southern Chilcotin Ranges Ecosection; the Sub-Boreal Interior no longer is extended south in the Quesnel lowland; the Boreal Plains no longer is seen to extend to the Muskwa Plateau Ecosection, rather that Ecosection has now been placed in the Taiga Plains. The number of Ecoregions, however has been increased from 30 in 1988, to 34 in 1991, to 43 in 1993, to 47 in 1995. The number of Ecosections, likewise, has increased from 78 in 1988, to 87 in 1991, to 110 in 1993, to 116 in 1995 (Demarchi 1988b, 1991, 1993, 1995). Further changes may be necessary in the future as mapping of the province’s ecosystems becomes both more detailed and more extensively applied.
Uses of the British Columbia Ecosystem Classification
The value of an Ecoregion classification to resource managers is that it will place any ecosystem in a local, regional, provincial, continental or global context, and therefore provide a framework for the understanding of what are often complex, interacting systems. The merits of the Ecoregion classification to recreationalists and the general public is that they can become more aware of the Province’s environment, and may understand which areas of the Province contain unique ecosystems, and which ecosystems are connected to other jurisdictions.
Since its first publication in Volume 1 of the “Birds of British Columbia” (Demarchi et al. 1990), the Ecoregion Classification for British Columbia has become widely accepted as the standard classification for describing regional ecosystems within the province, just as the Biogeoclimatic Ecosystem Classification is the standard classification for describing zonal ecosystems within B. C. (Meidinger and Pojar 1991). As Demarchi (1994 a, b) and Mah et al. (1996) have outlined, land use and conservation goals are set at provincial or regional levels using information that has been based on broad scale physiography, climate and vegetation (e.g. Ecoregions and Biogeoclimatic Zones). This information has been used by government resource agencies for provincial and regional land use planning, especially for the Protected Areas Strategy (see British Columbia Ministry of Forests 1992b; British Columbia Recreation Branch 1992; Lewis and MacKinnon 1992; Vold 1992; Province of British Columbia 1993a, b; Quesnel and Thiessen 1993; Demarchi 1994a), for a general background understanding of the province’s environment (see British Columbia Commission on Resources and Environment 1994a, b, c, d; Cuthbert 1994; O’Gorman 1995), for program activity planning (see Fuhr and Demarchi 1990; British Columbia Wildlife Program 1991; British Columbia Wildlife Branch 1994, no date), and as a standard against which biological data can be assessed (see Campbell et al. 1990, in press; British Columbia Wildlife Branch 1991; British Columbia Ministry of Environment, Lands and Parks 1993,1995; Province of British Columbia 1995). In addition many non-government environmental organizations use the Ecoregion Classification for Protected Areas proposals issues (see Moore 1991; Canadian Parks and Wilderness Society 1992, 1993, 1994 1995a, b; Western Canada Wilderness Committee 1992; BC Wild 1994; Senez 1994) and for a general understanding the Province’s ecological diversity (see: Wareham 1991; Hume 1993; Mackenzie 1995).
The British Columbia Ecoregion Classification has also been used as a means of understanding our regional ecosystems and resource management concerns in relation to those of our adjacent neighbours in Canada and the United States. Such products as the Ecoregions of Canada (Ecological Stratification Working Group 1995) in which the British Columbia Ecoregion level is used for National State of the Environment Reporting. In addition carnivore management specialists in American states adjacent to the south of the province have relied on the British Columbia Ecoregion classification to map regional ecosystems from British Columbia into the western United States (Demarchi 1994b), and eastern Washington, Northern Idaho, northwestern Montana, and southwestern Alberta (Demarchi and Lea 1992).