Biogeoclimatic Maps (zone or subzone/variant)

Background

The biogeoclimatic ecosystem classification (BEC) is an integrated hierarchical classification scheme that combines climate, vegetation and site classifications (see Meidinger and Pojar (1991) for a detailed description of the BEC system). Ecosystems ranging in scale from regional to local are defined using zonal (climatic) concepts and the vegetation of the zonal climax or near-climax ecosystems. At the regional level of the BEC scheme, the basic unit of zonal or climatic classification is the subzone. Grouping subzones forms zones, while subzone divisions define variants. Site series, which are the largest-scale ecosystem unit of the BEC system and exist at the local (site) level, are defined within variants, or subzones if variants are not described for a subzone. Site-series units describe all land areas that are capable of supporting a specific climax vegetation with a climatic area.

Delineating the geographical distribution of the ecological units that belong to an ecological classification scheme is broadly referred to as ecosystem, or ecological, mapping.

Biogeoclimatic Subzone/Variant Mapping

Biogeoclimatic Subzone/Variant (and phase) mapping is the stratification of a landscape into map units, according to a combination of ecological features, primarily climate and physiography using the classification concepts described above. BGC mapping provides information that is used:

  • to assist field workers in applying the Biogeoclimatic Ecosystem Classification (BEC) at the site level;
  • as a basis for more detailed ecological mapping such as Terrestrial Ecosystem Mapping (TEM) and Predictive Ecosystem Mapping (PEM);
  • as a framework for a variety of provincial level reporting tasks such as representativeness of the Protected Areas Strategy's system of protected areas;
  • to provide ecological context for the Regional Land Use Planning processes and Land and Resource Management Planning tables.

The original "legacy" Biogeoclimatic subzone/variant mapping that existed for the entire province (as of December 15, 1999) was digitized from paper maps. The scale of the source maps ranged from 1:600,000 to 1:100,000, which was appropriate for the original purpose of the mapping: to assist field workers in applying the Biogeoclimatic Ecosystem Classification as the site level. For that purpose, it was not particularly important that the mapping was neither highly accurate nor that it was referenced to a variety of base-map scales.

Since December 15, 1999, the regional ecologists have been working to systematically revise the "legacy" Biogeoclimatic subzone/variant mapping under the program name: “Big BGC” or "large-scale BGC mapping". The revisions being applied as part of the large-scale BGC mapping  program are primarily a provincial harmonization of the BGC-mapping scale, achieved by linking the BGC-unit boundaries to the TRIM base layer (1:20,000 scale). Eng and Meidinger (1999) describe the generic method to generate large-scale BGC mapping in BC. In most regions, revisions to subzone and zone boundaries and zonal reclassification are also being undertaken concurrently.  The Scale of Mapping PDF shows the current source and scale of biogeoclimatic subzone/variant mapping throughout the province.