Most of the province is presently mapped at 1:250,000 for the broad habitat classes. The habitat classes directly correspond to each of the BEU's described in this classification. However, the mapping was completed prior to the description of the units so additional, more detailed units appear in this document than those units found on the maps. As the descriptions of the various ecosystem units were developed, it was apparent that all of the vegetative diversity and expansive geographical distributions could not be adequately described without further classification. Similarly, some vegetated units were combined while more complex units, such as wetland and riparian units, were split creating new units. Some of these units rarely appear on the BEU maps because they cover such a small area at this scale. However, it is important to note that even though they do not appear very often, these units are wide-spread in distribution. This is typical of many of the wetland and riparian types, as well as some of the urban and sparsely vegetated units.
Currently, some areas of the province are being remapped using this updated BEU classification and eventually the entire province is to be completely remapped. In addition to the re-mapping, some of the nonforested ecosystem types, in particular the wetland and alpine communities, will be more extensively sampled and classified. This may create the need for further classification of the broad ecosystem units.
The written description of BEUs should enable the user to identify the unit either in the field or describe the unit in technical reports or publications. This description of the classification breaks down BEU classification and demonstrates the content of each section and the source of the information. The description of each unit provides information on an ecosystems distribution, subdivisions, climax vegetation, successional vegetation, physical environment, and any atypical sites. A distribution map and colour photograph(s) will also be provided to further assist in correctly identifying or describing each unit. The distribution maps show the biogeoclimatic zone(s), subzone(s) and variant(s) in which each of the broad ecosystem units occur.
Name and Symbol: Unit names contain the primarily dominant and/or characteristic climax and seral species and, if relevant, an ecological qualifier. Naming for non-forested units is often more generic (ex. Alpine Meadow(AM), Shrub Fen(SF)). A unique two letter upper-case code based on the unit name is provided for mapping; these names do not correspond directly with BEC classification. Examples include the Amabilis Fir - Western Hemlock broad ecosystem unit (FR) and the Black Cottonwood Riparian broad ecosystem unit (CR).
General Description: Describes a typical unit including the presence and relative abundance of the dominant species and other characteristic vegetation. Seral development and disturbance history are important biotic factors which may be described. Important geographical features such as elevation, latitude, proximity to the ocean, and soil moisture regime may also be included. Features deemed most characteristic of the unit are included.
Distribution: Depicts the geographical distribution of each BEU, within specified ecoprovinces, ecoregions and/or ecosections, as well as in relation to political boundaries, elevational limits, bodies of water, mountain ranges, and/or plateaus. Each of these BEU distributions has been developed based on the current distribution of associated BEC units as described in the forestry regional field guides. Note there is considerable range in the upper and lower elevational limits of most units due to climatic variability and differences in local topography.
Subdivision: BEUs are divided into subunits when there are clear differences in vegetation. Site series correlated to each unit are then divided geographically using physical boundaries (i.e., mountains, rivers, proximity to the ocean -coastal/interior/transitional, latitude north/south, or elevation) or climatically (i.e., moisture regime-hydric/mesic/xeric). Broad Ecosystem Units and subunits may be present in more than one biogeoclimatic zone.
Climax Vegetation: BEC site series climax vegetation tables and descriptions, edatopic grids, additional information in the Forestry Regional Field Guides, large scale mapping legends, and personal communications with regional ecologists are all sources of information used to generalize and describe the vegetation of a unit. Relative abundance and presence of vegetation in the canopy (tree species with height greater then 10m), shrub layer (shrubs and tree regeneration with height less than 10m), herb layer (ferns, graminoids, herbs, saprophytes and some woody species), and moss and lichen layer (moss, lichens and liverworts) are described. Species are recorded in their approximate order of abundance within each vegetation layer (see example units).
Successional Vegetation: Provides a brief description of the general characteristics of these ecosystems following disturbance. Typically, this description includes an account of the dominant vegetation and structural characteristics which occur as the unit moves through a gradual transition from an early pioneer vegetated state to an overmature climax state. For example, a forested unit may progress through a shrub/herb dominated community composed of fireweed and willow to an aspen dominated seral forest until reaching a spruce dominated climax state.
Physical Environment: Terrain, soil moisture, slope, aspect, elevation, and any additional physical factors common to the unit which influence vegetation are discussed. Most often BEUs occur over wide ranging physical characteristics.
Atypical Sites: Describes sites which occur within a given unit but have slightly different dominant vegetation species and/or physical environments than the typical situation described for the unit. An example is a moist devil's club dominated site occurring in a normally drier BEU where devil's club is typically a minor component.
Broad Ecosystem Units have been divided into ten classes of ecosystem types: