Gap-driven ecosystems comprise the following Biogeoclimatic
Ecosystem Classification zones: Coastal Western Hemlock (CWH),
Mountain Hemlock (MH), Spruce-Willow-Birch (SWB) and Alpine
Tundra (AT), and moister sub-zones of Interior Cedar-Hemlock
(ICH) and Engelmann Spruce-Sub-alpine Fir (ESSF). At lower elevations
(CWH, ICH) they are distributed principally along the wet, windward
side of mountain ranges (Insular, Coast, Omineca, Cariboo, Monashee,
Selkirk, Purcell and Rocky) and in smaller pockets (i.e. Bulkley
Valley and Elk Valley) as a result of localized storm-tracking.
They also include wet sub-alpine communities (MH, ESSF and SWB)
and alpine tundra (AT).
Two maps are shown below:
1 — Physiographic Regions
The first map shows the major physiographic regions of British
Columbia — mountains, depressions, plateaus and valleys.
The interaction of these topographic features and the prevailing
moist Pacific weather systems produces a sequence of wet windward
mountain slopes and drier, “rain-shadow” climates
in depressions, plateaus and major valleys. This physiographic
map will help you understand the distribution of natural disturbance
regimes in the Province, which are shown in the second map.
2 — Disturbance Regimes
The second map shows the relationship between the three
disturbance regimes and the major physiographic zones. Note
especially the location of gap-driven ecosystems.