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North Vancouver lies within the Coastal Western Hemlock Biogeoclimatic Zone (CWH). This is one of 14 biogeoclimatic zones that divide British Columbia.
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The CWH extends along a broad swath up the entire Pacific coast. There are 10 sub-zones within the CWH.
The CWH typically has a cool mesothermal climate (cool summers with mild winters) although hot dry spells can occur.
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On average, this zone has the highest annual precipitation (1000-4400mm) of the 14 zones. Most of it is rain.
Because of the high rainfall, the soils of the CWH tend to be leached and highly acidic.
In areas of high acidity and low nutrients, plant species have devised many interesting ways to scavenge the few nutrients that are there. The most significant of these is the use of mycorrhizal fungi as an extension of their root systems.
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Throughout the CWH, Western Hemlock is usually the most common tree species.
Western Red Cedar occurs frequently south of 56° N latitude.
Douglas-fir is widespread south of 53° N latitude in the drier parts.
Amabilis Fir and Yellow Cedar occur in the wetter parts.
Red Alder occurs on logged and other disturbed sites as a pioneer species.
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THE WATERSHED
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In the upper Mosquito Creek watershed, the transition can be seen between the lower elevation CWH dominated by Western Hemlock, and the higher elevation - which is dominated by Mountain Hemlock.
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Of the 10 sub-zones within the CWH, the upper watershed contains three:
Wet Maritime CHW in Area 1, Moist Maritime CWH in Area 2, and Dry Maritime CWH in Area 3.
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