It's the snow and not the amount of rainfall which sustains forests over the year.
Rainwater falls to the ground and quickly drains into rocky soil, quickly weaving its way to our streams and rivers. But snow melts from higher elevations and trickles down through the forest floor, retaining moisture in the soil over longer periods of time. Snow also insulates the soil from below-freezing air temperatures.
The annual snow pack melt carries organic nutrients to support the endless decomposition and growth cycles so characteristic of British Columbia’s coastal forests. Soil bacteria and fungi thrive in the dampness left by snow to create vast underground networks of mycelium (fruiting as mushrooms) which in turn produces enzymes to break down fallen and rotting logs. The gradual release of snow water into the forest floor every spring is critical to the well-being of our trees, young and ancient.
Conversely, a warming climate leaves less snow pack for this annual process, exposing the ground to lower temperatures and more frequent freeze-thaw occasions. That’s why it’s not uncommon to see very dry forests in the late summer, despite a having a rain-soaked winter. The stress on cedar trees from recent droughts is obvious when we see their scale-like leaves turn reddish brown.
The BC government now has a Drought Information Portal which provides up-to-date information on the drought conditions in the province. Locally, the Regional District of Nanaimo has watering restrictions which vary depending upon the local reservoirs and aquifers.