Meredith Gallogly
If you have found yourself grumbling at the prospect of yet more shoveling after each storm this winter, and irked by the deep drifts still impeding parking spots, walkways, and sight-lines, take solace in the fact that all this snow is a major boon for our ecosystems in the northeast.
Persistent snowpack acts as an insulating blanket for our landscapes, keeping soil from freezing too deeply and preventing frost heave, which can damage plant roots. It also shields vegetation from desiccating winds and sustains consistent soil moisture, improving plant growth and seed germination in the spring.
Just half a foot of lasting snow leads to the formation of a microhabitat called the subnivean zone. Right at the surface of the ground the heat of the earth turns snow into water vapor, creating pockets of air that small rodents use as tunnels and dens. These temperature-controlled labyrinths offer significant—though not absolute—protection from predators. Owls can still hear their prey moving under the snow and snatch them out from under it with a well-timed dive (see photo gallery).
So, the next time you feel the weight of the winter bearing down on you, remember that at least this year we have snow (not ice). Imagine the voles in your yard building a subnivean stronghold worthy of NIMH. Look for owl prints. And celebrate the lush spring season that surely awaits us.
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Vignettes of Snow Ecology
Owls often provide us with the best indication of where rodents may be tunneling below the surface of otherwise pristine snow pack. Their prints can tell the story of a clean hit (lefthand photo) or a messier struggle. In the middle photo, the snow has melted just enough to start revealing some subnivean tunnels.
The image at right shows mountain laurel (Kalmia latifolia) in a deep layer of protective snow, which shields its roots from harmful temperature fluctuations. The snow also provides a consistent source of moisture that keeps its leaves from drying out in the winter, something to which evergreen plants are uniquely susceptible (gardeners call this winter burn).
