Field Notes: The Fascinating Ecology of Snow

There’s a magic and marvel to a massive snowstorm that can almost not be explained. A quiet world, a forest painted white. But after weeks of shoveling ourselves out, barred from beloved hiking trails and cooped up indoors to escape the cold, it can be easy to wonder “what good is all this white stuff?” But the ecology of snow is fascinating, with hugely beneficial impacts on both our local micro environments and multiple key biological systems at a grander, planetary level. 

On the small scale, snow, while emblematic of the cold, is surprisingly warm, acting as an incredible insulator, like a thermal blanket, that protects a wide array of animals and plants and creates a critically important seasonal habitat for many of our nonmigratory and nonhibernating species. The snow itself, as it folds over rocks and roots, sticks and leaves, becomes filled with small pockets of air that catch and radiate the earth’s heat back downward, sheltering a whole little world beneath from the subzero temperatures, fierce winds, and hungry predators above. 

This invisible ecosystem between the surface of the ground and the top of the snowpack — home to mice and voles, shrews, wood frogs, beetles, centipedes, spiders, and more, along with a variety of mosses and plants — is called the subnivean zone or subnivium and, with a mere 6 inches of snow, it never gets below freezing. Larger animals like groundhogs, porcupines, and grouse may also live within and rely upon the subnivium, where they can remain alive and active throughout the cold months inside the cavities formed between earth and snow. Ever come across a web of caves and tunnel systems underfoot as the snow melts? That’s the handiwork of these subnivium dwellers below!

On a macro level, however, snow has a cooling effect. Because of its natural bright whiteness, snow has a high albedo–reflectivity. Snow reflects up to 90% of solar radiation back into space, which acts as a massive cooling mechanism for Earth’s climate. Exposed trees, plants, and soil, on the other hand, only reflect about 10-30%. By reflecting this solar energy rather than absorbing it, snow — just like the polar ice caps — helps maintain lower temperatures globally and mitigate extreme weather events associated with global warming and a changing, inconsistent climate. Since the 1970s, annual winter snowfall has decreased across the United States by an average of 46% as has the length of the winter season, contributing significantly to the accelerated warming of our planet, which consequently inhibits consistent snowfall — a vicious and unfortunate cycle!

Even as the snow melts it serves an essential purpose, replenishing groundwater levels, refilling our natural water sources and nourishing the soils with essential nutrients, namely nitrogen, as it gradually disappears. Snow is excellent for your garden! For ecosystems like ours here in the north that have adapted to the presence and subsequent melting of snow each winter, this becomes critical for maintaining a healthy water table and fertile growing conditions, making snow vital for keeping plants and animals (and us!) alive all throughout the year. 

Hannah Schiller is a local herbalist, ecologist, and environmental educator. She lives in Pine Plains with her partner and two children and is a member of the Pine Plains Conservation Advisory Council. You can read more of her nature writing on her Substack In the leaves.