Looking back at the most recent blogs, you may notice something: we like snow! Both as a substance to play in and study, snow intrigues us to no end. What’s truly amazing about snow it only exists for a short time through the winter. It can be studied and manipulated, and it can change environments. Here in New England, it will be gone by April.
However, during the dead of winter, if you look carefully, you can find some of the secrets that snow hides. Beneath the snow exists an entire world full of mice, rats, voles, weasels, frogs, shrubs, and other animals and plants. This world is called the “subnivean” environment, which means “beneath the snow.”
Snow is made up of mostly air. Even old snow that has been on the ground for a long time is only 20-25% ice; the rest of the snowpack is air. This makes snow an incredible insulator against the cold. Even if the air temperature outside is -10°F, the temperature at the bottom of the snowpack where it meets the ground will remain around 32°F. This means that animals and plants have a natural blanket to cover and protect them.
Many animals are active in the subnivean during the winter, including voles and mice. They dig holes through the snow and ice to then travel along the ground in search of old vegetation to eat. Short-tailed weasels (also known as Ermine) travel through the same holes to find and eat the voles and mice. In fact, short-tailed weasels are so active in the winter time that they must eat up to 50% of their body weight every day just to maintain enough calories.
It's not just animals that seek protection in the snow: there are even some plants, such as wintergreen, that keep their leaves through the winter and count on snow to cover them and keep them insulated from freezing temperatures.
Bringing the Subnivean World to the Classroom
The book “Over and Under the Snow,” by Kate Messner and Christopher Silas Neal is an amazing journey through the subnivean world. It a wonderful book for a group read or even for older students to read to each other.
And, if you and your class are feeling adventurous, head into the woods when there is a deep snowpack (more than 6 inches), find an undisturbed location, and dig a pit down into the ground.
Figure 1: A small rodent. Photo: Ronnie Meijer (CC BY 2.0)
Figure 2: Short-tailed weasel (ermine). Photo: Bryant Olsen (CC BY-NC 2.0)