Boreal Forest in Winter

The boreal forest is the largest tract of woodland on earth covering 11% of all land area, half again as large as the Amazon rainforest.  It stores 30% of the sequestered carbon on earth.  The area also contains a mosaic of wet meadows, ponds, lakes, marshes, and bogs interlaced among the trees.  Tree species include many conifers, dominated by spruce, plus aspen, birch, willow and alder.  The animal life is abundant, with every species that was there before European settlement still remaining.

The boreal forest is distinguished by short, hot, wet summers and long, dry, cold winters.  When the last glaciers retreated northward, many holes and fissures were left behind.  As the ice melted, all of these depressions were filled with water.  The underlying geology is mostly granite shield, a rock layer that holds the water in and contains few minerals that dissolve in water, yielding very clear water that does not promote algae or bacteria growth.  Most lake life is found in the shallow, warmer edges which also provide support to nearly all of the land-based fauna.

^{From upper left clockwise: Alder tree by Mantonature, Getty Images Signature; Spruce trees by Hannu Koskela, Getty Images; Willow tree by smarko , Pixabay; Aspen trees by Adamisovitsch, Getty Images}

Winter time presents many challenges including less sunlight, colder temperatures, less available water, less food and shelter, and increased severe storms.  Animals that are active daily have higher energy requirements in winter.  They must often change their dietary sources to whatever is available in winter.  Grey squirrels and beavers cache food during warmer periods.  Birds eat foods higher in calories such as nuts, seeds, dried fruit, and insects found under tree bark.  When changes are consistent from year to year, species develop adaptations to meet the requirements of each season and are able to live comfortably throughout the year.

Shelter becomes not only a place to hide from predators, but also provides protection from weather  extremes.  Snow of different thicknesses and weight covers the landscape.  Snow is also a great insulator, keeping cold winds away from exposed skin.  There is normally a layer of air between the ground and the snow cover immediately above.  Temperatures in this space are warmer than the exposed air above the snow creating a winter habitat that is vitally important for many species.  Mice and voles create burrows under the snow where they can huddle together for added warmth.  Similarly, air pockets surrounded by a heavy growth of conifer needles create spaces above the snow cover for birds and some larger mammals to shelter.  And many larger species will nestle into the snow pack to shelter from storms and wind.

Spruce grouse, Canachites canadensis, and willow ptarmigan, Lagopus lagopus, are not able to fly more than several yards.  They grow feathers on their feet to insulate them and aid in traction.  Grouse use the air layer at ground level to shelter in.

Ptarmigan, along with snowshoe hares, Lepus americanus, and short-tailed weasels, Mustela erminea, all change color to pure white to hide from predators.  Snowshoe hare and Canada lynx, Lynx canadensis, have very large feet that aid in walking on snow without sinking in.  Arctic fox, Vulpes lagopus, are winter specialists with compact bodies and short legs and ears that limit their exposure to cold, and large, furry paws that enable them to walk on top of the snowpack.  With their long, bushy tails wrapped around their heads, they can withstand winds and temperatures to fifty below zero.

You can learn more about this cold but wondrous habitat by searching online for boreal forest, referring to the southern portions of the habitat, or taiga, referring to the northern portions.  Also, look for information concerning seasonal adaptations for species in your own area, or visit a local natural history museum such as the Jurica-Suchy Nature Museum in Lisle, Illinois.