a plant or animal unable to live under heavy snow cover or snowfall. A heavy snow cover hinders an animal’s locomotion and food procurement. The northern boundary of distribution of reindeer, for example, coincides with the isoline of an average maximum depth of 50 cm of snow cover. Deeper snow hinders the animal’s movement. In early winter reindeer find pasture accessible where the snowfall is not very dense and the snow cover is no deeper than 40 cm; later in the winter, when the cover is denser, the animals can feed only in areas where the snow is no deeper than 20 cm. Especially dangerous is the combination of abundant snow with ice-covered ground.
Many plants cannot survive heavy snowfalls. The trunks of young birches and chokecherries arch over and sometimes break under the weight of snow. The branches of the Scotch pine and other plants break easily when covered by heavy snow.
REFERENCESFormozov, A. N. Snezhnyipokrov kak faktor sredy, ego znachenie v zhizni mlekopitaiushchikh i ptits SSSR. Moscow, 1946.
Poplavskaia, G. I. Ekologiia rastenii, 2nd ed. Moscow, 1948.
A. M. BYLOVA