When the snow starts to melt in the spring and summer, roots are adapted to keep moisture in, because strong winter winds dry out plants very quickly. When winter comes, some plants either keep their leaves to get a head start on the growing season, or shrivel down into bulbs and roots. Plants' roots are shallow because of the arctic and alpine tundra's thin soil. Also in the winter, snow provides a protective layer for the plants, by keeping them from the unforgiving arctic and alpine winds. These plants are so specially adapted to the tundra's climate, that snow can almost be seen as something beneficial and necessary for the plants survival.