Figure 4.7: Snow has many effects on vegetation, including
the ability to deform and break trees with its weight (see beech
trees, left). Trees with a narrow canopy (see spruce trees, right)
collect less snow and are less likely to suffer damage.
Photo: (left) Fillies Wo/UNEP/Still Pictures, (right) Terry Callaghan
shoots of bog moss
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. The weight of snow can deform and Snow also supports weight, including the various ground
break trees
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(Figure 4.7), branches and the soft tissues of pressures that passing animals exert. While snow can
plants such as grasses and forbs. Snow can facilitate the support small animals such as birds, small mammals,
spread of some woody plants by pressing branches to the hares and foxes with only minor deformation, larger
ground surface – the branches then develop roots and mammals such as reindeer and moose experience a crit-
form new individuals. Snow pressing directly onto veg- ical snow depth above which they cannot move. Snow
etation protects it, to some extent, from grazing. Plants can, therefore, enhance access across the landscape for
that are covered by the snow are also protected from dry- animals by smoothing the terrain or forming bridges
ing out in the winter and from erosion of tissues by ice across gullies, or it can inhibit access by being too deep
crystals. For this reason, the height of vegetation is often or too soft. The solid matrix of snow can be shaped and
uniform and correlated with snow depth
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. made into dens for polar bears. The consistency of snow
CHAPTER 4 SNOW 47