Greinar (Vísindafélag Íslendinga) - 01.01.1967, Blaðsíða 47

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phytes are more frequent on the mainland, but the per-
centage of annuals is higher on the outer Westman Is-
lands. The percentages of Geophytes and Hemicrypto-
phytes on the islands, however, are similar to that of the
mainland.
The plant communities
The vegetation of the outer islands can be classified
into four plant communities: The puffin-colony vegeta-
tion, the dry meadow land, the coastal cliff vegetation,
and the angelica cluster.
I. The puffin-colony type forms the bulk of the vege-
tation on the southern islands, and is usually situated on
slopes facing the sea where the puffin (Fratercula arc-
tica) nests in deep holes. The nesting holes are rather
closely packed, two to three holes per square metre. The
three main species of vascular plants growing there are:
Festuca rubra, Matricaria maritima and Stellaria media.
The Festuca predominates with an approximate cover of
70%, while Matricaria and Stellaria are the associated
species.
The soil is deep and damp with a high content of orga-
nic matter. The fertility level of the soil is extremely high
as a result of bird droppings. These high fertility condi-
tions are quite selective, presumably favouring the red
fescue rather than other grass species. At this level the
fescue remains highly vegetative and has a high ratio of
leaves to culms. The puffin-colony vegetation has an intense
bluish-green tint, contrasting with the bleaker tint of the
dry meadow land. This difference becomes more conspicu-
ous towards autumn, as the grass in the dry meadow land
reaches maturity and becomes higher in fiber content
and wilts earlier than in the puffin colony. The soil is
broken up by the puffin into small columns with tufts of
red fescue covering the network of tunnels and trenches.
Thus this honeycomb-structure of soil appears to be a
continuous mat of vegetation. However, where there is