Íslenskar landbúnaðarrannsóknir - 01.09.1980, Side 53

FLOKKUN GRÓÐURS í GRÓÐURFÉLÖG 51
often thick, most frequently with hum-
mocky surface. The vegetation of the
hummock tops varies considerably from
that of the depressions. Low-growing
shrubs dominate as far as cover and ap-
perance are concerned. This community
is among those most extensive in Iceland.
It comprises three main associations:
Heather heath, where Calluna, Empet-
rum and Vaccinium are most frequent;
Betula nana heath;
Salix heath.
3. Kobresia myosuroides heath
4. Juncus trifidus heath
5. Carex heath
6. Lichen heath
Is found mainly in the highlands where
the snowcover is continuous for 7—8
months.
II. Meadow vegetation
Found on well drained, thick soils, most
frequently without mounds. Grasses
(Gramineae) dominate and make up a
continous vegetative cover.
III. Snowpatches
Snowpatch vegetation develops in depres-
sions where the snow cover remains rela-
tively long into the summer season. Found
at high elevation or where cold, oceanic
weather conditions prevail. The soil is
usually deep, without mounds, moist in
sheltered patches. Comprises six main
associations:
Anthelia patch;
Salix herbacea patch;
Dwarf shrub patch;
Gramineae patch;
Forbs patch;
Carex lachenalii patch.
IV. Secondary succession vege-
ta tion
Occurs in areas previously denuded due
to wind or water erosion or where the
previous vegetation has been buried by
landslides.
V. Forbs
Occur in small patches in sheltered and
protected areas with fertile and moist
soils, often in forests and in “holes” in lava
fields inaccessible to sheep. This com-
munity includes a great number of plant
species and is closely related to the plant
community listed under III, e. above.
VI. Wood land
From a practical viewpoint, Betula
pubescens is the only native tree that
forms woodlands in Iceland. In addition,
however, scattered Sorbus aucuparia trees
occur in a few locations. The ground-
cover vegetation varies greatly according
to growth conditions but is mainly domi-
nated by different dwarf shrubs, grasses,
forbs, ferns and horsetail.
VII. Jadar (Semibog vegetation)
Forms intermediary strips between wet-
land and dryland soils', or is found as
patches on recently drained wetlands
undergoing subsequent vegetation
changes. Soil moisture conditions vary
and the surface is generally hummocky.