Flora and Vegetation of Iceland
(EA-Plant Sciences. Askell Löve)
FLORA AND VEGETATION OF ICELAND
CONTENTS
|
|
Page
|
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Topography
|
1
|
|
Climate
|
3
|
|
Flora
|
4
|
|
Vegetation
|
6
|
|
Moist Soils
|
6
|
|
Dry Soils
|
14
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Bibliography
|
23
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EA-PS. Love: Flora and Vegetation
in of Iceland
LIST OF FIGURES
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Page
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Fig. 1.
|
The main nunatak areas during the maximum glaciations
|
3a
|
EA-PS. Love: Flora and Vegetation of Iceland
PHOTOGRAPHIC ILLUSTRATIONS
With the manuscript of this article, the author submitted 8 photo–
graphs for possible use as illustrations. Because of the high cost of
reproducing them as halftones in the printed volume, only a small propor–
tion of the photographs submitted by contributors to
Encyclopedia Arctica
can be used, at most one or two with each paper; in some cases none. The
number and selection must be determined later by the publisher and editors
of
Encyclopedia Arctica
. Meantime all photographs are being held at The
Stefansson Library.
EA-Plant Sciences
(Askell Love)
FLORA AND VEGETATION OF ICELAND
TOPOGRAPHY
Iceland, the largest plinth on the submarine ridge crowing the Atlantic
between Scotland and Greenland, has a surface of about 104,785 square kilo–
meters. Its southernmost point lies at 63°19′ N. latitude, its northernmost
isle at 67°07′ N. latitude, its westernmost point at 24°32′ W. longitude, and
its easternmost skerry at 13°16′ W. longitude, the Arctic Circle touches the
northeastern part of the mainland. The shortest distance from Iceland to
Greenland is about 300 kilometers, to the Faeroes it is about 420 kilometers,
to Scotland about 800 kilometers, and to the Norwegian coast about 970 kilo–
meters.
Iceland is built up mainly by basic eruptives from the Tertiary, Pleisto–
cene, and Holocene, subsequently molded by abrasion, faults, and other denuding
agencies. The principal rocks are basalt and palagonite breccia, attaining a
total thickness of perhaps 4,000 meters. The oldest layers are at least some
200 meters below the present sea level, but the rocks underlying the basalt
formation are as yet unknown. In Paleocene times about half the total thick–
ness of the basalt was formed, and in the Eocene a lignite formation up to 50
meters thick accumulated, indicating a long period without great change. The
plant remains of this formation seem to suggest a climate of perhaps similar
character to that at present found in the temperate areas of North America
EA-PS. Lõve: Flora and Vegetation of Iceland
and southern England, although the remains have, so far, not been thoroughly
studied from modern viewpoints. It is suggested that during the Eocene the
mean annual temperature of the island was about 7° to 10°C higher than at
present.
Originally the plateau was built up of horizontal lava layers, but in
preglacial times a broad central zone of submergence, now filled up by the
palagonite
^
,
^
was formed. It is in this district that almost all the present–
day volcanoes are found. In the west and east, large areas are formed entirely
by the old basalt layers.
In the basalt districts in the northwest, north, and east, only two
topographical levels above the submarine shelf are discerned: (
1
) the coastal
and the valley plains from sea level up to an altitude of about 100 meters,
and (2) the tableland from about 600 up to about 1,000 meters. In the central
part of the country, however, at least three such levels are found: (
1
) the
coastal plains up to about 100 meters, (
2
) the Inland plateau or tableland
from 300 to 600 meters, and (
3
) the plateau horsts from 1,000 to 1,800 meters.
Above the plateau horsts some isolated volcanoes reach up to 2,118 meters (in
the case of Oraefa jökull). The present glaciation is mainly connected to tea
plateau horsts and volcanoes, as its limit is generally above 1,000 meters.
The Icelandic coast line is more than 6,000 km. in length. The coast in
much indented except in the south, but practically no coastal archipelago is
found. Although lowlands are fairly plentiful in the west, southwest, and
south, they are estimated to occupy not more than one-fifteenth of the country
as a whole.
At the present time, about one-seventh of the island is covered by perma–
nent ice, but during the Pleistocene glaciations only snail areas were
EA-PS. Lõve: Flora and Vegetation of Iceland
unglaciated; exceptions were in the mountainous coastal regions in the north–
west, east, and between Skagsf jördur and Skjalfandi in the north — i.e., the
so-called Eyjaf jördur district, the history of the glaciations in Iceland has
not been very closely studied as yet, but according to some geologists rather
large nunatak areas did exist within the above-mentioned areas during the max–
imum glaciation; it is to be presumed that on them persisted both plants and
small animals
^
(see Fig 1.)
^
Although no c
^
h
^
alk formations are found in Iceland, some real calciphilous
plant species occurs They are mainly restricted to the basalt regions.
According to geologists, the connection between Iceland and other countries
was disrupted in the late Miocene, and since then the country has been an iso–
lated island. This is, however, mainly an assumption.
CLIMATE
Iceland is situated in the region where the cold Polar Current and the
warm Gulf Stream mingle. The climate seems best considered subarctic in most
parts of the island. The mean temperature of July, the warmest month, varies
from approximately 7.2° to 10.6°C. (45° to 51°F.), but the winter temperatures
are not very low, the lowest January mean on record being −6.1°C. (21°F.), and
the highest l.4°C. (34.5°F.). The mean temperature during the year varies
from about 0° to 5°C, (32° to 41°F,). Frost may, however, be experienced in
every month of the year in all localities. In all places the weather is very
stormy, and the precip
^
it
^
ation is considerable in the southern and western parts
of the country, The snow lies in the northern lowlands for as much as 3 1/2
months in an average year, but only for 1 to 1 1/2 months in the southern parts
of the country. Solifluction is more common in the southern than in the northern
Fig. 1. The main nunatak areas during the maximum glaciation.
EA-PS. Lõve: Flora and Vegetation of Iceland
lowlands, but permafrost exists only in the inland plateau, mainly in the
northern and eastern parts of the country, where precipitation during the
^
w
^
inter months is relatively small. In some years the arctic drift ice will
affect the spring and summer temperatures, at least in the northern parts
of the country, but in most years it will only be found for a short time off
the north coast. Nevertheless, only in one year out of every five has the
coast been completely free from drift ice daring the last 150 years.
FLORA
The flora of Iceland is not yet thoroughly investigated, as large areas
have never been studied by a trained botanist, and only a few collections of
lower plants have been made by specialists. The number of species known is,
therefore, by no means complete, and some of the species and their lower units
are not as yet fully determined. The total number of species known at present
seems to be about 3,600, bacteria excluded. Of these, about 770 are freshwater
or marine diatoms; about 300 are other freshwater and aerial algae; the marine
algae recorded are only 200 (exclusive of diatoms); about 1,000 species of
fungi are known from the island; the lic
eh
^
he
^
ns known number about 350; the
bryophytes collected are about 450; 33 species of pteridophytes are known;
and about 550 spermatophytes, including
Taraxacum
and
Hieracium
. Of these
figures, however, only those of the spermatophytes, pteridophytes, and marine
algae are based on really detailed studies in many parts of the island.
It is assumed that a large part of the Icelandic flora has survived the
Pleistocene glaciations in the nunatak areas of the coastal refuges. This
suggestion is not only based on geobotanical studies of the present flora, but
also supported by studies of the flora of the interglacial layers observed in
EA-PS. Lõve: Flora and Vegetation of Iceland
some places in the southwest and north. According to preliminary calcula–
tions, at least 55% of the present flora of higher plants belong to the group
of glacial survivors; about 30% may have been introduced by man during the
last 1,000 to
[:
]
1,200 years; but the remaining 15% might perhaps belong to
the first-named group or have dispersed from other regions in postglacial
though prehistoric times. Among the lower plants, the percentage of glacial
survivors is estimated to be still higher.
Although the Icelandic flora is rather young, it includes some endemics.
Those known at present among the higher plants are:
[:
]
Ophioglossum vulgatum
var.
islandicum
,
Sesleria varia
subsp.
Islandicum
,
Roegneria
(
Agropyron
)
doniana
var.
stefanssonii
,
R. borealis
var.
islandica
,
Dactylorchis maculate
subsp.
islandica
,
Silene maritima
subsp.
islandica
,
Papaver radicatum
subsp.
islandicum
and subsp.
stefanssonii
,
Euphrasia rotundifolia
,
E. davidssonii
,
Galium pumilum
subsp.
islandicum
, and several
Hieracium
and
Taraxacum
micro-
species. If we exclude the last-named apomictic groups, less than 2% of the
flora of higher plants
^
are
^
so far known to be endemic types. However, this figure
will certainly become higher when closer studies of all the species are per–
formed.
Although the great majority of the Icelandic higher plants belong to the
group of circumpolar or at least circumboreal species, a rather high percentage
belong to groups present in Scandinavia or Eurasia but not in northeastern
America. There are also some species which belong to the group of “west-arctic”
plants, occurring in eastern North America, Greenland, and northern Scandinavia,
but not in Asia; and some species of this group are not met with in Scandinavia,
their area of distribution reaching from North America to Greenland and Iceland
only. The
^
^
most remarkable of these plants of more restricted range are:
EA-PS. Lõve: Flora and Vegetation of Iceland
Elymus mollis
(
E. arenariu
m
^
s
^
var.
villosus
),
Leucorchis
(
Habenaria
)
straminea
;
Platanthera
(
Habenaria
)
hyperborea
,
Salix cordifolia
var.
callicarpea
,
Cakile
edentula
subsp.
typica
,
Saxifraga aizoon
subsp.
neogaea
,
Epilobium latifolium
,
Galium brandegeei
, and
Plantago juncoides
var.
glauca
. Of the mosses, at
least
Bryoxiphium norvegicum
belongs to this group.
VEGETATION
As a whole, the vegetation of Iceland is characterized by the low number
of species withstanding the wet and relatively cold climate. Typical alpine
species are met with at sea level in the southwestern portions of the country
as well as about the outer parts of the fjords in the other regions, but in
the inner parts of the fjords in northern Iceland and the inner lowland in
the east, the climate is more continental and real alpine species are not found
at the lowest altitudes. The tree limit is at 200 to 300 meters in southern
and western Iceland, but in the northern and eastern parts it may reach up to
500 or 600 meters.
Moist Soils
Submarine Shelf and Littoral Zone
. The vegetation of the submarine
shelf is not very complicated and its characteristic types are almost the
same as in northern Norway and southern Greenland. Farthest from the coast
only the formation of crustaceous algae is met with, followed toward land
by the Lithothamnion, the deep-water associations of the Floridion (mainly
Polysiphonetum arcticae), the Desmarestion, and different associations of
the Laminarion, the Laminarietum digitatae, and the Laminarietum hyperboreae.
These are the communities of the depths, the Laminarietum saccharinae form–
ing most of the vegetation nearest the coast. Above this sublittoral zone
EA-PS. Lõve: Flora and Vegetation of Iceland
the Corallinion is met with, followed by Polysiphonetum urceolatae, Rhodomenion,
Chondetum, and Monostrometum. The comes the real littoral zone, dominated by
the Fucion and some communities of filifrom algae, the Ulotrixetum, Codioletum,
Bangietum, and Porphyretum. In the inner fjords of the west coast the Zoster–
etum occupies relatively large areas of muddy clay in the sublittoral zone, al–
though it became very much decimated by disease during the period 1930 to 1940
as in other parts of the North Atlantic. At one place only, in somewhat brack–
ish water in the sublittoral zone, the Ruppietum maritimae was observed.
Immediately above the littoral zone the Verrucarion and other lichen com–
munities are met with on stones and rocks, but on sandy and gravelly coasts
where the winter storms drive in masses of wracks (
Fucus
app.) the outposts of
higher vegetation are hapaxanthic species of
Polygonum
,
Atriplex
, and various
Cruciferae. On the sandy and gravelly beaches above this zone, there occurs
more or less open vegetation characterized by
Cakile edentula
,
Arenaria peploides
,
Potentilla anserina
(in the northernmost parts
P. egedii
),
Mertensia maritima
,
and
Tripleurospermum maritimum
. This zone seems to merge into the next which
consists of Festucetum cryophilae, Puccinellietum, and Agrostidetum, intermixed
with
Polygonum heterophyllum
,
Silene maritima
,
Cochlearia
,
Potentilla anserina
,
Thymus arcticus
,
Plantago maritima
(in the northernmost parts
P. juncoides
var.
glauca)
,
Galium verum
, and other more or less typical coastal plants.
In sheltered localities around the inner parts of some fjords, a closed
marsh is apt to be formed in places flooded by the sea during some time of the
year. The vegetation of these marshes seems to be exclusively the Puccinellie–
tum maritimae mixed with a few individuals belonging to the general
Carex
,
Juncus
,
Scirpus
,
Triglochin
,
Potentilla
, and
Plantago
.
EA-PS. Love: Flora and Vegetation of Iceland
Some parts of the coast, especially in the basalt regions, are formed
of steep cliffs, often populated by sea birds during the spring. Such situa–
tions are very rich in vegetation, the most frequent communities being com–
posed chiefly of
Festuca
,
Poa, Cochlearis
,
Sedum rosea
,
Angelica archangelica
,
and
Ligusticum scoticum
. On the cliffs thems
le
^
el
^
ves, many speci
^
e
^
s of lichens
and mosses from their varied and often colorful communities. On the more
grassy parts of the cliffs, Potentilleto-Bistortion vivipari and communities
belonging to the Ranunculeto-Oxyrion or the Geranietum silvatici are often
mixed with the Festuceto-Poeticum.
Lakes and Pools
. The vegetation of the lakes and pools is different in
eutrophic and oliotrophic water, but the difference has not yet been very
closely studied in Iceland. In deep lakes only Characeae and other algae
are met with, but in shallow lakes the vegetation belongs to the Littorellion,
including species of
Isöetes
,
Littorella
,
Subularia
,
Callitriche
,
Myriophyllum,
Hippuris
, and some other plants. The associations belonging to the Potamion
euro-sibiricum are common at least in the eutrophic lakes. Its typical repre–
sentatives are various species of
P
e
^
o
^
tamogeton
,
Sparganium
,
Ranunculus
, etc.
The shores of the lakes and shallow pools are almost entirely covered by
the Equisetetum fluviatile and Caricetum rostratae-Lyngbyae, follow
[:
]^
ed
^
by^
at
^
the
d
^
r
^
ier margins by Caricetum fuscae (with the moss
Drepanocladus exannulatus
)
and other marsh communities.
Running Water
. The vegetation of running water is almost the same as in
the lakes when the current is slow; but in rivers and streamlets with a strong
current, there are rather few higher plants — except, of course, at the banks.
Nostoc
spp. And other algae together with such mosses as
Fontinalis
,
Hygrohyphnum
EA-PS. Lõve: Flora and Vegetation of Iceland
and
Rhynchostegium
are frequent in the rivers, but in glacier streams no mosses
or higher plants are to be found.
Springs
. The vegetation of springs and of the banks of small streamlets
in both the lowland and the highland is extremely rich in mosses. Most of the
vegetation of the springs seems to belong to alpine associations. Examples
are (
1
) Mniobryo-Archangeletum and (
2
) Mniobryo-Epilobietum hornemanni, which
are not restricted only to the highlands, (
3
) Philonoto-Saxifragetum stellaris,
which is common almost all over the country, and (
4
) some communities belonging
to the Cratoneureto-Saxifragion aizoides in the northern and eastern parts of
the country. These last include the Cratoneureto-Crepidetum paludosae, the
^
Cratoneureto-Saxifragetum aizoides, and some other communities occupying small areas
and involving
^
Cratoneuron glaucum
,
Bryum ventricosum
,
Equisetum variegatum
,
Epilobium alsini–folium
, and some other species.
The vegetation of hot springs and solfataras is often rich in species of
algae and mosses, but as a whole it seems to be composed mainly of different
types of the Icelandic marsh and spring communities. About thirty species of
mosses, some higher plants, and several species of algae are exclusively met
with
[:
]
on warm soils. Drawf forms of higher plants are typical for such locali–
ties, owing to the effect of the high temperature on the time of flowering;
but these forms are only modifications.
Marshes
. The moist soils are predominantly the marshes. Their vegetation
may most easily be subdivided into two groups, the eutropic-mesotrophic marshes
or Caricetalia fuscae, and the meso-oligotrophic marshes or Scheuchzerietalia.
In addition, there are the shrub marshes or Oxycocco-Ledetalia, which are met
with in some areas.
The eutrophic-mesotrophic marshes are always typical infiltration ones,
i.e., they are formed mainly in places with running groundwater or those that
EA-PS. Löve: Flora and Vegetation of Iceland
are influenced by water from rivers and streamlets. They are grouped into
two rather different types of marshes, the Caricion atrofuscae-saxatilis,
which is mainly found
^
on basic soils
^
in the lowlands, and the Caricion canescentis-fuscae,
which is met with on more or less neutral soils and at high as well as low
levels.
At least five different marsh types belonging to the Caricioin atrofuscae–
saxatilis association
s
are known from Iceland.
(
1
) In sandy or gravelly localities near rivers and streamlets the
Caricetum microglochinis marshes are met with. Their characteristic species
seem to be
Carex microglochin
,
C. maritime
,
C. capillaries
,
C. fusca
,
Juncus
triglumis
, and perhaps
Bistorta vivipara
(
Polygonum viviparum
),
Epilobium
latifolium
, and
Pinguicula vulgaris
; the mosses most frequently associated
[:
]
are
Climacium dendroides
,
Drepanocladus intermedius
,
Philonotis tomen–tella
,
Oncophorus virens
, and
Swartzia Montana
. Some lichens such as
Cetraria
nivalis
are frequently met with, and various species of higher plants charac–
teristic of dry and moist soils may be associated in these marshes.
(
2
) In relatively dry localities, Caricetum atrofuscae-vaginatae marshes
are sometimes observed. They are rich in species and a useful indicator of
excellent soils. One of the two most characteristic species from Europe,
Carex atrofusca
, is not found in Iceland, but this marsh type in Iceland is
characterized by
C. vaginata
, with
C. dioeca
,
C. norvegica
,
C. saxatilis
,
C. adelostoma
(in a few places in the northwest),
Salix cordifolia
var.
callicarpea
,
Betula nana
,
Bistorta vivipara
,
Thalictrum alpinum
,
Vaccinium
uliginosum
, and several other species which are always found in these marshes.
Their cryptogamous flora is also rich in species, although only
Blindia acuta
,
Drepanocladus exannulatus
,
D. intermedius
, and the lichen
Cetraria islandica
are always present.
EA-PS. Löve: Flora
[:
]^
a
^
nd Vegetation of Iceland
(
3
) In very wet localities, often at the banks of shallow pools, Cari–
cetum saxatilis fens predominate, with the characteristic
Carex saxatilis
mixed with some individuals of
Eriphorum angustifolium
. In the drier parts
of this association, individuals of
Equisetum arvense, Juncus triglumis
,
Salix
cordifolia
var.
callicarpea
,
Bistorta vivipara
, and various other species of
higher plants are met with. The mosses always to be found in this association
are
Bryum ventricosum
,
Campyli
^
u
^
m
sp., and
Drepanocladus intermedius
.
(
4
) The marshes of the Caricetum flavae type are rather uncommon in
Iceland and perhaps totally absent in its southern parts. In only two places
in northern Iceland has
Carex flava
itself been observed, but in other places
the characteristic species of the association appear to be
Carex dioeca
,
C. capillaries
, and
C. fusca
,
Eriophorum angustifolium
,
Scirpus caespitosus
subsp.
austriacus
,
Juncus filiformis
,
Nardus stricta
,
Leontodon autumnalis
,
Pinguicula vulgaris
,
Thalictrum alpinum
, and the mosses
Drepanocladus inter–medius
and
Campylium
sp.
(
5
) The
^
remaining
^
marshes of this group are the relatively common Scirpetum
caespitosi-trichophorum subarcticum, with
Scirpus caespitosus
subsp.
austria
austria–cus
and
Eriophorum angustifolium
^
Eriophorum angustifolium
^
as the dominants, and including the mosses
Drepanocladus intermedius
and
Sphagnum
spp. as well as a number of additional
species.
The marshes of the Caricion canescentis-fuscae association are by far the
most common in Iceland, the main types being characterized as follows.
(
1
) Caricetum canescentis-fuscae is met with in different forms, the
most common one being characterized by
Carex fusca
and
C. canescens
, with some
individuals of
Eriophorum scheuchzeri
,
Juncus filiformis
,
Bistorta vivipara,
EA-PS. Löve: Flora and Vegetation of Iceland
Viola palustris
,
Pinguicula vulgaris
, and the bryophytes
Blasia pusilla
,
Bryum
duvalii
,
Drepanocladus exannulatus
,
Oncophorus wahlenbergii
,
Pellia neesiana
,
and
Philonotis fontana
. In all marshes of this type, iron bacteria are common.
(
2
) Saliceto-Caricetum fuscae is a marsh of the relatively dry type that
is met with especially in the zone between the above-mentioned moist one and
dry grasslands or heaths. It typical species are
Carex fusca
,
Salix phylici–folia
,
S. cordifolia
var.
callicarpea
,
Betula nana
,
Eriphorum angustifolum
,
and perhaps also
Parnassia palustris
subsp.
neogaea
,
Ranunculus acris
,
Bistorta
vivipara
,
Viola palustris
, and
Equisetum palustre
. The moss layer is composed
mainly of
Bryum duvalii
,
Climacia dendroides
,
Drepanocladus
sp., and
Poly–trichum
commune
^
commune
^
.
(
3
) Eriophoretum scheuchzerii forms mostly rather small marshes in some–
what sandy localities, and is frequently met with on relatively sterile, wet
soils along roadsides or in artificial holes in old marshes. Its species
are always few in number, those mostly observed besides
Eriophorum scheuchzerii
being
E. angustifolium
and some Carices, with, in addition, the moss
Drepano–cladus exannulatus
.
(
4
) The fens characterized by the association Drepanoclado-Caricetum
rostratae-canescentis are always small. The characteristic species are
Carex
rostrata
,
Eriphorum angustifolium
, and the mosses
Calliergon stramineum
and
Drepanocladus exannulatus
. In some places
Carex canescens
is one of the
dominating species, although it is frequently replaced by
Carex lyngbyei
. In
the somewhat drier parts of these fens, other Carices,
Potentilla palustris
,
Salix cordifolia
var.
callicarpea
, and
Spagnum
sp. are not infrequent.
(
5
) The Saliceto-Caricetum rostrata-canescentis association which covers
wide areas at least in the lowland is closely related to the one last discussed. The
EA-PS. Love: Flora and Vegetation of Iceland
dominants are:
Salix cordifolia
var.
callicarpea
,
S. phylicifolia
,
Betula
nana
,
Carex canescens
,
C. rostrata
, perhaps
C. lyngbyei
and
C. fusca
,
Erio–phorum angustifolium
,
Potentilla palustris
, and different moss species —
especially
Paludella squarrosa
and
Spagnum warnsdorfii
.
The meso-oligotrophic marshes are topographically determined complexes,
formed in places with a permanently high groundwater level, varying somewhat
with the seasons and the precipitation curve, but no
r
^
t
^
or only slightly in–
fluenced by springs. They may be divided into two rather different groups,
characterized in one case by the Stygio-Caricion limosae with loose and rotten
soil and few mosses, and a very poor algal vegetation in the microflora, and
in
^
the
^
other by the Leuko-Scheuchzerion, which is an uncommon type of Icelandic
marsh.
The Stygio-Caricion limosae includes all the fens listed under the Icelandic
name
fl
o
^
ó
^
i
in paper previously published on the vegetation of Iceland. These
fens may be divided into at least four different marsh types: (
1
) The Stygio-
Caricetum chordorrhizae with the characterizing species
Carex chordorrhiza
,
C. limosa
,
Eriophorum angustifolium
,
Drepanocladus exannulatus
,
Sphagnum
sp.,
and perhaps also some of
Carex lyngbyei
; (
2
) Stygio-Caricetum limosae, which
is a fen with
Carex limosa
and
C. rostrata
as the dominants, together with
Drepanocladus exannulatus
and some liverworts; (
3
) Stygio-Caricetum lyngbyei
is a fen with
Carex lyngbyei
,
C. fusca
, and perhaps
C. rostrata
,
Eriophorum
angustifolium
, and
Equisetum fluviatile,
as well as
Drepanocladus exannulatus
and some other mosses; (
4
) Stygio-Eriophoretum angustifoliae is a fen with
many variants, but
Eriophorum angustifolium
and
Drepanocladus exannulatus
as
the dominants.
EA-PS. Löve: Flora and Vegetation of Iceland
The Leuko-Scheuchzerion marsh is not only uncommon in Iceland but met
with only in
[:
]
very small areas. The chief type, perhaps, is that composed
of
Eriophorum angustifolium
,
Carex rostrata
,
Sphagnum lindbergii
, and
Drepano–cladus exannulatus
, intermixed with
Oxycoccus microcarpus
if it is not absent
from the region in question.
The Icelandic shrub marshes belong exclusively to the Oxycocco-Empetrion
hermaphroditi and are dominated or characterized by
Empetrum hermaphroditum
,
Betula nana
,
Sphagnum fuscu
s
^
m
^
,
S. russowii
,
Polytrichum, Dicranium
,
Cladonia
,
and
Cetraria
species. The most common associations seem to be: (1) the
Sphag
^
Sphag
^
no-Empetretum hermaphroditum with
Empetrum hermaphroditum
,
Betula nana
,
Vaccinium uliginosum
,
Sphagnum fuscu
s
^
m
^
,
Mylia anomala
, and
Polytrichum
sp.,
sometimes mixed with a few Carices,
Eriphorum angustifolium
, and
Oxycoccus
microcarpus
; and (2) the Cladinoso-Empetretum hermaphroditum which is drier;
with Sphagna almost absent. The characterizing species are
Empetrum
,
Betula
nana
,
Vaccinium uliginosum
, and various species of
Cladonia
; lichens are fre–
quently dominant, especially in regions with much wind erosion.
Dry Soils
The vegetation of the dry soils is classified into two main groups accord–
ing to the completeness of the plant cover. In the first group are the grass–
lands, the heaths, and the cultivated areas; in the second group are the wind-
eroded gravelly flats and sands and the clayey soils (Iceland
^
ic
^
flga
^
flag
^
.
Grasslands
. The vegetation of the grasslands seems to belong to the
Nardeto-Agrostion tenuis association with frequent tussocks due to frost action,
etc. The most common communities are: (1) Festucetum rubrae subalpinum with
Festuca rubra
,
Poa pratensis
subsp.
alpigena
,
Agrostis tenuis
,
Potentilla
EA-PS. Löve: Flora and Vegetation of Iceland
crantzii
,
Alchemilla
sp.,
Ranunculus acris
,
Taraxacum
spp. and many other
vascular plants, as well as mosses belonging to the general
Torula
,
Brachy–thecium
, etc. This is also the vegetation of most of the cultivated grass–
lands without foreign grass species. (2) Agrostetum tenuis subalpinum is
also met with both in the grasslands and in the cultivated areas. Its dom–
inating species are
Agrostis tenuis
,
Deschampsia caespitosa
and
D. alpina
,
Phleum commutatum
,
Bistorta vivipara
,
Ranunculus acris
,
Trifolium repens
,
Leontodon autumnalis
,
Taraxacum
spp.
^
,
^
Alchemilla
sp., etc. (3) Agrosteto–
Nardetum strictae is observed in some few places. It is characterized by
a high frequency of
Nardus stricta
,
Agrostis tenuis
,
Festuca ovina
and/or
F. vivipara
,
Anthoxanthum odoratum
,
Bistorta vivipara
, etc.
Heath Formations
. The Icelandic heath formations are by no means
thoroughly investigated as yet. They seem, however, to be classifiable
in the Rhacomitrion, Loiseleurieto-Arctostaphylion, Phyllodoco-Myrtillion,
and Juncion trifidi. The representatives of the Rhacomitrion are
f
differ–
ent types of the Rhacomitrietum, dominated by
Rhacomitrium hypnoides
and
other mosses. These communities occupy all the recent lava fields, as well
as stony flats in some areas of the lowland and highland, and they cover
wider areas than any other Icelandic plant federation. In relatively young
lava fields they are mixed only with a few species of lichens on the bare
stones, but later on
Cladonia
and
Cetraria
species are found in the moss cover.
They are followed by some few individuals of
Carex bigelowii
,
Lycopodium
selago
,
Equisetum pratense
,
Festuca
sp.,
Salix cordifolia
var.
callicarpaea
,
S. herbacea
,
Bistorta vivipara
,
Armeria maritima
,
Silene acaulis
,
Cassiope
hypnoides
,
Calluna vulgaris
,
Empetrum hermaphroditum
, as step by step the
Rhacomitrion is altered into different associations with
Vaccinium uligino–sum
, Salices, and different grasses, together with various mosses and lichens.
EA-PS. Löve: Flora and Vegetation of Iceland
In the end the vegetation of the lava fields will become typically heathy.
The most common communities of the Loiseleurieto-Arctostaphylion seem
to be: (
1
) the Loiseleurieto-Vaccinietum uliginosi, with
Loiseleuria
,
Vac–cinium uliginosum
,
Empetrum hermaphroditum
, several grasses, and a great
many mosses and lichens. (
2
) The Arctostaphyletum uva-ursi, with
^Arcto^–staphylos
,
Betula nana, Calluna vulgaris
,
Vaccinium uliginosum
,
Festuca vivi–para,
Anthoxanthum odoratum
,
Cladonia
sp., etc. (3)
Vaccinietum uliginosi
,
which forms some different types of heaths, mixed with
Juncus trifidus
,
Festuca vivipara
, etc., and a great many mosses and lichens. (
4
) Empetro–Betuletum nanae
also forms heaths with
Festuca vivipara
and a great number
of mosses and lichens, of then with open soil between the tussocks due to
wind erosion. In some regions
Empetrum hermaphroditum
is almost absent from
some of these communities, but this tends to be compensated by
Cladonia
and
Cetraria
. Rather wide areas are covered by associations with
Salix cordifolia
var.
C
callicarpea
,
Festuca vivipara
, or
F. ovina
, lichens, etc. These associa–
tions belong, perhaps, to a group which might be classified as (
5
) Lichenose–
Salicetum cordifoliae. Some heaths should be grouped in (
6
) the Empetro–
Cladinosum, that might only be a variant of (7) the Betuleto-Empetro-Cladinosum.
which is mainly met with in moraine areas with a light snow cover. It is char–
acterized by
Betula nana
, some small individuals of
B. tortuosa,
Empetrum
hermaphroditum,
Vaccinium uliginosum,
Festuca vivipara or
F. ovina, and
Cladonia,
Cetraria,
Polythrichum, and
Dicranum species, etc.
The Phyllodoco-Myrtillion heaths are met with only in localities with a
thick snow cover during the winter months. As the distribution of Phyllodoce
is restricted owing to historical factors, the most characteristic species of
this federation are
Vaccinium myrtillus
,
Betula nana
,
Deschampsia flexuosa
,
EA-PS. Löve: Flora and Vegetation of Iceland
Empetrum hermaphroditum
, and, in some parts of the country,
Calluna vulgaris
or
Phyllodoce coerulea
. Some of the groupings belonging to this association
are restricted to the vicinity of shrubby
Betula tortuosa
and are extremely
rich in thermophilous species.
The Juncion trifidi community covers wide areas in the lowland as well
as in the hi^g^hland. The most remarkable groupings seem to be (
1
) the Festuce–
tum viviparae, with
F. vivipara
,
Carex bigelowii
,
Luzula spicata
,
Cerastium
alpinum
,
Bistorta vivipara
,
Silene acaulis
,
Viscaria
(
Lychnis
)
alpina
,
Saxi–fraga caespitosa
, and
Cetraria nivalis
. In some places the dominating cryp–
togam is
Rhacomitrium hypnoides
. (2) Juncetum trifidi is not very common in
the lowland. It is formed mainly by
Juncus trifidus
,
Festuca vivipara
,
Luzula spicata
,
Carex bigelowii
,
Dryas octopetala
,
Salix herbacea
, as well
as some mosses and lichens.
Thymus arcticus
and
Saxifraga oppositifolia
frequently form part of this community even in the lowland.
Sands and Gravelly Flats
. The vegetation of the sands and gravelly
flats formed by wind erosion is, in all parts of the country, primarily
characterized by the Festucetum cryophilae mixed with
Festuca vivipara
,
Agrostis stolonifera
,
Calamagrostis neglecta
,
Silene maritima
,
Cardaminop–sis
(
Arabis
)
petraea
,
Epilobium latifolium
, and some few other species.
All of these species are met with at all altitudes, not being bound especially
to the seaside; the same is true of
Elymus mollis
, which is found especially
on moving sands, together with
Silene maritima
,
Potentilla anserina
, etc.
In more fixed sand, the Festucetum cryophilae is intermixed with the Elymetum,
and such species as
Armeria maritima
,
Galium verum
,
Kobresia myosuroides
,
Salix lanata
,
Salix cordifolia
var.
callicarpea
, and some others may be met
with in these communities more or less incidentally. The succession seems
EA-PS. Löve: Flora and Vegetation of Iceland
to proceed from Elymetum mollis through Festucetum cryophilae and Festucetum–
Agrostidetum to the closed community of the Festuceto-Salicetum lanatae. The
vegetation of the sands and gravelly flats is also characterized by some few
communities of mosses and lichens.
Clayey flats
with scattered knolls and stones occur mainly in the lowland.
Their vegetation is unusually rich in therophytes, and it is suggested that
they are the result of frost and fluctuations in water level, making it im–
possible for the plants to form a permanent vegetation cover. The vegetation
of the clayey flats may be divided into three different associations: (
1
)
the Koenigio-Sedetum villosi, which belongs to the Koenigio-Microjunceon
arcticum and the Epilobietalia alsinifolii; (
2
) the Eleocharetum acicularis
islandicum, which belongs to the Littorellion of the Littoretalia; and (
3
)
the Limoselletum borealis of the Nanocyperion flavescentis of the Isöetalia.
The first-mentioned grouping is a typical subarctic one, the second is com–
pletely European temperate, but the third seems to be a mixture of arctic
and temperate elements.
Valleys and Slopes
. The vegetation of the valleys and the slopes is
of almost the same type as the vegetation of the lowlands as regards the
fresh waters, grasslands, heaths, gravelly flats, and marshes, although
these last and grasslands are less frequent and lowland species are often
not encountered in the slope vegetation. One type of vegetation is, however,
almost restricted to the valleys and slopes, namely, the Icelandic “forests.”
These are made up mainly of
Betula tortuosa
with
Salix
shrubs as well as
Betula pubescens
var.
coriacea
,
B. callosa
,
Sorbus aucuparia
, and
Populus
^
tremula
^
, the two last-mentioned species being rare. The mean height of the
forest trees reaches only 2 to 3 meters, but the highest trees
m may reach
EA-PS. Löve: Flora and Vegetation of Iceland
10 or 12 meters. The groupings met with in the Icelandic forests seem to be
mainly the following: Betuletum Myrtillo-Hylocomiosum, Betuletum Empetro–
Hylocomiosum, and Betuletum Geraniosum subalpinum. In places without
Betula
forests this last-named is represented by a Salicetum Geraniosum alpicolum, or
by Geranietum silvatici alpicolum. Apart from the trees, these communities
seem to be characterized by the occurrence of
Geranium sylvaticum
,
Acetosa ari–folia
,
Milum effusum
,
Anthoxanthum odoratum
,
Alchemilla
sp.,
Angelica arch–angelica
,
Hieracum
sp., and in some parts of the country by
Epilobium angusti–folium
and
Roegneria
(
Agropyron
)
canina
. Besides these species, a great many
of the most thermophilous ones in the Icelandic flora are met with in these
communities, which are found only in sheltered localities in the valleys.
Higher up, the slopes become poorer in vegetation, and where the wind
erosion is too strong and the solifluction becomes too effective, the vegeta–
tion becomes very scanty — except in localities sheltered by ridges and
drifted snow. In these snow patches, the vegetation belongs mainly to the
Nardeto-Caricion bigelowii, Cassiopeto-Salicion herbaceae, and Ranunculeto–
Oxyrion. The main groupings of the Nardeto-Caricion bigelowii in Iceland are:
(
1
) the Nardetum chinophilum with
Nardus strict
e
^
a
^
^
Nardus strict
e
^
a
^
^
,
Carex bigelowii
,
Salix
herbacea
,
Bistorta vivipara
, etc., and various cryptogams; (2) Anthoxantho–
Deschampsietum flexuosae with
Anthoxanthum
[:
]
odoratum
,
Deschampsia flexuosa
,
Carex bigelowii
,
C. lachenalii
,
Lycopodium alpinum
,
Salix herbacea
,
Acetosa
arifolia
,
Gnaphalium norvegicum
,
Dicranum
,
Pohlia
,
Cetraria,
and
Cladonia
spp.;
and (3)
Caricetum
^Caricetum^
bigelowii-lachenalii with
C. bigelowii
,
C. lachenalii
, as
well as
Deschampsia flexuosa
,
Salix herbacea
,
Bistorta vivipara
,
Sibbaldia
procumbens
^
procumbens
^
, and cryptogams such as
Polytrichum
,
Drepanocladus
,
Cetratia
, and
Cladonia
^
Cladonia^ spp.
EA-PS
.
Löve: Flora and Vegetation of Iceland
The characteristic groupings of the Icelandic Cassiopeto-Salicion her–
baceae are: (
1
) the mainly alpine Cassiopetum hypnoides which is generally
composed of
Cassiope
,
Salix herbacea
,
Gnaphalium supinum
,
Carex bigelowii
,
and different mosses and lichens. (
2
) On the slopes as well as in alpine
regions, the Salicetum herbaceae boreale is characterized by
Salix herbacea
,
Carex bigelowii
,
C. rufina
(in some places only),
Sibbaldia procumbens
,
Gnaphalium supinum
, and different mosses and lichens. Here also is (3) the
Luzuleto-Ranunculetum glacialis, which is characterized by
Ranunculus glaci–alis
,
Luzula arcuata
s.l.,
Poa laxa
subsp.
flexuosa
,
Cardamine bellidifolia
,
and other plants often found in open alpine soils.
The groupings of the Ranunculaeto-Oxyrion so far observed in Iceland seem
to be: (
1
) the Phippsietum algidae with
Phippsia algida
,
Cerastium
sp.,
Carex
lachenalii
, etc., at the margins of some glaciers and on high-alpine slopes;
(2) Saxifrago-Ranunculetum pygmaeii with
Ranunculus pygmaeus
,
R. acris
,
Oxyria
digyna
,
Cerastium alpinum
,
Saxifraga cernua
,
S. rivularis
,
Sibbaldia procumbens
,
Veronica alpina
s.l.,
Gnaphalium supinum
, as well as
Salix herbacea
,
Carex
lachenalii
, and various mosses and lichens; (3) Oxyretum triviale, which is
formed mainly by
Oxyria digyna
,
Ranunculus glacialis
,
Salix herbacea
,
Veronica
alpina
s.l., and Gnaphalium supinum; (4) Ranunculetum acris
[:
] ch
[:
]
nophilum with
Carex bigelowii
,
C. lachenalii
,
Poa alpina
,
Festuca cryophila
,
Ranunculus acris
,
Acetosa arifolia
,
Bistorta vivipara
,
Oxyria digyna
,
[:
]
Cerastium
sp.,
Sibbaldia
procumbens
,
Alchemilla
sp.,
Gnaphalium supinum
,
Taraxacum
spp.,
Salix herbacea
,
and various cryptogams; and (5) Alchemilletum vulgaris chionophilum, one of
the most typical communities of the snow patches on the slopes and in the shel–
tered areas, which is composed primarily by species of the
Alchemilla vulgaris
EA-PS. Löve: Flora and Vegetation of Iceland
complex,
Deschampsia flexuosa
,
Sibbaldia procumbens
,
Salix herbacea
,
^
as
^
well
as
Taraxacum
spp.
Ver
[:
]
^
on
^
ica alpina
s.l.,
Gentiana nivalis
,
Ranunculus acris
,
etc.
Rocks and Stony Soils
. The vegetation of the mountain rocks and the
stony soils below them is rather variable at different places. In the shel–
tered localities below the rocks, the most common communities seem to be
the Veronico-Poeticum glaucae with
Poa glauca
,
P. nemoralis
,
Festuca vivipara
and
F. ovina
,
Roegneria
(
Agrop
h
yron
)
borealis
var.
islandica
,
Cystopteris
fragilis
,
Sedum annum
,
Geranium sylvaticum
, and
[:
]
other species; and the Arc–
tostaphyletum uva-ursi with
Arctostaphylos
,
Anthoxanthum odoratum
,
Potentilla
crantzii
, and perhaps
Juniperus
and some other species, where the soil is
not too bare.
The stony soils of the hillsides are characterized by rather sparse vege–
tation belonging to the Dryetum and other groupings of plants that are able
to thrive in soils with a high degree of solifluction activity and wide varia–
tions
[:
]
in moisture content. In the crevices of the rocks themselves,
many thermophilous species are met with as individuals or limited associations,
examples being the
Thymus arcticus-Saxifraga oppositifolia
association,
Sedum
roseum
, the
Saxifraga cotyledon-sedum roseum
association in eastern Iceland,
Cystopteris fragilis
, and other communities of higher and lower plants. On
wet palagonite rocks,
Bryoxiphium norvegicum
and other moss and higher plant
communities are met with, and on many of the basalt rocks in the mountains a
number of thermophilous species are found.
Central Highland
. The vegetation
[:
af]
^
of
^
the central highland is mainly com–
posed of the communities of the gravel flats, the sands, and the heaths of
EA-PS. Löve: Flora and Vegetation of Iceland
the slopes and lowland, although the number of species is lower and almost
all thermophilous representatives are absent. In sheltered localities, how–
ever, different types of marshes are met with. Moreover, in the highlands,
the typical vegetation of clayey flats is absent, while it is only in the
hi
^
g
^
hlands of northern Iceland that the typical vegetation of the permafrost
areas, the tundra marshes, is encountered.
The typical Icelandic tundra marshes are found mainly in almost flat
areas with a multitude of lakelets surrounded by fens of the Stygio–
Eriophoretum angustifoliae. Among these lakelets are giant tussocks up to
two meters in height and up to fifteen meters in length. The bogs between the
Stygio-Eriophoretum angustifoliae are covered with
Eriophorum angustifolium-Calamagrostis neglecta
associations. On the slopes and domes of the tussocks,
however, the vegetation is clearly of the hea
^
t
^
h type, belonging mostly to
associations of
Salix cordifolia
var.
callicarpea
,
Empetrum hermaphroditum
,
Cassiope hypnoides
,
Ristorta vivipara
,
Salix herbacea
,
S. lanata
,
Calamagrostis
neglecta
, and fiferent Carices, while on the very tops of the driest tussocks
are found only communities belonging to the
Rhacomitrion
.
EA-PS. Löve: Flora and Vegetation of Iceland
BIBLIOGRAPHY
1. Birkeland, B.J., and Föyn, N.J. “Klima von Nordwesteuropa und den Inseln
von Island bis Franz-Joseph-Land,” W. Koppen and R. Geiger,
Handb. Klimatol
, vol.3, pt. L, 1932.
2. Christiansen, M.P. “Studies on the larger fungi of Iceland,”
The Botany
of Iceland
, vol.3, 11, 1941.
3. ----. “The
Taraxacum
flora of Iceland,”
The Botany of Iceland
, vol.3,
12, 1942.
4. Gallöe, O. “The lichen flora and lichen vegetation of Iceland,”
The Botany
of Iceland
, vol.2, 6, 1920.
5. Gröntved, J. “The Pteridophyta and Spermatophyta of Iceland,”
The Botany
of Iceland
, vol.4, 1, 1942.
6. Hada
c
^
č
^
, E. “On the history of the flora of Iceland,”
Stud. Bot. Cechoslov
.
vol.9, 1948.
7. Hansen, H.M. “Studies on the vegetation of Iceland,”
The Botany of Iceland
,
vol. 3, 10, 1930.
8. Heering, W.
Das unbekannte Island
. Erfurt, 1935.
9. Hesselbo, A. “The Bryophyta of Iceland,”
The Botany of Iceland
, vol.1, 4, 1918.
10. Humlum, J. “Typer af de almindeligste Plantesamfund i det islandske Röjland,”
Naturens Verden
, vol. 20, 1936.
11. Iwan, W.
Island; Studien zu einer Landeskunde
. Stuttgart, 1935.
12. Jonsson, H. “The marine algal vegetation of Iceland,”
The Botany of Iceland
,
vol. 1, 1, 1912.
13. Larsen, P. “Fungi of Iceland,”
The Botany of Iceland
, vol.2, 9, 1932.
14. Lindroth, C.H. “Die Insektenfauna Islands und ihre Probleme,”
Zoolgiska Bior
.
Uppsala
, vol.13, 1931.
15. Löve, A.
Islenzkar jurtir
(Icelandic flora). Copenhagen and Reykjavik, 1945.
16. ----. “Chromosome numbers of Northern plant species,” Iceland . Univ. Inst.
Appl. Sci. Dep. Agric.
Rep
. B, vol.3, 1948.
17. Löve, A. and Löve, D. “Studies on the origin of the Icelandic flora. I,” Ice–
land. Univ. Inst. Appl. Sci. Dep. Agric.
Rep
. B, vol.2, 1947.
EA-PS. Löve: Flora and Vegetation of Iceland
18. Lynge, B. “Lichens from Iceland collected by Norwegian botanists in 1937
and 1939. I. Macrolichens,” Norske Videnskaps. –Akad. Mat.–
Nat. Kl.
Skrifter
, vol.7, 1940.
19. Östrup, E. “Fresh-water diatoms from Iceland,”
The Botany of Iceland
, vol. 2,
5, 1918.
20. ----. “Marine diatoms from the coasts of Iceland,”
The Botany of Iceland,
vol. 1, 3, 1916.
21. Petersen, J.B. “The aërial algae of Iceland,”
The Botany of Iceland
, vol.2,
8, 1928.
22. ----. “The fresh-water Cyanophyceae of Iceland,”
The Botany of Iceland
,
vol.2, 7, 1923.
23. Pjeturss, H. “Island.”
Handb. reg. Geol
., 4, 2, 1910.
24. Sörensen, T. “Untersuchungen uber die Therophytengesellschaften auf den
isländischen Lehmflächen (“Flags”),” Danske Vidensk. Selsk.
Biol
.
Skrifter
, vol.2, no. 2, 1942.
25. Stefansson, S., and Steindorsson, S.
Flora Islands
. 3rd ed. Akureyri, 1948.
26. Steindorsson, S.
The Floi-irrigation
. Reykjavik, 1943.
27. ----. “Studies on the vegetation of the central highland of Iceland,”
The
Botany of Iceland
, vol. 3, 14, 1945.
28. Thorarinsson, S. “Vatnajökull. Scientific results of the Swedish-Icelandic
investigations 1936-1937. Chapter II. The main geological and
topographical features of Iceland,”
Geografiska Ann
. 1937. Stockh.
29. Thoroddsen, T. “An account of the physical geography of Iceland with special
reference to the plant life,”
The Botany of Iceland
, vol.1, 2,
1914.
30. ----. “Island, Grundriss der Geologie und Geographie,”
Petermanns Mitt
.
Ergänzungsch
. Vol.152, 153, 1905, 1906.
Askell Löve