Jökull - 01.12.1986, Page 55

Table 4: Species groups 1 and 2 from Ketilsstadir (for
discussion, see text).
Species Group 1
Lathrobium brunnipes
Quedius umbrinus
Stenus spp.
Hydroporus nigrita
Hydraena britteni
Species Group 2
Patrobus septentrionis
Lesteva longoelytrata
Hypnoidus riparius
Othius angustus
Gabrius trossulus
Aphodius lapponum
Aleocharinae indet.
Otiorhynchus nodosus
ably reflects the changing nature of the ‘natural’ en-
vironment. The most likely explanation of this dis-
crepancy, aside from the possibility of climatic
change, is the activity of man in altering the bog habi-
tat for his own purposes.
Group 2 appears to be a characteristic post-Land-
nam association. Of these, Patrobus septentrionis,
Otiorhynchus nodosus and the Aleocharinae occur
Pre-Landnám, the remainder are exclusively post-
Landnám, although several are known elsewhere in
earlier deposits (Buckland et al., 1986). Only
Aphodius lapponum is directly associated with man.
The species are all commensurate with a somewhat
drier, more diverse habitat than that of the natural
bog.
CONCLUSION
The overview obtained by a study of the macrofos-
sils from the Ketilsstadir bog is one of relatively low
species diversity but high numbers prior to the arrival
of man. The bog surface seems to have been wetter
before Landnám and the anthropogenic influence on
the locality, reflected in an increased mineral com-
ponent of the deposits and changes in the insect
faunas, may well relate to grazing pressure, causing
erosion of the surrounding slopes and modifying the
flora of the bog and its environs. Some local drying of
the surface may relate to medieval peat exploitation.
The extensive and relatively frequent falls of tephra
would seem to have had no significant long term
effects upon the biota of the bog. As noted above,
however, the faunas from above the 300mm thick
tephra from the eruption of Katla in —1357, which
must have brought about widespread local extinction
of biota and temporary abandonment of farms in the
area, are much poorer than those immediately below,
suggesting that reimmigration from the nearest
‘refugia’ may have been a protracted process, although
a more extensive sampling programme would be
necessary to test the statistical validity of this state-
ment.
ACKNOWLEDGEMENTS
This multidisciplinary research project could not
have been carried out without the ready cooperation
of colleagues both in Iceland and Britain. Historical
and palaeoecological research has been funded by a
major award from the Leverhulme Trust to whom
primary acknowledgement must be made. In the field
the assistance of J.M. Buckland, A.J. Dugmore and
Mr. & Mrs. J.R.A. Greig is gratefully acknowledged
and the results owe much to discussions with the late
Kristján Eldjárn and the late Sigurdur Thórarinsson;
Erling Ólafsson kindly commented upon the fossil
insect data and G.R. Coope and P.J. Osborne com-
mented upon the various drafts of the manuscript.
Fieldwork was carried out in Iceland under National
Research Council permit nos. 1/80 and 48/80. The
cooperation of the farmers in the Ketilsstadir area is
appreciatively noted.
FOOTNOTES
1. Landnámabók — an account of the discovery and
settlement of Iceland, compiled in the late 13th
century (Benediktsson, 1969) or even early 12th
century (Rafnsson, 1974).
2. h = hundred, a measure usually expressed in long-
hundreds = 120; lh = 120 ells homespun or one
cow in value, i.e. the value of a 4 —8 yr. old cow
which had calved once.
3. Hired cattle provided a form of rent; the lease-
holder was obliged to rent a certain number of
cattle from the owner.
4. This information updates that previously pub-
lished in Buckland et al., (1981). In that paper, a
lapsus calumni allowed the weevil Tropiphorus
obtusus to be listed as Hypera suspiciosa.
REFERENCES
Balfour-Browne, F. 1958; British Water Beetles, 3.
Ray Society, London.
Bannister, P. 1960: The use of subjective estimates of
cover-abundance as the basis of ordination. Jour-
nal of Ecology, 54: 665—674.
Benediktsson, J. 1969: Landnámabók. Some remarks
on its value as a historical source. Saga-Book, 17:
275-292.
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