Fróðskaparrit - 01.01.2008, Side 179

ÚTBRBÐSLA AV SVARTAKLUKKUM (COLEOPTERA, CARABIDAE)
í ÚTNYRÐINGSEYSTUROY 0C HVUSSU ÁVIRKAST HON AV AVVEITING
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on the lower altitudes, which also is related
to the preferred conditions described above.
More, but not significantly more C.fuscipes
were found in the UD area than the OD area,
this can be related to the UD area being
more dominated by grassland than the OD
area (Fosaa et al., 2008 and Lindroth, 1986).
Hansen (2006) collecting in pitfall traps at dif-
ferent altitudes in an outfield finds Patrobus
septentrionis to be more abundant at higher
altitudes than lower altitudes, which is in good
agreement with Lindroth (1985) who
describes Patrobus septentrionis as a common
species in Scandinavia, occuring in mountains
above the timber limit, preferring marshes and
meadows. Bengtson (1981) found Patrobus
septentrionis also to be abundant in infield lo-
calities; most infield localities are meadows,
which make these localities suitable to Pa-
trobus septentrionis. The results from us
regarding altitude is likely related to the fact
that Calluna vulgaris, which also is a highly
preferable vegitation type to P. septentrionis
(Lindroth, 1985), is more common at the
higher altitudes in the OD area.
One possible reason for Patrobus atroru-
fus being more abundant at the lower alti-
tudes in the drained OD and ND areas can
be that the lower areas are more humid than
the upper areas, making these areas suitable
to Patrobus atrorufus (Lindroth, 1985). The
uppermost stations are situated just above
the intake, which makes them relatively
humid, but just below the water is taken by
SEV, therefore most of the upper stations are
relatively dry. So in the OD and ND areas the
rivers are being slowly filled again at the low-
est altitudes; this causes the river banks to
become more humid at the stations situated
at low altitudes, and according to Lindroth
(1985) Patrobus atrorufus likes to stay close
to water. Another reason - considering the
OD area - is the distribution of vegetation.
Patrobus atrorufus is more associated with
grassland than heather (Fosaa et al., 2008).
Heather is more abundant in the upper
areas, and grassland more abundant in the
lower areas; Patrobus septentrionis is quite
dominating in the upper areas and accord-
ing to Bengtson (1982) Patrobus atrorufus
and Patrobus septentrionus, which both are
very similar in size (Lindroth, 1985), only
show low to moderate overlap in habitat
utilisation. So competition, vegetation type
and probably influence from draining affect
the distribution of Patrobus atrorufus in the
OD area. The upper areas in the ND area are
very steep which makes them relatively dry
because of runoff, though the whole area is
quite humid because if its aspect. But further
down the area is less steep and as mensioned
earlier the rivers are reciving some water
again, also the grass is taller in places. No
heather is in the ND area and the vegetation
is very similar. Patrobus septentrionis is also
quite dominating in the ND area both on the
upper areas and lower areas; see Table 4, so it
does not seem as if Patrobus septentrionis is
capable of excluding Patrobus atrorufus from
the lover areas in the ND area. It seems likely
that structure of vegetation and humidity,
which is affected by draining control the dis-
tribution of Patrobus atrorufus. Also the
nearness of open water is likely important
(Lindroth, 1985), since some water has en-
tered the rivers again at the lower areas.
The steepnes of the higher altitudes in
ND are also one likely important reason for
Nebria rufescens and Nebria salina being sig-
nificantly more abundant at the higher alt-