Full-text - Norsk entomologisk forening

Norwegian stone/lies II 201
areas (Table I) where geographical, geological'
climatical (Figs. 2 and 3) and botanical
aspects could be studied separately.
The location of the study areas is shown in
Fig. 4. The arrows indicate more detailed
special investigations along the most probable
invasion routes to western Norway.
The areas chosen were: 1. The area north
of Boknafjord, Rogaland and the southernmost
areas of Hordaland. 2. The area around
Oslofjord. 3. North 0sterdal and the surrounding
areas. 4. The 0vre Heimdal area.
5. The area around Kautokeino. 6. The Alta
area. 7. South Varanger including Pasvik
and Korpfjell.
To categorize the main vegetation zones,
the system of Sjors (1963, 1967) was used.
According to this system, area 1 ranges from
the North Atlantic Pine-Birch Woodland
and heath region through the Sub-Alpine
Birch Woodland belt to the Alpine belts.
Area 2 is situated in the Boreo-nemoral zone,
area 3 in the Sub-Arctic and Boreo-montane
sub-zone and area 4 in the upper part of the
Sub-Alpine Birch Woodland and the Alpine
belts. Area 5 (Kautokeino) also lies in the
Sub-Alpine and Alpine belts. In area 6 (Alta)
there are pine woods in the lowest parts,
while most of the area lies in the Sub-Alpine
Birch Woodland belt and the Alpine belts.
In area 7, Pasvik is situated in the Sub-Arctic
and Boreo-montane sub-zone while the Korpfjell
area lies in the Sub-Alpine and Alpine
belts.
The major part of the study was undertaken
in area 1 where there are very marked
climatic and botanic gradients, and considerable
difference in the altitude within a relatively
small area, making it possible to investigate
an extremely large range at nearly
the same time.
SOUTHERN NORWAY
Area 1. North Rogaland and South
Hordaland
After a preliminary investigation of the
plecopteran fauna of 64 localities, covering
Fig. 4. The investigated areas (shaded) and the
presumed immigration routes towards the west
(arrows).
Fig. 5. The investigated parts of area 1. A =
coastal areas, B = central areas, C = inner fjords.
the whole of Rogaland and the southern
parts of Hordaland, the area between Boknafjorden
and Bemlafjorden-Akrafjorden was
chosen as the most representative for this
investigation. There are clear climatic and
vegetation gradients which make the area
suitable for examining the gradient of the
decrease in species which seems to occur
towards the coasts of Norway, especially the
western seaboard.
Area description
The area is shown in Fig. 5, and studies
were carried out in 41 localities.
Pre-Eocambrian rock complexes occur in
the lower sections of the valleys, phyllites
higher up the valley sides, and acidic igneous
rocks on the top. Drift materal consisting of
stones, gravel and sand occurs in the river
valleys of the inner area. In the lower areas
along the fjords, marine clay deposits occur
which become larger towards the coast (Holtedal
1960).
The coastal climate dominates over large