|FENNOSCANDIAN DISTRIBUTION OF THE CALICIALES|
Fennoscandia includes the four countries in northern Europe: Norway, Sweden, Denmark, Finland.
For evaluation of the floristic distribution patterns within Fennoscandia we use a system suggested by Bendiksen & Halvorsen (1981) and Okland & Bendiksen (1985). This system includes vegetation zones as described by Ahti et al. (1968). We have placed the species in groups according to the overall appearance of their Fennoscandian distribution patterns as far as it has been possible to ascertain it.
|Bendiksen and Halvorsen (1981) divide the
Fennoscandian vascular plant flora into five elements: Western, southern, south-eastern, eastern and alpine. In addition we
have one group of species with a ubiquitous distribution
pattern in Fennoscandia, and a remainder group
consisting of species with poorly known distribution
patterns. We have added our own data to the known Swedish
distributions (Tibell 1977, 1978b, 1980a, Santesson 1984
g et al. 1984) plus scattered information from Denmark
and Finland (Tibell 1969, 1976a, 1978a and 1980b).
The figure shows the total number of species in the seven groups mentioned above. Note the high number of eastern species (16) and the absence of western species (O). Some reasons for this are suggested in the discussion of the eastern element below.
There are no species in Norway belonging to the western element.
|Factors that may influence the distribution of species belonging to the southern element are: (1) the distribution of the substrate. Several of the lichens are restricted to deciduous trees having a southern distribution in Fennoscandia e.g. Ulmus, Fraxinus, and Quercus. (2) Low temperatures in the summer or low temperatures in the winter may also be delimiting.|
|The southern element is divided into four groups:|
|S I Strongly southern species. No species occur in this group.|
|S Z Southern species. Five species occur in this group:|
|Species in this group occur in the temperate and hemiboreal vegetation zones.|
|S 3 Slightly southern species, including two species:|
|Species in this group occur in the temperate, hemiboreal, and south boreal vegetation zones.|
|S 4 Widely distributed species with southern tendency, also including two species:|
|Species in this group occur in the temperate, hemiboreal, south boreal, and middle boreal vegetation zones.|
|High summer temperatures seem to be important for species belonging to the south-eastern element, although low winter temperatures cannot be disregarded.|
|The south-eastern element is divided into four groups:|
|SE 1 Strongly south-eastern species. No species occur in this group.|
|SE 2 South-eastern species. No species in this
|The species in this group occur as far north as the Nordland province, and they may reach the inner fjords of the Norwegian west coast. (In Sweden Chaenotheca phaeocephala has been collected as far north as Lule Lappmark).|
|SE 4 Widely distributed species with south-eastern tendency. No species occur in this group.|
Several factors have been suggested as important for the distribution of species in the eastern element: (1) The distribution of the substrate. Some of the lichens (Chaenotheca subroscida and Cyphelium karelicum) prefer Picea which has aneastern distribution in Fennoscandia. (2) Low humidity may be significant for some, but not for all species. (3) The snow cover may influence some species. (4) Competition, especially from bryophytes, may be of considerable importance at the Norwegian west coast. Species belonging to the eastern element fall into different ecological groups. Calicium denigratum, C. trabinellum, Cyphelium tigillare and Thelomma ocellatum occur on dry lignum in exposed habitats, while the other species grow under very humid or humid conditions. They occur in root caves, on well decomposed lignum of stumps, or they are corticolous in humid forests. The eastern element is divided into two groups:
|E I Eastern species. This group includes 10 species:|
|E Z Slightly eastern species, including four species.|
|The species in group E 2 reach the inner fjords of the Norwegian west coast while the species in group E 1 only reach the mountain chain.|
|Species belonging here probably do not tolerate high summer temperatures.|
|The alpine element is divided into three groups.|
|A 1 Pronounced alpine species. No species occur in this group.|
|A 2 Boreal-alpine species.|
|The species in this group are mostly distributed in alpine areas, but may also occur in the boreal vegetation zones.|
|Cyphelium pinicola grows in the most continental areas of Norway. It seems to have a disjunct distribution. The substrate (Pinus) is widely distributed in Norway, and climatic factors must be restricting the distribution of C. pinicola.|
|A 3 Southern hemiboreal-alpine species. No species occur in this group.|
These are widely distributed species in Fennoscandia.
These species have been collected only a few times in Fennoscandia and their distribution patterns are still insufficiently known: