Nicola Arndt und Matthias Pohl - Neobiota

Minerotrophic fens are very heterogeneous in their vegetation, morphology, development and age.
They occur over the whole of Europe regardless of any regionality. As a result it was necessary to
establish 10 specific mapping units. S17-S24 cover different types of brown moss and Sphagnum fens
occurring from the subarctic to the Mediterranean. Units S25 and S26 represent swamp (tall sedge) fen
mires, concentrated principally in the southernmost (Mediterranean, Pontic, Colchic) parts of Europe.
5 Zonality or azonality of regional mire complex types
In contrast to terrestrial zonal vegetation (forests, tundras, steppes, etc.) mires in general are
considered to be of azonal character, similarly to, e.g., alluvial vegetation, aquatic vegetation, etc., as
they are directly dependent on hydrological factors and rather independent of macroclimatic
conditions. Nevertheless, as indicated in the preceding paragraph, at least some mire complex types
display a distinct zonation related to the bioclimatic zones of terrestrial climax vegetation: polygonal
and palsa mires co-form the vegetational complex of the subarctic tundra zone, aapa mires appear in
the northern and middle boreal vegetation zones of the taiga. Lowland raised bogs of different types
are typical for the southern boreal, hemiboreal and neighbouring parts of temperate (nemoral)
vegetation of southern taigas and mixed deciduous forests. Similarly, the continental wooded raised
bogs occur mostly in the hemiboreal and temperate zones of mixed deciduous forests. To a certain
degree this is true also for blanket bogs. All of these regional mire complex types form a more or less
dominant and constant accompaniment within particular zonal vegetation. However, in this connection
it has to be stressed that the long-term postglacial development of both components within a zone
differs and that it has been controlled by quite different environmental factors or influences and by
different florogenetic sources.
In this respect, it has to be acknowledged that these regional mire complex types reveal a certain
indirect dependence on climate and show, at least in parts, some important features of vegetational
zonality. Evaluating all the above information we can, in accordance with ALJECHIN (1951), denote
these mires as intrazonal. They do not form any particular vegetation zone, being controlled by
specific hydrological, trophic and mesoclimatic conditions of the environment. However, the
macroclimatic situation indirectly determines to a high degree the qualities and intensities of these
direct influences. These mire types are characteristic elements of the particular vegetational
bioclimatic zones.
This is less true in the case of the montane and submontane raised bogs and, especially, minerotrophic
fens and swamp mires as they are not strictly bound to the specific zonal vegetation. Fens and swamps
are distributed over the whole of Europe and in all vegetation zones from the lowlands to the high
mountains and from the subarctic to the Mediterranean and Black Sea regions. These mire complex
types are, of course, typical examples of azonality.
Acknowledgement
The author is indebted to all colleagues who have contributed to the European mapping of mires. The
following colleagues should be especially mentioned: S. Eurola (Finland), T.K. Jurkovskaja (the
former territory of the U.S.S.R.), A. Moen (Norway), H. Sjörs (Sweden) and other national mire
experts. My special thanks are due to John Cross and John Rodwell who have contributed to
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