Nicola Arndt und Matthias Pohl - Neobiota

Furthermore, in the current vegetation some low species density types have been added due to
influence of humans. Thus, coniferous plantation, arable land (weed communities) and heathland are
relatively low in species density. On the other hand, cultural types of very high species density, like
grasslands and fresh meadows, also occur in the current landscape.
To get a tentative impression of the difference in overall species density between the natural
vegetation as shown by the European map, and the current vegetation, the figures of species density in
Tables 1 and 2 have been weighted by the relative area of the respective units and types. When the
values of Σ (species density x area in %) for natural and current vegetation are compared (1952 and
1094, respectively), it appears that the overall species density may be lower in the current landscape
than in the natural landscape. This is mostly due to the fact that the current landscape is dominated by
arable land. The presence in the cultural landscape of small areas of high density types, like speciesrich
grasslands, is far from being able to counterbalance the dominance of the arable fields.
The biodiversity of the Danish landscape generally has declined during the last century. This is due to
the intensification of agriculture with fertilization, use of pesticides, drainage and removal of small
biotopes as well as to declining use of meadows and salt marshes for grazing. The result is
fragmentation of the landscape and decline in population size of indigenous species (PRIP et al. 1995).
In return, the total number of species of vascular plants has never before been as high as it is today
(2675 species), caused by introduction of many species. The introduced species may damage biotopes
which are naturally species-poor, or they may become invasive and thereby outcompete indigenous
species (WIND 2000).
Possibly, maximum biodiversity of the Danish landscape since the beginning of the Neolithic occurred
during the centuries before the middle of the 19 th century. At that time the forests were partly replaced
by open, grazed species-rich biotopes, agriculture was not yet very intensified, and the landscape as a
whole was more wet and very varied. Probably the biodiversity at that time was higher than would be
found in the potential natural landscape. In this way the new Map of Natural Vegetation of Europe
may contribute to putting past and present European biodiversity into perspective.
Acknowledgements
I wish to thank Professor Kjeld Hansen and Dr. Lars Påhlsson for cooperation and discussion on the
Danish contribution to the European Vegetation Map.
References
ANDERSEN, S.T. (1977): Vegetationens historie efter sidste istid. – In: PETERSEN, P.M. &
VESTERGAARD, P. (Eds.): Noter til Vegetationsøkologi og plantegeografi. – København
(Københavns Universitet), p. 85-91.
BOHN, U.; GOLLUB, G. & HETTWER, C. [Bearb.] (2000): Karte der natürlichen Vegetation
Europas/Map of the Natural Vegetation of Europe. Maßstab/Scale 1:2.500.000. Teil 2/Part 2:
Legende/Legend, 153 S./p.; Teil 3/Part 3: Karten/Maps (9 Blätter/Sheets, Legendenblatt/Legend
Sheet, Übersichtskarte 1:10 Mio./General Map 1:10 million). – Münster (Landwirtschaftsverlag).
BUCHWALD, E. & SØGAARD, S. (2000): Danske Naturtyper i det europæiske NATURA 2000 netværk.
– Miljø- og Energiministeriet. Skov-og Naturstyrelsen, 88 p.
295