Nicola Arndt und Matthias Pohl - Neobiota

aktuellen Vorherrrschen der landwirtschaftlichen Nutzfläche. Die absolute Gesamtzahl der Arten in
der Landschaft liegt dagegen höher wegen der vielen eingeführten und neu zugewanderten Arten
1 Introduction
Up until now, little attention seems to have been devoted to the possible use of potential natural
vegetation as a baseline for evaluation of current landscape patterns (cf. RICOTTA et al. 2000). This is
due to problems involved in estimating and mapping potential natural vegetation of a given area of
land, especially if the area is subjected to intensive land use, as is mostly the case in the European
lowlands. The completion of the Map of Natural Vegetation of Europe at the scale 1 : 2 500 000
(hereafter ’the European map’) now provides us with a tool for comparing current and potential natural
vegetation of Europe, and thereby enables us to discuss, e.g., the role of humans in relation to the
development and structure of contemporary landscapes. In the present paper, the relationship between
potential natural and current vegetation of Denmark will be dealt with in order to estimate the impact
of human land use upon natural biodiversity of the Danish landscape.
Table 1: Vegetation units of the Map of Potential Natural Vegetation of Denmark. ’Local species density’ refers
to the number of species normally found within a stand (ca. 25 x 25 m) of the unit. ’Weighted species density’ is
local species density multiplied by the area (%) of the unit. Units more or less corresponding to NATURA 2000
habitat types are marked as follows: x: NATURA 2000 type, ο: high priority NATURA 2000 type, xx: includes
several NATURA 2000 types, xο: includes several NATURA 2000 types, one or several of which are of high
priority.
Natura
2000
X
286
Natural vegetation
Mapping unit Area (ha) Area (%) Local
species
density
Weighted
species
density
x F8 Oligotrophic birch-oak forest 560,700 13.0 20 260
F37 Oak-hornbeam forest 77,300 1.8 25 45
X F79 Oligotrophic beech forest 1,525,400 35.4 10 354
x F108 Meso-eutrophic beech forest 1,718,400 39.9 25 998
x F109 Beech forest on limestone 9,900 0.2 30 6
Ο T1 Wet alder woodland 55,000 1.3 30 39
U28 Oak-ash-elm-alder polder forest 61,500 1.4 25 35
Xx P4 Baltic sand dune complex 2,200 0.1 60 6
Xο P5 NW European sand dune complex 107,500 2.5 60 150
Xx P19 W European salt marsh vegetation 6,600 0.2 40 8
X P22 Baltic coastal saline grassland 15,700 0.4 40 16
Ο E10 Frisian-Danish coastal dune heath 75,300 1.8 15 27
Ο S8 Sphagnum magellanicum raised bog 22,000 0.5 15 8
Xx R1
Freshwater areas incl. R1 (= tall
reed swamps)
70,000 1.5 --- ---
Total 4,307,500 100.0 1,952