Group C1 (7 relevées) represents the seral situation of ‘‘dune 1a’’ and ‘‘dune
1b’’ between years 5 and 12. It also represents the situation of ‘‘dune 2’’ between
years 19 and 24, starting about 10 years after the stabilization of the dune. The
vegetation is characterized by a high number of species and increasing F. rubra.
In ‘‘dune 1a’’ and ‘‘dune 1b,’ A. arenaria declined, while A. arenaria and A. x
baltica have kept their position in ‘‘dune 2’’ so far.
Group C2 (4 relevées) represents the seral situation of ‘‘dune 1b’’ between years
12 and 24. Hemicryptophytes were the dominating life form. F. rubra dominated,
but A. arenaria and Lathyrus japonicus were also important, indicating that some
sand movement still occurred. The invasive phanerophyte Rosa rugosa became
established in year 17 and increased further to year 24.
Group C3 (4 relevées) represents the seral situation of ‘‘dune 1a’’ between years
12 and 24. The surface was stable, and the vegetation had become similar to
northwest European and Baltic grassland-like fixed dune with a high percentage of
hemicryptophytes, dominated by F. rubra, and with, for example, Trifolium
arvense and Anthyllis vulneraria, but still with A. arenaria present (e.g., Böcher
1954; Påhlsson 1995; Thorell et al. 2001).
Table 4.2 Important vascular plant species of the TWINSPAN groups
TWINSPAN group
A
B1
B2
C1
C2
C3
Total number of species
13
13
21
21
12
12
Cakile maritima
X
o
o
Senecio vulgaris
X
o
Chenopodium album
X
Festuca rubra
X
o
X
X
X
X
Ammophila arenaria
X
X
X
X
X
X
Leymus arenarius
X
X
o
Elytrigia junceiforme
X
X
o
o
Salsola kali
o
X
Ammophila x baltica
X
o
Taraxacum sp.
X
X
X
X
Erigeron acre
X
o
o
Cirsium arvense
X
o
Conyza canadensis
o
X
o
Senecio vernalis
o
o
X
X
o
X
Epilobium montanum
o
X
Lathyrus japonicus
o
X
X
o
Cirsium vulgare
o
o
X
o
Anthyllis vulneraria
X
Trifolium arvense
o
X
Cerastium semidecandrum
o
X
X
Rosa rugosa
o
X
Chamaenerion angustifolium
o
o
X
o
X species present in [40 % of the relevées; o important species also present in the group in
question, but in \40 % of the relevées
58
P. Vestergaard
1b’’ between years 5 and 12. It also represents the situation of ‘‘dune 2’’ between
years 19 and 24, starting about 10 years after the stabilization of the dune. The
vegetation is characterized by a high number of species and increasing F. rubra.
In ‘‘dune 1a’’ and ‘‘dune 1b,’ A. arenaria declined, while A. arenaria and A. x
baltica have kept their position in ‘‘dune 2’’ so far.
Group C2 (4 relevées) represents the seral situation of ‘‘dune 1b’’ between years
12 and 24. Hemicryptophytes were the dominating life form. F. rubra dominated,
but A. arenaria and Lathyrus japonicus were also important, indicating that some
sand movement still occurred. The invasive phanerophyte Rosa rugosa became
established in year 17 and increased further to year 24.
Group C3 (4 relevées) represents the seral situation of ‘‘dune 1a’’ between years
12 and 24. The surface was stable, and the vegetation had become similar to
northwest European and Baltic grassland-like fixed dune with a high percentage of
hemicryptophytes, dominated by F. rubra, and with, for example, Trifolium
arvense and Anthyllis vulneraria, but still with A. arenaria present (e.g., Böcher
1954; Påhlsson 1995; Thorell et al. 2001).
Table 4.2 Important vascular plant species of the TWINSPAN groups
TWINSPAN group
A
B1
B2
C1
C2
C3
Total number of species
13
13
21
21
12
12
Cakile maritima
X
o
o
Senecio vulgaris
X
o
Chenopodium album
X
Festuca rubra
X
o
X
X
X
X
Ammophila arenaria
X
X
X
X
X
X
Leymus arenarius
X
X
o
Elytrigia junceiforme
X
X
o
o
Salsola kali
o
X
Ammophila x baltica
X
o
Taraxacum sp.
X
X
X
X
Erigeron acre
X
o
o
Cirsium arvense
X
o
Conyza canadensis
o
X
o
Senecio vernalis
o
o
X
X
o
X
Epilobium montanum
o
X
Lathyrus japonicus
o
X
X
o
Cirsium vulgare
o
o
X
o
Anthyllis vulneraria
X
Trifolium arvense
o
X
Cerastium semidecandrum
o
X
X
Rosa rugosa
o
X
Chamaenerion angustifolium
o
o
X
o
X species present in [40 % of the relevées; o important species also present in the group in
question, but in \40 % of the relevées
58
P. Vestergaard