Keywords:
coastal protection
dune stabilization
dune grass
Contact: M. Schulze Dieckhoff. NLWK. Jahnstr. 1.
26506 Norden. Germany.
Location: Germany, North Sea, Lower Saxony, Norderney
The significance of some dune grasses for coastal
protection
Plant growth, especially of dune grass, plays a vital role throughout
all stages of dune formation. The first grass in the process of
dune building is the Sand Couch (Agropyron junceum), the
plant initiates foredunes on the seashore. Because this grass
tolerates salt concentrations of up to 6% it is most suitable
for planting on the low lying areas of the barrier dunes. When
the dunes have grown, the vegetation becomes denser and the quantity
of fixed sand increases, especially because of the colonization
of Marram Grass (Ammophila arenaria). This grass is used
most commonly for coastal protection since the fourteenth or fifteenth
century, but is not suitable for all dune regions. On the same
areas as the Marram the Baltic Marram Grass (Ammocalamagrostis
baltica), a completely sterile hybrid from Marram Grass and
Bush Grass, is found. It is more vigorous than Marram Grass, it
still grows on the older dunes and it seems to be more robust
and does not need as many nutrients, but because stocks for cutting
are limited, it is not used extensively for dune conservation.
Grey Hair-Grass (Corynephorus canescens) belongs to the
lawn forming dune grasses, tolerating only a small deposit of
sand but a shortage of nutrients. Because of this it can be found,
where Marram Grass decreases.
For coastal protection, planting of vegetative segments of dune
grasses plays a major role. In Germany, cuttings are usually taken
by thinning natural areas of dense growth. This causes several
problems, for example there is not always sufficient plant material
available, the quality of the plants is variable, the process
of cutting is time-consuming and labour-intensive. This is why
the cultivation of grasses was tested.
Results from the cultivation studies
The study focused mainly on Marram and Baltic Marram Grass. The
superiority of the Baltic Marram Grass was established. It could
be propagated at a far greater rate than Marram and it is less
grazed by rabbits. For both the survival rate of the nursery raised
plants in natural surroundings was even higher than of plants
taken from natural stocks, because of the constant good quality
of the plant material from the nursery. Both react well to nitrogenous
fertilizers, best results were obtained by two treatments with
5g N/m2. After this, within a single growing season, one plant
of Baltic Marram could propagate more than 6 new ones. Because
of the great success of the Baltic Marram, a method for field
propagation has been developed, further in 1990 an area of 2.8
ha was set aside to propagate this grass to have a sufficient
source for annual planting on Norderney.
The Sand Couch, Grey Hair-grass and Sand Sedge were all successfully
reared under nursery conditions. Further experiments in cultivation
and planting in the dunes with priority on combined planting of
various species are scheduled.
References
- Busching, H. (1992): Rising Populations of Wild Rabbit (Oryctolagus
cuniculus (L.)) endanger the Islands’ Vegetation and Coastal
Protection. In: Hilgerloh (ed.). Proceedings of the Third Trilateral
Working Conference on Dune Management in the Wadden Sea Area.
Norderney. Germany. (18.5.1).
- Schulze Dieckhoff, M. (1992): Protection Measures for the
Inner Dunes on the East Frisian Islands. In: Hilgerloh (ed.).
Proceedings of the Third Trilateral Working Conference on Dune
Management in the Wadden Sea Area. Norderney. Germany. (18.5.1).
- Schulze Dieckhoff, M. (1992): Propagating dune grasses by
cultivation for dune conservation purposes. In: Carter, Curtis
& Sheehy-Skeffington (eds.). Coastal Dunes: 273-281. Balkema.
Rotterdam. (BNd92).
