Keywords:
biogenic sand stabilization
vegetation
microarthropod
trampling
thatching
Location: Denmark, Houstrup & Køge Bay. Germany,
Spiekeroog.
Biogenic formation of soil structure in sand dunes
Dune stabilization in the sense of reduction of sand movement
is mainly attributed to the establishment and further development
of vegetation. Plants not only lower wind speed and catch drifting
sand, they also connect sand grains with their roots, extended
root hairs and exudates. Additionally, various soil biota play
an important role in the stabilization of dune sand and dune formation
by aggregate formation in dune sand and contribute in this way
to dune longevity. Aggregates may be built by exudates of bacteria,
by algae or hyphae of mycorrhizal fungi glueing and interweaving
mineral grains. Soil animals may directly affect aggregate formation
via their faeces or by excreted mucus, or their secretions may
be used as substrate for bacteria and fungi, which again influence
the soil structure.
Result: the effect of human trampling on vegetation
Various plants are structurally adapted to withstand injury depending
on their habit of growth, position of the growing point and its
ability to regenerate. The results of the investigations show
a decrease of the total vegetation cover on the paths, whereas
no significant decrease, but partly an increase in the number
of species was found. This indicates, that the species suffering
competition pressure in untrampled situation may profit from trampling
which suppresses sensitive but competitive species. However, the
number of species on the path centre compared with the wayside
zones is lower. Therefore, heavier trampling pressure results
in a decreased species diversity, whereas low levels of trampling
may be acceptable or even desirable in order to maintain vegetation
diversity.
Result: the effect of human trampling on the microarthropod
fauna
Similar to the vegetation, the number of species of soil microarthropods
were also most numerous on the wayside, whereas in the path-centre
the species number decreased in part dramatically. This may be
caused by decreased plant cover, which would result in a changed
microclimate, e.g. the increase in bulk density and the associated
reduction of pore space, changes in the hydrology and the temperature
of sediments. To prevent this, soil microarthropods may be protected
by thatching, a common management practice. But this is undesirable
as it may lead to eutrophication and the introduction of alien
vascular plant species.
References
- Andersen, U.V. (1996): The influence of human trampling on
the vegetation on artificial dune and coastal grassland in Denmark.
In: Salman, Berends & Bonazountas (eds.). Coastal Management
and Habitat Conservation: 427-438. EUCC. Leiden. The Netherlands.
(PCB96).
- Koehler, H., H. Harder, J. Meyerdirks & A. Voigt
(1996): The effect of trampling on the microarthropod fauna
of dune sediments. A case study from Jutland, Denmark. In: Jones,
Healy & Williams (eds.): Studies in European Coastal Management.
Samara Publishing Limited. Cardigan.
- Koehler, H., S. Hofmann &E. Munderloh (1992): The soil
mesofauna of white-, grey- and brown-dune sites in Jutland (Denmark)
with special reference to the Gamasina (Acari, Parasitiformes).
In: Carter, Curtis & Sheehy-Skeffington (eds.). Coastal
Dunes: 273-281. Balkema. Rotterdam. (BCD92).
- Koehler, H., E. Munderloh & S. Hofmann (1995): Soil microarthropods
(Acari, Collembola) from beach and dune: characteristics and
ecosystem context. Journal of Coastal Conservation 1: 77-86.
EUCC. Opulus Press Uppsala. Sweden. (KJc95a).
- Koehler, H., G. Weidemann (1993): Biogenic dune sand stabilization.
In: van Dijk (ed.): Management and Preservation of Coastal Habitats:
83-99. EUCC. The Netherlands. (PC95).
