Environmental Engineering Reference
In-Depth Information
project area or the immediate vicinity at the begin-
ning of building work. There can therefore be cases
of an interception in the vegetation sphere beyond the
immediate project area to achieve optimum success
through the division of available vegetation. The
area to be restored is therefore often larger than the
original project sphere.
The grass swards (0.2- 0.5 m
2
) are placed in groups
in dry locations, to prevent them from drying out, or
in a grid-like pattern in areas subject to high precipita-
tion. Site-specific seed is applied to sparse patches
between the swards. This seed has a stabilizing effect
on the vegetation-bearing layer. Due to the short
distances between the covered grass swards, it is pos-
sible for well-established vegetation to move into the
intermediate spaces (Fig. 15.2). In this way, these
patches will also be restored and inhabited in a nat-
ural way by species that are not available as seeds.
This method has been tested at altitudes of at least
2400 m and according to the latest advances in the
field. Especially suitable are moderately nutrition-rich
plant communities subject to little human influence,
such as those found on grazing land (of the most
differing types), high-growing perennials and green
alder bushes.
The conception of this restoration technique, and
above all the selection of grass-donor areas, is only
to be undertaken by appropriate experts. In steeper
areas (with a gradient of over 30%), and in terrain
endangered by erosion, the use of geological textile
matting or similar is planned for securing the covered
vegetation or for the protection of the topsoil against
erosion.
Fig. 15.2
Seed production of site-specific species
(harvest of
Poa alpina
), a precondition for ecological
restoration of alpine environments.
farming. Management takes place in the form of
extensive grazing or annual mowing (Persson 1995),
with or without the removal of organic material (only
small amounts of biomass).
Above all, in the first years of seeding with fertil-
ization, ski areas must be managed. Until the
achievement of sufficient grass density, at least over
the first two vegetation periods, no grazing or
trampling is to take place (Klug
et al.
2002). Annual
mowing is necessary following the appearance of
appropriately lush growth. This mowing removes
biomass and thus hinders the stifling of the growth
in winter. Tillering of the plants is also stimulated and
promotes grass density. If necessary, grazing should be
15.4.6 Management
Constant cultivation is not obligatory or necessary fol-
lowing the use of site-specific seed mixtures or plant
material. With the appropriate composition of the
seed mixtures or the use of appropriate plant mater-
ials, a restoration area can be left to itself, which is
greatly desired for the restoration of areas prone to
erosion, and those containing torrent and avalanche
barriers.
Management of ski-run restoration is in most cases
also necessary in areas not used predominantly for
