Environmental Engineering Reference
In-Depth Information
netting, which can be removed after a few weeks, has
proven successful. A certain degree of protection of
the soil against mechanical interference is achieved
with the mulch layer, and microclimatic conditions are
improved. The additional use of a cover crop has proven
useful. If the germination capacity of the hay flowers
is insufficient, important seed components can be
additionally purchased and sown.
The storage period should not exceed a maximum of
2-3 weeks in summer. Following the end of levelling
the grass turfs or pieces of vegetation are again laid
out and pressed in lightly.
With appropriate planning of the building process,
the direct use of vegetation turfs is possible without
intermediate storage.
Potted plants
15.4.4 Restoration with plant material
The plants and seeds are pre-cultivated in nurseries
and planted with a well-developed root stock at
the restoration site. Site-specific species with a good
vegetative growth are used for this (Grabherr &
Hohengartner 1989). One can also turn to mother plants
or seeds taken directly at the site by experts. With the
appropriate choice of species, excellent results can
be achieved at extreme sites in this way. The sup-
porting use of this method as a post-improvement
measure against sparseness in the restoration area is
favourable.
Sod clippings
Shoots or rosettes (mostly mechanically separated
vegetation turfs) are loosely distributed. Distribution
can take place mechanically in areas that can be driven
on. In this way, a much larger area can be restored
with well-established vegetation than with grass
swards. Restoration, however, is significantly more
sparse, and the danger of erosion higher.
Grass turfs
Ready-made sward (sod rolls)
Available and natural vegetation is above all the best
substance in the alpine zone for enduring restoration
identical to nature. Therefore, extreme care should be
taken when using such vegetation because destruction
or a lack of re-use must be strictly avoided.
Grass turfs (also known as grass swards) or larger
pieces of vegetation won during levelling or path con-
struction are grouped together following completion
of the work. They are very suitable for the rapid and
site-specific restoration of damaged areas. On steeper
banks, the grass turfs must be fixed with wooden nails.
Wherever possible the planting of grass turfs should
take place before shooting or after the start of the
autumn vegetation pause, just after the melting of snow
or immediately before the coming of snow in winter.
At these times the success of planting, even in the
extreme high zones, is very good.
Before levelling begins, the available grass or pieces
of vegetation are lifted together with the rooted soil
and laid again after levelling. Depending on whether
the turfs are cut manually, or lifted mechanically, their
size is 0.15 - 0.5 m
2
. If required they can be stored in
pits or stacked on pallets (maximum of 1 m wide ×
0.6 m high) to hinder drying out, stifling and rotting.
Sod rolls with site-specific vegetation are already
available in small amounts for differing starting sub-
strates. Sod rolls are produced at specialized firms over
a period of around 12 months until the sufficient
development of site-specific altitude species is ensured.
According to need and restoration aims, certain grass
mixtures can be produced beforehand. The grass is then
harvested to order and transported to the restoration
area. Thus a complete cover of restoration areas is
possible in the shortest possible time. This method is
especially interesting in restorations following small-
area interception and in extreme locations.
15.4.5 Combined techniques
Vegetation transplantation: combined
seed-sward process
In this special restoration technique, the covering
with grass swards, or other pieces of vegetation, is
combined with dry or wet seed. The grass swards
used must be appropriate to the desired site-specific
type of vegetation and are generally acquired from the
