Environmental Engineering Reference
In-Depth Information
grass cover, the measures can be limited to unsatis-
factory patches within the area.
Fertilizer of a slow and permanent effect should
be used, which promotes the build-up of humus and
has good plant tolerance. Attention should be given
to achieving a balanced nutritional relationship (Heer
& Körner 2002). The use of roughage-promoting or
unhygienic fertilizer should be avoided. Where pos-
sible, organic fertilizer such as well-rotted farmyard
manure, composted fertilizer or certified biological
compost (according to the existing legal regulations)
should be used. The use of fluid and semi-solid sew-
age should be avoided. The use of organic mineral
fertilizers with the appropriate characteristics (slow,
permanent release of nutrition) is possible. Their use
should be limited to the necessary degree in relation
to the positive additional effects of the organic fert-
ilizer (multiple effects, deposit effect, herb tolerance,
build-up of humus).
amounts of nutrition, and short-term management
measures lead quickly to natural, generally extensive
self-maintaining grass, which has high resistance
against subsequent uses for tourism and agriculture.
With the use of site-specific seed mixtures, the
required sowing volumes commonly used in practice
can be reduced from 200 -500 to 80 -160 kg ha
−1
.
Grasses and legumes were selected within the sphere
of several international research projects, which are
suitable for seed production in valley locations and
can be used in various site-specific alpine seed mix-
tures (Krautzer
et al.
2003, Peratoner 2003). In the
meantime, the ecological species suitable for high-zone
restoration will multiply over a broad area and can
then be graded according to altitude, original rock and
usage, packaged as high-quality restoration mixtures
and then marketed. The use of such site-specific seed
mixtures should be obligatory when sowing in high
zones.
Standards for seed mixtures
15.4.2 Restoration with seeds
Minimum standards for site-specific seed mixtures for
high-altitude restoration include the following. First,
when faced with a lack of indigenous plant material,
seed mixtures need to be used for restoration at high
altitudes. To avoid errors when using such mixtures,
alternative recipes are used that fulfil the following
criteria. Due to their natural area of distribution,
site-specific, high-altitude mixtures are divided into
main components and secondary components (see
Table 15.1). The main components encompass the
species currently commercially available. A further
series of site-specific species (grasses, legumes and
special herbs) are more or less offered commercially
and regularly in small amounts, which according
to definition may also be used as high-altitude seed.
High-altitude seed must comprise at least 60% main-
component seed, by weight. The remaining 40% of the
weight can be made up with secondary components
(Table 15.1). Secondly, mixtures must comprise at least
five species. The share of a single species must not
exceed 40% of the weight. Leguminosae must com-
prise at least 10% of the weight of high-altitude
mixtures. Thirdly, for high altitudes (> 2000 m) site-
specific, ready-made mixtures are generally usable to
only a limited extent. A special combination of site-
specific mixtures made up by experts is necessary.
Seed mixtures
The conventional high-zone mixtures available on
the market mainly comprise high-growing, non-site-
specific plants originally bred for grassland economy
in valley locations or as grasses for sporting events.
These species are adapted to lower, warmer locations
and are generally not suitable for restoration in high
zones (Florineth 1992). The high nutritional needs of
these species require long-term, expensive fertilization
measures to achieve the necessary grass density. These
species also show relatively high biomass production,
which again requires regular cutting, grazing or
removal of the materials arising. This is because
in the short vegetation period that occurs at high
altitudes the additional biomass that grows does
not decompose sufficiently, with the result that the
vegetation's stigmas would be choked. In many cases,
further use or management of the restored areas is not
wished for or possible.
Site-specific subalpine and alpine plants are adapted
to an optimum degree to the high-zone climate. They
produce little biomass, but with an appropriate choice
of species they do produce high-quality feed. Seeding
with site-specific seeds generally requires only small
