Environmental Engineering Reference
In-Depth Information
- can lead to extensive landslides and the formation of
shell - shaped erosion - scars (Stahr 1996 ; Tasser
et al
.
2003). Up to the time at which the natural vegetation
is re-established, there is a clear increase of erosion
processes, which continuously require more restora-
tion and preventative measures (Gray & Sotir 1996).
In addition to agricultural use, summer and winter
tourism in the last few decades has led to extensive
opening of alpine locations for recreational hiking and
skiing. There are already more than 13 000 ski lifts,
cable cars and other transport facilities throughout
the European Alps, most of which are used primarily
for tourism. Forty thousand ski runs with a total
length of 120 000 km have been built during recent
decades, of which one third are located in subalpine
and alpine zones (Krautzer & Klug 2009). Gradually
rising winter temperatures oblige ski resort owners to
invest in artifi cial snow equipment. Based on the most
recent calculations, ski runs in Austria alone now
cover more than 23 000 ha, of which more than
8000 ha are kept white and 'skiable' in winter with
artifi cial snow (Commission Internationale pour La
Protection des Alpes (CIPRA) 2004). All over the Euro-
pean mountain areas, thousands of hectares are bull-
dozed annually to keep the skiing areas attractive to
skiers. Necessary measures for the protection of the
facilities (torrent and avalanche barriers) also require
large areas each year.
In Arctic areas, awareness of disturbances is a much
more recent phenomenon. Pioneering attempts for res-
toration in North America started only in the early
1970s in connection to the construction of the Trans-
Alaskan pipeline (McKendrick 2000), which was built
between 1974 and 1977 to exploit the North Slope oil
fi elds. Hand in hand with the increasing resource
exploitation of the Arctic (mining and oil and gas
extraction), infrastructural interventions like road and
railway construction, pipelines, power lines and legal
requirements to 'restore' open cast mining areas are
the main reasons for interventions.
rehabilitation measures therefore demand a clear defi -
nition of restoration targets and awareness of limiting
factors.
15.3.1
Protection against erosion
Dynamic degradation processes such as soil erosion
may often exceed damaging effects of the initial
anthropogenic disturbances (Vasil'evskaya
et al
. 2006 ).
Erosion
, with all of its negative effects, such as loss of
vital topsoil, is therefore one of the main challenges in
the restoration work of Arctic-alpine environments.
Average slope gradients of 30-45% in the area of ski
runs, and often steeper (i.e. in the area of natural
erosion zones and avalanche barriers), make adequate
erosion protection measures and regulation of surface
runoff
a prerequisite for successful restoration. Results
of several assessments of
revegetation
indicate that
only suffi cient vegetation cover exceeding 70-80% sta-
bilizes the topsoil and reduces soil erosion to an accept-
able degree (Markart
et al
. 1997 ; Tasser
et al
. 1999 ;
Peratoner 2003). The achievement of such a vegeta-
tion cover within a relatively short time period is
crucial. Therefore, an adequate combination of appli-
cation techniques and adapted seed mixtures, or veg-
etative propagation material, should be the main
primary target for restoration. Under normal condi-
tions, minimum required cover can be achieved in the
second season of vegetative growth, but to achieve this
requires using techniques that also provide suffi cient
surface protection during the fi rst 2 vegetation years
(see also Figure 15.2). Especially the application of a
thin layer of mulch is a common and successful tech-
nique (section 15.4.3 ).
15.3.2
Maintenance of biodiversity
There has been a dramatic change in the attitude of
people to their environments in recent years. The
maintenance of
biodiversity
has become a special
concern of agrarian and environmental policy. Eco-
logical restoration projects with the target of creating
a site specifi c vegetation cover have obtained increased
importance in recent years. During the last decade,
evidence has accumulated concerning the crucial
importance of biological diversity, including genetic
diversity at the intraspecifi c level, for
ecosystem
15.3 RESTORATION TARGETS AND
LIMITATIONS
Most Arctic-alpine vegetation types are the result of a
long-lasting evolution of plant species and communi-
ties operating in relatively intact ecosystems. In most
cases, human interferences in Arctic-alpine areas lead
to drastic disturbance. Successful restoration and
