Environmental Engineering Reference
In-Depth Information
mes. For example, mowing, additional seeding, care-
fully dosed post-fertilization or grazing enclosures may
all be required. These measures sometimes are essen-
tial elements of restoration success.
It is not uncommon that extreme weather events
such as prolonged droughts or unusually harsh winters
hinder or delay planned restoration activities. Indeed,
even at the best of times, most restoration sites in
Arctic - alpine environments are diffi cult to access.
Long-term management of a site under restoration is
therefore usually time consuming and costly. Any set
of methods and materials that minimizes long-term
management is therefore to be favoured. Research
trials in the European Alps have shown that resto-
ration with site-specifi c seeds signifi cantly reduces
the need for management in the long run (Krautzer
et al
. 2004b ; Graiss
et al
. 2005). Despite higher initial
costs for site-specifi c seed material, the overall costs
compared to the use of commercial seed mixtures
decline due to a reduction of aftercare costs for reseed-
ing, fertilization and frequent cutting (Krautzer
et al
.
2006 ). The establishment of site - specifi c plants is also
important for creating forage for a range of animals,
such as moose (McKendrick 1999). However, also
unwanted grazing cattle or wild game seem to be
attracted by restored areas and may cause signifi cant
site disturbance and soil erosion. Thus, it is recom-
mended that until the establishment of suffi cient veg-
etation cover density, at least over the fi rst two growing
seasons, grazing or trampling should be prevented
(Klug
et al
. 2002), if necessary or possible by the use
of temporary fencing. However, in many Arctic-alpine
areas, fencing is not practical and the selection of res-
toration materials and methods should respect this
limitation.
15.5.1
Evaluation of success
Ecological restoration is still in its early stages in the
greater part of the alpine ecosystems and the cir-
cumpolar North. Several of the approved material
and methods from lower latitudes and altitudes have
failed when applied in the more diffi cult environments
we have discussed in this chapter. At various sites
in Arctic-alpine environments, successful restoration
efforts may require many years or even decades
(Streever
et al
. 2003 ; Rydgren
et al
. 2011 ). A single
late-spring frost event, unexpected lack of snow cover
or prolonged summer drought may turn apparent
success into failure. Thus, one can only learn from mis-
takes and gauge success if methods and measures are
evaluated over a suffi ciently long period of time of at
least 20 years.
In general, it is neither ecologically or economically
feasible, nor even necessary, to fully restore a disturbed
site to its 'original', pre-disturbance state. In many cir-
cumstances, it will be an acceptable solution to stabi-
lize the site and thus avoid self-accelerating erosion
processes, and consequently create benefi cial condi-
tions for site-specifi c succession. The establishment of
an adequate vegetation cover (as mentioned in this
chapter, 70-80%) has generally proved to be suffi cient
to achieve protection from erosion. However, in many
high-alpine and Arctic areas, vegetation cover may not
naturally attain or exceed such a high rate of cover.
Consequently, vegetation cover targets may differ
accordingly; for the North Slope of Alaska, the cover
performance standards varied for example between
10% cover within 10 years and 60% cover in 3 years
(Streever
et al
. 2003). Thus, monitoring and evalua-
tion should match the individual vegetation type found
naturally at the restoration site.
Although establishing plant cover as quickly as pos-
sible is an important goal of most high-altitude restora-
tion projects, natural succession may subsequently
lead to vegetation similar to the surroundings (McKen-
drick
et al
. 1997). Once again, the long-term view is
critical to success.
15.5
PERSPECTIVES
Arctic-alpine environments are under increasing pres-
sure due to increasing human exploitation, not to
mention climate change. Additionally, the number of
methods that are successfully applicable decline with
increasing latitude and altitude (Krautzer
et al
. 2006 ).
Even with the most sophisticated materials and
methods, it is not possible to restore every vegetation
type within a human life span. It is therefore advised
to avoid disturbances in the high Arctic and alpine
zones wherever possible.
15.5.2
Towards the future
As mentioned, ecological restoration of Arctic-alpine
ecosystems is relatively new, and as a result there
