Environmental Engineering Reference
In-Depth Information
The infl uence of microclimate, however, can surpass
that of the macroclimate and altitude (Ellenberg &
Leuschner 2010 ).
According to overall prevailing climatic conditions
(Veit 2002), alpine vegetation may be divided into
commonly corresponding altitudinal specifi c zones
(see Table 15.1.). Altitudinal changes of the above-
mentioned factors lead to a vertical sequence in various
climatic areas (Ozenda 1988), or life zones (Holdridge
1947), and a corresponding turn-over of biota. The
altitudinal zones are separated by borders that are
fairly easy to recognize: the subalpine zone is delimited
by the upper tree line, whereas the alpine zone is tree-
less, and the nival zone begins above the climatic snow
line. The subnival zone still may contain scattered veg-
etated areas.
and ' regional ' . Here we will use the term ' site - specifi c '
according to the Rule Book for Ecological Restoration of
the Austrian Grassland Society (Österreichische Arbeits-
gemeinschaft f ü r Gr ü nland ( Ö AG) 2000 ): (1) a plant
species is considered site-specifi c when it occurs natu-
rally under given site conditions; (2) a plant commu-
nity is considered site-specifi c (a) when it is generally
and permanently self-supporting or self-stabilizing fol-
lowing extensive use (or non-use), and (b) when the
production of agricultural or forestry products is not
its main function; and (3) vegetation established by
humans is called site - specifi c if the ecological ampli-
tudes of species applied match the environmental site
factors where restoration takes place and all plant
materials used within the restoration process origi-
nate directly from the project area or its vicinity, or are
obtained from ecologically comparable sites within the
natural area, respecting knowledge of local ecological
types or subspecies.
In the following we fi rst indicate the major threats
and disturbances occurring in Arctic-alpine ecosys-
tems, within an historic perspective, in order to identify
priority areas for ecological restoration (section 15.2).
Then, in section 15.3, we summarize materials and
methods for the ecological restoration and revegetation
of Arctic and alpine ecosystems, with special regard to
the extreme site conditions generally found there. It is
important to note that we do not offer 'recipes' for suc-
cessful restoration, but rather a set of possible tools,
with which positive results have been obtained in
several tundra restoration projects to date. Finally, we
refl ect on future perspectives.
15.1.3
Exploitation and restoration
Many of the world's Arctic-alpine ecosystems are the
result of about 10 000 - 15 000 years of natural suc-
cession since the end of the last ice age. When predict-
ing the result of human impact on tundra ecosystems,
caution is required (Billings 1973). Increased needs for
resources lead to steadily increasing exploitation and
thus disturbance of tundras, many of which are
still relatively pristine. Increased exploitation for the
demands of winter tourism leads to increased degra-
dation up to the subnival zone of alpine areas, where
revegetation may take decades. However, human
interferences may severely damage these systems
within seconds. Future use and exploitation of Arctic-
alpine ecosystems cannot be totally avoided but any
necessary disturbance should be carried out in ways to
minimize undesirable environmental impacts and con-
sequences. Thus, ecological restoration often starts
prior to the fi rst disturbance.
In principal the main goal of every restoration
effort in Arctic and alpine environments is the estab-
lishment of a suffi cient vegetation cover to prevent
erosion. Due to the vital importance of suffi cient plant
adaptation to growth limiting abiotic factors, we here
particularly emphasize the necessity to use site-specifi c
seed and plant material to obtain this goal. In this
regard, note that within the restoration ecology com-
munity - and the conservation biology community
as well - there is often a Babel-like confusion in res-
pect to the term 'site-specifi c', as well as the related
terms
15.2
THREATS AND DISTURBANCES
In Europe, over the last 150 years, agrarian utilization
in high altitude zones and other less productive areas
has clearly receded, which has in turn led to a corre-
sponding expansion of forested areas (Cernusca et al .
1996). As a result, the exploitation of alpine meadows
has intensifi ed in some areas or else, in other areas, is
completely abandoned. In the subalpine zone, during
the transition process from the intensively cultivated
alpine meadow areas back to the natural forest vege-
tation, a creeping destabilization of the ecological
systems of high alpine-meadow regions can arise. Sur-
face runoff from summertime precipitation increases,
and unless corrected immediately erosion gullies -
such as those that appear in cultivated alpine-meadows
' near - natural ' ,
' seminatural ' ,
' local ' ,
' native '
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