Environmental Engineering Reference
In-Depth Information
increasing altitude, the vegetation period is around
1 week less per 100 m of altitude (Reisigl & Keller 1987).
The differentiation of the macroclimate from the
microclimate, dependent on altitude and broad loca-
tion is important. The most important difference from
sites in valley locations can be briefly characterized
by the following factors (see Fig. 15.1).
15.2.2 Opening for tourism
Contrary to agricultural use, summer and winter
tourism in the last few decades has led to extensive
opening of high locations. There are already more than
13,000 lifts, cable cars and other transport facilities
throughout the Alps, which are used mostly for
tourism. Taking the calculations made in the middle
of the 1990s as a starting point, the actual area of ski
runs and lift facilities is more than 110,000 ha, of which
10,000 ha are already covered by artificial snow
(CIPRA 1998). Even if an exact estimation is not pos-
sible, at least half of these areas are in high zones.
As before, thousands of hectares are levelled annu-
ally as part of the opening for tourism and infra-
structural improvements, and these areas now require
restoration. Necessary measures for the protection of
the facilities (above all, torrent and avalanche barriers)
also require large areas each year.
• Temperature decreases in the air and in the deeper
levels of the Earth by an average of 0.6°C per
100 m of altitude. Frost is a possibility at all times
of the year in high zones; at the beginning and
end of the vegetation period an interchanging frost
climate generally predominates (Arenson 2002).
The climatic vegetation period with average daily
temperatures of over 10°C is around 67 days at an
altitude of 2000 m, which is one-third of the vegeta-
tion period in valley areas (Krautzer et al. 2003).
• The deep-ground temperatures in the mountains
strongly reduce the activity of micro-organisms.
Reduction of dead organic mass and thus the pro-
vision of basic mineral nutrition is inhibited. The
subterranean habitat is thus limited - contrary to
the grasses in warmer, lower zones - to the most
strongly warmed, humus-rich, generally acidic and
intensively rooted upper layers of the ground.
• Precipitation increases with altitude; in addition, on
the fringes of the Alps, where clouds from adverse
weather fronts - coming mainly from the Atlantic but
15.3 Specific alpine characteristics
15.3.1 Alpine climate
Plants at high altitudes are often subject to frequent
and often rough change of climatic factors. The trans-
ition of the seasons takes place very quickly. With
2400
beginning
of vegetation
period
soil temperature
°
C
growth days
(daily means
>5
15 cm below
surface
2200
°
C)
end of
vegetation
period
warm days
(almost 1 hourly
value >15
2000
°
C)
date of
flowering of
Poa alpina
1800
frost days
(almost 1 hourly
value <0
air temperature
°
C
°
C)
200 cm above
surface
1600
date of
flowering of
Festuca
nigrescens
1400
31Mar
1June
2 Aug
3 Oct
4
8
12
16
0
20
40
60
80
92
Date
Temperature ( ° C)
Vegetation period (days)
Fig. 15.1 Average changes of important phenological and climatic parameters according to altitude. After Krautzer
et al. (2003).
 
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