WEITRA –
Long Term Impact of the European
Windstorm Kyrill on Soil and
Rejuvenation Parameters
KARL GARTNER, MICHAEL ENGLISCH
a
Introduction
In Austria, especially the Northern part of the country was affected. A large part of
the stand of our site near Weitra together with measurement equipment was also
broken by Kyrill (see figure 1). About one year later the measurement equipment
was reinstalled to have the possibility to quantify and qualify the effects of the windthrow to soils and rejuvenation.
Site
The site is situated at an altitude of 850 a.s.l near Weitra in the Waldviertel (Northern
Lower Austria). Mean annual temperature of the nearby climate station Weitra (580
m a.s.l.) is 6.7°C. The mean annual precipitation of this station is 670 mm.
b
Figure 1:
Damages to trees and technical equipment after the windstorm Kyrill
The bedrock is granite and the prevailing soil types range from Humic Cambisol to
Podzol. The current stand is a Norway spruce monoculture. The bedrock, which
is poor in nutrients, and further nutrient loss from litter raking led to instable monocultures and the disappearance of deciduous species.
Instrumentation
The experimental site was established in 2002. The main research questions centred
around the reintroduction of deciduous species, soil amelioration and nutrient
cycling. The site was instrumented with a climate station as well as on-line soil water
content and soil temperature measurements. Further data included detailed chemical
soil analyses, tracer experiment data, growth data and LAI measurements. After the
damage due to Kyrill in 2007 the measurement equipment was reinstalled in April
2008.
40
Windstorm Kyrill 18-01-2006
35
30
25
20
Figure 2:
Meteorological station of the site
15
Results
10
Jun/10
minimum
Dez/09
maximum
Dez/08
Jun/08
Dez/07
Jun/07
Dez/06
Jun/06
Dez/05
Jun/05
Dez/04
Jun/04
Dez/03
Jun/03
0
average
Jun/09
5
Dez/02
Volumetric water content [Vol%]
Currently, the soil water content and soil temperatures are measured with eight
sensors in two different depths (10 and 40 cm). Additionally, a station measures the
meteorological parameters (figure 2).
month
a
40
Windstorm Kyrill 18-01-2006
35
30
25
20
15
5
month
Dez/09
Jun/09
Dez/08
Jun/08
Dez/07
Jun/07
Dez/06
Jun/06
Dez/05
Jun/05
Dez/04
Jun/04
Dez/03
Jun/03
0
10 cm
In figure 3a the time series of the averaged
water content of all sensors together with
their maxima and minima are illustrated.
The most visible change in the data after
the windthrow by Kyrill is that the soil
water content is a little bit higher and
remains much more stable than before.
The range of the values did not increase.
This behaviour is the same for both investigated depths (figure 3b). The reason for
this is probably the lower water demand
of the ground vegetation and the
remaining small trees.
40 cm
Conclusion
Jun/10
10
Dez/02
volumetric water content [Vol%]
Bundesforschungs- und Ausbildungszentrum für Wald, Naturgefahren und Landschaft
The storm Kyrill was an unusually violent windstorm. Its windspeeds reached up
to 225 km/h (measured at Aletsch glacier, Switzerland) and the storm caused
widespread damage across Europe.
As large trees ceased to exist after
the windstorm Kyrill, the water
consumption of the remaining vegetation is lower than before Kyrill, so the
soil remains wetter throughout the year.
b
Figure 3:
Monthly averaged soil water content at the site together with maximum and minimum values (a) and in the different depths 10 and 40 cm (b) before
and after the windstorm Kyrill.
Contact
Karl Gartner, Michael Englisch
Federal Research and Training Centre for Forests, Natural Hazards and
Landscape (BFW), Department of Forest Ecology and Soil; SeckendorffGudentweg 8, A-1131 Vienna, Austria
[email protected]
[email protected]
bfw.gv.at