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ŠUMARSKI LIST 13/2005 str. 39     <-- 39 -->        PDF

P. Kantor: POSSIBILITIES OF MOUNTAIN FORESTS IN REDUCING HIGH WATERS AND FLOODS Šumarski list SUPLEMKNT (2005). 31-39
Switzerland. Similar comparative studies were gradually
carried out in other forestry-developed European
countries. Also Czechoslovakia participated in the research.
Water-management problems were studied in
the forested Kychova river watershed and in the unwooded
watershed of the Zdechovka river (Välek
1958, 1977).


After World War 2, based on the incentive of academicians
Maran and Lhota, water-management research
was concentrated on the region of the Moravian-Silesian
Beskids. In an uninterrupted series since 1953 (!),
basic problems are studied of "forest and water" in two


fully forested partial watersheds (the Mala Räztoka
watershed with autochthonous mainly beech stands
and the Cervik watershed with autochthonous dominant
Norway spruce). A number of immensely valuable
findings from the field experiment stations can be obtained
from papers of Zeleny (1971, 1974), Jara bač
andChlebck (1988, 1996).


Similarly oriented research programmes were established
in Germany, Switzerland, Russia and other
countries (Brechtel, Hoyningen-Huene 1978,
Benecke, van der Ploeg 1978, Mit scherlich
1971, Schmaltz 1969 etc.).


A JOINT PROJECT OF THE FACULTY OF FORESTRY AND WOOD TECHNOLOGY,
MLJAF IN BRNO AND OF THE VULHM RESEARCH STATION IN OPOČNO


The field of problems mentioned above concerning
"forest/water" relationships tries to study also one of
the research programmes of the Faculty of Forestry
and Wood Technology (FFWT) in Brno in cooperation
with the Research Institute of Forestry and Game Management
(RIFGM) - Research Station in Opočno.
The project entitled "Mountain forest ecosystems and
their management aimed at reducing floods" is at present
financially supported by the Grant Agency of the
Czech Republic (Grant No. 526/02/0851). Permanent
research plots in the cadaster of Deštne in the Orlickć
hory Mts. where the water regime is studied of both


main species of mountain forests, viz Norway spruce
and beech in a standard commercial forest are part of
the project. Spruce is usually presented to the general
public as a species unsuitable from water-management
aspects whereas beech is to be a species with favourable
water-management effects. The measurement of all
parameters of water balance of the forest stands is carried
out at Deštne in an uninterrupted series since
1977. At present, a 27-year series of results is available
including findings on torrent floods in July 1997, July
1998 and from the last flood in the turn of the first and
the second decade of August 2002.


WATER REGIME OF SPRUCE AND BEECH


Water regime of forest ecosystems is primarily dependent
on the supply of atmospheric precipitation, on
the consumption of water by the forest (so-called summary
evaporation, ie: interception + transpiration +
evaporation from soil) and changes in the water supply
in soil.


Thus, the basic equation of water balance can be expressed
as follows:


0 = S-ITE±AVp..„where


O = runoff


S = open area precipitation


ITE = total evaporation (I = interception;


T = transpiration; E = evaporation from soil)


AVp = changes in the soil water supply


Thus, it is possible to state that so many water flows
out the forest which is not consumed for its physical
evaporation (interception, evaporation from soil), physiological
requirements (transpiration) and replenishment
of soil water supplies.


Consumption of water by forest stands - total evaporation
is naturally related to the biomass of forest
ecosystems, particularly the amount of assimilatory organs.
It is always markedly higher in coniferous spruce


stands (in the stage of pole stands and large-diameter
stands on average 15 to 20 t needle dry matter per ha)
than in beech stands (on average 2 to 4 t foliage dry
matter per ha, namely only in the course of 5 to 7
months of the growing season).


First, let us look at the simplified course of the water
balance of both types of stands under comparison.


At each of the precipitation, part of it is intercepted
in tree crowns being later evaporated. Considering the
data mentioned above, crowns of spruce trees intercept
substantially more precipitation than crowns of beech
trees. This fact was positively corroborated in all experimental
studies (Delfs 1955, Mitscherlich 1971,
Schmaltz 1969, Välek 1958, Zeleny 1974 etc.).
In a spruce stand in the Orlicke hory Mts., interception
amounted to, in an annual average, 210 mm (16 % precipitation),
in a beech stand only 85 mm (7 % precipitation).
The remaining part of precipitation falls through
tree crowns to soil or occurs as stcmflow. It is of interest
that the stcmflow of a mature beech tree amounts to as
many as 1500 1 water at a precipitation of 50 mm. In
spruce, on the other hand, the stemflow is markedly lower
(at the precipitation only 30 to 50 1).