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ŠUMARSKI LIST 3-5/1991 str. 119     <-- 119 -->        PDF

coke plant, etc.) the vegetation of East Istria, Rijeka-Bakar area and the forests
in Gorski kotar are exposed to the severe damaging effect of S02.

In the vicinity of the above sources, as well as in the areas of big towns (Zagreb,
Karlovac, etc.), S02 has a direct effect on vegetation. Besides other consequences,
it is reflected also in high S-concentrations in assimilation organs. At
some distances from the SOo source sulphur is first deposited in dry depositions
of sulphur, followed by damp depositions, while the remaining smaller part is
transported to more distant places. In this, rather large area the indirect effect
of S02 on eco-systems becomes fully visible, which is especially manifested in a
»new kind« of forest deterioration. The conversion of S02 into other compounds
and their deposition results in a decrease of sulphur concentrations in leaves, or
needles of conferous trees in the area of the Kvarner Bay and Gorski kotar and
further, but it increases the frequency of acid rains. In Gorski kotar, where the
largest zone of the Fir-tree, our most severly damaged tree, is located, the total
S-deposits amount to approximately 4 t S/km2 annually.

By using the micro-habitat method the presence of emissional acidification
of forest soils was determined in almost the whole of Croatia. This process has
been particularly pronounced in West Croatia. The same is applicable to the
loading of our forest eco-systems by lead and other heavy metals. In West Croatia
the stands in the south-western aspects and on higher altitudes are most
exposed, and in East Croatia the stands on the southern aspects and rifges of
Slavonian mountain range, are most exposed. High concentrations of lead and
zink have been determined in the surroundings of the thermo-electric power plant
Plomin and beside roads. However, the largest amounts of heavy metals are introduced
into the soil of lowland forests by polluted flood water. Extreme values
were determined on the inundation terrains of the Varaždin region, and also in
the lower stream of the Drava river, followed by the Danube, Sava, Česma, and

A few studies indicate the damaging effect of ozone and nitric oxides. The
progressively increasing load of forest eco-systems by nitrogen is demonstrated
by nutrition experiments carried out in the planations of Spruce and other species.
These experiments show that nitrogen insufficiency is less and less, and the
effects of the application of nitric fertiliziers are weaker.

The negative effect of fluorides has been determined in the vicinity of a Light
Metal Plant near Šibenik, while the Factory of Fertilizers in Kutina with its
depot for »forsforgipsa« phosphorus calcium phosphate presents a special problem
in this respect. In recent investigations disorders in tree nutrition were determined
in some cases as a consequence of direct and indirect effects of pollutants. While
in te vicinity of relevant sources of pollution an increased concentration of sulphur,
iron and nitrogen is most frequently found in the assimilation organs of trees,
on the other hand in the areas with increased frequency of acid rain, there was
a decrease in the concentration of magnesium and some other nutrients in the
Fir and Spruce needls. This is particularly important for the pure Fir stands
which belong to the acidophilous association of Blechno-Abietetum Horv., with
extremely acid, well drained soils.

Ke y words : emissions, forest eco-systems, damage, Croatia.