DIGITALNA ARHIVA ŠUMARSKOG LISTA
prilagođeno pretraživanje po punom tekstu



ŠUMARSKI LIST 13/2005 str. 219     <-- 219 -->        PDF

I. Tikvić, D. Puntarić, Ž. Zečić. D. Ugarković. Z. Seletković: THE IMPACT OF MONTANE FOREST Šumarski list - SUPLEMENT (2005), 202-21S
lebit (localities 1, 2 and 3). In terms of physical-chemical
indicators and oxygen regime, they belong to the
first-category water. In terms of nutritive and organic
matter, as well as microbiological indicators, the
springs in Velebit belong to the first-category water,
with the exception of the spring in the locality Velebit 2
(forest of common spruce), which belongs to the second-
category water with regard to nitrate concentrations.
In terms of fluoride, aluminum and iron concen-


Water quality of watercourses


Water acidity is predominantly due to carbon acid
and organic and mineral acids. The pH of natural waters
ranges approximately between 6 and 8. The range
of pH values in the studied watercourses and springs
was from 6.4 to 8.1. Electrical conductivity was proportional
to the quantity of dissolved matter in water.
Chemically clean water has low electrical conductivity,
but it increases with an increase in dissolved mineral
content. The highest average values of electrical
conductivity were found in the watercourses in the area
of Plitvice Lakes. In general, higher values of water
electrical conductivity were recorded in forest ecosystems
of protected areas (national park) than in water
from commercial forests. No differences were found
between the watercourses in and out of forests.


Oxygen saturation is the consequence of the absence
of microorganisms in water. Minimum oxygen saturation
in the studied localities was 86 %, and minimum
quantity of dissolved oxygen was 7.19 mg02/l. When
these results are compared with the results of water
analyses in the area of Croatia (Hrvatske Vode, 2002),
water quality in forest ecosystem watercourses is significantly
better than in the watercourses in urban areas.


Of nutrients, only nitrates were found in considerable
quantities. Nitrates are essential for the growth of
algae and microorganisms. When nitrate values are
low, the growth of these organisms is reduced, and the
water is clear and clean. The absence of ammonia, nitrites
and phosphorus indicates the absence of biological
activity, growth of algae and phytoplankton, and
eutrophication, which has a positive effect on the clarity
of water in streams. The absence of nutrients in the
studied watercourses is due to the immediate vicinity
of springs, shade provided by tree crowns and lack of
human impacts. Nitrate concentrations in the locality
Velebit 4 (the stream Tisovac, agricultural and partially
forested area) were two and a half times higher compared
to the values in the localities Velebit 1 and 3 (the
source of this stream in the forest of beech and fir). So


trations (NN 78/98), the springs have water in the first
category, with the exception of the spring Velebit 2,
where water is in the second category owing to iron
concentrations. With regard to the majority of water
quality parameters (with the exception of cyanide),
spring water in montane forest ecosystems belonged to
the first category, which confirms the positive effect of
forest ecosystems on water quality.


in montane forest ecosystems


mewhat higher nitrate values were recorded in the watercourses
out of forests (the river Orljava and the stream
Tisovac). According to B ink 1 ey et al.{\999), several
times higher nitrate concentrations were recorded
in the watercourses in agricultural areas in relation to
those in forest areas. However, forest management
may have an effect on water quality in montane watercourses.
One part of the forest area was clearcut and
the other part was left unaffected (control). There were
increased concentrations of potassium (K+), ammonia
ions (NH4T), nitrogen oxide (N03~), organic nitrogen
and total nitrogen in forest watercourses where management
treatments were applied, whereas changes in
the concentration of calcium (Ca~+), magnesia (Mg"+),
sodium (Na+), sulphate (S04~~) and chlorine (CI) were
less distinct. The highest negative impact of clearcutting
referred to leaching, mostly of nitrates and phosphates,
into ground and surface waters.


Despite the increasing use of pesticides in agriculture,
no pesticides were found in the studied watercourses.
The reason is extensive agricultural production
in montane Croatia. Increased bacteria concentrations
in the river Orljava indicate polluted waters outside
forest ecosystems and in the vicinity of settlements
and roads. Higher oil content was also recorded in the
samples Papuk 2 and 4, as well as Velebit 4, which are
all outside the forest.


Metals were found in very low concentrations, with
the exception of increased iron concentrations. The
amount of iron in the river Orljava exceeded the allowed
value by 160 times, which is attributed to the impact
of the surrounding agricultural and urban areas.
Aluminum was found in the largest number of samples,
and the highest concentrations were recorded in
the samples Papuk 2 and Velebit 4. Both localities are
outside the forest and near human settlements and are
affected by traffic and the adjacent agricultural areas.
As for manganese, no values exceeding the allowed
values for the first-category water were detected.


Water quality monitoring


To establish successful monitoring of the effects of stations, sampling dynamics, measuring indicators, de-
montane forest ecosystems on water quality, special at- velopment of water quality databases, etc. The compatention
should be paid to the selection of measuring ny Hrvatske Šume manages forests covering over one