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ŠUMARSKI LIST 13/2005 str. 216     <-- 216 -->        PDF

I. Tikvič. D. Puntarić. Ž. Zečić. D. Ugarković. Z. Seletković: TUF. IMPACT OF MONTANIi FOREST ... Šumarski list SUPLEMENT (2005). 202-218
ecosystems are considered the most stable hydro-geological
ecosystems on Earth, which is corroborated by
preserved soils in hilly and mountainous areas that sustain
natural forests, and by clear and clean waters despite
considerable aerial pollution and other adverse
factors. Precipitation passing through the forest canopy
(throughfall), leaf litter and forest soil is naturally purified
and reaches underground layers in the form of
drinking water. Trees and shrubs intercept precipitation
and influence seepage, runoff and percolation (surface
and ground runoff), soil erosion, filtering and purification
(Tikvić and Seletković, 2003). This influence
depends on the existing ecological and biological
factors. The most important ecological factors are relief,
parent substrate, soil and climate whereas biological
factors include tree species, forest ecosystem structure
and anthropogenic impacts. Springs, streams, underground
and surface waters largely depend on the
condition of the surrounding forest ecosystems. Natural
or artificial changes in the condition of a forest
ecosystem may cause changes in hydrological processes
and chemism of watercourses (Bau ml er and
Zech, 1999). According to Gallcr (1975; Starče vi
ć, 2000), a forest may intercept and purify about
2,000 mJ of water per ha annually. Bearing in view the
size of the forested area in Croatia, very large quantities
of water are filtered by forest ecosystems annually.
However, all ecosystems suffer from continuous and
increasing pollution, which is reflected on water quality
in forest ecosystems. Harmful effects of polluted air
and rain on forest trees, soil, water and the human
health have been confirmed by a number of researchers


RESEARCH AREA


The paper explores water quality of watercourses in
the area of Papuk, the Plitvice Lakes National Park and
Velebit. Samples in the area of Papuk were taken from
the streams Brzaja and Dubočanka, and from the river
Orljava. In the Plitvice Lakes National Park samples
were provided by the streams Sušanj and Rječica, and
in the area of Velebit from three springs and from the
stream Tisovac. Table 1 gives the basic characteristics
of the study area.


Indicators of the general ecological water condition
(physical-chemical indicators, oxygen regime, nutrients,
microbiological and biological indicators), as well
as the use of water (metals, organic compounds and radioactivity)
were sampled and analyzed using the Croatian
norms in the Institute of Public Health of the City of
Zagreb. Physical-chemical indicators (pH and electrical


(Fi lip an et al, 1996). Prpić et al. (1994) reported
contamination of forests and agricultural areas with lead.
According to these authors, forest soils are several
times more polluted with lead than agricultural soils,
which may be attributed to the structure of a forest and
its role in water purification. However, B i n k e y et al.
(1999) detected nitrate and phosphate concentrations
in the watercourses of agricultural areas in the USA
that exceeded those in forest watercourses by nine times.
Despite increasing pollution in forests, waters in
hilly and mountainous watercourses in Croatia have retained
their purity and clarity, owing primarily to the
positive effect of forest ecosystems.


Hydrological processes in forests are also affected
by forest management practices. Proper management
with forests sustains the optimal condition of a forest
ecosystem and ensures commercial and other forest
functions. Management treatments have short-term negative
effects on hydrological forest function, but this
function is restored several years after thinning and selection
cutting (Rosen et al., 1996, Bau ml er and
Zech, 1999).


According to Anders son et al. (2000), the problem
of forest water quality is one of the vital priorities
in forest ecosystem research. Yet, impacts of a particular
tree species, soil type, different parent substrates
and man on water quality in forest ecosystem watercourses
still remain to be investigated. This paper analyzes
waters in montane Croatia and assesses the impact
of different forest ecosystems on the quality of
water in watercourses.


AND METHODS
conductivity) and dissolved oxygen were determined
with electrometric analysis, while chemical oxygen demand
(COD) was determined with potassium permanganate
titration. Nutrients (nitrates and nitrites) were determined
spectrophotometrically, and metals were determined
with the electrochemical method. Of organic
compounds, mineral oils were determined with infrared
spectroscopy, while phenols, lindane, polychlorinated
byphenils (PCB) and DDT were determined with spectroscopy
and gas chromatography. Microbiological indicators,
or aerobic bacteria count, were determined by
counting bacterial colonies growing on a nutritive medium
at 22 °C and 37 °C. According to Water Classification
Regulations (NN 77/98) and based on the allowed
border values of individual indicators, waters were classified
in different categories (I - V).


RESEARCH GOAL


The goal of research was to assess water quality of Another goal was to analyze differences in water qualiwatercourses
in different forest ecosystems and exploty
with regard to site and stand conditions and establish
re the effects of forest ecosystems on water quality. differences in water quality of watercourses in and out