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ŠUMARSKI LIST 3-4/1997 str. 60     <-- 60 -->        PDF

D. Böhm: AKTUALNI PROBLEM ZAŠTITE I OČUVANJA NACIONALNOG PARKA PLITVIČKA JEZERA
The 1970 decision on integration of the Park management with the Hotel company
opposed law and constitution. Now just another activity of the integrated
company, nature protection thus lost its authoritative function. The new company
acquired the name "Nacionalnipark", a unique example worldwide, that a hotel
company offered its guests, besides other facilities, its own national park. Freed
from all limitations, the company made efforts to increase the revenues. In the
years before the aggression and war against Croatia, the visitors rose to 900,000
in a year. This multitude mainly dwelt on 200 hectares of the attractive lake and
waterfall zone.


The drainage problems became more obvious. The initial primitive disposal of
waste waters endangered lake Kozjak and the group of lower lakes. In the seventies,
the building of partial pipeline began, though without cleaning system, immediately
endangering the survival of the lower lakes due to frequent interruptions of
pump work. However, the damaging effects remained unnoticed. The consequences
of this irresponsibility are today clearly visible in eutrophication and
swamping of the lake Kozjak and the lower lakes.


Begun in the eighties, the third complete drainage system has remained unfinished
and out of work until the present day. The steady fertilization of the lake water
leads to eutrophication of the natural oligotrophic lakes, endangering the basic
biodynamic growth of travertine barriers, waterfalls and other formations.


The second article deals with the basic regressive phenomena in the National
park aquatorium. The deforestation over large areas has caused land erosion.
Normally a natural process, land erosion has been accelerated by man, and large
areas have been filled up with eroded material.


Another undesired and dangerous regressive process is caused by large quantities
of beech and maple leaves brought by wind and surface water. In the thousands
of years of its creation, the lake system has not witnessed such enormous input
of organic waste from forests, because the lake and stream zone had been protected
by the thick belt of fir and spruce forests, a barrier against the leaves from
the higher beech habitats. Fir and spruce settled on the lowest and coldest locations
around the waters. The upper lakes are the brilliant illustration of the vegetation
turn due to temperature inversion. These had been the relations thousands
of years ago, before the first settlements in the 16th and 17 th centuries, when man
started to cut conifers for building purposes. Uncontrolled felling with countless
sawmills disturbed the natural state and structure of the forests, replacing
conifers by beech and maple on the reclaimed soil. The gradual and long eutrophication
of the Upper lakes began through the leaves decomposition that set loose
nitrogen, phosphorus, potassium and other nutrients.


The conclusion contains the suggestions for improvements of the disturbed environment
of the National park. Besides the measures brought in 1994 by the
Park´s management in exile, including the urgent transfer of the hotel facilities
and other residential objects to locations outside the park, wattle fencing should
be immediately put around the waterways and lakes to prevent leaves from entering
the water and the planting of fir and spruce seed. Besides these measures, the
lakes should be dredged in many critical places by powerful refill systems to remove
the debris and large layers of leaves. The protection against sewage water
and leaves would decrease the pressure of nutrients in the aquatorium, while the
dredging would deepen and fill up the locations down to the depth where swamp
vegetation would not be able to settle.


With other suggested measures, a new silviculturalplan should be made in accordance
with the ecological principles. The protection of forests, forestlands, waters
and grassland should be based on a risk-erosion study by one of the acknowledged
methods (e.g. Coen-Holland).


The Plitvice lakes should in future be used as a cultural, scientific and educational
object of the world heritage. Any forms of exploitation should be eliminated


- hotel industry, forest exploitation, and water-supply necessities.
Supported by government, home and foreign institutions in a long-term
process, this improvement operation will have a real chance to succeed.


Šumarski list br. 3-4, CXXI ( 1997). 161-170