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ŠUMARSKI LIST 13/2005 str. 251     <-- 251 -->        PDF

ZAKLJUČCI
Šumarski list - SUPLHMRNT (2005), 249-250


Na temelju iznesenih referata i rasprava na ovome nja erozije tla vodom, zatim poplava i bujica te uloge
Međunarodnom skupu o utjecaju šume na spriječava-šume u pročišćavanju izvorskih voda, donose se ovi


ZAKLJUČCI


1.
Dugoročna, 50-godišnja istraživanja hidroloških
prilika u dva sijeva u Beskidima (Češka), ukazuju
kako su prirodni retencijski kapaciteti šume ograničeni
kad se pojave najintenzivnije oborine. Prilikom
obnove šume potrebno je što prije stvoriti
šumski pokrov i očuvati šumsko tlo s visokim kapacitetom
infiltracije.
Tijekom ovih istraživanja nije bilo statistički značajnih
razlika u površinskom otjecanju između
obnovljene (dovršni sijek) i obrasle površine
(Vicha).


2.
Prirodne šume u Hrvatskoj koje čine 95 % državnih
šuma (80 % površine svih šuma su državne)
pokazuju veliku učinkovitost u smislu sprječavanja
erozije tla, ublažavanja pojave visokih vodnih
valova i pročišćavanja izvorskih voda do kategorije
pitkosti. Uzgojne postupke njege i obnove,
kako u regularnim tako i u prebornim šumama,
potrebno je obavljati tako da se očuva pokrovnost
šumskoga tla i njegova mogućnost upijanja i
pročišćavanja vode.
Očuvanjem stabilnosti šume i povoljne strukture
sastojine osigurat će se potrebna sirovinsko-energetska
funkcija i potpuno djelovanje svih općekorisnih
funkcija (Matić).


3.
U trajnim pokusnim plohama u planinskim šumama
Orhicke hory a Češkoj istražuju se hidrološke
prilike od 1977. godine. Iz tih istraživanja
proizlazi kako smrekove i bukove šume učinkovito
ublažavaju nepovoljan utjecaj neprekidne oborine
do 100 mm. Kod oborine iznad 150 mm profil tla
se potpuno zasiti vodom što dovodi do nekontroliranoga
otjecanja (Kantor).
4.
Šikara bijeloga graba (Carpinus orientalis Mili.) u
submediteranskom području Hrvatske vrlo učinkovito
suzbijaju eroziju tla vodom. Površinska otjecanja
oborinskih voda u toj degradi ranoj šumi su
vrlo mala, a erozija je potpuno isključena. Istraživanja
su obavljena u dvije pokusne plohe u šikari
bjeloga graba od kojih je jedna posječena. Prosječni
godišnji koeficijent otjecanja u posječenoj
površini iznosio je 0,0192, a u neposječenoj
0,0156. Kako se vidi razlike su vrlo male. Nešto
veće razlike pokazao je maksimalni koeficijent
otjecanja.
Autori (Topic, Butorac) upozoravaju kako posječenu
površinu treba što prije sanirati jer bi moglo


doći do povećanja nepovoljnoga hidrološkog utjecaja
na tlo. Ovaj pokus pokazuje kako degradacijski
oblici autohtone šumske vegetacije učinkovito
suzbijaju eroziju tla vodom, dok njihovo tlo zasigurno
dobro pročišćava vodu koja ulazi a krško
podzemlje.


5.
Šume u Hrvatskoj nalazimo pretežito u prostoru
čije reljefne i klimatske značajke ukazuju na srednji
do visoki stupanj orodibilnosti tla. Na temelju
karte Republike Hrvatske izrađene prema programu
CORINE obavljena je procjena rizika od erozije.
Umjereni rizik utvrđenje na 26,5 %, a visoki rizik
na 44,8 % površine (Husnjak i dr.).
6.
Saniranje i smirenje nekadašnje bujice u Senjskoj
dragi smatra se jednim od najuspješnijih projekata
u Sredozemlju kojega je ostvarila šumarska struka.
Radovi su započeli u 19. stoljeću pošumljavanjem
22 kulture-branjevine crnoga bora na mozaično raspoređenoj
površini od 320 ha i tehničkim zahvatima,
izgradnjom 62 različita bujična objekta.
Danas je Senjska draga zelena, bujice i erozija više
nema, a grad Senj koristio je do nedavno za svoj
vodovod 25 izvora pitke vode koji su se sukcesivno
pojavljivali poslije pošumljavanja (Ivančević).


7.
Šumski ekosustavi su učinkoviti pročišćivači voda.
Zahvaljujući šumskom tlu, njegovaj posebnoj
strukturi, kemijskom sastavu i bogatstvu živoga
svijeta, šuma mehanički, biološki, a djelom i kemijski
pročisti oborinsku vodu koja u podzemne
tokove i izvorišta ulazi pitka. Posebna učinkovitost
dakazana je u nizinskim i poplavnim šumama koje
zadržavaju N i P od umjetnih gnojiva iz agrara.
Kakvoća podzemne vode bila je znatno bolja u
šumi nego li u poljodjelskim povšinarna na visočju
Drahany u Češkoj (Klimo i Kulhavy).
Lizimetrijska istraživanja u istim šumskim nizinskim
ekosustavima pokazala su razlike u pročišćavanju
voda a različitim područjima u Hrvatskoj
(Vrbek i dr.).
8.
Istraženo je opće stanje vodotoka u gorskim područjima
Hrvatske u Papuku, Velebitu i Nacionalnom
parku Ptitvička jezera. Analizirano je fizikalno-kemijsko
stanje voda; sadržaj hranjivih tvari, kovina,
organskih spojeva, mineralnih ulja i drugih pokazatelja
kakvoće vode. Skoro svi vodotoci imali su
vode visoke kakvoće. Nije. bilo razlike u-kakvoći
vode između Nacionalnoga parka i višenamjenskih


ŠUMARSKI LIST 13/2005 str. 252     <-- 252 -->        PDF

ZAKLJUČCI
Šumarski list - SUP1.EMENT (2005), 249-250


šuma u kojima se provode uzgojni postupci njege.
Voda manje kakvoće ustanovljena je u vodotocima
u blizini naselja i izvan šume.


Utvrđenoje kako nema raztika u kakvoći vode koja
potječe iz različitih šumskih ekosustava, što ukazuje
na opći povoljan utjecaj šume na pročišćavanje
vode, bilo onene koja ulazi u vodotok povšinskim
otjecanjem (pročišćavanje kroz akumulacijski horizont
tla) ili iz podzemnih tokova kao i izvorska
voda (Tikvić i dr.).


9.
Vrijednost općekorisnih funkcija šume u posljednje
vrijeme postale su predmetom sve češćih pokušaja
šumarskih znanstvenika koji se bave vrednovanjem
siravinsko-energetske funkcije odnosne
neposredne koristi od šume. Kako se zapravo radi
o neprocjenjivoj vrijednosi skrivenoga ekološkoga
i biološkoga kapitala, većina takvih pokušaja koji
se temelje na načelima profitne ekonomike predstavlja
značajno podcjenjenu vrijednost.
U izlagnju na ovome skupu iskazana je vrijednost
protuerozijske i vodozaštitne uloge šume prema
metodologiji danoj u podzakanskome aktu Zakona


o šumama Republike Hrvatske zbog sprječavanja
jeftine rasprodaje i prenamjene hrvatskoga šumskoga
bogatsva (Prpić, Jurjević, Jakovac). Iako je i
tako dobivena vrijednost tih dviju najznačajnijih
funkcija šume također podcjenjena (iznos pokazatelja
procjene nije se mijenjao 9 godina), ona je
usprkos tome dva puta veća od posljednjega objavljenog
vrednovanja.


10. Izlaganja na ovome skupu pretežito potvrđuju kako
šumski ekosustavi vrlo učinkovito utječu na kruženje
vode u krajoliku ublažavanjem visokih vodenih
valova, sprječavanjem erozije tla vodom i
pojave bujica, i kako su dobar pročistač oborinskih
i poplavnih voda, koje se procjeđuju u podzemne
tokove ispod šume.
Po učinkovitosti najbolja je prirodna šuma s više


namjenskom ulogom kaja osigurava sirovinsko


energetsku i općekorisne funkcije.


To je šuma prirodnoga sastava s drvećem koje nije
postiglo fiziološku prezrelost i u životu šume predstavlja
optimalno stanje proizvodnje i zaštite prirode
i okoliša.


Kako su protuerozijska i vodozaštitna uloga šume i
njihovo održavanje vrlo značajni, istraživanja u
tom području potrebno je nastaviti i šumarstvu osigurati
udjel u odlučivanju o prostornim planovima
kao i naknadu za korištenje pitke vode, budući da
njezina proizvodnja u šumi traži sofisticiran uzgojni
postupak sa šumskom sastajinom. Hrvatsko
šumarstvo potrebno je osloboditi vodnoga doprinosa
budući, daje šuma jedan od najkorisnijih vodoprivrednih
objekata.




ŠUMARSKI LIST 13/2005 str. 254     <-- 254 -->        PDF

CONCLUSIONS
Šumarski list - SUPLF.MENT (2005), 251-252


water quality between the National Park and multipurpose
forests subjected to silvicultural tending
treatments. Water of inferior quality was found in
watercourses in the vicinity of settlements and outside
forests.


No differences were found in the quality of water
arriving from various forest ecosystems. This is an
indication of a generally favourable impact of forest
on water purification, whether water enters a watercourse
as surface runoff (purification through the
accumulation soil horizon) or arrives from underground
flows as spring water (Tikvić et al.).


9.
Values of non-commercial forest functions have
more recently captured the interest of forestry
experts dealing with the evaluation of raw material-
energetic function, or direct use of forests. Since
they are in fact hidden ecological and biological
capital of invaluable worth, the majority of activities
based on the principles of profitable economy
represent significantly underestimated values.
The value of anti-erosive and water-protective role
of forests was presented at the symposium according
to the methodology set down in the by-act of the
Forest Act of the Republic of Croatia. The intention
was to prevent cheap sale and conversion of the
Croatian forest wealth (Prpić, Jurjević, Jakovac).
Although the value of these two most important forest
functions is also underestimated (the amount of
assessment indicators has not changed for 9 years), it
is still twice as high as that from the last evaluation.


10. The papers presented at this symposium have confirmed
that forest ecosystems efficiently influence
water cycling in the landscape by mitigating high
water waves, preventing water-induced soil erosion
and torrents, and purifying precipitation and
flood water, which is percolated in underground
flows below the forest.
The highest efficiency is manifested by a multi-purpose
natural forest, which ensures both the raw
material - energetic function and non-commercial
forest functions.


Natural forest is a forest with a natural structure
whose trees have not reached physiological over-
maturity. In the life of a forest, natural forest is in
the optimal stage of production and protection of
nature and the environment.


Since the anti-erosion and water-protective role of a
forest and its preservation is of prime importance,
research in this field should continue. Forestry
should be granted the power to make decisions
related to spatial plans. It should also receive compensation
for the use of drinking water, since its
production in a forest requires sophisticated silvicultural
treatments of forest stands. In view of the
fact that forest is one of the most useful water management
facilities, the Croatian forestry should be
exempt from paying water fees.




ŠUMARSKI LIST 13/2005 str. 253     <-- 253 -->        PDF

CONCLUSIONS Šumarski list SLiPLEMENT
(2005). 251-252
The following conclusion have been drawn on the forests in the prevention of water-induced soil erosion,
basis of the discussions and papers presented at the floods and torrents and spring water purification:
International Symposium dealing with the role of


CONCLUSIONS


1.
Research of fifty years on hydrological conditions
in two basins in the Beskidi Mountains (Czech
Republic) has shown that extreme precipitation
restricts natural retention capacities of forests. The
most urgent task in the process of forest regeneration
involves the establishment of the forest cover
and the preservation of forest soil with high infiltration
capacity.
Research did not reveal any statistically significant
differences in surface runoff between the regenerated
(final cut) and forested area (Vicha).


2.
Natural forests in Croatia, of which 95 % are state
forests (80 % of all forested areas), are very efficient
in preventing soil erosion, mitigating high
water waves and purifying and converting spring
water into drinking water. The application of silvicultural
tending and regeneration treatments in
both regular and selection forests should be aimed
at preserving the forest soil cover and the soil´s
capacity to absorb and purify water.
3.
Hydrological conditions in mountain forests of
Orlicke hory in the Czech Republic have been
investigated since 1977. According to research,
spruce and beech forests can efficiently mitigate
unfavourable impacts of continuous precipitation
of up to 100 mm. Precipitation above 150 mm
completely saturates the soil profile with water,
which leads to uncontrolled runoff (Kantor).
4.
The scrub of oriental hornbeam (Carpinus (mentalis
Mill.) in the sub-Mediterranean region in
Croatia efficiently curbs water-induced soil erosion.
Surface runoff of precipitation water in this
degraded forest is very low and erosion is completely
absent. Research was conducted in two
sample plots situated in the oriental hornbeam
scrub, of which one was cut down. The average
annual runoff coefficient in the cleared plot was
0.0192, whereas in the scrub-covered plot it was
0.0156. As seen from the above, the difference is
very small. Slightly bigger differences were manifested
by the maximal runoff coefficient.
The authors (Topic, Butorac) point out that the cut
area should be restored as quickly as possible in
order to prevent adverse hydrological impacts on
the soil. This experiment shows: a) that degraded
forms of autochthonous vegetation efficiently
restrict water-induced soil erosion, and b) that soil


purifies the water reaching the subterranean karst
area.


5.
Forests in Croatia are predominantly located in
areas whose relief and climatic characteristics indicate
medium to high degree of soil erodibility. To
assess the risk of erosion, a map of the Republic of
Croatia was used, which was constructed in the
CORINE programme. Moderate risk was found in
26.5 % and high risk in 44.8 % of the area (Husnjak
et ai).


6.
One of the most successful projects undertaken by
the forestry profession in the Mediterranean area
was the regulation of the former torrent in Senjska
Draga. The activities started in the 19™ century
and included afforestation of 22 cultures-enclosures
of black pine in a mosaic-like area of 320 ha,
and the construction of 62 different torrent facilities.
Today, Senjska Draga is a green area free of torrents
and erosion. Until very recently, the water supply
system of the town of Senj used drinking water
from 25 springs that have occurred successively
after afforestation (Ivančević).


7.
Forest ecosystems are efficient water purifiers.
Owing to the forest soil, to its special structure,
chemical composition and wealth of animate
world, the forest purifies precipitation water
mechanically, biologically and partially chemically.
Such water enters underground flows and
springs in the form of drinking water. Lowland and
floodplain forests have proven particularly effective
in retaining N and P from agricultural artificial
fertilizers. The quality of groundwater was much
better in a forest than in agricultural areas in the
Drahany Highlands in the Czech Republic (Klimo
and Kulhavy).
Lyzimetric research in identical lowland forest
ecosystems showed differences in water purification
in various areas of Croatia (Vrbek et al.).


8.
The general condition of watercourses was investigated
in montane areas of Papuk, Velebit and the
Plitvice Lakes National Park in Croatia. Investigation
included the physical-chemical condition of
water, as well as nutrient content, metals, organic
compounds, mineral oils and other indicators of
water quality. Almost all watercourses contained
water of high quality. There was no difference in