DIGITALNA ARHIVA ŠUMARSKOG LISTA
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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 |