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| ŠUMARSKI LIST 13/2005 str. 146 <-- 146 --> PDF |
IZLAGANJE NA ZNANSTVENOM SKUPU - PRESENTATION AT THE INTERNATIONAL SYMPOSIUM Šumarski list SUPLLMENT (2005) 144-1 UDK 630* 907 + 231 + 524 STRUKTURA I PRIRODNA OBNOVA PREDPLANINSKE ŠUME OBIČNE SMREKE SA ZAŠTITNOM FUNKCIJOM U NISKIM TATRAMA (SLOVAČKA) THE STRUCTURE AND NATURAL REGENERATION OF A SUBALPINE SPRUCE FOREST WITH PROTECTIVE FUNCTION IN NIZKE TATRY MOUNTAINS (SLOVAKIA) Stanislav KUCBEL* SAŽETAK: U radu se razmatra problem sastojinske strukture, prirodne obnove i uzgojnih zahvata u zaštitnim šumama u planinskom dijelu Slovačke. Primarna zaštitna funkcija (posebice zaštita od erozija, od lavina i zaštita voda) u planinskoj šumi zahtijeva trajnu prisutnost stabilne, prirodno obnovljene šume s diferenciranom strukturom. Kako bismo mogli opisati i kvantiflcirati tu strukturu, osnovane su tri trajne pokusne plohe na lokalitetu Prašiva u Niskim Tatrama. U radu se analiziraju posebna strukturna obilježja istraživane sastojine te na temelju dobivenih rezultata kvantijiciraju osnovna strukturna obilježja za šumu na velikim visinama. Rezultati pokazuju da visinska šuma u idealnom stanju i pod sličnim ekološkim uvjetima treba imati sljedeća svojstva: gustoću stabla 1000-15000 kom/ha, padajuću distribuciju promjera, prisutnost triju jasno ocrtanih etaža -gornja 75 %, srednja 15 % i podstojna 10%, temeljnicu 34-40 m /ha, drvnu zalihu 300-400 m3/ha u skladu s proizvodnom sposobnosti staništa. Osim svojstava strukture modela, u radu se analizira status i količina prirodne obnove, koja je neophodna za stalnu izmjenu generacija u šumi na velikoj visini. U prirodnoj obnovi prisutne su dvije vrste stabala (obična smreka i jarebika). Zbog svojih ekoloških karakteristika, jarebika je prevladavajuća vrsta stabla u prirodnoj obnovi na svim istraženim plohama. Broj prirodno obnovljene obične smreke u visinskom razredu iznad 20 cm ključanje za izmjenu generacija i može se već smatrati relativno sigurnim početkom nove generacije. Rezultati pokazuju da bi broj prirodno obnovljenih stabala u visinskim razredima iznad 20 cm trebao biti barem 600 kom/ha, pod uvjetom da postoji dovoljna rezerva u visinskom razredu ispod 20 cm. Ključne riječi: predplaninska šuma, sastojinska struktura, obična smreka, prirodna obnova UVOD - Introduction Šumske sastojine s prioritetnim funkcijama zaštite kao šume posebne namjene. Visoka nadmorska visina tla (tj. antierozivnim i antilavinskim) zauzimaju oko šuma ima općenito muitifunkcijski učinak, a spomenu 336.641 ha (16,7 %) od cjelokupne šumske površine te su funkcije obično najvažnije. U podkategonju zašRepublike Slovačke. Sve ove sastojine pripadaju netitnih šuma (tj. šume velike nadmorske visine) ubrajakomercijalnim šumama, bilo u kategoriji zaštite, bilo mo 49.500 ha. Problem šumskouzgojnih zahvata u planinskim i * Ing. Stanislav Kucbel, Katedra za uzgajanje šuma, predplaninskim sastojinama držao se jednim od margiŠumarski fakultet, Tehničko sveučilište, Zvolen, nalnih problema u slovačkom šumarstvu. Opadajuća Masarykova 24, 96053 Zvolen, Slovak Republic, vitalnost i relativno intenzivno sušenje pojedinih sta e-mail: kucbel@vsld.tuzvo.sk |
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S. Kucbel: STRUKTURA I PRIRODNA OBNOVA PREDPEANINSKE ŠUME OBIČNE SMREKE Šumarski list SUPLEMENT (2005), 144-153 bala i čitavih sastojina na nekim lokalitetima tijekom posljednjih 15-20 godina usmjerili su pozornost na probleme planinskih šuma. Utjecaj imisija i ekstremne vremenske situacije uzrokovane globalnim klimatskim promjenama bili su vjerojatno ključni čimbenici što su aktivirali proces sušenja. Rezultati istraživanja (Gubka 1998, 1999) te iskustvo praktičnih šumara pokazali su, da osim spomenutih čimbenika, nestabilna sastojinska struktura ostaje ključni problem šuma velikih nadmorskih visina. To je posljedica nepostojećih uzgojnih regulacija, a to uzrokuje malu otpornost na ometanje i visoku vjerojatnost katastrofalnih oštećenja. Rješenje problema šumarskih zahvata u planinskim šumama traži poznavanje i razmatranje njihovih specifičnosti prema šumama na niskim položajima. Želimo li razumjeti dinamiku planinskih šuma, trebamo primijeniti znanje dobiveno iz dugoročnog istraživanja primarnih šuma u sedmoj šumsko-vegetacijskoj fazi. Proučavanjem životnog ciklusa obične smreke primarnih šuma ustanovljene su neke prirodne tendencije s negativnim utjecajem na stabilnost tih šuma (Korpel 1989, Schmidt-Vogt 1991, Leibundgut 1993). To su uglavnom tendencija razvijanja manje stabilnih jednoslojnih struktura s horizontalnim sklopom tijekom dugog optimalnog stadija, stagnacija procesa obnove, te sklonost katastrofalnom uništenju, što uzrokuje gubitak tražene strukture tijekom dugog razdoblja. Na temelju tih otkrića većina autora (Leibundgut 1978,Korpel 1980, Mayer-Ott 1991, Schmidt - Vogt 1993) mišljenja su da obična prirodna smrekina šuma nema stalnu sposobnost ispunjavanja svih zaštitnih funkcije, posebice na pogodnim položajima. Planinska šuma s optimalnom sastojinskom strukturom, što je rezultat namjernih šumarskih zahvata, stabilnija je od primarne šume obične smreke, te se tako ciljane uzgojne regulacije čine potrebnim kao trajna zaštita. Kao trajna šumska zaštita u planinskim visinama karakteristični bi trebali biti prisutnost individualnih stabala, stabilnost pojedinih stabala i čitave sastojine te postepena prirodna obnova. To omogućuje stabilnu prirodnu obnovu te višedobnost i višeslojnost šume. Vremenski neograničena trajnost strukture i trajna obnova opći su atributi preborne šume. Stoga mnogi autori (Kuoch 1972, Trepp 1981, Bischoff 1987, Ott 1988, Frehner 1989, Ott et al 1997) drže takozvanu planinsku prebornu šumu (Gebirgsplenterwald) idealnim uzorkom šume obične smreke na položajima velikih nadmorskih visina. Prirodno dugoročni proces prirodne obnove je jedna od specifičnosti planinskih šuma. Trajna prirodna obnova bez ograničenja zaštitnih utjecaja, što osigurava promjenu šumskih generacija, ključni je problem u planinskim šumama. Ott (1988) drži obnovu sastojine za "slabu kariku u lancu šumske dinamike" u rastu šume blizu granice stabla. Trepp (1961) smatra da šumskouzgojnc regulacije ispunjavaju svoju svrhu u planinskim šumama samo u slučaju da su sposobne osigurati njihovu prirodnu obnovu. METODE Istraživanje je obavljano blizu Korytnice u sjevernoj slovačkoj. Na lokalitetu Prašiva u zapadnoj dijelu Niskih Tatra, tri trajne pokusne plohe postavljene su u sastojini sa zaštitnom funkcijom. Plohe su postavljene u dijelovima gdje je sastojinska sruktura najdiferenciranija, tako daje idealna struktura planinske šume aproksimatizirana. Svaka ploha bila je 30 x 30 m, te je uključivala transekciju širine 10 m. Na pokusnim plohama dobivene su određene sastojinske karakteristike i stanje prirodne obnove na transekciji, pa je na temelju njih prosječno kvantificiran model sastojinske strukture. Pokusne plohe postavljene su na zapadnoj padini na prosječnoj visini 1.300 m iznad mora. Nagib je između 50 % i 70 %, a pokriven je s čistom sastojinom obične smreke (Picea abies /U Karst.), s rijetkom prisutnošću običnog gorskog jasena (Sorbus aucuparia L.) i planinskog bora (Pinus mugo Turra). Prema šumskoj tipologiji, tri šumske zajednice mogu se ovdje naći: Sorbeto-Piceetum (60 %), Fagetum abietino-piceosum (30 %), te Mughetum acidofilum (10 %). Za ovaj odjel šumskogospodarstveni plan zaključuje prosječnu dob od 180 godina i prosječni sklop krošanja od 0.7. - Methods Na trajnim plohama izmjeren je niz od pojedinih sljedećih parametara: vrsta drveća, DBH (preko 1 cm), drvni razred (prema gornjoj visini - gornji, srednji i donji sloj), defolijacija (vizualna procjena opadanja asimilacijskih organa je 10 %). Uz te podatke izmjerene su sljedeće varijable na transekciji: visina, visina na mjestu gdje počinje razvoj krošnje, radijus krošnje (u 4 smjera) te položaj debla na transekciji (koordinate x i y). Na svakoj je plohi zabilježen otpadni drvni materijal te njegova duljina, promjer u sredini duljine, i stupanj raspadanja (1 - nedavno srušeno, zdravo, 2 - djelomice trulo, vrstu drva moguće odrediti, 3 - uznapredovalo raspadanje, vrsta se ne može odrediti) za svaki izmjereni trupac. Analize prirodne obnove obavljene su na transekciji. Zabilježena su sva individualna stabla prema vrsti i visinskom razredu (do 20 cm, 21-50 cm, 51-80 cm, 81-130 cm, 131 cm do DBH lem). |
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S. Kucbel: STRUKTURA I PRIRODNA OBNOVA PREDPLANINSKR ŠUME OBIČNI: SMREKE Šumarski list - SUPLEMENT (2005), 144-153 REZULTATI - Results Sastojinska struktura Stand structure Vrijednosti temeljnih dendrometrijskih osobina na određenim pokusnim plohama sumirane su u Tablici 1. Na temelju dobivenih debljinskih frekvencija te s obzirom na ostale sastojinske karakteristike, moguće je držati broj debala od 1000-1500 ha"´ dovoljnim (svi živi primjerci s preko 7cm DBH). Broj stabla s manje od 500 ha"1 mogu biti jedan od pokazatelja nestabilne homogene strukture ili prisutnosti većih površina bez kontinuirane šumske sastojine. 300 S c 1 Krivulje debljinske raspodjele jedna su od temeljnih karakteristika sastojinske strukture (SI. 1). Na svakoj promatranoj pokusnoj plohi krivulje distribucije su manje ili više silaznog oblika, stoje tipično za diferenciranu strukturu (vrlo slično strukturi preborne šume). Neke vidljive razlike između određenih ploha proizlaze iz prikazanih brojki. Iako je distribucija na Plohi 1 silaznog oblika, na njoj se nalazi prilično velik broj stabala višeg debljinskog razreda (stabla gornjeg sloja). Regulacija strukture trebala bi biti usmjerena na smanjenje 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 Debljinski razred (cm) - diameter class (cm) Slika 1. Distribucijske krivulje na pojedinim pokusnim plohama Figure 1 Distribution curves on particular research plots Tablica 1. Osnovne karakteristike sastojine na pojedinim plohama Table l Basic stand characteristics on particular PRPs parametar -parameter vitalna -vital broj -number sušenje -dead standing ukupno -total broj >7cm -number >7 cm temeljnica -basal area drvna zaliha -growing stock sklop krošanja -crown canopy prosječna defolijacija -average defoliation gornj i -upper srednji -middle slojevi -layers donji -lower ukupno -total PRPI PRP2 PRP3 ha-1 789 1444 1822 % 88,75 94,20 79,23 ha"1 100 89 478 % 11,25 5,80 20,77 ha1 889 1533 2300 % 100,00 100,00 100,00 ha"1 411 978 1044 nr.ha"1 40,78 41,81 34,17 m .ha"1 444,22 387,17 268,43 % 55 76 76 % 10,35 7,08 9,57 ha"1 133 167 211 % 16.90 11,54 11,59 ha"1 56 178 267 % 7,04 12.31 14,63 ha"1 600 1100 1344 % 76,06 76,15 73,78 ha1 789 1444 1822 % 100,00 100,00 100,00 |
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S. Kuchel: STRUKTURA I PRIRODNA OBNOVA PREDPLANINSKE ŠUME OBIČNU SMREKE ... Šumarski list - SUPLEMENT (2005). 144-153 pojedinih primjeraka gornjeg sloja u korist drveća iz temelju tih osobina sastojine mogu vrednovati kao vitalsrednjeg i nižeg sloja. Debljinska distribucija na Plohi 2 ne i zdrave. najviše aproksimira traženi model. Pojedina stabla iz Analiza frekvencije drveća prema slojevima pokazudonjeg sloja (debljinski razredi 2-4) su srednje defici-je da otprilike 3/4 svih pojedinih primjeraka koncentrijentni. Ploha 3 pokrivena je s najmlađim sastojinama. rano u donjem sloju, dok je ostalih 25 % podijeljeno u Jedan dio te plohe je u fazi rasta guštika i šibljaka. Ovaj različitim omjerima u srednji i gornji sloj. Nakon vredhomogeni dio predstavlja nestabilni element koji traži novanja sastojinske strukture na pojedinim plohama, šumskouzgojne mjere. Zahvati bi trebali smanjiti broj najprikladniji odnos slojeva čini se model 75 % donjeg stabala i diferencirati sastojinu. sloja, 15 % srednjeg sloja i 10 % gornjeg sloja. Taj se Prema dobivenim podacima bazalno područje trebamodel odnosi na omjer prema broju stabala, u slučaju lo bi se kretati između 35 nr.ha"1 i 40 nV.ha"´ u danoj omjera površine, svaki sloj bi trebao imati otprilike istu površinu (tj. 1/3 sastojinske površine). strukturi. Drvna zaliha ima sasvim drukčije vrijednosti na određenim pokusnim plohama (od 268,43 m´.ha"´ do Grub drvni otpad (GDO) važna je komponenta pla444,22 m´.ha"1). S obzirom na sastojinsku strukturu kao ninske šume, posebice sa stajališta njenih procesa obi na utjecaj izvanrednih primjeraka (npr. jedno stablo s nove. Tablica 2 sumira rezultate volumena sastojine DBH od 88 cm na Plohi 1 povećava ukupnu drvnu zalipodijeljeno prema vitalnim, dubećim ili ležećim mrhu za više od 80 m3.ha_1) moguće je predložiti optimalnu tvim stablima. Volumen ležećeg mrtvog drva kreće se drvnu zalihu na razini od 300 m\ha"´ do 400 m3.ha"1, u od 43,56 m3.ha ´ na Plohi 2 do 71,67 m3.ha_l na Plohi 1 skladu s proizvodnim uvjetima položaja. Stupanj opadau apsolutnim vrijednostima. nja lišća kreće se ispod 10 % na svim plohama, pa se na Tablica 2. Drvna zaliha i volumen grubog drvnog otpada prema pojedinim plohama Table 2 Growing stock and volume of coarse woody debris according to PRP PRP vitalna vital sušenje dead pozicija standing lying ukupno total broj number ha"1 789 100 156 1045 PRPI volumen volume m .ha"1 % 444,22 80,57 35,44 6,43 71,68 13,00 551,34 100,00 broj number ha1 1444 89 78 1611 PRP2 volumen volume m´.ha"´ % 387,17 84,84 25,6 5,61 43,6 9,55 456,37 100,00 broj number ha1 1822 478 289 2589 PRP 3 volumen volume m .ha"´ % 268,43 66,21 88,28 21,77 48,74 12,02 405,45 100,00 Osim ukupne količine GDO, omjer određenih stadivoljnu količinu GDO, ali se može reći da što su gori ja raspadanja važan je ponajprije volumen GDO u druuvjeti za prirodnu obnovu u sastojini, to više mora biti gom i trećem stadiju raspadanja, zato što samo trupci u količine GDO. Raspodjela čitave biomase na promatom stanju osiguravaju odgovarajuće uvjete za razvoj tranim plohama jc sljedeća: otprilike 80-85 % otpada prirodne obnove. S tog su gledišta najbolji uvjeti na na vitalna stabla, ostatak se dijeli u omjeru 1:2 između Plohi 1, gdje je gotovo sav GDO barem dejlomično is-dubećeg i ležećeg mrtvog drva. Drukčija je situacija trunuo te stvara pogodnu sjemenu podlogu za smrekine samo na Plohi 3, gdje je primijećen vrlo velik broj dusadnice. Iz danih podataka teško je kvantificirati do-bećeg mrtvog drva. PROCESI OBNOVE - Regeneration processes Na svim pokusnim plohama nalaze se tri vrste važna i stalna komponenta sastava vrsta u planinskoj drveća u prirodnoj obnovi - obična smreka (Picea abies šumi, smreka ostaje determinantna vrsta ovih sastojina i l\.l karst.) i gorski jasen (Sorbus aucuparia L.). Iako stoga broj i struktura obnove smreke ima ključno značetablice 3 i 4 također prikazuju ukupni broj posebnih nje za obnovu sastojine. Drugi razlog, koji ne dozvoljaprimjeraka (smreka + jasen), ove vrijednosti kao i komva izravnu usporedbu, je ritam rasta i ekološki zahtjevi paracija brojeva prema vrstama drveća imaju samo ori-ovih triju vrsta, kao i različita dinamika procesa obnove. jentacijsko značenje. Prvi razlog je taj, da iako je jasen |
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S. Kucbel: STRUKTURA I PRIRODNA OBNOVA PRKDPLANINSKE SUME OBIČNE SMREKE Šumarski list - SUPLEMENT (2005), 144-153 Tablica 3. Broj prirodnih obnova prema visinskim kategorijama (izračunato po hektaru) Table 3 Number of natural regeneration according to height categories (calculated per hectare) Ploha PRP Ploha 1 PRP 1 Ploha 2 PRP 2 Ploha 3 PRP 3 Vrsta tree species smreka -spruce gorski jasen -rowan ukupno -total 0/ /o smreka -spruce gorski jasen -rowan ukupno -total % smreka -spruce gorski jasen -rowan ukupno -total % <20cm 21-50 cm 1333 100 1067 1467 2400 1567 36,73 23,98 934 67 733 2867 1667 2934 25,91 45,61 1001 567 368 4600 1369 5167 16,36 61,74 Za vrednovanje procesa obnove u sastojinama posebno je zanimljiva visinska kategorija preko 20 cm. Dok su sadnice ispod 20 cm visine tek vrlo nesiguran početak nove generacije, a njihov broj po hektaru su više dokaz trajnog razmnožavanja u sastojinama, pojedini primjerci preko 20 cm (ili 50 cm) relativno su sigurni i sposobni za sudjelovanje u sljedećoj sastojinskoj generaciji. Usporedba smreke s jasenom u Tablici 4 pokazuje prevagu jasena u visinskoj kategoriji preko 20 cm. Gorski jasen (jarebikina mukinja) predstavlja najmanje 2/3 obnove, a na Plohi 1 i 2 čak više od 80 %, Tablica 4. Omjer vrsta drveća u prirodnoj obnovi Table 4 Ratio or tree species in natural regeneration Ploha PRP Ploha 1 PRP 1 Ploha 2 PRP 2 Ploha 3 PRP 3 visina-height Vrsta ispod -under 20 cm tree species ha1 % smreka -spruce 1333 55,54 jarebika -rowan 1067 44,46 ukupno -total 2400 100,00 smreka -spruce 934 56,03 jarebika -rowan 733 43,97 ukupno -total 1667 100,00 smreka -spruce 1001 73,12 jarebika -rowan 368 26,88 ukupno -total 1369 100,00 Pitanje dovoljne količine prirodne obnove smreke za planinske sastojine moguće je objasniti uz primjenu kalkulacije koju je izradio Ott etal. 1977. Autor spominje, da područje prirodne obnove u planinskoj šumi traba najmanje od 1/6 do 1/3 sastojinske površine. Uzmemo li prosjek od 1/4 i uobičajeni broj zasađenih smreka (2.500 ha"1), prosječan broj mora biti 600 stabala po hektaru. U slučaju daje stvarni broj smreke od preko 20 cm (ili 50 cm) iznad ove granice, a postoji dovoljna rezerva u visinskom razredu ispod 20 cm, dinamika procesa obnove može se držati zadovoljavajućom. visina -height 51-80 cm 81-130 cm 130cm + ukupno total % 67 167 267 1934 100,00 2067 0 0 4601 100,00 2134 167 267 6535 100,00 32,65 2,56 4,09 100,00 - 133 100 533 1767 100,00 733 333 0 4666 100,00 866 433 533 6433 100,00 13,46 6,73 8,29 100,00 - 433 300 867 3168 100,00 233 0 0 5201 100,00 666 300 867 8369 100,00 7,96 3,58 10,36 100,00 - stoje posljedica njenog bržeg rasta u ranijoj dobi. U visinskoj kategoriji ispod 20 cm, broj smreka i jasena je otprilike jednak, s izuzetkom Plohe 3. Analiza visinskih razreda pokazuje relativno visoku smrtnost pojedinih primjeraka jasena, posebice u višim kategorijama, gdje samo minimalan broj dosegne visinu od preko 80 cm. Naprotiv, smreka ima prilično uravnotežen omjer u kategorijama preko 20 cm, što može značiti da ukoliko sadnica smreke dosegne visinu od 20 cm, možemo ju smatrati relativno sigurnom. više -over 20 cm ha1 % 601 14,53 3534 85,47 4135 100,00 833 17,48 3933 82,52 4766 100,00 2167 30,96 4833 69,04 7000 100,00 ukupno — loiui ha1 % 1934 29,59 4601 70,41 6535 100,00 1767 27,47 4666 72,53 6433 100,00 3168 37,85 5201 62,15 8369 100,00 Usporedba stvarnih brojeva s graničnom vrijednošću pokazuje dovoljan broj obnova smreke u razredima preko 20 cm na Plohama 2 i 3. Količina obnove na Plohi 1 doseže upravo limit od 600 ha"´. Količina smreka od preko 20 cm može se smatrati dovoljnom. Dugoročno gledano, broj smreka ispod 20 cm je problematičan (on je ispod 1.500 ha"´ na svakoj plohi). Pretpostavimo li visoku smrtnost sadnica, broj se ne čini dovoljnom rezervom, a trajna obnova sastojina mogla bi biti ugrožena u budućnosti. |
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S. Kucbcl: STRUKTURA I PRIRODNA OBNOVA PREDPLANINSKE SUME OBIČNE SMREKE ... Šumarski liši -SUPLEMENT (2005). 144-153 DISKUSIJA I ZAKLJUČCI - --Discussion and conclusions U ovom radu korišteni su podaci s pokusnih ploha. Analiza strukture koja aproksimira idealnu sastojinsku strukturu u planinskim šumama omogućila je donošenje nekih djelomičnih zaključaka u odnosu na model planinske šumske strukture. Rezultati se mogu usporediti s podacima iz Švicarskih Alpa koje je objavio Trepp (1961). Prema ovom autoru, najvažni atributi grupne preborne strukture planinske šume su sljedeći: nakupinasta ili grupna struktura, obnova na maloj površini, srednja drvna zaliha (340-380 m3 ha"1) i na prikladnim terenima, trajni razvoj pirrodne obnove na ekološki diferenciranim mikropoložajima. Na ovoj pokusnoj plohi broj stabala je bio 720/ha, a njegova distribucija po slojevima bila je kako slijedi: donji sloj 58,3 %, srednji 13,8 %, te gornji sloj 27,7 %. Autor vrednuje drvnu zalihu na plohi kao suviše veliku, te preporučuje maksimalnu zalihu od LITERATURA Bischoff, N., 1987: Pflege des Gebirgswaldes, Bundesamt fur Forstwesen and Landschafts schütz, EDMZ Bern, 379 s. Frehner, M., 1989: Beobachtungen zur Einleitung der Naturverjungung an einem nordexponierten Steilhang im subalpinen Fichtenwald, Schweiz. Z.Forstwesen, 140 (11), s. 1013-1022. G ubk a, K., 1998: Struktura porastov pod homou hranicou lesa na lokalite Jasienok, Acta Facultatis Forestalis XL., Zvolen, s. 29-39. G übk a, K., 1999: Struktura smrekovćho porastu pod hornou hranicou lesa v dielci 105 na LS Maluzinä, Acta Facultatis Forestalis XLI, Zvolen, s. 107-119. KorpeL, S., 1980: Vyvoj a struktura prirodnych smrekovych lesov Slovenska vo vzt´ahu k protilavinovej ochrannej funkcii, Acta facultatis forestalis XXII, Zvolen, s. 9-39. KorpeL, Š., 1989: Pralesy Slovenska, Veda, Bratislava, 332 s. Kuoch, R., 1972: Zur Struktur and Behandlung von subalpinen Fichtenwäldern, Schweiz. Z. Forstwesen, 123(2), s.77-89. 350 m3 ha"´, čak na najprikladnijim položajima. Sto se tiče prirodne obnove, izračunao je 2.160 stabala po hektaru u visinskom razredu od ispod 30 cm; u visinskom razredu 31-150 cm -1.220 ha"´, a u razredu od preko 150 cm bilo je 620 ha"1. Usporedbom s tim rezultatima, posebice se brojke u kategoriji ispod 20 cm na našim pokusnim plohama čine malima, te, kao što je rečeno prije, one nisu dovoljna rezerva za trajnu obnovu. Osim održavanja diferencirane strukture šumskouzgojni zahvati trebaju se usmjeriti na podršku postojećoj prirodnoj obnovi, tako da se stvore prikladni svjetlosni i termalni uvjeti za njihov daljnji rast i razvoj. Najbolji način da se to postigne je posjeći nekoliko stabala zasjene iz gornjeg sloja. Sto se tiče povećanja broja sadnica u kategoriji ispod 20 cm, bilo bi dobro ostaviti neke od posječenih stabala u sastojim, kako bi se stvorile sjemene podloge za pojavu sadnica. -References Leibundgut , H., 1978: Über die Dynamik europäischer Urwälder, Allg. Forstz. 33, s. 686-690. Leibundgut , FL, 1993: Europäische Urwälder, Verlag Paul Haupt, Bern-Stuttgart, 260 s. Mayer, FL, E. Ott, 1991: Gebirgswaldbau -Schutzwaldpflege, Gustav Fischer Verlag, Stuttgart, 587 s. Ott, E., 1988: Die Gebirgswaldpflege -eine Vielfalt sehr variationsreicher Optimierungsaufgaben, Schweiz. Z. Forstwesen, 139 (1), s. 23-26. Ott, E., M. Frehner, H. Frey, P. Lüscher, 1997: Gebirgsnadelwälder, Verlag Paul Haupt, Bern, 287 s. Schmidt-Vogt,H., 1991: Die Fichte, Bd.II/3, Paul Parey Verlag, Hamburg Berlin, 781 s. Trepp, W., 1961: Die Plenterform des Heidelbeer- Fichtenwaldes der Alpen, Schweiz. Z. Forstwesen, 112(10), s. 337-350. Trepp, W., 1981: Das Besondere des Plenterns im Gebirgswald, Schweiz. Z. Forstwesen, 132 (10), s. 823-846. |
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PRESENTATION AT THE INTERNATIONAL SYMPOSIUM šumarski list - SUPLEMENT (2005), 144-153 THE STRUCTURE AND NATURAL REGENERATION OF A SUBALPINE SPRUCE FOREST WITH PROTECTIVE FUNCTION IN NIZKE TATRY MOUNTAINS (SLOVAKIA) Stanislav KUCBEL SUMMARY: The paper deals with issue of the stand structure, natural regeneration and silvicultural interventions in the protective forests in a mountain region of Slovakia. The priority protective function (especially anti-erosive, anti- avalanche and water-protective) of the mountain forests requires permanent presence of a stable, natural regenerating forest with a differentiated structure. To be able to describe and quantify this structure three permanent research plots have been established in locality Prasiva in Nizke Tatty Mountains. The paper analyses particular structure characteristics of researched stand and on the basis of acquired results the basic structure characteristics for a high-elevation forest are quantified. The results has shown the high-elevation forest should have in an ideal state under similar ecological conditions roughly these characteristics: stem density 1000-1500 pes./ha, falling diameter distribution, the representation of particular tree layers - upper 75 %, middle 15 %, lower 10%, basal area 35-40 m2/ha, growing stock 300-400 m3/ha according to the production ability of the site. Besides the characteristics of model structure the paper analyses the state and the quantity of natural regeneration, which is necessarily needed for the steady exchange of generations in a high-elevation forest. In the natural regeneration two tree species (Norway spruce and rowan) are present. Because of its ecological characteristics rowan is the prevailing tree species in the natural regeneration on all researched plots. The number of Norway spruce natural regeneration in the height classes above 20 cm is crucial for the generation exchange and can already be considered as a relatively secure beginning of a new generation. The results have shown the number of natural regeneration individuals in the height classes above 20 cm should be at least 600 pes./ha, under the condition of sufficient reserve in the height class under 20 cm. Keywords: subalpine forest, stand structure, Norway spruce, natural regeneration INTRODUCTION Forest stands with priority soil-protective (i.e. anti-vation forests have generally a multi-function effect erosive and anti-avalanche) and water-protective funcand the mentioned functions are usually the most imtions take roughly 336,641 ha (16.7 %) within the total portant ones. To the subcategory b. of protection foforest area of Slovak Republic. All of these stands berests (i.e. high-elevation forests) we count about long to the non-commercial forests, either to the cate49,500 ha. gory of protection or special purpose forests. High-ele-The issue of the silvicultural interventions in the high-montane and subalpine stands has been considered one of the marginal problems for Ing. Stanislav Kucbcl, Department of Silviculture, the forestry in Slovakia in the past. Decreasing vitality Forestry Faculty, Technical University, Masarykova 24, 96053 Zvolen, and relatively intensive breakdown of single trees as Slovak Republic, e-mail: kucbel@vsld.tuzvo.sk well as whole stands on some localities during the last |
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S. Kucbel: THE STRUCTURE AND NATURAL REGENERATION OF A SUBALPINE SPRUCE KOREST ... Šumarski list- SUPLEMENT (2005). 144-153 15-20 years have focused the attention on the problems of high-elevation forests recently. The immission impact and extreme weather situations caused by global climatic changes have been probably the crucial factors which have activated the process of the breakdown. The research results (Gubka 1998, 1999) as well as the experiences of practical foresters have shown, beside the mentioned factors, the unstable stand structure remains the key problem of high-elevation forests. This is the result of absent silvicultural regulation and it causes the low resistance to the disturbances and high probability of calamity breakdown. Solution of the problems of silvicultural interventions in high-elevation forests requires to know and to consider their specifics to the forests in lower altitudes. If we want to understand the natural dynamics of high- elevation forest we can use the knowledge obtained from the long-term research of primeval forests in the 7th forest vegetation stage. Studying the life cycle of the Norway spruce primeval forests some natural tendencies with negative impact on the stability of high- elevation forest have been found out (Korpel ´ 1989, Schmidt-Vogt 1991, Leibundgut 1993). These are mainly the tendency to develop a less stable mono- layered structure with horizontal canopy during the long-time optimum stage, the stagnation of regeneration processes and the proneness to the calamity breakdown which causes the loss of required structure for a relatively long period. On the basis of these findings the most authors (Leibundgut 1978, Korpel´ 1980, Mayer-Ott 1991, Schmidt-Vogt 1993) tend to think a Norway spruce natural forest doesn´t have, especially on the convenient sites, the permanent ability to fulfil all protective functions. A high-elevation forest with optimal stand structure which is the result of intentional silvicultural interventions is more stable than a Norway spruce primeval forest and thus the pointed silvicultural regulations seem to be necessary for the permanent protective effect. For the forest with permanent protective effect in the high altitudes the permanent presence of the tree individuals on the site, stability of single trees as well as of the whole stand and gradual natural regeneration should be characteristic. This needs satisfies a stable, natural regenerating, uneven-aged and multi-layered forest at most. Time unlimited durability of structure and permanent regeneration are in general the attributes of a selection forest. Therefor most authors (Kuoch 1972, Trepp 1981, Bischoff 1987, Ott 1988, Frehner 1989, Ott et al. 1997) consider so- called mountain selection forest ("Gcbirgsplenterwald") the ideal pattern of a Norway spruce forest in the high-altitude sites. Naturally long-time process of natural renewal is one of the specifics of the high-elevation forest. The permanent natural regeneration without the limitation of protective effects, which secures the change of forest generations, is the crucial problem in the high-altitude forest. Ott (1988) consider the stand renewal "the weak link in the chain of forest dynamics" in the forest growing near the tree limit. According to Trepp (1961) the silvicultural regulations fulfil their purpose in the high-elevation forests only in the case they are able to secure their natural renewal. METHODS The research was conducted near Korytnica in northern Slovakia. On the locality Prasivä in west part of Nizke Tatry Mountains three permanent research plots (PRP) in a stand with protective function were established. The plots were placed in the parts where the stand structure was most differentiated so that it was approximating an ideal structure of the mountain forest. Every plot had a dimension 30 x 30 m and included a transect with the width of 10 m. On the research plots particular stand characteristics as well as the state of natural regeneration on the transect were acquired and on the basis of them the model stand structure was approximately quantified. The research plots were situated on a west slope in the average altitude 1,300 m a.s.l., the slope ranged from 50 to 70 %. The slope is covered with pure Norway spruce (Picea abies (L.) Karst.) stand with rare presence of rowan (Sorbus aucuparia L.) and mountain pine (Pinus mugo Turra). According to the forest typology three forest communities could be found Sorbeto-Piceetum (60 %), Fagetum abietino-piceosum (30 %) and Mughetum acidofilum (10 %). For this compartment the forest management plan states the average age 180 years and average crown canopy 0.7. On the PRP the set of following parameters was measured for every individual: tree species, dbh (over 1 cm), tree class (according to the top height - upper, middle and lower layer), defoliation (visual estimation of the loss of assimilation organs in 10 %). In addition to this data next variables were measured on the transect: height, height where the crown development begins, crown radius (in four directions) and the position of the stem on the transect (x, y - coordinates). On every PRP coarse woody debris was registered as well and the length, diameter in the middle of length and the decomposition grade (1 - recently fallen, sound, 2 - partly rotted, tree species can be determined, 3 - advanced decay, tree species cannot be determined) of each log was measured. |
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S. Kucbel: TI Ili STRUCTURE AND NATURAL REGENERATION OF A SUBALP1NF. SPRUCE FOREST ... Šumarski list- SUPLEMFNT (2005). 144-153 The analyses of natural regeneration was conducted cies and height classes (up to 20 cm, 21-50 cm, 51-80 on the transect. All individuals according to tree spe- cm, 81-130 cm, from 131 cm to dbh 1 cm) were noted. RESULTS Stand structure The values of basic dendrometric traits on particular research plots are summarized in Table 1. On the basis of the obtained diameter frequencies and regarding other stand characteristics it is possible to consider the stem number of 1,000-1,500 ha"1 as sufficient (all living individuals with dbh over 1 cm). If only the large timber is taken into consideration (individuals with dbh over 7 cm), the stem number should range from 500 to 1,000 ha"´. The stem numbers with less than 500 ha"1 can be one of the indicators of an unstable homogenous structure or of the presence of wider parts without continuous forest stand. Diameter distribution curves are one of the basic characteristics of a stand structure (Fig. 1). On every observed research plot the distribution curve has more or less distinctly decreasing shape, which is typical for a differentiated structure (very close to a selection forest structure). Some visible differences between particular research plots follow from the figures. Although the distribution on the PRP 1 has a decreasing shape, there is a quite high stem number in higher diameter classes (trees of the upper layer). The regulation of the structure should head to the reduction of the upper layer individuals in favour of the trees from middle and lower layer. The diameter distribution on the PRP 2 is approximating the required model at most. The individuals from the lower layer (diameter classes 2 and 4 cm) arc moderately deficient. The PRP 3 is covered with the youngest stand. A part of the plot is in the growth phase of thicket and small pole-stage stand. This homogenous part represents an unstable element which requires a silvicultural measure. The intervention should reduce the stem number and differentiate the stand. According to obtained data the basal area should range from 35 to 40 m2 ha 1 by the given structure. The growing stock has quite different values on particular research plots (from 268.43 m3 ha 1 to 444.22 m ha 1). Considering the stand structure as well as the influence of outliers (e.g. one stem with dbh of 88 cm on PRP 1 increases the total growing stock for more than 80 m3 ha"1) it is possible to propose the optimum growing stock on the level from 300 to 400 m3 ha"´, according to the production conditions of the site. The defoliation grade ranges under 10 % on all plots and on the basis of this characteristic the stands can be evaluated as vital and healthy. The analysis of tree frequencies according to the layers shows that approximately 3/4 of all individuals are concentrated in the lower layer, whilst other 25 % are divided by different ratio into middle and upper layer. After the evaluation of stand structure on particular plots the most appropriate ratio of the layers seems to be the model: 75 % lower layer, 15 % middle layer and 10 % upper layer. The model concerns the ratio according to the stem number, in the case of area ratio each layer should take roughly the same area (i.e. 1/3 of the stand area). Coarse woody debris (CWD) is an important component of a high-elevation forest especially from the viewpoint of its regeneration processes. Table 2 sums up the results of the stand volume divided according to vital, standing and lying dead trees. The volume of lying deadwood ranges from 43.56 m3 ha"´ on PRP 2 to 71.67 m3 ha"1 on PRP 1 in absolute values. Besides the total amount of CWD the ratio between particular grades of decomposition is important, above all the volume of CWD in the 2nd and 3rd grade of decomposition, because only the logs in this state provide appropriate conditions for the development of natural regeneration. From this point of view the best conditions are on the PRP 1 where almost all CWD is at least partly rotted and creates a convenient seedbed for spruce seedlings. From given data it is difficult to quantify the sufficient amount of CWD but it is possible to say the worse are the conditions for the natural regeneration in the stand, the higher should be the amount of CWD. The distribution of the whole biomass on the observed plots is following: approximately 80-85 % fall on vital trees, the rest is divided in ratio 1:2 between standing and lying deadwood. Different situation is only on PRP 3, where a quite high number of standing deadwood has been observed. REGENERATION PROCESSES Two tree species are present in the natural regeneration on all research plots - Norway spruce {Picea abies IL.I Karst.) and rowan (Sorbus aucuparia L.). Although the tables 3 and 4 show also the total number of individuals (spruce + rowan), this values as well as the comparison of the numbers according to the tree species have only an orientation meaning. The first reason is, that although rowan is an important and permanent |
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S. Kucbel: THE STRUCTURE AND NATURAL REGENERATION OF A SUBALPINE SPRUCE FOREST ... Šumarski list - SUPLEMENT (2005), 144-153 component of the species composition in the high-elevation forest, spruce stays the determinant tree species of these stands and therefore the number and structure of spruce regeneration has the crucial importance for the stand renewal. The second reason which does not allow the direct comparison is the growth rhythm and ecological demands of these tree species as well as the different dynamics of the regeneration process. For the evaluation of the regeneration processes in the stands especially the height category over 20 cm is interesting. While the seedlings under 20 cm are only a very insecure beginning of the next generation and their numbers per hectare are more the proof of the permanent breeding in the stands, the individuals over 20 cm (or 50 cm) are relatively secure and able to take part on the next stand generation. The comparison of the spruce and rowan representation in table 4 shows the prevalence of rowan in the height category over 20 cm. Rowan presents at least 2/3 of the regeneration, on PRP 1 and 2 even more than 80 % what is the consequence of her faster growth at the lower age. In the height category under 20 cm the numbers of spruce and rowan are approximately equal, excepting PRP 3. The analysis of the height classes shows relatively high mortality of rowan individuals especially in higher categories, where only a minimal number of them reaches the height over 80 cm. On the contrary, spruce has a quite balanced ratio in the categories over 20 cm DISCUSSION AND In this paper the data acquired from three research plots were used. The analysis of a structure which is approximating an ideal stand structure for the high- elevation forest allowed stating some partial conclusions regarding the model of the high-elevation forest structure. The results can be confronted with the data from Swiss Alps published by Trepp (1961). According to this author the most important attributes of the group selection forest structure on high-elevation sites are following: cluster or group structure, small-scale regeneration, middle growing stock (340-380 m3 ha"1) also on convenient sites, continuous development of the natural regeneration on ecologically differentiated micro- sites. On this research plot the tree number was 720 ha, its distribution into layers: lower 58.3 %, middle 13.8 % and upper layer 27.7 %. The author evaluates the growing stock on to plot too high and recommends the maximum growing stock about 350m3 ha"1 even for what let assume if the spruce seedling has reached the height of 20 cm we can consider it relatively secure. The question of sufficient amount of spruce natural regeneration for high-elevation stand renewal can be answered according to a calculation of Ott et al. (1997). The author mentions the area of natural regeneration in a high-elevation forest should take at least from 1/6 to 1/3 of the stand area. If we use an average of 1/4 and the usual number of planted spruce (2,500 ha"1), the approximate reference number should be 600 individuals per hectare. In the case the real number of spruce over 20 cm (or 50 cm) is above this limit and there is a sufficient reserve in the height class under 20 cm, the dynamics of regeneration process can be considered satisfying. The comparison of the real numbers with the boundary value shows a sufficient number of the spruce regeneration in the classes over 20 cm on PRP 2 and 3. The amount of the regeneration on the PRP 1 reaches just the limit 600 ha"1. Generally the amount of spruce individuals over 20 cm can be considered sufficient. From the long-term view the number of spruce individuals under 20 cm is problematic (it lies under 1,500 ha-1 on each PRP). Assuming the high seedling mortality the number seems to be no sufficient reserve and the continuous regeneration of the stand could be endangered in the future. CONCLUSIONS most convenient sites. In terms of natural regeneration he found out 2,160 individuals per hectare in the height class under 30 cm, in the height class 31-150 cm 1,220 ha"´ and in the class over 150 cm 620 ha"1. Compared with these results, especially the numbers in the category under 20 cm from our research plots seem to be low and as mentioned before they are not a sufficient reserve for continuous renewal. Besides the maintenance of the differentiated structure the silvicultural interventions should be concentrated on the support of the existing natural regeneration by means of creating appropriate light and thermal conditions for their further growth and development. The best way to do this is to cut several shading trees from upper layer. On behalf of the increase of the seedling number in the category under 20 cm it would be appropriate to leave some of the cutting stems in the stand and thus create perspective seedbeds for the seedling emergence. |
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E. Klimo: VODOZAŠTITA - URAVNOTEŽENJE VODNIH ODNOSA U PROSTORU Šumarski lis! SUPLliMENT (2005), 154 3. Skupina referata: VODOZAŠTITA - URAVNOTEŽENJE VODNIH ODNOSA U PROSTORU I PROČIŠĆAVANJE IZVORSKIH VODA Skupu predsjedava: Prof. dr. sc. Emil Klimo Referati gornje skupine odnose se na kakvoću vode uvjetovane utjecajem različitih šumskih ekosustava zatim na lizimetrijska istraživanja, monitoring podzemnih voda, vrijednost protuerozijske i vodozašitne funkcije šume, kakvoću vode u gorskim vodotocima, utjecaj šume na kemijski sastav oborinske vode te podatak o količini sitnoga korijenja obične smreke. U ovoj skupini održano je 10 referata. Tri referata održali su znanstvenici iz Češke, dva iz Slovačke i pet iz Hrvatske. Klimo i Kulhavy referiraju o pozitivnom utjecaju nizinske i gorske šume u Češkoj na kakvoću vode. Huška referira o utjecaju šume i vode na ekologiju krajolika, Vrbek i dr. daju rezultate lizimetrijskih istraživanja u šumi hrasta lužjaka i običnoga graba u različitim područjima Hrvatske, Prpić, Jurjević i Jakovac izlažu rezultate obračunatih vrijednosti protuerozijske i vodozaštitne funkcije šuma za državne šume u Republici Hrvatskoj dobivene po službenoj metodologiji iz Zakona o šumama Republike Hrvatske, Pilaš i dr. izvješćuju o do sada instaliranom monitoringu podzemnih voda u Hrvatskoj, a Janeček iz Praga preporučuje CN metodu za procjenu mogućega utjecaja vode iz šumskoga sliva. Tikvić, Seletković i dr. istražuju utjecaj različitih šumskih ekosustava na kakvoću vode u vodotocima dok Tikvić, Seletković, Magdić i Sojat istražuju stanje i odnose oborinskih voda u šumama Nacionalnoga parka Plitvička jezera. Kovar ukazuje u svome referatu na važnost "aktivne zone" tla te daje rezultate istraživanja za slivove različite šumovitosti za ekstremne godine (vlažne i sušne) u Češkoj. Jaloviar iz Zvolena referira o istraživanju raspodjele sitnoga korijenja u rizosferi kulture obične smreke sađene u različitim razmacima. 3rtl group of papers: WATER PROTECTOIN -BALANCING WATER RELATIONS IN SPACE AND PURIFYING SPRING WATERS Chaired by: Professor Emil Klimo, PhD The papers in this group deal with water quality in different forest ecosystems, lyzimetric research, groundwater monitoring, the value of anti-erosive and water-protective forest functions, water quality in mountain watercourses, the impact of forests on the chemical composition of precipitation and data on the quantity of tiny roots of common spruce. Three papers were presented by Czech, two by Slovakian and five by Croatian scientists. Klimo and Kulhavy report on the positive impact of lowland and montane forests on water quality in the Czech Republic, Huska reports on the effect of forests and water on landscape ecology, Vrbek et al. present the results of lyzimetric research in the forest of pedunculate oak and common hornbeam in different areas of Croatia, Prpić, Jurjević and Jakov ac provide the results of calculated values of anti-erosive and water-protective forest functions for state forests in the Republic of Croatia obtained by using the official methodology set down in the Forest Act of the Republic of Croatia, Pilaš et al. report on the installed groundwater monitoring in Croatia, and Janaček from Prague recommends the use of the CN method for the assessment of some possible effects of water from a forest catchment area. Tikvić, Seletković and others investigate the impact of different forest ecosystems on the quality of water in watercourses, whereas Tikvić, Seletković, Magdić and Sojat explore the condition and relations in precipitation waters in the forests of the Plitvice Lakes National Park. Rovar points to the importance of "active soil zone " and provides research results for differently forested catchments for extreme years (wet and dry) in the Czech Republic. Jalovarfrom Zvolen reports on research into the distribution of tiny roots in the rhizosphere of a common spruce culture planted with different spacing. |