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Dendrokronološka in dendroekološka analiza propadajočih vladajočih in sovladajočih jelk (Abies alba Mill.) v dinarski fitogeografski regiji : doktorska disertacija
Levanič, Tom (Author), Torelli, Niko (Mentor) More about this mentor... This link opens in a new window, Kotar, Marijan (Co-mentor), Eckstein, Dieter (Reviewer), Čufar, Katarina (Reviewer)

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Abstract
V dinarski fitogeografski regiji smo izbrali 7 raziskovalnih objektov z najmanj 15 drevesi na objekt. V raziskavo so bile vključene samo odrasle vladajoče in sovladajoče jelke ne glede na osutost krošnje. Sušic in umirajočih jelk nismo upoštevali. Na dveh izvrtkih ali enem kolobarju na drevosmo izmerili širine branik. Več zaporedij širin branik smo združili v lokalno kronologijo za objekt. Slovenska dinarska kronologija pokriva obdobje 1790-1995 in vizualno dobro sovpada z nemškimi. Rastni trendi lokalnih kronologij za različno prizadeta drevesa se po letu 1960 obrnejo strmo navzdol. Depresija doseže najnižjo točko leta 1976, nato pa se začne prirastekpovečevati. Obdobje depresije je najmanj prizadelo navidezno zdrave jelke, najbolj pa močno prizadete. V zadnjih 100 letih smo identificirali 20 značilnih let (11 negativnih in 9 pozitivnih). Topli spomladanski meseci in poletni z več padavinami so najbolj ugodni za prirastek jelke. Z odzivnimi funkcijami smo pojasnili od 30 do 60% variabilnosti širin branik, kar pomeni, da metoda ne daje vedno zadovoljivih rezultatov. Z debelno analizo smo identificirali tudi do 11 izpadlih branik, ki smo jih s pomočjo regionalne kronologije postavili v čas. Negativni vpliv gospodarjenja se kaže v stalnem zniževanju lesne zaloge in s tem povezanim upadanjem širine branike. Lesna zaloga pod 450 m3/ha ne zagotavlja več ugodne sestojne klime za jelko. Poseki visoke jakosti povzročijo pri jelki stres, na katerega se odzove z upadom prirastka. Po nekaj letih se, pri ne prehudem posegu, prirastek povrne na nivopred posegom. Delež kasnega lesa z višino debla upada, vendar lahko to zakonitost modificira sekundarna krošnja. Prirastna ritmika odziva juvenilnegain adultnega lesa je primerljiva.

Language:Slovenian
Keywords:gozdovi, Slovenija, dinarsko fitogeografsko območje, propadanje gozdov, jelka, dendrokronologija, ekologija, disertacije
Work type:Dissertation (m)
Tipology:2.08 - Doctoral Dissertation
Organization:BF - Biotechnical Faculty
Year:1996
Publisher:[T. Levanič]
Number of pages:XV, 166 f., [53] f. pril.
Place:Ljubljana
UDC:630*17:630*56(043.3)=163.6
COBISS.SI-ID:66185 Link is opened in a new window
Views:824
Downloads:224
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Secondary language

Language:English
Abstract:
Seven geographical locations with at least 15 trees were selected in the Dinaric phytogeographic region. All trees, except dead and clearly dying ones,were analysed. Tree-ring widths were measured on two cores or on one stemdisc. Slovene Dinaric silver fir chronology was built on this basis. It covers the period 1790-1995. Comparison of the Slovene regional chronology with the South German and the Bavarian one revealed moderate visual comparability but not very high statistical values. Growing trends in the local chronologies of differently affected silver firs decline rapidly after the year 1960 and reach their minimum in 1976. Thereafter the radial incrementincreases. Especially weak silver firs were most heavily affected. Inthe last 100 years 11 negative and 9 positive signature years were detected.Warm spring months and moderately warm summer months with above average precipitation are most favourable for the increment. Tree-ring width variability can be explained by response functions in the 30-60% range. This indicates that the method doesnćt always give satisfactory results. In the stem analysis 11 missing rings were dated and identified with the help of the regional chronology. Unappropriate forest management has negative influence onsilver fir increment. A fast reduction of the growing stock below 450 m3/ha can provoke a destruction of selfprotecting mechanisms in the forest site and its mechanical and biological stability is endangered. Silver firs respond to the instability of the forest stand with decrease of increment and reductions of the crown. The amount of latewood decreases acropetally, however this trendcan be modified by secondary crown. The growing rhythm of the juvenile and adult wood is comparable.


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