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Query: "author" (Tom Levanič) .

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Letna in sezonska debelinska rast dreves na ploskvah intenzivnega monitoringa v Sloveniji
Tom Levanič, Matej Rupel, Andreja Vedenik, 2024, original scientific article

Abstract: V okviru intenzivnega monitoringa gozdnih ekosistemov že od leta 2009 s pomočjo ročnih dendrometrov spremljamo de- belinsko priraščanje dreves na letnem nivoju. Gre za dopolnilni podatek o debelinskem priraščanju dreves, ki ga pridobimo v okviru petletnih inventur na ploskvah intenzivnega monitoringa. Letno dinamiko debelinskega priraščanja spremljamo z dvema tipoma ročnih dendrometrov : plastičnimi, nemškega proizvajalca, in nerjavnimi, češkega proizvajalca. S spremljanjem debelinske rasti z ročnimi dendrometri želimo ugotoviti vpliv okoljskih in podnebnih dejavnikov na rast dreves med dvema petletnima inventurama. Tako dobimo bistveno boljše podatke o stanju priraščanja dreves kot s petletnimi inventurami, kjer ekstremni dogodki izginejo v povprečju. V letu 2022 smo dodatno na vse ploskve namestili tudi elektronske dendrometre z visoko frekvenco spremljanja spreminjanja debelinskega prirastka na ploskvah intenzivnega monitoringa v Sloveniji. Z njimi želimo ugotoviti vplive okoljskih in podnebnih dejavnikov na znotraj sezonsko dinamiko debelinskega priraščanja. To je ključno za razumevanje vpliva negativnih podnebnih dejavnikov na debelinsko priraščanje dreves.
Keywords: podnebne spremembe, bukev, Fagus sylvatica, dob, Quercus robur, smreka, Picea abies, ročni dendrometer, elektronski dendrometer
Published in DiRROS: 06.12.2024; Views: 134; Downloads: 36
.pdf Full text (522,59 KB)

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How beech provenance affects the structure of secondary xylem, leaf traits, and the ectomycorrhizal community under optimal growth conditions
Tanja Mrak, Jožica Gričar, Tina Unuk Nahberger, Gregor Božič, Luka Krajnc, Peter Prislan, Domen Arnič, Tom Levanič, Hojka Kraigher, 2024, original scientific article

Abstract: Beyond growth parameters and drought tolerance, comparatively little is known about the functioning of different beech (Fagus sylvatica L.) provenances. We investigated properties of leaves, stem secondary xylem, and ectomycorrhiza (ECM), and explored their interdependencies to identify the best performing beech provenance in optimal growth conditions. The study was conducted on 23-year-old trees in a provenance trial. The investigated provenances originated from Atlantic (Belgium—BE), Alpine (Italy—IT, Slovenia—SI), and continental climates (the Czech Republic—CZ). A significant effect of provenance was observed for stem vessel diameters and conductive area, as well as for foliar %C, δ13C, δ15N, and δ18O. δ13C as a proxy of intrinsic water use efficiency (iWUE) showed that the highest iWUE was achieved in BE provenance. Individuals with a better iWUE had wider growth rings regardless of provenance. Better iWUE was associated with lower specific leaf area (SLA). ECM community composition and diversity indices did not differ significantly among the provenances. Specific ECM taxa were associated with individuals with high SLA, δ13C, δ15N, and δ18O. In optimal growth conditions with no stress events, BE is a promising provenance due to an efficient water conducting system with high vessel diameters and conductive area, and high iWUE, while Alpine provenances showed an adaptation of their water conducting system to freezing conditions at their original locations. Integrating findings from different compartments improves our understanding of functioning of different beech provenances.
Keywords: Fagus sylvatica, provenance trial, stable isotopes, specific leaf area, xylem vessels, ectomycorrhizal fungi
Published in DiRROS: 19.04.2024; Views: 616; Downloads: 902
.pdf Full text (2,11 MB)
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Osnove dendrokronologije : študijsko gradivo pri predmetu "Dendrokronologija UN BSc"
Tom Levanič, 2012, other educational material

Keywords: dendrorkonologija, učbeniki
Published in DiRROS: 26.10.2023; Views: 929; Downloads: 222
.pdf Full text (4,09 MB)

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Differences in ratio of carbon stable Isotopes among barley grain milling fractions with various concentrations of beta-glucans
Tom Levanič, Blaž Cigić, Mateja Germ, Ivana Polišenská, Kateřina Vaculová, Igor Pravst, Darja Kocjan Ačko, Ivan Kreft, 2023, original scientific article

Abstract: The grains of three barley varieties were milled and sieved to obtain respective milling fractions with a content of beta-glucans (b-G) from 1.4 to 10.7%. The enriched fraction obtained by the extraction and precipitation contained 24.7% of b-G. The differences between the ratio of stable C carbon isotopes were established. Milling fractions with coarse particles had more beta-glucans and a more negative ratio of δ 13C isotope in comparison to the respective intact barley grain. However, the enriched fraction had a less negative isotope ratio. So, it is not expected that the deviation from the stable isotope ratio of grain in milling fractions is the result of the content of b-G, but it depends on other barley grain constituents. In different parts of barley grain, there are substances with different stable isotope ratios, and by milling and sieving, they are assorted to the same milling fraction with most of the b-G. The method for determining the ratio of a stable carbon isotope in diverse barley grain fractions, applied in this investigation, is potentially opening the possibility for an additional method of screening the concentration of bioactive constituents in barley grain.
Keywords: beta-glucans, starch, barley, stable isotopes, nutrition, milling
Published in DiRROS: 02.08.2023; Views: 824; Downloads: 423
.pdf Full text (893,76 KB)
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