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Query: "author" (Luka Krajnc) .

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1.
Tree rings, wood density and climate–growth relationships of four Douglas-fir provenances in sub-Mediterranean Slovenia
Luka Krajnc, Jožica Gričar, Jernej Jevšenak, Polona Hafner, Robert Brus, 2022, original scientific article

Abstract: Tree rings, wood density and the climate–growth relationship of four Douglas-fir provenances were analysed separately for the juvenile and adult phases. Four provenances were selected from an existing IUFRO provenance trial planted in 1971 based on their diameter at breast height and vitality. Increment cores were extracted from individual trees, on which we measured tree-ring widths (RW), earlywood widths (EWW) and latewood widths (LWW). Wood density was assessed in standing trees using resistance drilling. The climate–growth correlations were calculated between provenance chronologies of RW, EWW, LWW and latewood share, and the day-wise aggregated Standardised Precipitation-Evapotranspiration Index (SPEI). The analysis was done separately for the juvenile and mature phases of growth. Provenances 1064 (Jefferson) and 1080 (Yelm) exhibited larger annual radial increments than provenances 1028 (Merrit) and 1089 (Cathlamet). The two provenances with the highest annual radial increment in the juvenile phase did not exhibit the same trend in the adult phase. In all provenances, RW, and consequently EWW and LWW, were wider in the juvenile than in adult phase. The share of latewood was in all cases higher in juvenile wood than in mature wood. All four provenances had similar wood densities in both analyzed growth phases. Our analysis showed that when selecting the most promising provenance for planting, possible changes in relative growth rate from the juvenile to adult phase need to be considered.
Keywords: Pseudotsuga menziesii, SPEI, juvenile phase, adult phase, latewood share, resistance drilling
Published in DiRROS: 21.11.2022; Views: 38; Downloads: 12
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2.
Prva licitacija vrednejše hlodovine iz gozdov v lasti RS
Peter Prislan, Luka Krajnc, Božidar Lovro Birkić, 2021, professional article

Keywords: Slovenija, cene lesa, hlodovina, licitacija, dražba
Published in DiRROS: 12.11.2022; Views: 52; Downloads: 13
.pdf Full text (3,92 MB)

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Ocenjevanje kakovosti stoječih dreves
Luka Krajnc, 2022, professional article

Abstract: Spremljanje kakovosti lesa se začne v gozdu, saj je poznavanje trenutnega stanja eden izmed ključnih dejavnikov pri usmerjanju nadaljnjega razvoja gozda v smer večje kakovosti lesne surovine. Usmerjanje razvoja gozdov v smer večje kakovosti in s tem večje dodane vrednosti lesu pa za začetek terja merljivost kakovosti. Brez tega je presoja morebitnih ukrepov v sestoju skoraj nemogoča ali vsaj zelo otežena. Trenutno uporabljena metodologija za ocenjevanje kakovosti stoječih dreves na stalnih vzorčnih ploskvah Zavoda za gozdove Slovenije temelji na neveljavnih žagarskih standardih in bi jo bilo treba posodobiti za splošno uporabo v gozdarstvu. V prispevku je na kratko opisana obstoječa metodologija, predstavljen je pregled obstoječih metodologij ocenjevanja kakovosti stoječih dreves različnih držav in predlagana nova metodologija za ocenjevanje kakovosti dreves. Osnovni cilj opisanega dela je bil razvoj metodologije, s katero bi lahko objektivno primerjali kakovost debel med različnimi sestoji in bi omogočala sortiranje prostornine dreves v potencialne gozdnolesne sortimente (t.i. »sortimentacija«). Uporaba predlagane lestvice kakovosti za opis kakovosti stoječih dreves je lahko eden izmed pripomočkov pri odločanju kam, koliko časa ali sredstev vložiti v gozdnogojitveno ukrepanje v posameznem sestoju.
Keywords: kakovost stoječih dreves, kvaliteta debla, gozdnolesni sortimenti, sortimentacija stoječega drevesa
Published in DiRROS: 17.10.2022; Views: 126; Downloads: 28
.pdf Full text (734,44 KB)

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Določanje prostornine dreves s krivuljami za opis oblike debla (KOOD)
Luka Krajnc, Gal Kušar, 2022, original scientific article

Abstract: Krivulje za opis oblike debla (KOOD) (ang. t.i. »taper functions«) zvezno opisujejo odnos med višino drevesa in premerom debla na ravni posameznega drevesa, od tal do vrha drevesa. Z njihovo uporabo lahko na katerikoli višini od tal (ali od vrha drevesa) določimo premer debla in tako lahko npr. pri izračunih prostornine drevesa ali sortimentov izberemo poljuben zgornji najmanjši premer, izračunamo srednje premere posameznih sortimentov ali izračunamo prostornino posameznih poljubno izbranih delov debla. Kar potrebujemo za izračun prostornin kot vhodni podatek, je drevesna vrsta, prsni premer ter višina (izmerjena ali izračunana iz višinske krivulje) ter KOOD. Na primeru smreke predstaviva prednosti in omejitve omenjenih krivulj ter narediva primerjavo izdelane slovenske KOOD za smreko in obstoječih nemških KOOD. Rezultati določanja prostornine dreves po obeh KOOD so primerljivi. S pomočjo sekcijskih meritev premerov, bodisi ročnih ali optičnih, lahko tuje KOOD lokalno prilagodimo za slovenske razmere. Z uporabo KOOD izboljšamo zanesljivost določanja prostornine dreves in omogočimo nove preračune prostornin potencialnih sortimentov
Keywords: taper krivulje, krivulje za opis oblike debla, KOOD, izračun prostornine drevesa, smreka
Published in DiRROS: 12.07.2022; Views: 252; Downloads: 72
.pdf Full text (285,00 KB)

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A comparison of radial increment and wood density from beech provenance trials in Slovenia and Hungary
Luka Krajnc, Peter Prislan, Gregor Božič, Marjana Westergren, Domen Arnič, Csaba Mátyás, Jožica Gričar, Hojka Kraigher, 2022, original scientific article

Abstract: Provenance trials are a valuable source of information, especially in species such as European beech (Fagus sylvatica L.), which will likely increase its distribution due to global warming. The current study compares radial increment and wood density of beech provenances in the juvenile development stage from contrasting environments in Europe (Belgium, Slovenia, Czech Republic, Italy) planted at a mesic to wet site in Slovenia and a xeric site in Hungary. Existing data (past measurements of diameters and height) were combined with new measurements of tree height, diameter, dendrochronological and resistance drilling density measurements to assess differences in provenance radial growth. The wood density data were evaluated using a Bayesian general linear model. In order to study the differences in radial increment in more detail, two weather-wise contrasting years (2014 and 2017) were selected from the last decade, based on calculations of the 12-month Standardized Precipitation-Evapotranspiration Index. The differences in average tree-ring width among provenances at each sampled site appeared to be relatively small when averaged over a whole decade of data. However, according to year-to-year data, some provenances grew faster than others, especially in favorable weather conditions. In unfavorable conditions, the differences in tree-ring widths among provenances were smaller. For most provenances, variation in tree-ring widths within the same provenance increased in unfavorable conditions. The difference between the provenances with the highest and lowest wood densities at both locations did not exceed 5%. The model results indicate that the Idrija (Slovenia) provenance probably has a higher median wood density than other studied provenances at both sites. Although the current study confirmed some differences in wood density between provenances and trial locations, the differences are negligible in practice due to their low magnitude and the fact that the analyzed trees were still juvenile. As beech has a diffuse-porous wood, negligible differences in wood density would also be expected in adult trees. Beech provenances for planting in relation to changing weather should probably be chosen for their ability to survive more extreme weather events rather than to improve radial increment or wood density, especially as the differences in wood density of juvenile trees are relatively small.
Keywords: Fagus sylvatica, tree-ring width, common garden, resistance drilling
Published in DiRROS: 15.04.2022; Views: 218; Downloads: 265
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10.
Relationships between wood-anatomical features and resistance drilling density in Norway spruce and European beech
Domen Arnič, Luka Krajnc, Jožica Gričar, Peter Prislan, 2022, original scientific article

Abstract: Environmental conditions affect tree-ring width (TRW), wood structure, and, consequently, wood density, which is one of the main wood quality indicators. Although studies on inter- and intra-annual variability in tree-ring features or density exist, studies demonstrating a clear link between wood structure on a cellular level and its effect on wood density on a macroscopic level are rare. Norway spruce with its simple coniferous structure and European beech, a diffuse-porous angiosperm species were selected to analyze these relationships. Increment cores were collected from both species at four sites in Slovenia. In total, 24 European beech and 17 Norway spruce trees were sampled. In addition, resistance drilling measurements were performed just a few centimeters above the increment core sampling. TRW and quantitative wood anatomy measurements were performed on the collected cores. Resistance drilling density values, tree-ring (TRW, earlywood width–EWW, transition-TWW, and latewood width–LWW) and wood-anatomical features (vessel/tracheid area and diameter, cell density, relative conductive area, and cell wall thickness) were then averaged for the first 7 cm of measurements. We observed significant relationships between tree-ring and wood-anatomical features in both spruce and beech. In spruce, the highest correlation values were found between TRW and LWW. In beech, the highest correlations were observed between TRW and cell density. There were no significant relationships between wood-anatomical features and resistance drilling density in beech. However, in spruce, a significant negative correlation was found between resistance drilling density and tangential tracheid diameter, and a positive correlation between resistance drilling density and both TWW + LWW and LWW. Our findings suggest that resistance drilling measurements can be used to evaluate differences in density within and between species, but they should be improved in resolution to be able to detect changes in wood anatomy.
Keywords: wood structure, Fagus sylvatica, Picea abies, quantitative wood anatomy, xylem anatomy, wood density, increment borer
Published in DiRROS: 08.04.2022; Views: 228; Downloads: 200
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