11. Relationships between wood-anatomical features and resistance drilling density in Norway spruce and European beechDomen 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: 597; Downloads: 437
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12. Sodobna izhodišča redčenj : povezovanje načel izbiralnega redčenja, situacijskega redčenja, redčenja šopov in skupin ter redčenja spremenljive gostoteJurij Diaci, Dušan Roženbergar, Gal Fidej, Domen Arnič, 2021, professional article Abstract: V Evropi so razširjeni različni načini redčenj, ki so delno odgovor na različne cilje gospodarjenja; delno so posledica tradicije in različnih kulturnih okolij. S spremembami v okolju in zaostrovanjem družbeno-ekonomskih razmer ter splošnim nazadovanjem nege gozdov postajajo odločitve o najprimernejšim načinu in intenzivnosti redčenj vse pomembnejše. V prispevku primerjamo situacijsko redčenje, redčenje šopov in skupin, redčenje spremenljive gostote in pri nas ustaljeno izbiralno redčenje. Navajamo usmeritve, kako redčenja kombinirati ter kako izbrati primeren način in program redčenj. Na temelju sinteze dosedanjih raziskav izpostavljamo, da so za utemeljeno izboljšanje načinov redčenj pomembni poskusi v naravi.
Keywords: gojenje gozdov, nega gozda, redčenje, racionalizacija, stabilnost sestoja, porazdelitev izbrancev
Published in DiRROS: 29.10.2021; Views: 1270; Downloads: 379
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13. Gostota lesa - metode določanja in pomen pri razvoju gozdno lesnega biogospodarstvaDomen Arnič, Miha Humar, Davor Kržišnik, Luka Krajnc, Peter Prislan, 2021, original scientific article Abstract: Gostota lesa je fizikalna lastnost, ki je enostavno določljiva in nakazuje na številne druge lastnosti lesa in s tem tudi na njegovo uporabnost v lesno-predelovalni industriji, gradbeništvu ali energetiki. Ker je odvisna od vlažnosti ter poroznosti, se v stroki pojavljajo različne definicije gostot lesa, med katerimi je največkrat uporabljena gostota lesa v absolutno suhem stanju. Namen prispevka je predstavitev različnih načinov določanja gostote lesa ter pomen hitrega in natančnega določanje tega parametra kakovosti pri razvoju gozdno lesnega biogospodarstva. V stroki obstaja več neposrednih in posrednih metod določanja gostote; najbolj običajen in razširjen je volumetrični pristop, sledi postopek ocenjevanja gostote s penetrometrom, rezistografom, visokofrekvenčno denzitometrijo, rentgenskimi žarki, infrardečo spektroskopijo ter mikrovalovi. Les je surovina, ki ji bo v prihodnosti pomen še naraščal, saj je ključna za razvoj trajnostnega biogospodarstva. Natančno in pravočasno določanje gostote lesa bo omogočalo ustrezno razporejanje in usmerjanje tokov te surovine med posameznimi konvencionalnimi in novimi sektorji (področji rabe) in posledično bolj učinkovito in trajnostno rabo.
Keywords: lastnosti lesa, gostota lesa, rezistograf, penetrometer, rentgenska denzitometrija, visokofrekvenčna denzitometrija, gozdno lesno biogospodarstvo
Published in DiRROS: 28.03.2021; Views: 4136; Downloads: 2490
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14. Modeling of time consumption for selective and situational precommercial thinning in mountain beech forest standsDomen Arnič, Janez Krč, Jurij Diaci, 2021, original scientific article Abstract: Rationalization and optimization of work is becoming increasingly important in the European forestry sector. In this study a tool for modeling three different precommercial thinning approaches in young beech mountain stands was developed based on several field studies. The simulation examines three primary types of precommercial thinning: selective thinning and two types of situational thinning. We studied the impact of the number of candidates/crop trees and the impact of harvesting intensity on the structure and consumption of productive time. We found that in terms of costs situational precommercial thinning is more rational than selective precommercial thinning, that harvesting intensity has a significant impact on time consumption and that the number of candidates or crop trees has a significant impact on time consumption as well as on the relationships between main and auxiliary productive time. The modeling has shown that situational thinning is an alternative to selective thinning and that, in addition to requiring smaller and more efficient harvesting machines, it offers a cost-effective and ergonomic option (more walking, less chainsaw operation) for the pre-commercial thinning of young forest.
Keywords: precommercial thinning, selective thinning, situational thinning, modeling, crop tree
Published in DiRROS: 22.03.2021; Views: 1236; Downloads: 692
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15. Predlog kazalnikov stanja gozdno-lesnega sektorja v slovenskem biogospodarstvu : Javna gozdarska služba v letu 2020 : naloga 5: pripravljanje strokovnih podlag in predlogov normativov za opravljanje del v gozdovihDomen Arnič, Špela Ščap, Peter Prislan, Nike Krajnc, 2020, treatise, preliminary study, study Keywords: biogospodarstvo, raba lesa, kaskadna raba, tokovi lesa, krožno gospodarstvo
Published in DiRROS: 11.12.2020; Views: 1213; Downloads: 356
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16. Growth-limiting factors and climate response variability in Norway spruce (Picea abies L.) along an elevation and precipitation gradients in SloveniaJernej Jevšenak, Ivan Tychkov, Jožica Gričar, Tom Levanič, Jan Tumajer, Peter Prislan, Domen Arnič, Margarita Popkova, Vladimir V. Shishov, 2020, original scientific article Abstract: Norway spruce (Picea abies L.) is among the most sensitive coniferous species to ongoing climate change. However, previous studies on its growth response to increasing temperatures have yielded contrasting results (from stimulation to suppression), suggesting highly site-specific responses. Here, we present the first study that applies two independent approaches, i.e. the nonlinear, process-based Vaganov-Shashkin (VS) model and linear daily response functions. Data were collected at twelve sites in Slovenia differing in climate regimes and ranging elevation between 170 and 1300 m a.s.l. VS model results revealed that drier Norway spruce sites at lower elevations are mostly moisture limited, while moist high-elevation sites are generally more temperature limited. Daily response functions match well the pattern of growth-limiting factors from the VS model and further explain the effect of climate on radial growth: prevailing growth-limiting factors correspond to the climate variable with higher correlations. Radial growth correlates negatively with rising summer temperature and positively with higher spring precipitation. The opposite response was observed for the wettest site at the highest elevation, which positively reacts to increased summer temperature and will most likely benefit from a warming climate. For all other sites, the future radial growth of Norway spruce largely depends on the balance between spring precipitation and summer temperature.
Keywords: Vaganov-Shashkin model, climate-growth correlations, tree rings, process-based modelling, dendroTools, dendroclimatology
Published in DiRROS: 21.10.2020; Views: 1224; Downloads: 979
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17. Določanje vlažnosti drv z električnim uporovnim merilnikomPeter Prislan, Domen Arnič, Špela Ščap, Nike Krajnc, Aleš Straže, 2020, professional article Abstract: Vsebnost vode (vlažnost) je med pomembnejšimi kazalniki kakovosti drv. Za čim učinkovitejše in okolju prijazno delovanje Uredba o emisiji snovi v zrak iz malih kurilnih naprav navaja, da mora biti vsebnost vode v drveh manj kot 20 %. Za hitro preverjanje vsebnosti vode v drveh bi bila smiselna uporaba električnih uporovnih merilnikov. V pričujočem prispevku primerjamo meritve, opravljene z elektrouporovnimi merilniki različnih izvedb ter referenčno gravimetrično metodo. Rezultati kažejo, da gravimetrični metodi najbolj primerljive rezultate kažejo uporovni merilniki, ki omogočajo kompenzacijo gostote lesne vrste in temperature. V prispevku razpravljamo o uporabi različne terminologije in definicije lesne vlažnosti (t.j. relativna in absolutna vlažnost lesa, vsebnost vode) ter predlagamo postopek za čim boljšo oceno vlažnosti z enostavnimi elektro-uporovnimi merilniki.
Keywords: lesna goriva, lesna biomasa, vsebnost vode, kakovost drv
Published in DiRROS: 06.04.2020; Views: 2104; Downloads: 654
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18. Raba lesa v slovenskem biogospodarstvuDomen Arnič, Peter Prislan, Luka Juvančič, 2019, original scientific article Abstract: Krčenje zalog fosilnih goriv, netrajnostno izkoriščanje naravnih virov in podnebne spremembe so dejavniki, ki pospešujejo prehod v biogospodarstvo. Tovrsten prehod omogočajo tehnologije in novo znanje pretvorbe biomase v različne produkte, med seboj povezane v kaskadnih in (energetsko in snovno) krožnih proizvodnih ciklih. Eno ključnih področij biogospodarstva je področje rabe lesa, ki trenutno prispeva eno tretjino k skupni dodani vrednosti slovenskega biogospodarstva. Glede na stanje v državah s primerljivimi naravnimi in strukturnimi danostmi Slovenija v razvoju biogospodarstva zaostaja. V pričujočem delu smo predstavili generične dejavnike, ki vplivajo na razvoj biogospodarstva ter pripravili pregled stanja slovenskega biogospodarstva na področju rabe lesa. Stanje slovenskega biogospodarstva uvrščamo v širši evropski okvir ter ocenjujemo nadaljnje možnosti razvoja rabe lesa.
Keywords: biogospodarstvo, lesna biomasa, obnovljivi viri energije, raba lesa, biorafinerije, kaskadna raba lesa
Published in DiRROS: 20.12.2019; Views: 2604; Downloads: 751
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19. Primerjava izbiralnega redčenja in situacijskega redčenja v bukovih letvenjakih na MeniniDomen Arnič, Janez Krč, Jurij Diaci, 2018, original scientific article Abstract: Nazadovanje opravljanja nege ob večanju stroškov dela je privedlo do razmer, ko je treba proučiti možnosti izboljševanja ustaljenih načinov nege. S tem namenom smo v bukovih letvenjakih na območju Menine naredili primerjalno raziskavo med izbiralnim redčenjem in situacijskim. Postavili smo osem raziskovalnih ploskev, po štiri za vsak način redčenja. Naredili smo analize mešanosti, gostot in plastovitosti sestojev, odkazil, popisov izbrancev ter ciljnih dreves, časovno študijo in oceno težavnosti dela s pomočjo merilnika srčnega utripa. Ugotovili smo, da v rasti in globini krošenj svetloljubne drevesne vrste zaostajajo za bukvijo. Pri situacijskem redčenju sta bili značilno manjši poraba časa za posek ter poraba goriva in maziva. Poraba časa na konkurenta je bila med načinoma primerljiva. Težavnost dela se med načinoma redčenj ni razlikovala.
Keywords: nega mladega gozda, situacijska nega, situacijsko redčenje, izbiralno redčenje, racionalizacija
Published in DiRROS: 07.03.2018; Views: 3279; Downloads: 798
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