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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. Nasl. z nasl. zaslona. Opis vira z dne 8. 4. 2022. Bibliografija: str. 11-13.

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. Wood density is an important physical property that can be easily measured and is closely related to many other wood properties. Furthermore, wood density is a good indicator of the usability and applicability of wood in the wood processing, construction and energy industries. Because it is strongly dependent on moisture content and porosity, there are various definitions of wood density in the literature, among which the density measured on the basis of dry matter and volume is the most commonly used. The aim of this paper is to present different methods for wood density determination and the importance of collecting such data for the development of the forest-based bioeconomy. In practice, there are several direct and indirect methods of density measurement in addition to the most basic volumetric approach, the density of wood can be measured by penetrometer, resistograph, high frequency densitometry, X-rays, near infrared spectroscopy and microwaves. Wood will continue to grow in importance, as it is one of the key raw materials for the transition to a sustainable bioeconomy. The accurate and timely determination of wood density allows for the appropriate distribution and direction of flows of this raw material between individual conventional and new sectors (areas of use) and thus its more efficient and sustainable use.

Persian oak (Quercus brantii Lindl.) is a valuable native species in Iranian forests with very limited availability of data on its wood properties. The objective of the current study was to determine the influence of altitude and slope on physical properties and fiber dimensions of Persian oak wood. In addition, the relationship among wood properties, site conditions (temperature and rainfall) and growth traits of trees (tree height, DBH, basal area, age, crown diameter, crown basal area, volume and annual diameter increment) were studied by principal component analysis (PCA). Three altitude levels (1730, 1980 and 2250 m) and three slope classes (&lt, 30%, 30&ndash, 45% and &gt, 45%) were considered in the current study. It was determined that trees growing in the intermediate altitude (1980 m) showed the highest oven-dry density values, and those in the lowest altitude (1730 m) revealed the lowest ones. The results also indicate significant statistical differences between altitude levels and slope classes on the fiber length, fiber diameter and volumetric swelling at the 99% confidence interval while no significant differences were found between average values of oven-dry density among different altitudes and slopes. PCA analysis indicated that altitude and temperature are the most important factors affecting the wood properties. Knowledge of the relationship between wood properties and environmental factors are essential in terms of both forestry management and wood applications.

Proučili smo vlažnost in gostoto lesa ter zunanje morfološke spremembe na različno prizadetih drevesih navadne bukve (Fagus sylvatica L.) ob koncu prve vegetacijske dobe po velikem žledolomu v Sloveniji v letu 2014. Potrdili smo povezanost med deležem še aktivnega koreninskega sistema in stopnjo porjavelosti (izsušenosti) krošnje dreves ter porazdelitvijo vlažnosti lesa v deblih dreves. Pri najbolj prizadetih drevesih smo v prevodnem zunanjem delu beljave potrdili padec vlažnosti lesa pod mejo naravne biološke odpornosti (u < 60 %). Po prvi vegetacijski dobi, nismo potrdili splošnega padca gostote lesa (in z njim povezanega poslabšanja mehanskih lastnosti), ki bi bil posledica okužbe in razkroja lesa z glivami Moisture content and wood density of variously damaged uprooted European beech (Fagus sylvatica L.) trees were studied at the end of the first vegetation period after ice storm damage in Slovenian forests in 2014. The study confirmed significant correlation between the amount of active root system and necrosis of leaves and changed moisture content and its distribution in the trunks. The moisture content of wood below 60 % was confirmed in sapwood of extremely damaged trees, indicating diminished protection against wood destroying organisms. We could not confirm any reduction of wood density which would indicate deterioration of wood at the end of the first vegetation period after ice storm damage

Bori v gozdovih Slovenije predstavljajo približno 6 % lesne zaloge. Predhodne raziskave so pokazale, da med rastišči obstajajo razlike, tako v pojavnosti obsega in intenzivnosti jedrovine, kot tudi v širini branik. V literaturi ni mogoče najti natančnih podatkov o zvezi med deleži ranega in kasnega lesa ter dimenzijsko stabilnostjo. Dimenzijska stabilnost je pomembna z vidika uporabe lesa in ni odvisna le od ojedritvenih procesov ter od deleža ekstraktivnih snovi v lesu. S pomočjo finega brušenja in visoko-ločljivostnega skeniranja smo izdelali kvalitetne fotografije površin lesa na prečnih prerezih rdečega bora. S programsko opremo NIS-Elements ter ImageJ smo dobili razmerje med ranim in kasnim lesom ter izmerili širine branik. Pridobljene parametre posameznega vzorca smo nato uporabili za preučevanje korelacij med širinami branik ter deleži ranega in kasnega lesa, gostoto in dimenzijsko stabilnostjo. Rezultati so pokazali, da so drevesa iz ugodnejših rastišč imela les s širšimi branikami, ki je imel večji delež ranega lesa. Les z večjim deležem ranega lesa je imel manjše skrčke in nižjo gostoto. Vzorci lesa z ožjimi branikami so imeli večji delež kasnega lesa, večji volumski srček in večjo prečno krčitveno anizotropijo. Istočasno pa ima les z ožjimi branikami višjo gostoto in z njo povezane boljše mehanske lastnosti. Pines in the forests of Slovenia represent approximately 6% of the forest stock. Previous studies have shown that there are differences between habitats, in both the incidence of scale and intensity of heartwood, as well as the width of the growth rings. No accurate data is possible to find in the literature on the relationship between the shares of early and late wood and dimensional stability. Dimensional stability is important in terms of the use of wood and does not depend only on the enzymatic processes and on the portion of extractive substances in the wood. With fine grinding and high-resolution scanning we made high quality photos of the surfaces of wood on the cross-sections of Scotch pine. With computer software NIS-Elements and Image-J we calculated the ratios between early wood and late wood and we measured the width of the growth rings. Then we used gathered data of each sample to study correlations between widths of the growth rings and percentage of early and late wood, between density and dimensional stability. Results showed that the trees from better growth sites had wood with wider growth rings and bigger percentage of early wood. Wood with bigger percentage of early wood had smaller shrinkage and lower density. Wood samples with narrower growth rings had bigger percentage of late wood, bigger volume shrinkage and bigger transverse anisotropy. At the same time the wood with narrower growth rings has higher density and better mechanic properties correlated to higher density.

Navadna smreka (Picea abies (L.) Karst.) je zaradi svoje razširjenosti, zgradbe lesa in dolge življenjske dobe razmeroma pogost objekt dendrokronoloških raziskav. Doslej objavljene slovenske smrekove kronologije so bile sestavljene na podlagi širin branik, prispevek pa predstavlja prve denzitokronologije v Sloveniji in opisuje metodo določanja maksimalne gostote kasnega lesa branike (MXD). Raziskava je potekala na dveh različnih smrekovih rastiščih - Pokljuki in Sorškem polju. Na obeh lokacijah smo v vzorec zajeli po 13 dreves. Rezultati, dobljeni na Sorškem polju, so pokazali višje vrednosti MXD in manjše število značilnih let. Analiza je pokazala tudi pozitivno korelacijo med MXD in temperaturami v avgustu in septembru. Norway spruce (Picea abies (L.) Karst.) is frequently the object of dendrochronological research owing to its distribution, wood structure and longevity. The Norway spruce chronologies published in Slovenia so far have been based on tree-ring widths. This article presents the first density chronologies and describes the method of determining maximum latewood density (MXD). Two different sampling sites were selected (Pokljuka and Sorško polje) and 13 sampling cores were taken from each site. The results showed positive correlation between MXD and temperatures in August and September. Furthermore,higher MXD values and less pointer years were observed at the lowland Sorško polje site.

Proučili smo fizikalne lastnosti (vlažnost in gostoto) lesa različno prizadetih izruvanih dreves navadne bukve (Fagus sylvatica L.) ob koncu prve vegetacijske dobe po velikem žledolomu v letu 2014. Raziskava je potrdila povezavo med deležem še aktivnega koreninskega sistema in stopnjo porjavelosti (izsušenosti) krošnje dreves ter vlažnostjo lesa in njenim razporedom. Pri zelo prizadetih drevesih smo v prevodnem zunanjem delu beljave potrdili zmanjšanje vlažnosti lesa pod mejo naravne biološke odpornosti (u < 60 %). Po prvi vegetacijski dobi nismo mogli potrditi zmanjšanja gostote lesa (in z njim povezanega poslabšanja mehanskih lastnosti), kar bi potrdilo okužbo in razkroj lesa z glivami. Physical properties (moisture content and density) of wood of variously damaged uprooted European beech (Fagus sylvatica L.) trees were studied at the end of the first vegetation period after the ice storm damage in Slovenian forests in 2014. The research confirmed significant correlation between the amount of active root system and necrosis of leaves and changed moisture content and its distribution in the trunks. The moisture content of wood below 60 % (indicating extinguished protection against wood destroying organisms) was found in sapwood of extremely damaged trees. At the end of the first vegetation period after damage we could not confirm any reduction of wood density (and reduced mechanical properties) which would indicate deterioration of wood.

Dimenzijske spremembe in vpliv variabilne zgradbe lesa smo proučevali na jedrovini, mladostnem lesu in beljavi evropskega macesna (Larix decidua Mill.) ter na jedrovini sibirskega macesna (Larix sibirica (Münch) Ledeb.). Dimenzijsko stabilnost smo ugotavljali s spremljanjem krčenja (ß) in nabrekanja (alfa) ter z določanjem kazalnikov dimenzijske stabilnosti: diferencialnega nabreka (q), koeficienta nabrekanja (h) v radialni in tangencialni smeri ter sorpcijskega kvocienta (s). Prirastne značilnosti smo ocenili iz širin ranega in kasnega lesa, kjer smo določili tudi gostoto smolnih kanalov. Ugotovili smo, da med evropskim in sibirskim macesnom ni statistično značilnih razlik v dimenzijski stabilnosti lesa. Med seboj sta si najbolj podobna jedrovina in mladostni les evropskega macesna. Pri vseh meritvah je imel les sibirskega macesna najmanjšo variabilnost. The swelling and shrinking of juvenile wood, sapwood and heartwood of European larch (Larix decidua Mill.) were compared to Siberian larch (Larix Sibirica (Münch) Ledeb.) heartwood. The dimensional stability was examined by observation of shrinking (ß) and swelling, and by determining the indicators of dimensional stability: differential swelling (q), swelling coefficient (h) in radial and tangential direction, and by sorption quotient (s). The growth characteristics were assessed from width of earlywood and latewood, where the resin duct density was also determined. There were no statistically distinctive differences between European and Siberian larch in wood dimensional stability. The heartwood and juvenile wood of European larch were very similar. In all measurements the wood of Siberian larch had the lowest variability.