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The importance of renewable and environmentally acceptable materials in the construction industry is increasing. Wood is one of the most important construction materials and its use in building applications has further expanded in recent decades, mainly due to the development of modern composites, firstly glue lam, OSB (Oriented Strand Board), LVL (Laminated Veneer Lumber) and a considerable breakthrough was later achieved with the development of cross-laminated timber. In order to enable even more extensive and reliable use of wood in outdoor applications, factors affecting a wood’s service life need to be understood. It is well known that fungal degradation of wood is predominantly affected by temperature and wood moisture content. In order to elucidate the influence of these two factors, long-term monitoring of temperature, relative humidity and moisture content at the newly-built Annex of the Department of Wood Science and Technology was carried out. The Annex is designed from CLT composites and glue-lam beams and was finished in December 2015. The results clearly show that microclimatic conditions in the monitored building in the first years of use are far below the limit required for fungal decay or mould growth.

Na podlagi meritev v obdobju 1962–2017 smo na raziskovalnih ploskvah na nekdanjih novinah v katastrski občini Koprivna izračunali debelinske, višinske in volumenske prirastke za najpomembnejši drevesni vrsti - smreko in macesen. Na raziskovalnih ploskvah, ki so bile prepuščene naravnemu razvoju, so srednjetemeljnični premeri manjši, število dreves pa večje od tistih v primerljivih gospodarskih gozdovih. V zadnjih tridesetih letih se je zaradi visokih sestojnih gostot zmanjšalo debelinsko priraščanje dreves smreke in macesna. Z dendrokronološko analizo smo ocenili vpliv klimatskih dejavnikov na priraščanje smreke in macesna. Na podlagi dendrokronološke analize smo ugotovili, da se leta z negativnim odzivom dreves v debelinskem prirastku od leta 1984 pojavljajo pogosteje. Based on previous measurements from 1962 to 2017 on forest research plots located on former slash-and-burn farming areas in the cadastral municipality of Koprivna, the diameter and height increment as well as volume increments of the two main tree species - spruce and larch - were calculated. These set-aside natural research plots have a smaller mean basal area diameter, but the number of trees is higher than in comparable managed forests. Due to the high-density of tree stands over the past thirty years, radial increment of spruce and larch has declined. To determine the influence of environmental factors on radial growth of spruce and larch, a dendrochronological analysis was conducted. According to the dendrochronological analysis of radial increment of trees, the number of years with a negative response has been higher since 1984.

Flame treatment is an ancient technique for surface protection of wood. Further processing of charred wood elements depends on aesthetic and protective requirements. This study presents some general properties and weathering behaviour of the Norway spruce (Picea abies (L.) Karst.) and the European larch (Larix decidua Mill.), protected by variations of sanding, charring, charring + brushing, and coating treatments. Charring and charring + brushing reduced the original mass of the samples by up to 8% and notably changed their colour (ΔE* ≤ 75). A study of chemical properties showed that charring dehydrated the wood and degraded lignin and hemicelluloses. The surface roughness of the wood after charring and charring + brushing increased by as much as 560%, while coating with waterborne acrylic high build stain had no effect on the roughness of these surfaces. The type of surface treatment of the wood did not affect the uptake of the coating in the wood samples, but the uncoated and coated spruce wood absorbed more water than larch wood. Higher water absorption was observed in the samples treated by charring, and it decreased when the char layer was removed by brushing. The film of a waterborne high build stain reduced water uptake only for surfaces treated by sanding and charring + brushing. Larch wood exhibited higher surface hardness (EHz ≤ 1.70 MPa) than spruce wood (EHz ≤ 0.89 MPa), with the brittle char layer reducing the determined hardness of the tested surfaces. During two years of natural weathering, the char layer was removed from the wood surface, even if the samples were additionally coated. The greatest colour changes during weathering were observed on samples treated by sanding (ΔE* ≤ 60) and sanding + coating (ΔE* ≤ 33), followed by samples treated with charring + brushing (ΔE* ≤ 10) and samples treated with charring (ΔE* ≤ 9). In summary, treating wood by charring in combination with brushing was the best wood protection technique.

Tree recruitment models are important for predicting the dynamics of uneven-aged forests. Previous studies of recruitment of European beech, Norway spruce and silver fir have shown different ecological amplitudes of these species. However, recruitment in uneven-aged stands and the values of environmental factors at which the greatest and poorest recruitment can be expected remain poorly explained. The main objectives of this study were to 1) explain how 39 stand, site and climatic factors and their interactions influence the number of recruited trees in uneven-aged forests; 2) determine the optimal and critical ranges of influential factors, including stand basal area, number of trees, proportion of tree species, shade casting, soil pH, site productivity, temperature and precipitation; and 3) estimate the maximum expected response of recruitment to changes in stand density while controlling for the effect of other limiting factors. A Tobit censored regression model was used to consider that the observed range of the number of recruited trees is censored at zero. The models were parametrized and validated using 30,963 forest inventory plots (200 m2 each) in uneven-aged forests in Slovenia. The models, which used 9 stand, 6 site and 3 climatic factors, explained 15 %, 10 % and 8 % of the total variation of the number of recruited spruce, fir and beech, respectively. Stand structure was the most important factor, with stand basal area (BA) and the proportion of the studied species having the greatest effect. Site factors including soil pH and rockiness were important for fir recruitment. The number of recruited beech and spruce was positively influenced by decadal precipitation. Higher temperatures decreased recruitment of spruce. Beech was the only species sensitive to shade casting. Recruitment of beech was higher if shade was imposed by tree species other than beech. The optimal and critical ranges of limiting factors differ between species. The model suggests that the optimal stand basal area for recruitment of beech is ≤ 19 m2/ha, which is higher than that for spruce (≤ 16 m2/ha) but lower than that for fir (≤ 28 m2/ha). The maximum predicted response of the studied species to changes in stand basal area shows that stand density control is efficient for regulating recruitment of spruce and beech, but not for fir. The suggested sensitivities and threshold values may be used in individual tree growth models or simulation–optimization studies in support of forest management decisions. Nasl. z nasl. zaslona. Opis vira z dne 5. 12. 2022. Bibliografija: str. 11-13.

Wood coatings prolong the service life of wood-based products, but they are usually of synthetic origin. The aim of the present article is to reduce the fossil-based compounds in a commercial waterborne acrylic coating by CNC addition and to test its performance. The coatings were applied on European beech and Norway spruce wood in order to test durability against Gloeophyllum trabeum (brown wood rot) and Trametes versicolor (white wood rot). Artificial weathering and blue stain, contact angle, physical tests (adhesion, impact and scratch test), chemical (FTIR) and morpho-anatomical analysis (SEM) were carried out. CNC addition increased viscosity, limiting the spreading of the coating into wood pores as visible after SEM observation, which reduced coating adhesion on the substrate. CNC improved fungal resistance as seen by a reduced mass loss and FTIR spectroscopy thanks to crosslinks formation, which reduced water sorption as well. Color change was not significant, and, on the other hand, glossiness was reduced but resulted as more homogeneous than control. CNC addition gave good results also in blue stain protection. CNC improved scratch resistance, but no visible change to impact was registered. CNC has promising results in coatings depending on wood and fungal species and presence of further commercial additives (biocides).

Norway spruce (Picea abies) is one of the most important commercial conifer species naturally distributed in Europe. In this paper, the composition and abundance of essential oil and hydrosol from the needles and branches of P. abies were investigated with an additional evaluation of changes related to different times of the year, annual shoots and branches, and differences in composition under different microenvironments. Essential oils and hydrosols obtained via hydrodistillation were analyzed using gas chromatography–mass spectrometry (GC-MS), where 246 compounds in essential oil and 53 in hydrosols were identified. The relative amounts of monoterpenes, sesquiterpenes, and diterpenes in essential oil changed significantly during the year, with the highest peak of monoterpenes observed in April (72%), the highest abundance of sesquiterpenes observed in August (21%), and the highest abundance of diterpenes observed in June (27%). The individual compound with the highest variation was manool, with variation from 1.5% (April) to 18.7% (June). Our results also indicate that the essential oil with the lowest allergenic potential (lowest quantity of limonene and linalool) was obtained in late spring or summer. Location had no significant influence on composition, while the method of collection for distillation (whole branch or annual shoots) had a minor influence on the composition. All nine main compounds identified in the hydrosol samples were oxygenated monoterpenes. The composition of P. abies hydrosol was also significantly affected by season. The method of preparing the branches for distillation did not affect the composition of P. abies hydrosol, while the location had a minor effect on composition.

Nasl. z nasl. zaslona. Opis vira z dne 3. 2. 2023.

Phase change materials (PCMs) are ideal for thermal management solutions in buildings. This is because they store and release thermal energy during melting and freezing. Spruce (Picea orientalis (L.) Peterm.) sapwood was impregnated with n-heptadecane (100%) as a PCM. The decay-resistance properties and thermal energy storage (TES) characteristics of the n-heptadecane-impregnated wood were studied. The phase change properties of n-heptadecane (nHD)-impregnated wood were characterized by Fourier-transform infrared (FTIR), thermogravimetry (TGA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses. As confirmed by DSC analysis, nHD-impregnated wood demonstrated moderate performance in storing and releasing heat during the phase change process. Significant increases were observed in the 2800–3000 cm−1 and 1471 cm−1 peaks in FTIR spectra of wood samples impregnated with nHD, which showed C–H stretching in methyl and methylene groups and asymmetric deformation vibration of the paraffin methyl group (CH3–) and C–O stretch in lignin, respectively. It was observed that there was a change in the crystal structure of spruce wood samples after nHD impregnation. This study revealed that PCMs are resistant to wood-destroying fungi. The performance of nHD-impregnated spruce wood proves that it can be used as a thermal regulating building material to reduce energy consumption. In addition, it has been proven on a laboratory scale that the PCM used is highly resistant to biological attacks. However, large-scale pilot studies are still needed.

Namen diplomske naloge je bil preučiti vpliv izpostavljenosti lesene strešne kritine vremenskim in biološkim dejavnikom. Ugotoviti smo hoteli tudi kako različne tehnike zaščite vplivajo na povečevanje trajnosti in življenjsko dobo skodel. V diplomski nalogi smo omenili, kako se je lesena kritina skozi leta razvijala in kako posamezne lastnosti lesa vplivajo na trajnost, ter katere lastnosti hočemo izboljšati za boljše rezultate. Zanimale so nas tudi razlike, ki so se pojavile na pokritih in izpostavljenih delih skodel. Eksperimentalno delo smo pričeli z dokumentacijo in izdelavo vzorcev nezaščitene, termično modificirane in s Silvanolinom zaščitene smrekovine. Vzorcem smo določili hrapavost, vodoodbojnost (stični kot), tlačno trdnost in količino preostalega bakra. Po obdelavi in analizi podatkov smo ugotovili in potrdili, da je zaščita lesenih streh nujna. Po osmih letih uporabe nismo zabeležili razlik v kakovosti zaščite s Silvanolinom in termično modifikacijo. Do razlik prihaja le v ceni in estetiki, kar pa je velikokrat zelo pomembno pri odločitvi za kaj se odločimo. The aim of this thesis was to investigate the influence of weathering and biological factors on wooden roofs. We also wanted to find out how different protection techniques affect the durability and service life of shingles. In the thesis, we reviewed how wood roofing has evolved over the years and how each property of wood affects sustainability, and which properties we wanted to improve for better results. We were also interested in the differences that occur on the covered and exposed parts of the shingle. We began the experimental work by documenting and making samples of unprotected, thermally modified, and Silvanolin-protected spruce wood, from which we then determined the roughness, water repellency (contact angle), compressive strength, and amount of copper remaining in them. After processing and analyzing the data, we determined and confirmed that the protection of wooden roofs is necessary. After eight years of application, we did not find any differences in the quality of protection with Silvanolin and thermal modification. The differences are only in terms ofprice and colour, although these are often very important factors when choosing a product.

Drevesne vrste vplivajo na tla z vnosom nadzemnega in podzemnega opada, absorpcijo hranil in vode iz različnih plasti tal ter s sodelovanjem z različnimi talnimi organizmi. V magistrski nalogi smo preučevali vpliv dveh drevesnih vrst na kemijske lastnosti tal, mikrobno biomaso in sestavo talnih mikrobnih združb. Tla smo vzorčili v bukovem (Fagus sylvatica L.) in smrekovem (Picea abies (L.) Karsten) sestoju z isto združbo tal na isti matični podlagi. Na lokaciji bukovega sestoja je bil pred 20-30 leti mešani sestoj jelke, smreke in bukve, v katerem je jelka prevladovala. Vsebnost skupnega organskega C (Corg), skupnega N, topnega Corg in topnega N je bila v zgornjih 10 cm tal značilno večja v smrekovem kot v bukovem sestoju (11,54 vs. 9,00 % 0,63 vs. 0,52 % 15,30 vs. 9,45 mg C kg-1 suhih tal 2,90 vs. 1,65 mg N kg-1 suhih tal zaporedoma). V bukovem sestoju pa je bila, v primerjavi s smrekovim, na tej globini večja nasičenost z izmenljivimi bazičnimi kationi (84,60 vs. 43,60 %), predvsem Ca. Značilnih razlik v pH tal med sestojema nismo zaznali, kar kaže na veliko puferno sposobnost tal in s tem počasen odziv pH na spremembe v sestavi sestoja. Mikrobni biomasni ogljik, določen z metodo fumigacije s kloroformom, je bil v zgornji globini značilno večji v smrekovem v primerjavi z bukovim sestojem (584,66 vs. 491,98 mg C kg-1 suhih tal). To pa ne velja za mikrobni biomasni dušik in mikrobno biomaso ocenjeno s količino skupne DNK, kjer nismo zaznali značilnih razlik. Številčnost mikrobne združbe bakterij, gliv in krenarhej smo določili s kvantitativno verižno reakcijo s polimerazo (qPCR). Značilnih razlik med sestojema v številčnosti bakterij in gliv ni bilo. Značilno večja številčnost je bila pri krenarhejah v smrekovem sestoju v spodnji globini, v zgornji pa je bila ta mejna (p = 0,053). Rezultati te študije so pokazali vpliv drevesnih vrst na izbrane lastnosti tal, vendar bi bilo, upoštevajoč, da sestoja nista bila povsem primerljiva, smiselno preveriti tudi vpliv starosti sestoja in primerljivost ostalih okoljskih razmer. Potrebne so nadaljnje bolj poglobljene študije sestave mikrobnih združb, npr. mikoriznih gliv. Tree species influence the soil by adding above- and below-ground litter, absorbing nutrients and water from different soil layers, and interacting with different soil organisms. In this master thesis, the influence of two tree species on soil chemistry, microbial biomass, and community composition was investigated. Soil was sampled down to parent material in beech (Fagus sylvatica L.) and spruce (Picea abies (L.) Karsten) stand with the same soil group on the same parent material. In the place of the beech stand, there was a mixed stand of fir, spruce and beech 20-30 years ago, dominated by fir. The contents of total organic C (Corg), total N, soluble Corg, and soluble N in the top 10 cm of soil were significantly higher in the spruce than in the beech stand (11.54 vs. 9.00 % 0.63 vs. 0.52 % 15.30 vs. 9.45 mg C kg-1 dry soil 2.90 vs. 1.65 mg N kg-1 dry soil respectively). Beech stand was found to have a higher base saturation compared to the spruce stand at this depth (84.60 vs. 43.60 %), mainly Ca. No significant differences in soil pH were observed, indicating a high buffering capacity of the soil and thus a slow response of pH to changes in stand composition. Microbial biomass C, determined by the chloroform fumigation method, was significantly higher in the spruce stand compared to the beech stand in the upper depth (584.66 vs. 491.98 mg C kg-1 dry soil). This is not the case for microbial biomass N and microbial biomass estimated by the total DNA, for which we found no significant differences. The abundance of the total microbial community, bacteria, fungi and Crenarchaea, was determined by quantitative polymerase chain reaction (qPCR). There were no significant differences in the abundance of bacteria and fungi. Significantly higher abundance was observed for Crenarchaea in the spruce stand at the lower depth, while it was marginal at the upper depth (p = 0.053). The results of this study showed the influence of tree species on selected soil properties, but given that the two stands were not entirely comparable, it would be worthwhile to also check the influence of stand age and the comparability of other environmental conditions. Further, more in-depth studies on the composition of microbial communities, e. g. mycorrhizal fungi, are needed.

Plasma treatment is becoming a mature technique for modification of surfaces of various materials, including wood. A better insight in the treatment process and the impact of the plasma on properties of wood bulk are still needed. The study was performed on Norway spruce and common beech wood, as well as their thermally modified variations. The formations of the airborne discharge, as well as mass changes of the treated wood, were monitored. The impact of such treatment on wood-coating interaction was investigated by evaluating the dynamic wettability and penetration into wood. At the wood surface, plasma streamers were observed more intense on denser latewood regions. Wood mass loss was higher with increasing number of passes through the plasma discharge and was lower for thermally modified wood than for unmodified wood. Plasma treatment increased the surface free energy of all wood species and lowered the contact angles of a waterborne coating, these together indicating enhanced wettability after treatment. Finally, the distribution and penetration depth of the coating were studied with X-ray microtomography. It was found that the coating penetrated deeper into beech than into spruce wood. However, the treatment with plasma increased the penetration of the coating only into spruce wood.

Naravno pomlajevanje visokogorskih gozdov je upočasnjeno. Nanj vplivajo številni dejavniki, njihovo poznavanje je pomembno za gozdnogojitveno ukrepanje in nadaljnje gospodarjenje. Leta 2020 smo v visokogorskem smrekovem gozdu na severnem pobočju na Pohorju pod Veliko Kopo analizirali pet starih vrzeli, velikih od 0,09 do 0,16 ha in starih približno 34 let, ter mladje v njih. Mladje je bilo raznodobne strukture in glede na gostote, zastiranje, višine in višinsko priraščanje najbolj razvito v osrednjem in severnem (prisojnem) delu vrzeli. Iz analize lahko potrdimo velik pomen svetlobe za naravno obnovo na proučevanih rastiščih. Pomembni so tudi drevesni ostanki. Začetna velikost vrzeli je bila primerna za obnovo, vendar bi bilo vrzeli smiselno postopno širiti proti severu, pri tem je smotrno upoštevati ekološke dejavnike. Natural regeneration of high mountain forests is slow. It is influenced by many factors, the knowledge of which is important for silvicultural measures and future management. In 2020, we analysed regeneration in five approximately 34-year-old gaps, ranging in size from 0.09 to 0.16 hectare in a high mountain spruce forest on the northern slope of the Pohorje Mountain below Velika Kopa. The young trees were of heterogeneous structure and, in terms of densities, coverage, heights, and height increment, were most developed in the central and northern (sunward side) part of the gap. The analysis confirms the high importance of light for natural regeneration in the studied sites. Woody debris was also important. The initial size of the gap was suitable for regeneration, but later it would be reasonable to gradually extend the gap northwards, taking ecological factors into account.

Na desetih drevesih smreke z rastišča pod Karavankami smo vizualno ocenjevali kakovost lesa, ter jo primerjali s kakovostjo izdelanih 4 m dolgih sortimentov po višini posameznega drevesa. K vizualnemu ocenjevanju smo dodali še nedestruktivno določanje kakovosti. Na prsni višini stoječih dreves smo z napravo Arborsonic 3D® izdelali akustične tomografe, pri izdelani hlodovini pa smo z analizo frekvenčnega odziva določali vzdolžno hitrost zvoka. Na posameznih sortimentih po celotni višini dreves smo na osnovi radialnih izvrtkov dodatno izvedli še dendrokronološko analizo. Po višini dreves, od koreničnika do krošnje, se je kakovost izdelane hlodovine zmanjševala, večinoma zaradi števila in velikosti grč ter prisotnosti juvenilnega lesa. Tangencialna hitrost na obodu dreves, izmerjena z 2D akustičnim tomografom, je bila nižja pri drevesih z večjim prirastkom v adultnem obdobju. Povprečna vzdolžna hitrost zvoka je pri hlodovini kakovostnega razreda B in C znašala posamično 4196 m/s in 4155 m/s. Značilno nižjo hitrost zvoka 3714 m/s smo potrdili v najslabšem D-kakovostnem razredu. Ti sortimenti so večinoma izhajali iz 5. (16 – 20 m) in 6. vertikalne pozicije (> 20 m) v drevesih. Hlodovino tega kakovostnega razreda je mogoče na osnovi vzdolžne hitrosti zvoka zanesljivo razvrščati in ločiti od preostalih bolj kakovostnih sortimentov. We visually assessed the quality of ten spruce trees from a site below the Karavanke Mountains and compared it with the quality of 4-m-long logs made along the height of a single tree. The visual assessment was supplemented by a non-destructive method. For this purpose, acoustic tomographs were made at breast height of standing trees using the Arborsonic 3D® instrument, and longitudinal sound velocity was determined by longitudinal vibrations in the logs. We also performed an analysis of the radial growth of the wood on individual logs along the height of the trees. Depending on the height level in the trees, from the stump to the top, the quality of the logs produced decreased, mainly due to the number and size of branches, knots and the presence of juvenile wood. The tangential velocity at the circumference of trees measured with a 2D sonic tomograph was lower for trees with wider growth rings of adult wood. The average longitudinal sound velocity for logs in quality classes B and C was 4196 m/s and 4155 m/s, respectively. A much lower sound velocity of 3714 m/s was found in the poorest quality class D. These worst class logs mostly came from the 5th (16 - 20 m) and 6th vertical positions (> 20 m) in the trees. Logs of this quality class can be reliably sorted and separated from other assortments of higher quality based on longitudinal sound velocity.

Non-native forest tree species have been introduced in Europe since the 16th century, but only in the second half of the 20th century the significance of the seed source origin for their economic use was recognized, resulting in the establishment of numerous provenance trials at a national, regional, European and International level, as those led by IUFRO. Breeding programs have also been launched in the continent for the most economically important species. Aim of this work is the formulation of provenance recommendations for planting of five non-native tree species in Europe (Douglas fir, grand fir, Sitka spruce, lodgepole pine and black locust), based on the information obtained from twenty countries, in the frame of the EU FP-1403 NNEXT Cost Action. The survey revealed that official and non-official national recommendations, based on provenance research results, have been elaborated and followed at a different level and extend for the above five species, but only for Douglas fir recommendations exist in almost all the participating to the survey countries. The compilation of provenance recommendations across Europe for each species is presented in the current work. Besides the recommended introduced seed sources, European seed sources are also preferred for planting, due to ease of access and high availability of forest reproductive material. European breeding programs yielding genetic material of high productivity and quality constitute currently the seed source of choice for several species and countries. Consolidation of trial data obtained across countries will allow the joint analysis that is urgently needed to draw solid conclusions, and will facilitate the development of ‘Universal-Response-Functions’ for the species of interest, rendering possible the identification of the genetic material suitable for global change. New provenance trial series that will test seed sources from the entire climatic range of the species, established in sites falling within and outside the environmental envelopes of their natural ranges, are urgently needed to pinpoint and understand the species-specific climate constraints, as well as to correlate functional traits to the seed origin and the environmental conditions of the test sites, so that the selection of suitable forest reproductive material of non-native tree species in the face of climate change can be feasible.

We present xylem formation in Norway spruce (Picea abies (L.) Karst.) in 2015 at Panška reka, near Ljubljana, Slovenia (ca. 46°00'N, 14°40'E, 400 m a.s.l.) with a temperate climate. The research was a part of a long-term project, which involves different sites and tree species. We measured the widths of cambium and the formation of xylem growth rings with differentiating cells in postcambial (PC) and secondary wall formation (SW) phases, and mature cells (MT). The results for 2015 were compared with those for previous years (2009%2011) in the same species and site, and with the published data from wood formation studies in conifers from all over Europe. The latter were used in two-factor regression models which confirmed the effects of latitude and altitude on the critical dates of onset, end, and duration of xylem production. The models thus helped us to predict/reconstruct phenology of wood formation in conifers in Europe Študija prikazuje nastajanje lesa smreke (Picea abies (L.) Karst.) v rastni sezoni 2015 na rastišču Panška reka v bližini Ljubljane (pribl. 46°00'N, 14°40'E, 400 m n.v.). Raziskava je del večletnega projekta spremljanja nastajanja lesa več drevesnih vrst na različnih rastiščih. V okviru raziskave smo spremljali širino kambijeve cone ter nastajajoče branike lesa, kjer smo ločili celice v fazah postkambialne rasti (PC) in nastajanja sekundarne celične stene (SW) ter zrele (MT) celice. Rezultate smo primerjali z ugotovitvami študije, opravljene na smreki z istega rastišča v rastnih sezonah 2009%2011 ter s podatki, objavljenimi za več vrst iglavcev z različnih rastišč po Evropi. Primerjave smo uporabili za izdelavo regresijskih modelov z dvema neodvisnima spremenljivkama. Modeli so potrdili vpliv zemljepisne širine in nadmorske višine na kritične datume začetka in konca ter na trajanje nastajanja lesa. Modeli so omogočili rekonstrukcijo fenologije nastajanja lesa iglavcev po Evropi

The use of wood-based materials in building and construction is constantly increasing as environmental aspects and sustainability gain importance. For structural applications, however, there are many examples where hybrid material systems are needed to fulfil the specific mechanical requirements of the individual application. In particular, metal reinforcements are a common solution to enhance the mechanical properties of a wooden structural element. Metal-reinforced wood components further help to reduce cross-sectional sizes of load-bearing structures, improve the attachment of masonry or other materials, enhance the seismic safety and tremor dissipation capacity, as well as the durability of the structural elements in highly humid environments and under high permanent mechanical load. A critical factor to achieve these benefits, however, is the mechanical joint between the different material classes, namely the wood and metal parts. Currently, this joint is formed using epoxy or polyurethane (PU) adhesives, the former yielding highest mechanical strengths, whereas the latter presents a compromise between mechanical and economical constraints. Regarding sustainability and economic viability, the utilization of different adhesive systems would be preferable, whereas mechanical stabilities yielded for metal-wood joints do not permit for the use of other common adhesive systems in such structural applications. This study extends previous research on the use of non-thermal air plasma pretreatments for the formation of wood-metal joints. The plasma treatments of Norway spruce [Picea abies (L.) Karst.] wood and anodized (E6/EV1) aluminum AlMgSi0.5 (6060) F22 were optimized, using water contact angle measurements to determine the effect and homogeneity of plasma treatments. The adhesive bond strengths of plasma-pretreated and untreated specimens were tested with commercial 2-component epoxy, PU, melamine-urea formaldehyde (MUF), polyvinyl acetate (PVAc), and construction adhesive glue systems. The influence of plasma treatments on the mechanical performance of the compounds was evaluated for one selected glue system via bending strength tests. The impact of the hybrid interface between metal and wood was isolated for the tests by using five-layer laminates from three wood lamellae enclosing two aluminum plates, thereby excluding the influence of congeneric wood-wood bonds. The effect of the plasma treatments is discussed based on the chemical and physical modifications of the substrates and the respective interaction mechanisms with the glue systems. Nasl. z nasl. zaslona. Opis vira z dne 18. 1. 2022. Objavljeno na spletu 17. 1. 2022. Št. prispevka 796474. Bibliografija: str. 9-10.

Non-native forest tree species have been introduced in Europe since the 16th century, but only in the second half of the 20th century the significance of the seed source origin for their economic use was recognized, resulting in the establishment of numerous provenance trials at a national, regional, European and International level, as those led by IUFRO. Breeding programs have also been launched in the continent for the most economically important species. Aim of this work is the formulation of provenance recommendations for planting of five non-native tree species in Europe (Douglas fir, grand fir, Sitka spruce, lodgepole pine and black locust), based on the information obtained from twenty countries, in the frame of the EU FP-1403 NNEXT Cost Action. The survey revealed that official and non-official national recommendations, based on provenance research results, have been elaborated and followed at a different level and extend for the above five species, but only for Douglas fir recommendations exist in almost all the participating to the survey countries. The compilation of provenance recommendations across Europe for each species is presented in the current work. Besides the recommended introduced seed sources, European seed sources are also preferred for planting, due to ease of access and high availability of forest reproductive material. European breeding programs yielding genetic material of high productivity and quality constitute currently the seed source of choice for several species and countries. Consolidation of trial data obtained across countries will allow the joint analysis that is urgently needed to draw solid conclusions, and will facilitate the development of ‘Universal-Response-Functions’ for the species of interest, rendering possible the identification of the genetic material suitable for global change. New provenance trial series that will test seed sources from the entire climatic range of the species, established in sites falling within and outside the environmental envelopes of their natural ranges, are urgently needed to pinpoint and understand the species-specific climate constraints, as well as to correlate functional traits to the seed origin and the environmental conditions of the test sites, so that the selection of suitable forest reproductive material of non-native tree species in the face of climate change can be feasible, This paper is an output from the European COST Action FP1403 ‘Non-native tree species for European forests—experiences, risks and opportunities’ (NNEXT), and specifically the Working group “Pathways”, in which all authors participated and contributed information in the relevant questionnaire

Ocena poškodovanosti dreves z elektronsko paramagnetno resonanco Mn2+ ionov

Izsledke dendrokronološkega raziskovanja na podlagi dreves višjih socialnih položajev v smrekovem debeljaku smo primerjali z ocenjevanjem prirastka na raziskovalnih ploskvah v smrekovih sestojih na Pokljuki. Za primerjavo dendrokronološke analize z izsledki o prirastku na raziskovalnih ploskvah smo uporabili le del podatkov do standardizacije dendrokronoloških krivulj, ker nismo želeli odstraniti starostnega trenda iz časovne vrste opazovanj. Na raziskovalnih ploskvah, ki so bile postavljene pred 60 leti, smo z zaporednimi meritvami premerov dreves ocenjevali debelinske prirastke, lesne zaloge in volumenske prirastke v posameznih obdobjih. Variabilnost povprečnega debelinskega prirastka v najvišjih debelinskih razredih na raziskovalnih ploskvah je bila primerljiva z ocenami za dominantna drevesa, analizirana v dendrokronološki analizi. Podatki iz dendrokronoloških raziskovanj so dobro izhodišče in v veliko oporo pri ocenjevanju dinamike razvoja v gozdnih sestojih ter pri presojanju o spremembah v 5- ali 10-letnih obdobjih zaporednih gozdnih inventur We compared the results of dendrochronological research of mature spruce trees from the stand canopy with the assessment of radial increment on the study plots in spruce stands on Pokljuka. In the comparison, we use raw measurement data (age trend was not removed) from dendrochronological analysis of radial growth of spruce trees and compare them with the findings on radial growth on the research plots. On the research plots established 60 years ago, we assessed DBH increments, growing stocks, and volume increments in individual periods using serial tree diameter measurements. Variability in average DBH increment in the highest DBH classes on the research plots was comparable to assessments for dominant trees analyzed in the dendrochronological analysis. The data from the dendrochronological analysis provide a good baseline and important support for assessing developmental dynamics in forest stands and evaluating changes over 5- or 10-year periods of continuous forest inventories.

Proučevali smo vpliv temperature termične modifikacije na utrjevanje in kakovost lepilnih spojev. Uporabili smo les smreke, ki je bil termično modificiran pri temperaturah 150, 170, 190, 210 in 230 °C ter različna lepila: fenol-formaldehidno (FF) za vroče lepljenje ter tri lepila za hladno lepljenje: polivinilacetatno (PVAc), poliuretansko (PU) ter melamin-urea- formaldehidno (MUF). Utrjevanje lepil smo spremljali z merjenjem reoloških lastnosti z reometrom pri čemer smo namesto standardnih aluminijastih diskov uporabili diske iz termično modificiranega lesa z različno stopnjo modifikacije ter z različnimi vlaţnostmi. Uporabili smo oscilatorni test z "multiwave" tehniko merjenja. Ugotovili smo, da so PVAc, PU ter MUF lepila utrjevala počasneje glede na stopnjo termične modifikacije lesa, vendar so bili razlogi različni. PVAc in MUF lepili sta utrjevali počasneje zaradi slabše absorpcije vode v modificiran les, PU lepilo pa zaradi niţje vlaţnosti modificiranega lesa. Termična modifikacija lesa je vplivala tudi na striţno trdnost lepilnih spojev. Striţna trdnost FF lepilnih spojev je padala z naraščanjem temperature modifikacije lepljencev, kar je bila posledica manjše utrjenosti lepila in niţje trdnosti modificiranega lesa. Po namakanju v vodi se je striţna trdnost FF spojev prepolovila, vendar so bolj modificirani preskušanci obdrţali večji deleţ začetne trdnosti. Povprečna efektivna penetracija FF lepila je sicer nekoliko naraščala s stopnjo modifikacije, vendar razlike niso bile statistično značilne. Termična modifikacija je zmanjšala omočitev površine lesa z vodo, toda izboljšala omočitev površine lesa s FF lepilom. Pri spojih s PVAc lepilom sta striţna trdnost spojev in deleţ loma po lesu padala s stopnjo termične modifikacije tako pri suhih preskušancih kot po namakanju preskušancev v vodi. Trdnost suhih PU lepilnih spojev se je zniţala glede na stopnjo termične modifikacije lesa, vendar manj kot pri PVAc lepilu. Po namakanju preskušancev v vodi pa sta se trdnost PU spojev in deleţ loma po lesu povečevala s stopnjo modifikacije lesa. Razlog je bil verjetno v navzemu vode in nabrekanju lesa. Navzem vode med 24 urnim namakanjem lepljencev v vodi je padal s stopnjo termične modifikacije lesa. Pri MUF lepilu je striţna trdnost suhih spojev padala s stopnjo termične modifikacije nekoliko bolj kot pri PU lepilu, vendar precej manj kot pri PVAc lepilu. Po namakanju preskušancev je striţna trdnost MUF spojev padla na polovico začetne trdnosti suhih spojev ter bila neodvisna od stopnje termične modifikacije, vendar je deleţ loma po lesu ostal 100 %. Skupna ugotovitev pri vseh lepilih je bila, da višja kot je bila stopnja termične modifikacije, manjša je bila deformacija pri kateri je prišlo do loma ter bolj krhek je bil lom. Skupna delaminacija PVAc lepilnih spojev je bila precej velika in se je povečevala s stopnjo termične modifikacije lesa. Pri PU in MUF lepilnih spojih izrazite delaminacije ni bilo. In the thesis the effect of the temperature used for the thermal modification of wood on the curing of adhesive and on bond performance was investigated. Spruce wood, heat treated at temperatures of 150, 170, 190, 210 and 230 °C, and four different types of adhesives were used: one adhesive for hot pressing, phenol-formaldehyde (PF), and three adhesives for cold setting: polyvinyl acetate (PVAc), polyurethane (PU) and melamine-urea-formaldehyde (MUF). The curing of the adhesives was monitored by measuring their rheological properties with a rheometer. Wooden discs, prepared from wood that had been subjected to different degrees of thermal modification and having different moisture contents, were used, instead of standard aluminium discs. The oscillation test with the "multiwave" measurement technique was used. It was found that the PVAc, PU and MUF adhesives cured more slowly depending on the degree of thermal modification, but the reasons for the retardation of curing were different. PVAc and MUF curing was slower because of the lower degree of adsorption of water in the modified wood, whereas the PU cured slower because of the lower moisture content of the modified wood. Thermal modification had a significant influence on the shear strength of the adhesive bonds. The shear strength of the PF adhesive bonds decreased with an increasing temperature of thermal modification, because of the lower degree of adhesive cure and the lower strength of the modified wood. After soaking in water, the shear strength of the PF joints reduced by half, but the more strongly modified specimens retained a greater proportion of the initial shear strength. The average effective penetration of the PF adhesive slightly increased with the degree of thermal modification, but these differences were not statistically significant. Thermal modification reduced surface wetting with water, but improved wetting with the PF adhesive. The shear strength and wood failure of the PVAc adhesive bond (of dry specimens and after soaking in water) decreased with a higher degree of thermal modification. The shear strength of the PU adhesive bonds decreased with degree of thermal modification of the wood, but less than in the case of the PVAc adhesive bonds. After soaking in water the shear strength and wood failure of the PU adhesive bonds increased with the degree of thermal modification. The reason was probably water intake and swelling of the wood. The water intake after 24 h of soaking decreased with the degree of thermal modification of the wood. The shear strength of the MUF adhesive bonds decreased with the degree of thermal modification slightly more than that of the PU adhesive bonds, but much less than that of the PVAc adhesive bonds. After soaking in water the shear strength of the MUF adhesive bonds dropped to half the initial dry strength, and was observed to be independent of the degree of thermal modification. The average wood failure of the wood remained at 100 %. In the case of all the adhesives bonds is was noticeable that with a higher degree of thermal modification the deformation was smaller when failure of the bond occurred, and that the failure was more brittle. The total delamination of the PVAc adhesive bonds was quite high, and increased with the degree of thermal modification of the wood. Delamination of the PU and MUF adhesive bonds was not pronounced.

V magistrski nalogi je preučena uporabnost ultrazvoka za zaznavanje notranjih anomalij v stoječih drevesih. V sestoju so bila z ultrazvokom izmerjena drevesa bukve in smreke ter popisane njihove zunanje značilnosti. Na licitaciji vrednejših sortimentov so bili z ultrazvokom izmerjeni sortimenti gorskega javorja z in brez rebraste teksture. Preizkušane so bile hitrosti prehoda v 7 smereh ter 2 ravninah. Oblikovanih je bilo 7 novih spremenljivk, izpeljanih iz frekvenčnega spektra, dobljenega s FFT. Prisotnost trohnobe v smreki in rdečega srca v bukvi statistično značilno vplivajo na hitrosti ultrazvoka in analizirane frekvenčne spremenljivke, v obeh primerih prisotnost anomalije zmanjša hitrost ultrazvoka. Verjetnost rdečega srca se povečuje s prsnim premerom in večvrhatostjo. Hitrosti ultrazvoka so neuporabne za napovedovanje rdečega srca v bukvi, vključitev frekvenčnih spremenljivk v binarno logistično regresijo izboljša pravilnost napovedovanja (iz 80 % na 81,8 %). Prisotnost poškodb oboda in zniževanje hitrosti v tangecialnih smereh zmanjša verjetnost prisotnosti trohnobe pri smreki, model pravilno uvrsti 88,5 % analiziranih dreves. Model smo izboljšali z vključitvijo frekvenčnih spremenljivk na 91,5 %. Postopek meritev v sestoju, ki smo ga pohitrili z izključitvijo hitrosti iz modela, pravilno uvršča 87,3 % analiziranih smrek. Med sortimenti gorskega javorja z in brez rebraste teksture so bile odkrite statistično značilne razlike v hitrosti ene izmed smeri in pri več frekvenčnih spremenljivkah. In this master thesis the use of ultrasound on standing trees to detect inner anomalies has been studied. Standing trees of beech and Norway spruce were measured with ultrasound in forest stands, outer characteristics of trees were also recorded. Logs of sycamore maple with and without fiddleback figure were also measured using ultrasound. 7 measuring directions were tested in two planes. 7 new variables were created using frequency spectrum. Presence of rot in spruce and of red heart in beech significantly impact speed of sound and the frequency spectrum. Presence of anomalies lowered ultrasound velocity in both species. Probability of red heart presence increases with breast height diameter and number increased with tree forking. Speed of ultrasound is not usable in predicting presence of red heart in beech. Frequency spectrum variables contribute to predicting red heart presence, as model accuracy improves after including them from 80 % to 81,8 %. Presence of previously inflicted injuries and low speeds of sound in tangential plane increases probability of rot presence in spruce, the developed model accurately classifies 88,5 % cases. To speed up the measurement process speeds of ultrasound were excluded from the model, the new model is accurate in 87,3 % cases. Statistically significant differences were found in speed of sound in tangential wood direction and in some of the frequency spectrum variables between sycamore maples with or without fiddleback figure.

Cilj ovog rada bio je odrediti otpornost na abrazijsko trošenje drva domaće smreke (Picea abies) u longitudinalnom smjeru, od tangencijalnog (LT) do radijalnog presjeka (LR). Ispitivanje otpornosti na abraziju provedeno je standardnom metodom „suhi pijesak – gumeni kotač“. S obzirom na relativno ujednačenu gustoću abradiranih uzoraka, otpornost na trošenje izražena je preko gubitka mase. Srednja vrijednost gustoće uzoraka drva smreke iznosila je 0,433 g/cm3. Utvrđeno je da otpornost na abraziju ovisi o orijentaciji abradirane površine. Iako je rasipanje rezultata vrlo veliko izražen je trend smanjenja abrazijskog trošenja s povećanjem kuta kojeg zatvara trošena površina s tangencijalnim presjekom, od 0° do 90°. Najmanju otpornost na abrazijsko trošenje ima tangencijalni presjek, a najveću radijalni. Srednji gubitak mase u radijalnom presjeku je za 48 % manji u odnosu na tangencijalni, a na abradiranoj površini zakrenutoj za 45°, srednji gubitak mase manji je za oko 9 %. The aim of this study was to determine the abrasion resistance of domestic spruce wood (Picea abies) in the longitudinal direction, from tangential (LT) to radial cross section (LR). The abrasion resistance test was performed by the standard method "dry sand – rubber wheel". Given the relatively uniform density of the abraded samples, the wear resistance is expressed through weight loss. The mean density of spruce wood samples was 0.433 g/cm3. It was found that the abrasion resistance depends on the orientation of the abraded surface. Although the scattering of the results is very large, there is a pronounced trend of decreasing abrasion wear with increasing angle closed by the worn surface with a tangential cross section, from 0° to 90°. The tangential cross section has the lowest abrasion resistance and the radial cross-section the highest. The mean weight loss in radial cross section is 48% lower compared to the tangential, and on the abraded surface rotated by 45°, the mean weight loss is reduced by about 9%.

V diplomskem delu smo analizirali površino smrekovega (Picea abies (L.) Karst.) lesa, po obdelavi z dielektrično barierno razelektritveno (DBD) plazmo in premazovanju površin. Uporabili smo transparentna brezbarvna premazna sredstva (na osnovi organskih topil in vode) ter okolju prijaznejše sredstvo (tungovo olje). Znano je, da na estetske in fizikalne lastnosti lesa (npr. barva, sijaj, oprijemna trdnost, napake) negativno vpliva izpostavitev površin vremenskim in okoljskim vplivom. Z določanjem stičnih kotov na obdelanih in neobdelanih površinah smo preučili vpliv spreminjanja parametrov obdelave na omočljivost lesa. Po izpostavitvi zunanjim pogojem smo vzorce spremljali v časovnih obdobjih enega, treh, šestih mesecev in ob koncu preskusa (po 10 mesecih). Ugotovili smo, da je obdelava lesa s plazmo zmanjšala stopnjo okuženosti na prostem izpostavljenih premazanih površin z biotskimi dejavniki in posredno, da je pozitivno vplivala na globino penetracije premaza, ni pa imela pomembnejšega vpliva na obarvanje in sijajnost površin ter oprijemnost premazov. In this thesis, we analysed the surface of spruce (Picea abies (L.) Karst.) wood after treatment with dielectric barrier discharge (DBD) plasma and subsequent surface coating. We used transparent colourless coatings (solvent- and water-borne) and a more environmentally friendly agent (tung oil). It is known that the aesthetic and physical properties of wood (eg. colour, gloss, adhesive strength, defects) are negatively affected by the exposure of surfaces to weather and environmental influences. By determining the contact angles on treated and untreated surfaces, we studied the influence of changing treatment parameters on the wettability of wood. After exposure to external conditions, the samples were monitored over time periods of one, three, six months and at the end of the test (after 10 months). The results showed that the plasma treatment of wood decreased the degree of contamination of coated surfaces, exposed in exterior, with biotic factors, and indirectly it had a positive effect on the penetration depth of the coatings, but did not have such significant effect on the colour, gloss of surfaces and adhesion of coatings.

Les v zadnjem času pridobiva na veljavi kot gradbeni material. Ko ga uporabljamo za gradbene namene, želimo, da lesni izdelki čim dlje časa obdržijo funkcionalnost. Še posebej zunaj vgrajen les je izpostavljen lesnim škodljivcem, če pa je poleg tega še v stiku z zemljo, pa je ogroženost še večja. Leseni koli, ki smo jih preučevali v diplomskem projektu so bili zabiti v zemljo na otroškem igrišču v Ljubljani. Kljub impregnaciji z bakrovimi pripravki so delno strohneli že po petih letih. V primeru neustrezne zaščite je trajnost impregniranega lesa povsem primerljiva z nezaščitenim lesom. Vizualna analiza kolov je potrdila, da so bili razkrojeni z glivami rjave trohnobe. Iz trhlih kolov smo pripravili dve vrsti vzorcev. Prvi so bili za določanje vsebnosti bakra v lesu in drugi za določanje tlačne trdnosti. Vsebnost bakra v lesu smo analizirali z napravo Oxford instruments XRF analyser, tlačno trdnost pa z Univerzalnim testirnim strojem Zwick-Roell Z100. Prišli smo do spoznanja, da so bili koli slabo impregnirani in so vsebovali premalo bakra, zato so v kratkem obdobju izgubili veliko tlačne trdnosti. Importance of wood as building material is increasing. When we use it for construction purposes, we want to retain its mechanical properties as long as possible. Used outdoor, wood is exposed to wood deterioration agents in ground contact its exposure is even more threatning. The researched wooden posts were applied in the ground at the playground in Ljubljana. Despite the fact that they were impregnated with a Cu preparation, they were completely degraded after 5 years. Their service life was thus comparable to service life of untreated wood. Wood posts were degraded by brown-rot fungi. 2 kinds of samples were prepared from investigated posts used for determination of Cu content and compressive strength. The results clearly show that wood posts were poorly impregnated. Mechanical properties degraded in quite short time.

Smrekovina in macesnovina spadata med tiste vrste lesa, ki se pri nas v obliki masivnega lesa najpogosteje uporabljajo kot gradbeni, konstrukcijski in stavbni les. Za takšen namen uporabe je poleg mehanskih lastnosti lesa zelo pomembna tudi naravna odpornost lesa. Znano je, da je smrekovina neodporna drevesna vrsta, medtem ko macesnovina spada v razred zmerno odpornih drevesnih vrst. Ker se pri obeh drevesnih vrstah mehanske lastnosti lesa izboljšujejo (povečujejo) z gostoto oz. z ožanjem branik, nas je zanimalo, kakšen vpliv ima pri teh 2 lesnih vrstah širina branik na naravno odpornost lesa in hkrati tudi na delež vsebnosti ekstraktivov, katerim na splošno predpisujemo največji vpliv na naravno odpornost lesa. Te vplive smo ugotavljali v skladu s standardom SIST EN 113. Izdelali smo vzorce lesa smreke in macesna z različnimi širinami branik in jih izpostavili 3 vrstam gliv razkrojevalk. Nekaterim vzorcem lesa smo pred izpostavitvijo 3 glivam razkrojevalkam z ekstrakcijo izločili ekstraktive in tako poskušali določiti delež ekstraktivov za posamezen razred širin branik. Ugotovili smo, da širina branik obeh lesnih vrst nima vpliva na delež ekstraktivov v lesu. Z gravimetrično metodo smo po izpostavitvi glivam razkrojevalkam preučevali vpliv širine branik na naravno odpornost obeh lesnih vrst in ugotovili, da splošnega značilnega vpliva ni. Spruce and larch wood are wood species which are, in the form of solid wood most frequently used for building, construction so as lumber. Therefore besides the mechanical properties of wood, durability of wood is also very important. It is known that spruce wood is classified as non-durable, while larch wood is classified as moderately durable. Furthermore, at both tree species it is well known that mechanical properties and ring width (density) are correlated. The impact of ring-widths on natural durability of wood and ratio of extractives, which generally provide natural durability of wood, was researched. Therefore, wood samples of spruce and larch with different ring-widths were prepared. Some specimens were extracted prior the exposure to different wood decay fungi (SIST EN 113) to determine the portion of extractives for individual class of rings-widths. The results showed that ring-width in both wood had no effect on the portion of extractives in wood. Gravimetrically determined mass loses of the specimens showed that tree-ring widths of both tested species did not have the impact on fungal decomposition.

Na podlagi preteklih meritev v obdobju od 1962 do 2017 smo na raziskovalnih ploskvah na nekdanjih novinah v katastrski občini Koprivni izračunali debelinske, višinske in volumenske prirastke za najpomembnejši drevesni vrsti – smreko in macesen. Na teh raziskovalnih ploskvah, ki so bile prepuščene naravnemu razvoju, so srednje temeljnični premeri manjši, število dreves pa večje od tistih v primerljivih gospodarskih gozdovih. V zadnjih tridesetih letih se je zaradi visokih sestojnih gostot zmanjšalo debelinsko priraščanje dreves smreke in macesna. Z dendrokronološko analizo priraščanja smreke in macesna smo ocenili vpliv klimatskih dejavnikov na priraščanje smreke in macesna. Na podlagi dendrokronološke analize smo ugotovili, da se leta z negativnim odzivom dreves v debelinskem prirastku od leta 1984 pojavljajo pogosteje. Based on past measurements from 1962 to 2017 on the forest research plots, located in the former slash-and-burn farming areas in the cadastral community of Koprivna, the diameter and height increments as well as volume increments of the two major species – spruce and larch – were calculated. Those set-aside natural research plots have a smaller quadratic mean diameter. The number of trees, however, is higher than in the comparable managed forests. Due to the high-density tree stands in the last thirty years, the spruce and larch trees radial has decreased. In order to determine the impact of environmental factors affecting spruce and larch radial growth, dendrochronological analysis was conducted. According to the dendrochronological analysis of the radial increment of trees the number of years with a negative response has been higher since 1984.

Premena čistih smrekovih sestojev je eden poglavitnih gojitvenih izzivov v Evropi. Človek je z gozdno pašo, oglarjenjem in golosečnim sistemom s sadnjo smreke močno spremenil tudi gozdove v Alpah, za katere pogosto mislimo, da so naravni. Naravna obnova zasmrečenih gozdov je marsikje zelo težavna, uspeh obnove pa je ključni element trajnosti gozda in vseh njegovih funkcij. Raziskavo smo izvedli v zasmrečenih predalpskih jelovo-bukovih gozdovih v raziskovalnih območjih Jelendol in Krašica. Meritve so bile izvedene leta 2003 in 2008 na 18 objektih v Jelendolu in leta 1993, 1998 in 2010 na 32 objektih na Krašici. Vpliv ekoloških dejavnikov na uspešnost naravnega pomlajevanja smo proučili s pomočjo linearnih mešanih modelov in posplošenih linearnih mešanih modelov. Na obeh raziskovalnih objektih smo ugotovili sukcesijski razvoj v smeri večjega deleža listavcev, v Jelendolu se poleg smreke v mladju uveljavlja bukev in na Krašici gorski javor. Drevesne vrste imajo različne potrebe po ekoloških dejavnikih, ki se dodatno spreminjajo z višinskim razvojem mladja. Za pomlajevanje bukve je temeljnega pomena bližina semenskih dreves. Najboljša nasemenitev se razvije pod sestojem in v malih vrzelih, vendar je za preživetje zadostnega števila klic potrebna predvsem zadostna količina difuznega sevanja, ki jo dosežemo šele z oblikovanjem srednje velikih vrzelih. V obeh območjih potrebuje mladje za nadaljnjo rast več svetlobe, pri čemer je na niže ležeči Krašici dovolj že vrzel premera ene drevesne višine, medtem ko mora biti vrzel v Jelendolu večja. Razvoj pomlajevanja v Jelendolu je bistevno počasnejši kot na Krašici. V obeh območjih obnovo značilno zavira velika rastlinojeda divjad. Conversion of pure Norway spruce stands is one of the principal silvicultural challenges in Europe. With forest grazing, charcoaling, and clear-cutting for spruce planting, man has severely altered Alpine forests that we often deem to be natural. Natural regeneration of forests replaced by spruce is often rendered difficult and the success of regeneration is the key element of sustainability of the forest and all of its functions. The study was carried out in subalpine fir-beech forests replaced by spruce in the study areas Jelendon and Krašica. Measurements were carried out in 2003 and 2008 on 18 plots in Jelendol, and in 1993, 1998 and 2010 on 32 plots in Krašica. The impact of ecological factors on success of natural regeneration was studied with linear mixed models and generalised linear mixed models. In both study areas we established successional development towards a greater share of broadleaves spruce and beech are being recruited in Jelendol and spruce and sycamore maple in Krašica. Tree species have different needs with regard to ecological factors and the ecological requirements change depending on the height of regeneration. The presence of seed trees is the key factor for beech regeneration. Establishement of seedlings is best below closed canopies and in small gaps, but survival of sufficient number of seedlings requires sufficient amount of diffuse radiation, which is not available until gaps are medium-sized. In both study areas regeneration required more light for continued growth in the lower-altitude Krašica, gaps the size of one tree height are sufficient, while in Jelendol gaps must be larger. Development of regeneration is significanty slower in Jelendol. In both sites regeneration is strongly affected by overbowsing.

Na pohorskih prehodnih barjih smo preučevali rast dreves in strukturo sestojev. Na barju Petinove jame smo postavili 4, na Klopnovrških barjih pa 5 raziskovalnih ploskev v velikosti 200 m2 . Razmere za rast so manj ugodne na barju Petinove jame, ki ima bolj ombrotrofni značaj. V bližnjem gozdu na avtomorfnih tleh smo postavili ob vsakem obravnavnem barju še po eno referenčno ploskev v velikosti 400 m2 . Drevesom na ploskvah smo popisali strukturne značilnosti in na vsaki ploskvi izvedli debelno analizo 30 dreves. Na barju Petinove jame so drevesa nižja kot na Klopnovrških barjih ter dosegajo manjše prsne premere, premere na koreninskem vratu ter manjše višinske in debelinske prirastke. Na barjanskih ploskvah je značilna šopasta razmestitev dreves, na referenčnih ploskvah pa naključna. Na barjih so bili v 19. in 20. stoletju izkopani melioracijski jarki, kar se odraža na povečanem vzniku in priraščanju dreves v letih po izkopu. Z oddaljevanjem od melioracijskih jarkov se zmanjšujejo gostota dreves, temeljnica, temeljnica koreninskega vratu, lesna zaloga, povprečni prsni premer, starost in višina dreves ter variabilnost višinske in debelinske strukture, vendar zmanjševanje večinoma ni statistično značilno. Nadzemna konkurenca nima vpliva na priraščanje dreves na barju Petinove jame, na Klopnovrških barjih pa vpliva na debelinsko in temeljnično priraščanje dreves. Za obe obravnavni barji smo izdelali kronologiji, ki se medsebojno dobro ujemata. Največji negativni vpliv na rast dreves na barjih imajo padavine v aprilu in maju. Ugotovili smo, da se struktura ter funkcije delno pa tudi površina habitatnega tipa Prehodna barja nenehno spreminjajo. Prehodna barja ogrožajo človeške aktivnosti in podnebne spremembe, saj se zaradi segrevanja ozračja intenzivneje zaraščajo, posledično pa se zmanjšuje njihova površina. We have analysed tree growth and stand structure of transitional bogs on Pohorje. 4 research plots of an area of 200 m2 on the peat bog Petinove jame and 5 research plots on the peat bog Klopnovrška barja were established. Growing conditions are less favourable on the peat bog Petinove jame, which is more ombrotrophic. Furthermore, reference plots with an area of 400 m2 were established adjacent to each bog in the forest on the automorphic soil. Structural characteristics of trees on plots were measured and stem analysis of 30 trees on each plot was performed. Trees on the peat bog Petinove jame are lower than those on peat bog Klopnovrška barja and have smaller diameters at breast height, root collar diameters, height increment and diameter increment. Trees on bogs have clustered distribution, and trees on reference plots have random distribution. In the 19th and 20th century, drainage ditches were excavated, which is reflected on increased tree emergence and tree growth in years after excavation. With moving away from drainage ditches, tree density, basal area, root collar basal area, growing stock, average diameter at breast height, age, height and variability of height structure and variability of diameter structure of trees are decreasing. However, this decrease is generally not statistically significant. Aboveground competition does not influence the diameter and basal area increment on the peat bog Petinove jame, but does it so on the peat bog Klopnovrška barja. Chronologies for both bogs have been made and they correspond well to one another. Precipitation in April and May has a negative impact on tree growth on bogs. We found that the structure, functions and partly the area of habitat type Transition mires and quaking bogs are constantly changing, and that they are threatened by climate change and human activity. Due to global warming, the transitional bogs are intensely overgrown and their size is gradually decreasing.

Soljenje cest vpliva na kemijske lastnosti tal in posledično na fiziološke parametre in rast rastlin v obcestnem prostoru. Vpliv soljenja smo preučevali na območju Pokljuke (Triglavski narodni park), kjer smo izbrali vzorčna mesta, ki so ob intenzivno soljenem cestnem odseku in referenčno mesto brez tega vpliva. Meritve rasti rastlin in fizioloških parametrov smo opravili na smreki (Picea abies). V letih 2009 in 2010 smo izmerili naslednje parametre: fotokemično učinkovitost FS II, vodni potencial, transpiracijo, vsebnost klorofila a in b ter kationov (Na+, K+, Ca2+ in Mg2+) v iglicah. Na teh vzorčnih mestih smo odvzeli vzorce tal in snega. Analizirali smo kemijske parametre in sicer, električno prevodnost, vsebnost bazičnih kationov, oziroma kationsko izmenjalno kapaciteto (Ca2+, Mg2+, K+, Na+). Analize so pokazale bistveno večje vsebnosti Na+ v snegu ter v tleh v spomladanskem obdobju. Statistično značilne razlike med soljenimi in nesoljenimi rastišči so se pokazale v ksilemskem vodnem potencialu, kot tudi v biomasi poganjkov. Za vzorčno mesto V1s, kjer so tla plitvejša, smo pri večjem številu fizioloških parametrov izračunali statistično značilne razlike z referenčnim rastiščem (V6ns), saj so razmere tam za rast smreke manj ugodne, vpliv soljenja pa se zaradi manjše kapacitete tal za vodo prej odrazi. V letu 2013, po zimi, ko je bilo porabljeno največ soli, je bila prirast rastlin statistično značilno manjša na obeh soljenih lokacijah, v primerjavi z nesoljeno. Application of de-icing salt affects the chemical properties of the soil, and consequently the growth and physiology of the plants in the road-side areas. Effects of de-icing salt applied for road maintenance was studied in the area of Pokljuka (Triglav National Park), where a reference site without the impact and two sites exposed to intensive use of de-icing salt were selected. Plant growth rate and selected physiological parameters were measured on Norway spruce (Picea abies). The following parameters were measured in the years 2009 and 2010: photochemical efficiency of photosystem II (PS II), water potential, transpiration, the content of chlorophyll a and b and the cations (Na+, K+, Ca2+ and Mg2+) in the needles. In these sites, soil and snow samples were taken for further analyses, where the chemical parameters, namely, the electrical conductivity, and the cation exchange capacity (Ca2+, Mg2+, K+, Na+) were measured. Analyses showed significantly higher levels of Na+ in the snow and in the soil in the spring samples. Statistically significant differences between salted and unsalted sites were calculated in case of plant water potential, as well as in the biomass of shoots. In the site V1s, where the soil is shallower, most of physiological parameters showed statistically significant differences in comparison with the reference site (V6ns). Most probably, due to less favourable growth conditions and lower water capacity of those soils, the effects of de-icing salt are more pronounced. In the year 2013, after the winter, when the highest amount of salt was applied, the growth of plants was significantly lower at both salted sites, in comparison with the unsalted, reference site.

Po ţledolomu 2014 je v gozdovih ostalo veliko poškodovanih, a ţivih dreves. Ker znanja o dogajanju v poškodovanih drevesih primanjkuje, smo v Arboretumu Volčji Potok izvedli raziskavo na drevesih, ki so v ţledolomu utrpela poškodbo krošnje. Izbrali smo 14 bukev in 12 smrek, jih razvrstili v 4 razrede glede na stopnjo poškodovanosti krošnje (K % nepoškodovana, A % do 50 %, B % med 50 in 75 %, C % več kot 75 % poškodovana krošnja), v dvotedenskih intervalih na njih odvzemali mikroizvrtke z orodjem Trephor in opazovali spremembe v krošnjah. Iz mikroizvrtkov smo pripravili mikroskopske preparate lesa, kambija in skorje in jih analizirali s svetlobnim mikroskopom in sistemom za analizo slike. Poškodovanost krošnje ni vplivala na čas olistanja pri bukvi in pojav mladih poganjkov pri smreki. Bukve so revitalizirale svoje krošnje različno uspešno ne glede na stopnjo poškodbe krošnje. Smreke še niso revitalizirale svojih krošenj. Poškodovane bukve so proizvedle od 20 do 95 %, poškodovane smreke pa 35 % oţje ksilemske branike kot nepoškodovane. Manjši je bil tudi prirastek floema. Produkcija lesa se je v poškodovanih bukvah začela in zaključila prej kot v nepoškodovanih, na drugi strani se je v poškodovanih smrekah začela kasneje in zaključila prej kot v nepoškodovanih. Izmed štirih razredov poškodovanosti so se pri bukvi največje razlike v kambijevi aktivnosti pokazale med razredoma A in B, pri smreki pa med razredoma K in A. After the severe ice storm of 2014 a high number of damaged trees were not removed from forests. Due to lack of general knowledge about processes occurring in damaged trees, a study involving 14 European beech and 12 Norway spruce trees was conducted in Arboretum Volčji Potok. Trees were categorized by crown injury injury class K % undamaged, A % damaged less than 50 %, B % damaged between 50 and 75 % or C % damaged more than 75 %. During the 2014 growth season microcores were collected every fortnight using a Trephor tool. Changes in crowns were also observed and noted. Transverse sections of microcores were prepared and observed using light microscopy and a picture analysis system. Crown injury had no effect on leaf unfolding date in beech and young sprouts occurrence in spruce. Success of crown restoration in beech differed from tree to tree regardless of severity of crown injury. No crown restoration was seen in spruce. On average, xylem rings were 20 to 95 % narrower in damaged beech trees and 35 % narrower in damaged spruce trees compared to the undamaged trees. Damaged trees also produced narrower phloem rings. In damaged beech trees xylogenesis started and finished sooner than in undamaged ones. On the other hand xylogenesis started later and finished sooner in damaged spruce trees compared to the undamaged ones. The biggest differences in cambial activity in beech appeared between class A and class B, and in spruce between class K and class A.

V diplomski nalogi je analizirana rast smreke (Picea abies) in bukve (Fagus sylvatica) na strmih legah v Bohinju. Smreke in bukve so bile izbrane na različnih naklonih, nadmorskih višinah ter legah. Skupaj je bilo analiziranih 60 dreves smreke in 60 dreves bukve, ki so se uvrščale zlasti v vladajočo ali sovladajočo plast sestojev. Na vsakem drevesu sta bila odvzeta dva izvrtka, in sicer na panju ter na prsni višini (1,3 m od tal). Smreka je ob nižji povprečni starosti dosegala višje višine kot bukev. Povprečni debelinski in višinski prirastki smreke so bili večji v primerjavi z bukvijo. Na priraščanje je v največji meri vplivala starost drevja. Sproščene smreke so imele širše branike, bukve pa ne. Odvisnost širin branik od klimatskih spremenljivk je bila praviloma statististično neznačilna, nekoliko v tem pogledu izstopajo avgustovske temperature. In this work the growth of Norway spruce (Picea abies) and European beech (Fagus sylvatica) on steep slopes in Bohinj was analysed. Spruce and beech tree were selected at different inclinations, elavations and aspects. In total, 60 spruce trees and 60 beech trees mostly of dominant and co-dominant social layer were analysed. On each tree two increment cores were taken, on the stump and at the breast height (1,3 meter above ground). The spruce trees were on average higher and a bit younger. Average diameter and height increments of beech were lower in comparison with spruce. The strongest effecton growth rates had tree age. Spruce trees with released crowns had wider tree-rings, what does not hold true for beech trees. The dependence of tree-ring width on climate variables was mainly statistically nonsignificant, with the small exception of August temperatures.

V diplomski nalogi je analizirano priraščanje smreke (Picea abies) glede na starost, utesnjenost krošenj in rastne razmere na območju Pokljuke in Jelovice. V ta namen je bilo postavljenih 18 ploskev. Na vsakem izmed analiziranih dreves je bil odvzet izvrtek na prsni višini (1,3 m od tal), in sicer za prirastek v zadnjih 30 letih. Petim dominantnim drevesom na vsaki ploskvi pa je bil odvzet izvrtek do stržena. Rezultati so pokazali, da med razvojnimi fazami pri debelinskem prirastku praktično ni razlik in da se tudi odrasla smreka (debeljaki) odziva na redčenje s povečanim prirastkom. Za nobeno razvojno fazo kot tudi za vse smreke strehe sestoja nismo ugotovili razlik v debelinskem prirastku pri različni utesnjenosti. Prav tako so rezultati pokazali, da tekoči volumenski prirastek sestoja upada linearno glede na sklep sestoja in da se s starostjo odzivnost temeljničnega prirastka glede na jakost konkurence celo povečuje. This undergraduate thesis analyses the increment of Norway spruce (Picea abies) depending on age, canopy density and growth conditions in the Pokljuka and Jelovica area. In order to do this we set up 18 research plots. Each of the analysed trees was bored at breast height (1.3 m from the ground) to analyse the growth in the last 30 years. Five dominant trees per plot, on the other hand, had a sample taken to the pith. The results showed that there are hardly any differences between the developmental phase regarding diameter increment and that adult spruces (mature tree stands) respond to thinning by increasing growth, as well. There were no differences in the diameter increment for varying degrees of crown density in any of the developmental phases or for the whole stand canopy population. The results also demonstrated that the current increment in the volume of the stands decreases linearly depending on the density of the tree canopy stand and that the responsiveness of the basal area increment on the degree of competition from other trees actually increases with age.