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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).

European beech (Fagus sylvatica L.) is an important component of forests in the alpine and continental biogeographical regions of Croatia. This study aimed to (1) analyze the long-term response of beech to climate, (2) identify potentially critical climatic conditions that could negatively affect the radial increment (RI) and vitality of beech, and (3) evaluate differences in the response of beech between the two biogeographical regions in Croatia. We used the 16 × 16 km Croatian ICP Forests Level 1 network. On a total of 25 plots, we cored between 5 and 24 trees for dendrochronological analysis. Tree-ring widths (TRW) were measured and standardized using cubic spline. TRW chronologies for the two regions were calculated and correlated to the temperature and precipitation data and Standardized Precipitation and Evapotranspiration Index (SPEI) using bootstrapped correlations. Continental region precipitation from April to August and alpine region precipitation from June to August were significantly important for RI. Temperature was less important for RI than precipitation in both regions, but the importance of the negative impact of above-average temperatures in the continental region and the positive impact of above-average precipitation in the alpine region has increased over the last two decades. A comparison with the 3-month SPEI confirmed the significant influence of high temperatures and the lack of precipitation in August on the RI of beech trees in both regions. Nasl. z nasl. zaslona. Opis vira z dne 28. 6. 2023. Bibliografija: str. 20-22. Abstract.

We evaluated three estimation methods for fitting the three-parameter Weibull distribution to even-aged European beech (Fagus sylvatica) forests by using experimental tree diameter data collected in 3709 sample plots (500 m2 each). The maximum likelihood estimation method (MLE), the method of moments (MOM) and the method of modified moments type 1 (MM1) were applied for fitting the Weibull function. The goodness-of-fit of stand parameters (total tree number, stand basal area, dominant stand diameter and mean quadratic diameter) was tested by MAE and RMSE, and the probability and cumulative density functions of trees per 5 cm diameter classes were additionally tested by the Kolmogorov-Smirnov test and compared with Kolmogorov-Smirnov’s D statistic. All three methods are suitable for estimating stand parameters based on the fitted Weibull function. Fitting the diameter distribution per 5 cm diameter classes at the plot level was less accurate due to the low number of trees or irregular diameter distribution of trees. The MM1 method was found to be the most suitable for fitting the three-parameter Weibull distribution to beech forests represented by data derived from small plots. Nasl. z nasl. zaslona. Opis vira z dne 5. 12. 2022. Bibliografija: str. 489-490. Abstract.

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.

Climate is a strong predictor of the geographic distribution of tree species, and thus climate change may trigger shifts in the distribution of a tree species and/or its demographic structure. In the study, we aim to comprehensively compare the distributions of four life stages of European beech (Fagus sylvatica) (i.e., regeneration, recruitment, young trees and mature trees) in forests in Slovenia, Central Europe, which are characterized by strong gradients of elevation (ELV), temperature (TEMP) and precipitation (PREC) to detect possible shifts in distribution and demography. Beech life stages were surveyed on 3366 plots. To depict disparities between ELV, TEMP and PREC distributions of beech life stages, we applied several non-parametric methods: basic statistical tests to study differences in medians, means, and 1st and 9th deciles; generalized additive models to study shifts in the optimum; and extreme value analysis to study shifts at the trailing and leading edges. A substantial shift in juvenile beech stages upward and toward colder sites was detected. However, the shift was not uniform along the distributions; the most significant shift was detected at the leading edge of ELV (+73 m) and TEMP (−2.6 °C), but surprisingly there was no beech movement identified at the trailing edge. The observed shift may be a result of the interplay between climate change, high spatial variability in microclimate, unexceptional droughts in the recent past, changes in forest use and possible limitations in the migration ability of beech and its adaptation capacity. Nasl. z nasl. zaslona. Opis vira z dne 23. 8. 2022. Bibliografija: str. 13-16.

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.

V raziskavi smo primerjali vrednosti dinamičnega in statičnega modula elastičnosti 7- in 11-slojne vezane plošče z različnimi kombinacijami usmeritve tkiva posameznih slojev furnirjev. Dinamični modul smo določili iz lastnih frekvenc prvega in drugega nihajnega načina nihanja, kjer smo uporabili Bernoulli-Eulerjevo enačbo, statični modul pa s 4-točkovnim upogibnim testom. Rezultati so pokazali, da ima vezana plošča največji modul elastičnosti pri usmeritvi tkiva zunanjega sloja 0°, nato pa z naraščanjem kota modul pada. Dinamični modul je od statičnega v povprečju za 12 % večji pri 7-slojnih ploščah in za 14 % pri 11-slojnih ploščah. Dinamični modul, določen iz druge lastne frekvence, je v primerih, kjer ni vpliva striga, enak modulu iz prve lastne frekvence, ko pa se pojavi vpliv striga, se modul zniža. Iz omenjene raziskave lahko potrdimo, da sta tako statični kot tudi dinamični način določanja modula elastičnosti vzorcev vezane plošče ustrezna, vendar pa je treba pri dinamičnem načinu preveriti vpliv striga.

The quality potential and possibilities of using beech logs and sawn wood was investigated. Twenty-seven beech logs, with a mean diameter of 48 cm, were cut from 10 trees from a Hacquetio epipactidis-Fagetum site in SE Slovenia. The trees were pre-selected according to the national 5-level quality scale for forest stand evaluation, using two trees per class. Beech logs were classified according to the EN 1316-1 and sawn afterwards into unedged boards of 35 mm nominal thickness. Altogether, 250 boards were visually graded according to the rules of the European Organisation of the Sawmill Industry (EOS). Longitudinal vibration of logs and boards with the determination of stress wave velocity by MTG timber grader was additionally included into the quality assessment. In the case of logs, we confirmed significance of the relationship between visually assessed log quality and stress wave velocity. The stress wave velocity in logs was also related to the stress wave velocity in boards, where it varied considerably, especially for low-graded material. In the case of sawn wood, the relationship between sawn wood grade and stress wave velocity was insignificant. The research confirmed the possibility of presorting of logs, visually or non-destructively, for better classification and utilization of sawn timber.

The aim of the present paper is to assess the non-destructive indicating properties of Slovenian beech (Fagus sylvatica) logs and correlate them with the mechanical properties of the final product, which is boards. Beech logs were visually graded according to the standard procedure and vibrational frequencies were measured. Logs were further on sawn into boards which were also non-destructively tested in wet and dry conditions. Finally, the boards were experimentally tested in tension. Special focus was directed towards visual parameters of the beech logs and their influence on the overall quality of the output material. The longitudinal natural frequencies of the logs were studied as potential indicating properties. The results showed that a majority of the visual log grading parameters do not result in good quality timber in terms of strength and stiffness properties, and only few are decisive for the final classification. The coefficient of determination of the static MOE vs. dynamic MOE of logs was r2=0.13, whereas vs. the MOE of wet boards was r2=0.49. Using a few visual characteristics in combination with dynamic measurements of logs and of wet boards could help to increase the yield of high quality beech wood.

In composite materials, the use of failure criteria is necessary to determine the failure forces. Various failure criteria are known, from the simplest ones that compare individual stresses with the corresponding strength, to more complex ones that take into account the sign and direction of the stress, as well as mutual interactions of the acting stresses. This study investigates the application of the maximum stress, Tsai-Hill, Tsai-Wu, Puck, Hoffman and Hashin criteria to beech plywood made from a series of plies of differently oriented beech veneers. Specimens were cut from the manufactured boards at various angles and loaded by bending to failure. The mechanical properties of the beech veneer were also determined. The specimens were modelled using the finite element method with a composite modulus and considering the different failure criteria where the failure forces were calculated and compared with the measured values. It was found that the calculated forces based on all failure criteria were lower than those measured experimentally. The forces determined using the maximum stress criterion showed the best agreement between the calculated and measured forces.

Na Ljubljanskem Barju v Sloveniji smo opravili dendrokronološke raziskave lesa iz eneolitskega koliščarske naselbine Parte-Iščica. Iz struge reke Iščice smo odvzeli vzorce 1237 kolov iz lesa jesena (Fraxinus sp.), jelše (Alnus glutinosa Gaertn.), bukve (Fagus sylvatica L.), jelke (Abies alba Mill.), javorja (Acer sp.), breze (Betula sp.), leske (Corylus sp.), belega gabra (Carpinus betulus L.), topola (Populus sp.), hrasta (Quercus sp.), vrbe (Salixsp.) in bresta (Ulmus sp.). Prevladovali so vzorci jesena, jelše in bukve s 70 %, 9 % in 7 %. Dendrokronološke analize smo opravili na jesenovih, bukovih, hrastovih in jelovih kolih, ki so imeli nad 45 branik. Na osnovi 285 relativno datiranih vzorcev smo sestavili dve jesenovi in eno bukovo kronologijo, dolžin 136, 113 in 105 let. Večje količine lesa, posekanega v istem koledarskem letu, nakazujejo potek gradbenih aktivnosti na kolišču. Po prvih rezultatih radiokarbonskega datiranja uvrščamo koliščarsko naselbino v prvo polovico tretjega tisočletja pred našim štetjem. From the Parte-I{~ica Eneolithic pile dwelling in the Ljubljana Moor, Slovenia, timber was collected for dendrochronological investigations. In the river bed of the I{~ica river samples were selected from 1237 vertical piles of ash (Fraxinus sp.), alder (Alnus glutinosa Gaertn.), beech (Fagus sylvaticaL.), fir (Abies alba Mill.), maple (Acer sp.), birch (Betula sp.), hazel (Corylus sp.), hornbeam (Carpinus betulus L.), poplar (Populus sp.), oak(Quercus sp.), willow (Salix sp.), and elm (Ulmus sp.). Those of ash, alder, and beech predominated with 70 %, 9 %, and 7 % respectively. Samples ofash, beech, oak, and silver fir containing more than 45 tree-rings were usedfor tree-ring analyses. 285 samples were cross-dated and three floating chronologies, two of ash and one of beech, were constructed. Their length was 136, 113, and 105 years. The large amount of timber cut in the same calendar year provides information on building activities on the site. The first 14C dates indicate that the pile dwelling existed in the first half of the 3rd millennium BC.

Pragozdni rezervati so odličen objekt za analizo naravnega razvoja sestojev, ki poteka brez vpliva človeka, oziroma je ta močno zmanjšan. Leta 1984 so bile v Rajhenavskem Rogu postavljene stalne raziskovalne ploskve s skupno površino 1,91 ha, namenjene analizi odraslega sestoja. Leta 2020 je bila izvedena peta ponovitev popisa. Smrtnosti in vrasti jelke in bukve si niso podobne in se skozi čas spreminjajo. V celotnem obdobju ni bilo zaznane vrasti jelke skozi merski prag. Prav tako so se močno zmanjšale njene gostote v prvem debelinskem razredu (DBR), čemur vzrok so predvsem velike populacije jelenjadi. Stalno odmiranje in pomanjkanje vrsti jelke je privedlo do splošnega upada jelke skozi vse DBR. Nasprotno, število bukve v prvem DBR skozi vsa obdobja vztrajno narašča, njena vrast pa je vidna tudi v ostalih DBR. Ti trendi napovedujejo vztrajno nadomeščanje jelke z bukvijo, kar lahko dolgoročno privede do spremenjene drevesne sestave. V zadnjih treh meritvah je opazno večanje števila živih-zlomljenih dreves, od vetra izruvanih dreves in dreves, ki so podlegla padcem drugih dreves, kar kaže na večanje ekstremnih vremenskih pojavov, predvsem manjših vetrolomov. Old-growth reserves serve as natural laboratories for analysing the dynamics of forest stands without direct influence of humans. In 1984, permanent research plots were placed in the Rajhenavski Rog with a total area of 1.91 ha intended for the analysis of long-term demography. A fifth iteration of the census was carried out in 2020. Mortality and recruitment of beech and fir, the two dominant species, varied over time. Throughout the monitoring period, no ingrowth of the fir was detected, and its density in small diameter classes declined over time, likely due to large populations of red deer. The lack of recruitment and continuous mortality also resulted in a general decline in fir across all diameter classes. In contrast, the number of beech in the smallest diameter class has steadily increased over time, and recruitment of beech is notable across most diameter classes. These trends highlight a steady replacement of fir by beech, which may lead to a long-term change in species composition at the site. In the last three measurements, there has been an increase in the number of live-snapped, uprooted, crushed trees, indicating an increase in disturbance induced tree mortality, especially smaller windthrow events.

Regression of conifers in European mixed old-growth mountain forests has been observed for a long period and studied from different aspects. Old-growth (OG) forests in Bosnia and Herzegovina (BiH) have not experienced heavy air pollution and chronic overbrowsing that have affected many other European OG forests, while climatic and anthropogenic disturbances have been well documented. We analysed stand structure in the Janj OG forest, compared it with inventories of Lom and Perucica OG forests (BiH) and with earlier inventories of the same reserves. At present, OG forest Janj is characterized by a high growing stock (1215 m$^3$·ha$^{−1}$). This is due to good site quality, prevalence of conifers (84%) and dominant endogenous processes in recent decades. In all three OG forests, indicators of structural change exhibited progression of European beech over time. Historical evidence revealed the occurrence of warm summers and droughts followed by bark beetle outbreaks in the 1920s, 1940s and early 1950s, which in turn influenced a marked conifer decline. It seems likely that repeated canopy opening released waves of European beech regeneration. These stand structural changes have delayed the rejuvenation of conifers and can help explain the early observations of conifer decline.

V zadnjem času po vsej Sloveniji opažamo hiranje navadne bukve (Fagus sylvatica L.). Cilj prispevka je predstaviti dolgoročen trend osutosti krošnje navadne bukve v Sloveniji in pojasniti delež osutosti bukove krošnje s pomočjo podatkov iz popisa povzročiteljev poškodb v okviru vsakoletnega popisa razvrednotenja in poškodovanosti gozdov. Pri tem smo uporabili podatkovno zbirko o spremljanju osutosti in poškodovanosti dreves na M6 stalnih vzorčnih ploskvah (Nivo I) na sistematični mreži 16 % 16 km v obdobju 1993%2020. Rezultati kažejo, da se je povprečna osutost bukove krošnje od leta 1993 do 2020 povečala iz 13,9 % na 32,2 %. Dolgoročen linearen trend je pokazal, da se je povprečna osutost bukove krošnje povečala za 0,63 % na leto. Za trend povprečne osutosti bukve je bilo prelomno izjemno sušno leto 2003, ko se je trend osutosti povečal iz 0,61 % na 0,94 % na leto. Trend večanja osutosti bukve smo zaznali na vseh obravnavanih lokacijah. Ugotovili smo, da se povprečna osutost bukve hitreje veča na jugu in zahodu države. Katastrofalen žledolom leta 2014 je povzročil drastično spremembo povzročiteljev osutosti bukve. V obdobju pred žledolomom leta 2014 so osutost bukove krošnje najbolje pojasnjevale poškodbe zaradi žuželk. Po žledolomu leta 2014 so se povečale poškodbe bukve zaradi žleda, gliv, neposrednih človekovih vplivov (obsežne sanacije žledoloma) in drugih dejavnikov. Žledolom je na bukovih gozdovih pustil trajne posledice, saj so poškodbe zaradi žleda in posledično sanacije vidne še dandanes, kar je razvidno tudi iz popisa povzročiteljev poškodb bukve. V zadnjih dveh letih, 2019%2020, so glive najpomembnejše povzročiteljice poškodb bukve. Po letu 2014 pa se je zmanjšala poškodovanost bukve zaradi žuželk. Natančnih vzrokov za splošno slabšanje zdravstvenega stanja bukve po vsej Sloveniji še ne poznamo. Recently, we noticed decline of the common beech (Fagus sylvatica L.). The aim of this article is to present the long- -term trend of the common beech defoliation in Slovenia and to explain the defoliation share using the data from the inventory of damage agents in the framework of the annual inventory of the forest devaluation and damage. Thereby we applied the database on the monitoring of the tree defoliation and damage on the M6 permanent sampling plots (Level I) on the systematical 16 % 16 km grid in the period 1993%2020. The results show the average defoliation of the beech increased from 13.9 % to 32.2 % from 1993 to 2020. The long-term linear trend has shown that the average beech defoliation increased for 0.63 % yearly. The extremely dry year 2003, when the defoliation trend increased from 0.61 % to 0.94 % yearly, represented the milestone for the average beech defoliation trend. The trend of beech defoliation increase was detected in all studied locations. We found that the average beech defoliation is increasing more rapidly in the south and west of the country. The disastrous ice storm in 2014 caused a drastic change in the beech defoliation causes. In the period before the ice storm in 2014, the defoliation of the beech was best explained by the damage due to the insects. After the 2014 ice storm, increased the damages of the beech due to sleet, fungi, direct manmade impacts (ample ice storm sanitations) and other factors. The ice storm caused permanent consequences on the beech forests and the damage due to the ice storm and consequent sanitation are still visible today, which is also visible from the inventory of the beech damage agents. In the last two years, 2019%2020, fungi are the most important cause of beech damage. After 2014, the beech damage due to the insects decreased. The exact causes for the general decrease of beech health throughout Slovenia are not known yet.

V delu smo analizirali vpliv termične modifikacije na obdelovalne lastnosti bukovine, kjer smo ocenjevali kakovost obdelane površine po operaciji skobljanja, rezkanja in struženja nemodificirane in modificirane bukovine. Po obdelavi smo površine vizualno ocenili z ocenami od 1 do 5, glede na napake zatrganih, lomljenih in dvignjenih vlaken ter podali povprečno oceno za vsako vrsto operacije kot tudi odstotek preizkušancev z različno vrednostjo podane ocene. Ugotovili smo, da je povprečna ocena termično modificirane bukovine pri skobljanju boljša v primerjavi z nemodificirano bukovino, vendar pa ANOVA analiza ni potrdila statistično značilnih razlik. Ravno tako ni statistične razlike pri rezkanju, medtem ko je pri struženju vpliv modifikacije statistično značilen, saj je kakovost površine termično modificirane bukovine bistveno boljša. Iz opravljene analize lahko sklepamo, da ima termična modifikacija pozitiven vpliv na kakovost obdelane površine bukovine. The work analyses the influence of thermal modification on the machining properties of beech wood, where the quality of the surface is evaluated after the operation of planing, routing and turning of unmodified and modified beech. After machining, the surface is visually assessed with grades from 1 to 5, with respect to defects of raised, fuzzy and torn grain. As a result an average grade for each type of operation is given, as well as the percentage of each grade. It has been found out that the average grades of thermally modified beech wood in planing were better compared to unmodified beech, but ANOVA analysis did not confirm differences between them. There was also no difference in routing, while in turning the influence of modification was significant, since the surface quality of the thermally modified beech was significantly better compared to that of unmodified beech. From the analysis it can be concluded that thermal modification has a positive effect on the quality of the machined surface.

Raziskava je potekala na območju Kočevskega Roga, ki predstavlja del Dinarskega gorovja v južni Sloveniji. Raziskovalne objekte so obsegale tri, leta 2001 izsekane vrzeli z razporeditvijo vzorčnih ploskev v mreži 5 x 5 m, na katerih smo izvedli tretjo meritev razvoja mladovja. Na vzorčnih ploskvah velikosti 2, 25 m² smo ocenjevali deleže zastrtosti tal, gostoto mladja, poškodovanost mladja, drevesno sestavo in rast dominantnih osebkov. Gostota jelke, gorskega javorja in bukve v mladju se je v primerjavi z meritvijo leta 2006 zmanjšala. Delež zastrtosti tal z mladovjem se je povečal, zmanjšal pa se je delež zastiranja z zelišči, skalami in drevesnimi ostanki. Poškodbe terminalnega poganjka zaradi objedanja so se pri bukvi v primerjavi s prejšnjima meritvama zmanjšale in so bile zabeležene pri 5 % dreves, medtem pa sta se deleža močno poškodovanih osebkov jelke in gorskega javorja v primerjavi s prejšnjima meritvama povečala na 37 % za jelko in 38 % za gorski javor. Delež osebkov s pokončno razrastjo se je povečal (79 %), zmanjšala pa sta se deleža osebkov z deformacijo stebla (6 %) in osebkov s plagiotropno razrastjo (14 %). Obraten in nepričakovan trend je bil opažen pri analizi oblike poganjkov, kjer se je delež osebkov z enoosno rastjo terminalnega poganjka zmanjšal (56 %), delež osebkov z dvovrhato (36 %) in metlasto (8 %) rastjo pa se je povečal. HD razmerje se je od prejšnje meritve povečalo z 74 na 86,7. Po končani analizi podatkov smo ugotovili, da v izbranih vrzelih mladje jelke in gorskega javorja ne prerašča v zgornje višinske razrede. To lahko v prihodnosti privede do biotskega in ekonomskega siromašenja teh gozdov. The research took place in the area of Kočevski Rog, which represents a part of Dinaric Mountains in the South of Slovenia. Research plots were set up inside three, in 2001 cut down canopy gaps using 5 x 5 m grid. During the third measurement of regeneration development we assessed the ground coverage of tree regeneration and vegetation, the density of tree regeneration, browsing damage and the growth of dominant saplings on the plot. The density of silver fir, sycamore maple and beech in the first regeneration layer decreased compared to the 2006 measurement. The proportion of regeneration coverage increased, while the proportion of ground vegetation, rock coverage and coarse woody debris decreased. Damage rates of terminal beech shoots decreased to 5 %, while the proportion of severely damaged specimens of silver fir and sycamore maple increased compared to previous measurements to 37 % for silver fir and 38 % for sycamore maple. The proportion of stems with upright growth increased to 79 %, while the proportions of specimens with stem deformation (6 %) and specimens with plagiotropic growth (14 %) decreased. A reverse and unexpected trend was observed in the analysis of shoot shape, where the proportion of stems with single terminal shoots decreased (56 %), while the proportion of specimens with two terminal shoots (36 %) and broom shape growth (8 %) increased. The HD ratio has increased since the previous measurement from 74 to 86,7. After completing the data analysis, we found out that silver fir and sycamore maple do not recruit to higher regeneration layers which can cause future decrease of biotic and economic value of these forests.

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.

Temporal variability of leaf senescence (autumn phenology) was observed in 2020 in 11 European beech (Fagus sylvatica) trees in Tivoli, Rožnik and Šišenski hrib Landscape Park in Ljubljana, Slovenia, previously this year observed also for spring phenology. General leaf colouring (LC) BBCH94 occurred, between 19 and 24 October 2020, with lower inter-individual variability than that of leaf unfolding (LU), BBCH11. The trees had active leaves (LC-LU) between 177 and 199 days. In only 3 trees total leaf fall (LF), BBCH97, occurred before 19 November 2020. LC of the tree included in the long-term monitoring program of the Slovenian Environment Agency ARSO occurred on 24 October 2020. This is 7 days later than 65-year average of the same tree/location and is ascribed to weather conditions. Investigation of tree tissues showed that the width of the last formed tree-ring in the wood varied between 0.39 and 9.61 mm and in phloem between 0.09 and 0.26 mm and that the tissues reflect health condition of the trees. V letu 2020 smo spremljali jesensko fenologijo listov 11 dreves evropske bukve (Fagus sylvatica) v Krajinskem parku Tivoli, Rožnik in Šišenski hrib v Ljubljani, Slovenija. Pri istih drevesih smo spomladi spremljali proces olistanja. Splošno obarvanje listov (LC), BBCH94, je nastopilo med 19. in 24. oktobrom 2020, v ožjem časovnem intervalu kot spomladansko olistanje (LU), BBCH11. Drevesa so imela aktivne liste (LC-LU) od 177 do 199 dni. Samo s 3 dreves je do 19. novembra 2020 odpadlo vse listje (LF), BBCH97. Pri drevesu, ki je vključeno v dolgoletni program spremljanja fenologije listov Agencije Republike Slovenije za okolje ARSO, je obarvanje listov nastopilo 24. oktobra 2020, kar je za 7 dni kasneje od 65-letnega povprečja za isto drevo / lokacijo. Raziskave drevesnih tkiv so pokazale, da je znašala širina zadnje branike v lesu med 0,39 in 9,61 mm in v floemu med 0,09 in 0,26 mm in da tkiva nakazujejo zdravstveno stanje dreves.

The District Forestry of the Duchy of Lauenburg (Schleswig-Holstein) changed silvicultural system in beech forests from "shelterwood with delayed clearance" to "group selection felling" due to economic, political and nature conservation reasons. The comparison of both systems showed advantages of group selection system regarding growth of valuable large diameter trees and higher overall income of about 10%, but small loss of regeneration growth and quality due to the effects of edging. The ecological values are in favour of group selection system due to similarities in forest horizontal structure withold-growth forest. Gozdna uprava vojvodine Lauenburg (Schleswig-Holstein) je zaradi ekonomskih, političnih in naravovarstvenih razlogov spremenila gozdnogojitveno zvrst v bukovih gozdovih iz "zastornega gospodarjenja z odloženo pospravilno sečnjo" v zvrst "strukturiranega trajnega gozda s skupinsko prebiralno sečnjo". Primerjava obeh zvrsti je pokazala prednosti skupinskega prebiranja z vidika rasti vrednih dreves z velikih premerov in ca. 10 % višji skupni donos, a je hkrati nakazala nekoliko slabše priraščanje in kakovost mladja zaradi robnih učinkov. Ker je skupinsko prebiralna struktura gozda bliže teksturi življenjskih faz pragozda, je njena ekološka vrednost ocenjena višje.

Feasibility of nuclear magnetic resonance (nMR) was tested for research of anatomy and moisture content of wood. A three m high living beech tree (Fagus sylvatica L.) was imaged by magnetic resonance using the 3D spin-echo microscopic imaging technique at isotropic spatial resolution of 100 mm to follow structural changes in the topped branch caused by healing response mechanisms of the tree. Conventional light microscopy was also employed to verify tree structures detected on MR images. Conventional light microscopy revealed anatomical structures and three year age of the tree branch. MR images clearly showed pith, radially oriented xylem rays, early wood vessels with a delineated border between early and late wood, as well as the cambial zone with current xylem and phloem growth increment. We studied water concentration in the branch and the depth of dehydration formed in 22 hours after the mechanical injury. The dehydrated region extended to the mm depth from the wound location. First passive response of the injured branch tissue reflects in the initial decrease of the moisture content that was detected by MR imaging. Finally, we processed 3D MR microscopy data by the ImageJ image processing program to depict the spatial water concentration in the tree branch and to determine tissues with high water content. Preverjena je bila uporaba jedrske magnetne resonance (Nmr) za raziskave anatomije in vlažnosti lesa. Na tri metre visoki živi bukvi (Fagus sylvatica L.) smo uporabili 3d spin-echo mr-mikroskopsko tehniko slikanja s prostorsko resolucijo 100 mm in opazovali strukturo odrezane vejice ter spremljali dinamični odziv drevesa na mehansko poškodbo. Za potrditev struktur, vidnih na slikah, smo uporabili svetlobno mikroskopijo. Svetlobna mikroskopija je razkrila anatomsko zgradbo in triletno starost vejice bukve. Slike so jasno razkrile stržen, radialno orientirane večredne ksilemske trakove, traheje ranega lesa, vključno z mejo med ranim in kasnim lesom, kot tudi kambijevo cono s tekočim ksilemskim in floemskim prirastkom. Preučevali smo koncentracijo vode v vejici in globino dehidracije, ki je nastala v 22-tih urah po poškodbi in je segala v globino približno 5 mm od poškodbe. Hitra izguba vlažnosti odseva začetni pasivni odziv prizadetega tkiva. S pomočjo 3d mikroskopije in računalniškega programa Imagej nam je uspelo izdelati prostorski model vode v lesu, ki prikazuje tkiva v vejici z značilno višjo vlažnostjo.

Fourteen local tree-ring chronologies of beech (Fagus sylvatica L.) from different sites in Slovenia, elevations 300-1,415 m a.s.l., were constructed. Basic statistics of the chronologies (raw, standard and residual), climatic influence on tree growth, and growth variability among the sites are presented in the article. Dendroclimatological analysis showed that summer (particularly June) temperatures have negative and precipitation positive effect on tree-ring widths of beech on eleven sites in central, SE and SW Slovenia. The beech from highly elevated site in the Julian Alps above Tolmin (elevation 1200-1,450 m) showed positive response to summer temperatures. The whole variability in studied beech chronologies can be resumed in three sources of variation (principal components - PC): (PC_1) response of trees to June climate, (PC_2) altitude, and (PC_3) biogeographical differences.

V raziskavi smo preučevali količinsko-kakovostni izkoristek bukovine od stoječega drevesa do žaganega lesa. Zanimala nas je ocena kakovosti posameznih dreves in njen vpliv na kakovostne razrede proizvodov iz tega lesa. Pri razvrščanju stoječih dreves smo upoštevali aktualno 5-stopenjsko lestvico ocenjevanja kakovosti Zavoda za gozdove Slovenije (ZGS). Pri ocenjevanju gozdnih sortimentov smo uporabljali standard SIST EN 1316-1:2013, pri ocenjevanju žaganega lesa pa pravila Evropskega združenja žagarske industrije (EOS). Na vzorcu ocenjenih in nato posekanih dreves smo ugotavljali povezave med kakovostjo dreves, iz njih izdelanih sortimentov okroglega lesa in kakovostjo končnih žagarskih izdelkov. V vzorec so bila enakovredno zajeta drevesa vseh petih kakovostnih stopenj. Pri izdelavi gozdnih sortimentov smo dobili največ hlodov B-kakovosti (51 %) in največ žaganega lesa EOS-C-kakovosti (52 %). Iz bukovih dreves odlične kakovosti smo dobili 35 % najkakovostnejših sortimentov in iz teh sortimentov 8 % najkakovostnejšega žaganega lesa. Odločilni kriterij razvrščanja po kakovosti so pri sortimentih okroglega lesa slepice in pri žaganem lesu mrtve in trhle grče. The research addresses beech wood, from a standing tree to sawn wood. It focuses on the quality evaluation of individual trees and its impact on the later products made of the respective wood. For the needs of observing the quality of standing trees, the current 5-class scale for quality evaluation of the Slovenia Forest Service (SFS) was used. To evaluate the wood assortment, the SIST EN 1316-1:2013 standard was applied, while the evaluation of sawn wood was performed as per the rules of the European Organisation of the Sawmill Industry (EOS). On the basis of the sample of evaluated and eventually harvested trees, the correlations between the quality of trees, roundwood products made of them and the quality of final sawn products were established. The sample equally included trees of all five quality classes. The production of wood assortment provided the most logs of B quality (51%) and the highest quantity of sawn wood of EOS-C quality (52%). Beech trees of excellent quality provided 35% of the wood assortment of highest quality and these provided 8% of the sawn wood of the highest quality. The key criteria for the classification by quality were covered knots for forest products and dead and unsound knots for sawn wood.

Finger joints with standard geometries and adhesives used for joining coniferous wood are not sufficient in terms of strength when gluing beech wood. A numerical model of finger joined beech lamellas was prepared and simulations of tension tests were made. Parametric studies with multiple variables referring to geometrical properties of finger joints and two different types of applied adhesives were performed. The results showed a high influence of the finger joint geometrical parameters. Experimental tests on the tension strength of the finger joints were performed. To validate the numerical model, 20 mm long finger joints were produced and tested. Two types of adhesives were used, MUF and PRF. The finger joints were pressed under two different pressures. Prior to tension testing, the dynamic modulus of elasticity was measured with a strength grading machine and strength grade assignments were made. The influence of joining of the boards on the dynamic modulus of elasticity was analysed. The results of the tension tests of the finger joints showed a clear influence of the finger joint geometry, where highest strengths were obtained with longer and thinner fingers, while the influence of the adhesive seems to decrease with the length of finger joints

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

V tem delu smo raziskali vsebnost proantocianidinov v lesu bukve. Drevesa smo posekali v Kočevskem Rogu. Požagali smo jih tako, da smo dobili vsa potrebna tkiva za nadaljno raziskavo. Najprej smo izžagali kolute, ki smo jih nato razžagali, zmleli in posušili. Dobljene vzorce smo nato ekstrahirali, izvedli smo po dve ekstrakciji. Najprej smo izvedli ekstrakcijo po Soxhletu. Z njo smo dobili vsebnost vseh snovi, ki so topne v mešanici metanola in vode, ter vsebnost celokupnih hidrofilnih ekstraktivov. Nato smo izvedli še dietiletrsko ekstrakcijo, s katero smo dobili vsebnost lipofilnih ekstraktivov. Vsebnost proantocianidinov smo določili z UV-Vis spektrofotometrijo. Raziskava je pokazala, da imajo največjo vsebnost lipofilnih ekstraktivov vzorci poranitvenega dela, mrtve in žive grče. Najmanjšo vsebnost lipofilnih ekstraktivov smo izmerili v rdečem srcu. Največjo vsebnost celokupnih hidrofilnih ekstraktivov smo našli v mrtvi in živi grči. Najmanjšo vsebnost pa smo izmerili v rdečem srcu. Največjo vsebnost celokupnih ekstraktibilnih snovi smo našli v živi grči, najmanjšo v rdečem srcu. Največjo vsebnost proantocianidinov imajo vzorci mrtve grče, sledijo vzorci žive grče. Najmanjšo vsebnost pa imajo ponovno vzorci rdečega srca. V vseh primerih imajo vzorci rdečega srca najmanjšo vsebnost merjenih substanc. In this study we researched the content of proanthocyanidins in beech wood. The trees were cut down in the Kočevski Rog forest. We cut down the trees in a way that enabled us to get all necessary tissues for further research. At first, we cut the reels, which were then sawn, milled and dried. Next, we extracted the resulting samples, we performed two extractions. Firstly we performed the Soxhlet extraction, which enabled us to measure the content of all substances soluble in mixture of methanol and water, and the content of hydrophilic extracts. Next, we performed the diethyl ether extraction. This method enabled us to trace the lipophilic extracts. The content of proanthocyanidins was measured using the UV-Vis spectrophotometry. Our research showed that the highest amount of lipophilic extracts can be found in samples of wounded wood tissue, dead and alive tree knots. The lowest amount of lipophilic extracts was tracked in the red heart. The highest amount of hydrophilic extracts was again found in dead and alive tree knots, while the lowest was again found in the red heart. The highest content of total extractible substances were found in live knots, the lowest, again in red heart. We traced the highest amount of proanthocyanidins in dead tree knots, followed by alive tree knots. The lowest content of proanthocyanidins was found in the red heart. In all cases the samples of the red heart had the lowest amount of traced substances

Cilj diplomske naloge je bil evidentirati in smiselno grupirati znano sedanjo in preteklo rabo lesa bukve (Fagus sylvatica L.) in preučiti dodane vrednosti nekaterih izbranih izdelkov. Analizo rabe lesa smo opravili tako, da smo pregledali obstoječo literaturo in internetne vire ter evidentirali izdelke na tržnicah, trgovinah, muzejih in v domačem okolju. Evidentirali smo 460 izdelkov in jih razvrstili v 28 skupin. Iz različnih skupin smo izbrali štiri izdelke (impregniran bukov prag, žagan les, stensko uro in bukova drva) in zanje izračunali različne kazalnike dodane vrednosti. Analize so pokazale, da po kazalniku skupne dodane vrednosti izdelka najboljše rezultate dosegamo s proizvodnjo žaganega lesa, po kazalniku deleža dodane vrednosti v prodajni ceni izdelka pa je najboljši rezultat pri proizvodnji stenske ure in drv, izdelanih iz hlodovine slabše kakovosti. V slednjih dveh izdelkih je tudi največ vloženega dela in/ali kapitala. Ugotovili pa smo tudi velik vpliv kakovosti lesa na izračune dodane vrednosti The objective of this study is to list and group accordingly the known present and past uses of beech wood (Fagus sylvatica L.) and study the added value of selected products. Analysis of wood usage was carried out by studying books and internet sources, as well as searching and listing products in the markets, shops, museums and in everyday life. We found 460 products and sorted them into 28 groups. We choose 4 products each from a different group (railway sleepers, sawn timber, a clock, and firewood) and calculated different added value rates. Analysis showed that according to the added value rates, the best results are achieved by sawn timber production, but according to percentage of added value in the price of the product the best results are achieved in the production of a clock and firewood from beech of lesser quality. In the case of the latter 2, there was the highest amount of input work and capital. We established that wood quality has a big influence in added value rates

Preiskovali smo 2 bukvi (Fagus sylvatica L.), požagani v urbanem gozdu na pobočju Rožnika, Ljubljana. Namen naše preiskave je bil ugotoviti vsebnost celokupnih fenolov in delež ekstraktibilnih snovi v beljavi, rdečem srcu in reakcijskih conah na različnih višinah vzdolž drevesa. Drevesa smo razžagali, odvzeli vzorčne kolute, jih skrbno pregledali, označili vzorce, jih izžagali, zmleli in posušili. Lesni prah smo nato ekstrahirali v hladni vodni raztopini 80 % metanola s pomočjo magnetnega mešala. Delež celokupnih fenolov smo določili spektrofotometrično po Folin-Ciocalteau metodi. Ugotovili smo, da je vsebnost celokupnih fenolov v drevesu št. 1 večja v beljavi in reakcijski coni, rdeče srce pa ima nižjo povprečno vsebnost celokupnih fenolov kot rdeče srce v drevesu 2. Najvišja povprečna vsebnost celokupnih fenolov je v lesu reakcijske cone (drevo št. 1). Drevo 2 ima največjo povprečno vsebnost celokupnih fenolov v lesu beljave, sledi ji reakcijska cona najmanjši povprečni delež celokupnih fenolov pa je v lesu rdečega srca. Rdeče srce bukve je tkivo, ki vsebuje najmanj ekstraktibilnih snovi in najmanj fenolnih. Porazdelitev fenolnih snovi v drevesu odraža fiziološko funkcijo, ki jo imajo ta tkiva v drevesu. 2 beech trees (Fagus sylvatica L.), cut down in urban forest of Rožnik in Ljubljana, were investigated. The aim of our work was examination of content of total phenols and content of total extractable substances in sapwood, red heart and reaction zones at different heights along the trees. The trees were dissected and discs removed. They were carefully examined macroscopically the samples were marked, dissected, milled and dried. Then wood powder was extracted in cold 80 % aqueous solution of methanol by aid of magnetic stirrer. Contents of total phenols were determined spectrophotometrically according to Folin-Ciocalteau method. We found out that the content of total phenols was higher in sapwood and reaction zone in the tree No. 1 than in the tree No. 2. Red heart in tree No. 1 had lower content of total phenols then the red hart in tree No. 2. The highest average content of total phenols was in reaction zones in tree No. 1. The tree No. 2 had the highest content of total phenols in sapwood, following by reaction zone, whereas the least phenolic compounds were found in red heart in both trees. Distribution of phenolic compounds in the tree reflects its physiological function of tissues in the living tree.

In spring of 2020 we observed leaf phenology in mature European beech (Fagus sylvatica) trees in Tivoli, Rožnik and Šišenski hrib Landscape Park in Ljubljana, Slovenia (46.05°N, 14.49°E, 310 m a. s. l.). A group of 11 trees was selected for daily monitoring of leaf development. We recorded seven phases from dormant buds, through leaf unfolding till development of mature leaves. At the same time, photos were taken to illustrate the leaf development. First developing leaves were observed on 4 April in one tree. General leaf unfolding, as defined by International Phenological Gardens (IPG), was observed in different trees between 7 and 25 April 2020. The occurrence and duration of individual phases of leaf development showed great variation within and between trees. General leaf unfolding of the tree included in the long-term monitoring program of the Environmental Agency of the Republic of Slovenia (ARSO) occurred on DOY 105 (14 April 2020), which is 4 days earlier than long-term average of the same tree/location, and this is ascribed to above average temperatures in the winter of 2019/2020. V Krajinskem parku Tivoli, Rožnik in Šišenski hrib v Ljubljani (46,05°S, 14,49°V, 310 m n. m.) smo spomladi leta 2020 opazovali fenologijo razvoja listov odraslih dreves navadne bukve ( Fagus sylvatica ). Izbrali smo skupino enajstih dreves za dnevno opazovanje, beleženje in fotografiranje razvoja listov. Razlikovali smo sedem faz od mirujo - čih brstov, preko različnih faz olistanja do zrelih listov. Prve razvijajoče se liste smo na enem drevesu opazili 4. aprila 2020. Fazo splošnega olistanja, kot jo določa metodologija Mednarodnih fenoloških vrtov, smo pri različnih drevesih beležili od 7. do 25. aprila 2020. Pri nastopu in trajanju različnih faz razvoja listov smo zabeležili velike razlike znotraj posameznega drevesa in med drevesi. Splošno olistanje pri drevesu, ki ga dolgotrajno opazuje Agencija RS za okolje (ARSO), je nastopilo na zaporedni dan 105 (14. aprila 2020), kar je 4 dni prej kot kaže dolgoletno povprečje za isto drevo/lokacijo. Slednje pripisujemo nadpovprečno visokim temperaturam v zimi 2019/2020

Dinarski jelovo-bukovi gozdovi so med bolj ohranjenimi gozdovi v Sloveniji. Kljub dolgoletni tradiciji načrtovanja in gospodarjenja se pojavljajo problemi, ki so povezani predvsem z nazadovanjem jelke (Abies alba Mill.) in neusklajenostjo živalske in rastlinske komponente v tem tipu gozda. Za uspešno gospodarjenje je poznavanje razmer v naravi prepuščenih sestojih (pragozdovih) ključnega pomena. V raziskavi smo primerjali štiri pragozdove (Rajhenavski Rog, Pečka, Krokar in Strmec) s primerljivimi oddelki v gospodarskem gozdu. Primerjali smo svetlobne razmere, pomlajevanje in teksturne ter strukturne značilnosti. Ugotovili smo, da je v gospodarskem gozdu statistično značilno več svetlobnega sevanja kot v pragozdu. Tudi drugi ekološki kazalniki kažejo na bolj izravnane razmere v PG. Razlike se kažejo tudi v pomlajevanju ter v strukturnih in teksturnih značilnostih. Pomlajevanje v pragozdu poteka izrazito malopovršinsko, medtem ko v gospodarskem gozdu, zaradi gospodarjenja spuščamo v sestoje več svetlobe. Take svetlobne razmere bolj odgovorjajo bukvi (Fagus sylvatica L.), ki jelko pogosto prehiti v rasti. V gospodarskem gozdu je gostota dreves večja, dimenzije dreves so manjše in večja je vrstna pestrost. Rezultati nakazujejo, da z gospodarjenjem pospešujemo vse ostale drevesne vrste, razen bukve. V arhitekturi mladja ni razlik, kar je verjetno posledica močnega vpliv rastlinojedov. Rezultati so potrdili, da z gojenjem gozdov spreminjamo sestojno zgradbo, da bi ohranili konkurenčno manj sposobne drevesne vrste, kot so iglavci in svetloljubne vrste. Kljub razlikam v zgradbi, pa proučevani raznomerni gospodarski gozdovi nakazujejo številne atribute staroraslih gozdov in s tem ustreznost Natura 2000 usmeritvam. Dinaric mixed mountain forests are among the most well-preserved forests in Slovenia. Despite long-standing tradition of forest planning and management problems occur which are particularly connected to fir (Abies alba Mill.) recession and disproportion between plant and animal component in this forest type. For successful management, knowledge of conditions in naturally developing stands (old-growth forests) is of key importance. Our research has compared four old-growth forests (Rajhenavski Rog, Pečka, Krokar and Strmec) to comparable sections of managed forest. Light conditions, regeneration, and textural and structural characteristics were compared. Significant differences have been found between old growth forests and managed forests. Light in this forest type is among the more important ecological factors as it is crucial for successful regeneration. It has been found that there is statistically significantly more light radiation in managed forest than in old-growth forest. Also other ecological indicators point to more equalized conditions in old-growth forest. Differences appear also in regeneration and structural and textural qualities. Regeneration in old-growth forest takes place on markedly small areas, while in managed forest more light is let into stands due to management. These light conditions favour beech which often takes over fir in growth. In managed forests the tree densities and diversity are higher. It appears that through management all other tree species are promoted except for beech (Fagus sylvatica L.). There was no difference in tree architecture of young trees which can be likely attributed to a strong influence of herbivores. The results confirmed that the silviculture changes the stand structure in order to maintain a competitive less capable species, such as conifers and light demanding species. Despite the differences in structure, the studied managed forests suggests several attributes of old-growthness and the adequacy of the Natura 2000 guidelines.

Raziskovali smo vpliv prahu na spektralne in funkcionalne lastnosti listov navadne bukve (Fagus sylvatica L.). Vpliv prašnih delcev smo ugotavljali na treh lokacijah ob kamnolomu in ga primerjali z referenčno lokacijo v dveh rastnih sezonah. V tretji sezoni smo izvedli poskus v delno nadzorovanih razmerah z dodajanjem prahu v dveh različnih koncentracijah. Opravili smo meritve izbranih anatomskih, biokemijskih in fizioloških lastnosti listov. Izmerili smo odbojne in presevne spektre listov s prahom in tistih, ki smo jim prah odstranili v območju 280%880 nm. Ugotavljali smo povezanost med prisotnostjo prahu, lastnostmi listov in optičnimi lastnostmi. Rezultati iz narave, kjer so bile koncentracije prahu nizke (največ 0,25 + 0,11 mg/cm2), so pokazali razlike v anatomskih, biokemijskih in fizioloških lastnostih listov bukve na različnih rastiščih, kar ni bilo povezano le s prisotnostjo prahu, ampak je bilo tudi posledica okoljskih razmer na rastišču. Rezultati kratkotrajnega poskusa so pokazali, da le prisotnost apnenčastega prahu na listih bukve v visokih koncentracijah (8,98 + 4,05 mg/cm2) močno spremeni odbojnost listov navadne bukve v vidnem in UV-spektru, medtem ko nižje koncentracije prahu na listih nimajo velikega vpliva. Prepustnost sončne svetlobe skozi list je spremenjena v vidnem in v NIR-območju. To se je odrazilo v povečani koncentraciji fotosinteznih barvil in zmanjšanju vsebnosti snovi z zaščitno vlogo: antocianov in UV-absorbirajočih snovi. Redundantna analiza je pokazala, da je koncentracija prahu v naravnih razmerah pojasnila le 16 % (p < 0,001) variabilnosti odbojnih spektrov. V kratkotrajnem poskusu z visokimi koncentracijami prahu je prisotnost prahu razložila 67 % (p < 0,001) variabilnosti odbojnih spektrov ter 12 % (p < 0,001) variabilnosti presevnih spektrov. We studied the influence of limestone dust on spectral and functional properties of European beech leaves (Fagus sylvatica L.) at three different locations along a limestone quarry and compared them to a reference location in two growing seasons. In the third season measurements were conducted in an independent experiment under partially controlled conditions by the controlled feeding of limestone dust in two different concentrations of the dust. Measurements of anatomical and biochemical properties of the leaves were performed. The reflectance spectra of the leaves with the dust and of those where the dust was removed were measured in the range of 280%880 nm. The effect of the dust on the measured parameters was studied and correlations among the presence of dust, leaves' and spectral reflectance properties were analysed. The results from nature where the dust concentrations were low (max 0,25 + 0,11 mg/cm2) showed differences in anatomical, biochemical and physiological characteristcs of beech leaves from different test sites. This was not only a consequence of the presence of the dust but also of the environmental conditions on the test sites. The results of the short experiment showed that only high concentrations (8,98 + 4,05 mg/cm2) of limestone dust on beech leaves significantly changed the reflectance properties of the leaves of common beech in the visible and UV spectra, while low concentrations had no major effect on the leaves. The transmittance of the sunlight through the leaves was changed in the visible and near infrared spectra, which was reflected in the increased concentration of photosynthetic pigments and reduced substances for photoprotective function: anthocyanins and UV absorbing substances. The redundancy analysis revealed that the dust concentration in natural conditions explained only 16 % (p < 0,001) of the variability of the reflection spectra. In the short experiment with high dust concentrations the presence of the dust explained 67 % (p < 0,001) of the variability of the reflection spectra and 12 % (p < 0,001) of the variability of the

V raziskavi smo želeli ugotoviti vpliv temperature zraka in tal ter koncentracij CO2 tako na sadike bukve kot tudi na ektomikorizne glive (ECM). Poskus smo zastavili na enoletnih sadikah bukve Fagus sylvatica L., posajenih v rizotrone pri različnih temperaturah: v klimatizirani komori (15-20 °C) brez dodatnega hlajenja korenin (CR-) in z dodatnim hlajenjem korenin za 4-5 °C (CR+), v rastlinjaku s povišanimi temperaturami zraka (GH) in zunaj (OUT), kjer so bile sadike izpostavljene naravnim temperaturam zraka. Na sadikah smo izvajali nedestruktivne analize korenin tekom poskusa in destruktivno analizo celotnih sadik ob koncu tri-letnega poskusa. Največji delež drobnih korenin, več kot 98% in najmanjši povprečni premer korenin so imele sadike v rastlinjaku. Delež mikoriznih korenin je bil v tretmajih CR+, CR- in GH med 10,3% in 11,4%, medtem ko je bilo v tretmaju zunaj za polovico manj mikoriznih korenin (5%). Za opis vplivov temperatur in povišanih koncentracij CO2 v zraku na koreninske sisteme in nadzemni del sadik smo izračunali indekse rasti. Dokazali smo značilen (p

Analizirana je bila poškodovanost gozdnih sestojev zaradi naravnih motenj. Analiza je bila izvedena na dveh prostorskih ravneh. Na krajinski ravni so bili za gozdnogospodarsko enoto Brezova reber (velikost 1.722 ha) glede na podatke o sanitarnem poseku za obdobje 1973%2011 analizirani količina, struktura in dinamika poseka po vzrokih sanitarne sečnje ter vpliv rastiščnih in sestojnih dejavnikov na sanitarni posek. Ugotovljeno je bilo, da je verjetnost pojavljanja poškodb v negovanih sestojih zaradi naravnih motenj v prvih treh letih po negovalni sečnji značilno višja. Poškodbe zaradi snega so verjetnejše v mlajših sestojih, poškodbe zaradi vetra in insektov pa v starejših. Na pojav naravnih motenj vpliva več rastiščnih kot sestojnih dejavnikov. Z multiplo linearno analizo je bila potrjena interakcija med različnimi naravnimi motnjami. Na sestojni ravni je bila v raziskovalnem objektu Brezova reber (oddelek 25c in 26c, velikost 0,81 ha) analizirana poškodovanost dreves zaradi snegoloma leta 2012. Sestoji so glede na gojitveno obravnavo razdeljeni v tri stratume: A) klasično izbiralno redčenje, B) izbiralno redčenje s stalnimi izbranci in C) brez ukrepanja. Deleţ poškodovanih dreves in izbrancev je največji v stratumu A, med stratumoma B in C pa so bile odkrite razlike v deleţu poškodovanih večvrhatih dreves. Z binarnim logističnim modelom je bilo ugotovljeno, da so bili močneje sproščeni izbranci (število posekanih konkurentov na izbranca) manj poškodovani. V stratumu A so se poškodovana drevesa pojavljala na celotni površini, večinoma ob izbrancih, v stratumu B pa so bila poškodovana drevesa tudi znotraj šopov indiferentnih dreves ter manj ob izbrancih. V stratumu C so bile poškodbe najmočnejše v delih sestoja z večjim številom drevja. The aim of this thesis is to analyze damage to forest stands due to natural disturbances. The study was carried out at two spatial levels. At the landscape level it analyzed, based on the amount of salvage logging for the period 1973-2011, the volume, structure and dynamics of the causes of salvage logging as well as the impact of site and stand factors on the salvage logging for the Brezova reber forest management unit (the area of 1.722 ha). It was found that the probability of damage occurrence due to natural disturbances is significantly higher during the first three years after logging. Damage due to snow was more likely to occur in younger stands, while damage caused by wind and insects was more likely to occur in older stands. Natural disturbances are more strongly influenced by site than by stand factors. Interaction between the different natural disturbances was confirmed using multiple linear regression. At the stand level in the Brezova reber research site (departments 25c and 26c, the area of 0.81 ha) the 2012 snow damage of stand trees was analyzed. The stands in research sites were divided into three treatments: A) classical selective thinning, B) selective thinning with fixed crop trees and C) control plots for natural development. The highest percentage of damaged trees and crop trees was recorded in treatment A. Differences in the percentage of damaged forked trees were found between treatment B and treatment C. Using the binary logistic model it was found that crop trees that were more released (the number of felled competitors per crop tree) were less damaged. In treatment A damaged trees appeared on the entire surface, mostly near crop trees. In treatment B damaged trees were also inside the clusters of indifferent trees, but less near crop trees. In treatment C the damage was most severe in the part with the highest stand density.