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21.
Analysis of the response of a roadway bridge under extreme flooding-related events: Scour and debris-loading
Mirko Kosič, Luke J. Prendergast, Andrej Anžlin, 2023, original scientific article

Abstract: Hydraulic actions on bridges are a leading cause of failure, especially due to the occurrence of scour erosion. Due to climate change, flooding and scour risks are exacerbating for bridges worldwide, leading to a significant stress burden on asset management agencies. Assessing structures for scour has received significant attention in recent years, however, there are few studies which investigate the influence of scour on the components of a bridge to understand how various elements interact. Moreover, the presence of debris loading, which can occur due to flooding causing debris to become lodged at structures, has not received significant attention. Debris can worsen scour conditions and increase hydraulic loading on a bridge. In this paper, an analysis of the response of various components of a roadway bridge when exposed to extreme flooding is conducted. The influence of scour and debris on hydraulic loading, internal forces, modal periods, and utilization ratios of various bridge components is ascertained. A numerical model is developed using OpenSees employing two different methods to model the soil-structure interaction. Results for several flooding scenarios show how the various bridge elements are influenced by variations in water height and velocity, scour depth, and presence of debris.
Keywords: local scour, wood debris, flooding, resilience, soil-structure interaction, bridges, open access
Published in DiRROS: 29.05.2023; Views: 271; Downloads: 216
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22.
Different wood anatomical and growth responses in European beech (Fagus sylvatica L.) at three forest sites in Slovenia
Domen Arnič, Jožica Gričar, Jernej Jevšenak, Gregor Božič, Georg von Arx, Peter Prislan, 2021, original scientific article

Abstract: European beech (Fagus sylvatica L.) adapts to local growing conditions to enhance its performance. In response to variations in climatic conditions, beech trees adjust leaf phenology, cambial phenology, and wood formation patterns, which result in different treering widths (TRWs) and wood anatomy. Chronologies of tree ring width and vessel features [i.e., mean vessel area (MVA), vessel density (VD), and relative conductive area (RCTA)] were produced for the 1960%2016 period for three sites that differ in climatic regimes and spring leaf phenology (two early- and one late-flushing populations). These data were used to investigate long-term relationships between climatic conditions and anatomical features of four quarters of tree-rings at annual and intra-annual scales. In addition, we investigated how TRW and vessel features adjust in response to extreme weather events (i.e., summer drought). We found significant differences in TRW, VD, and RCTA among the selected sites. Precipitation and maximum temperature before and during the growing season were the most important climatic factors affecting TRW and vessel characteristics. We confirmed differences in climate-growth relationships between the selected sites, late flushing beech population at Idrija showing the least pronounced response to climate. MVA was the only vessel trait that showed no relationship with TRW or other vessel features. The relationship between MVA and climatic factors evaluated at intra-annual scale indicated that vessel area in the first quarter of tree-ring were mainly influenced by climatic conditions in the previous growing season, while vessel area in the second to fourth quarters of tree ring width was mainly influenced by maximum temperature and precipitation in the current growing season. When comparing wet and dry years, beech from all sites showed a similar response, with reduced TRW and changes in intra-annual variation in vessel area. Our findings suggest that changes in temperature and precipitation regimes as predicted by most climate change scenarios will affect tree-ring increments and wood structure in beech, yet the response between sites or populations may differ.
Keywords: Fagus sylvatica, wood anatomy, tracheograms, dendrochronology, intra specific plasticity
Published in DiRROS: 22.07.2022; Views: 499; Downloads: 353
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23.
Relationships between wood-anatomical features and resistance drilling density in Norway spruce and European beech
Domen Arnič, Luka Krajnc, Jožica Gričar, Peter Prislan, 2022, original scientific article

Abstract: Environmental conditions affect tree-ring width (TRW), wood structure, and, consequently, wood density, which is one of the main wood quality indicators. Although studies on inter- and intra-annual variability in tree-ring features or density exist, studies demonstrating a clear link between wood structure on a cellular level and its effect on wood density on a macroscopic level are rare. Norway spruce with its simple coniferous structure and European beech, a diffuse-porous angiosperm species were selected to analyze these relationships. Increment cores were collected from both species at four sites in Slovenia. In total, 24 European beech and 17 Norway spruce trees were sampled. In addition, resistance drilling measurements were performed just a few centimeters above the increment core sampling. TRW and quantitative wood anatomy measurements were performed on the collected cores. Resistance drilling density values, tree-ring (TRW, earlywood width–EWW, transition-TWW, and latewood width–LWW) and wood-anatomical features (vessel/tracheid area and diameter, cell density, relative conductive area, and cell wall thickness) were then averaged for the first 7 cm of measurements. We observed significant relationships between tree-ring and wood-anatomical features in both spruce and beech. In spruce, the highest correlation values were found between TRW and LWW. In beech, the highest correlations were observed between TRW and cell density. There were no significant relationships between wood-anatomical features and resistance drilling density in beech. However, in spruce, a significant negative correlation was found between resistance drilling density and tangential tracheid diameter, and a positive correlation between resistance drilling density and both TWW + LWW and LWW. Our findings suggest that resistance drilling measurements can be used to evaluate differences in density within and between species, but they should be improved in resolution to be able to detect changes in wood anatomy.
Keywords: wood structure, Fagus sylvatica, Picea abies, quantitative wood anatomy, xylem anatomy, wood density, increment borer
Published in DiRROS: 08.04.2022; Views: 573; Downloads: 424
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24.
Assessment of the condition of Balsam poplar trees (Populus balsamifera L.) in a residental area of Bratsk
Elena Runova, Vasilij Verkhoturov, Lyudmila Anoshkina, Ivan Garus, 2021, original scientific article

Abstract: In this study, we investigated the health status of balsam poplar (Populus balsamifera L.) trees in a residential area of the city of Bratsk (Irkutsk Oblast, Russia). Visual and instrumental assessment of the health status of pruned and unpruned trees was performed. The identified internal defects in the tree were analyzed with a Resistograph device, which enabled the extent of decayed wood to be determined. Visual analysis revealed various types of damage: dried branches, brittle crowns, frost cracks, mechanical damage, curvature of trunks, decay and inclusions of foreign bodies. We compared trees with and without canopy pruning. We found that pruned trees were significantly more damaged than non-pruned trees. Decomposing wood at different stages of development was found in all the trees studied. A tree passport combining the visual and instrumental assessment data was compiled for each tree. The results of the research were used to formulate conclusions and recommendations for improving the management of urban trees in order to restore their ecological and aesthetic functions.
Keywords: Populus balsamifera L., visual analysis, Resistograph, urban area, wood, decay
Published in DiRROS: 01.12.2021; Views: 3006; Downloads: 1820
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25.
Drought stress can induce the pathogenicity of Cryptostroma corticale, the causal agent of sooty bark disease of sycamore maple
Nikica Ogris, Ana Brglez, Barbara Piškur, 2021, original scientific article

Abstract: Reports of sooty bark disease of maples caused by the fungus Cryptostroma corticale have recently been emerging from across Europe. The aims of our study were to describe the first report of sooty bark disease in Slovenia, to determine the pathogenicity of C. corticale, to confirm the optimum temperature for the growth of the fungus, and to determine the mass loss of Acer pseudoplatanus wood inoculated by C. corticale. We confirmed the presence of C. corticale on A. pseudoplatanus via morphological and molecular analysis. The optimal growth of C. corticale was measured in vitro on potato dextrose agar and was determined to occur at 25 °C. Pathogenicity tests were performed on 30 saplings of A. pseudoplatanus under two treatments, humid and drought stress, and the fungus was pathogenic in both treatments. The mean length of bark lesions and wood discoloration of the drought-stressed saplings was significantly greater than that in the humid treatment. Re-isolations of C. corticale were successful from all inoculated saplings, and thus Koch%s postulates were confirmed. The mass loss of A. pseudoplatanus wood was determined by mini-block test in a period of 10 weeks and was observed as minimal. Based on the results, we conclude that C. corticale is a weak and opportunistic pathogen that most likely expresses itself intensively under hot and dry conditions.
Keywords: pathogenicity, drought stress, optimal growth, climate change, mass loss, mini-block test, wood rot, opportunistic pathogen, saprophyte, endophyte
Published in DiRROS: 23.03.2021; Views: 1120; Downloads: 855
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26.
Hands-on guidelines for private woodlot owners in Slovenia, Latvia, Estonia, Sweden and Spain
2021, dictionary, encyclopaedia, lexicon, manual, atlas, map

Keywords: Net4Forest, Erasmus+, quality classes, wood defects, quality wood, forest fires, roundwood sales
Published in DiRROS: 22.03.2021; Views: 817; Downloads: 462
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27.
The effect of bedrock and species mixture on wood density and radial wood increment in pubescent oak and black pine
Luka Krajnc, Polona Hafner, Jožica Gričar, 2020, original scientific article

Abstract: Wood density and radial wood increment were examined in trees of pubescent oak (Quercus pubescens Willd.) and black pine (Pinus nigra Arnold., subsp. nigra) in relation to stand mixture and underlying bedrock. Trees of both species from pure and mixed stands were sampled across two types of bedrock, limestone and flysch. Trees from each species were similar in age. Wood density was estimated in standing trees using resistance drilling and increment cores were taken from a smaller subsample of trees of both species. Tree-ring, earlywood and latewood widths were measured and compared to radial profiles of wood density. The influence of stand mixture, diameter at breast height and bedrock on wood density was examined using a Bayesian general linear model. Wood density was significantly higher in pubescent oak than in black pine. Stand mixture was found to affect wood density positively, although the magnitude of the effect was relatively small when compared to other influencing factors also included in the current study. The effect of diameter on wood density was positive on both bedrocks in pubescent oak and negative or neutral in black pine. The size of the effect varied by bedrock and species. On flysch bedrock, the influence of diameter on wood density was stronger than it was on limestone. These indirect bedrock effects on wood density are probably a result of different soil fertility rather than the bedrock itself. There was a notable difference in radial wood increment in both species across the two bedrocks, whereas the differences in densities were smaller. Higher wood densities found on flysch in the subsample of pubescent oaks are likely an effect of higher proportions of latewood, while the opposite trend was observed in black pine. Higher wood density was found on limestone in black pine despite higher latewood percentages on flysch. In the context of forest management, the species composition of the naturally occurring mixtures in the sub-Mediterranean region should be adjusted slightly to favor pubescent oak, since it is a climax species and will bind more carbon for longer than black pine due to higher wood densities. Future forest management should also promote the overall development of pubescent oak trees in sub-Mediterranean stands. The results are especially important in the European context, because the share of sub-Mediterranean stands is expected to rise with global warming.
Keywords: Karst, wood structure, resistograph, resistance drilling, Quercus pubescens, Pinus nigra, limestone, flysch
Published in DiRROS: 14.01.2021; Views: 1086; Downloads: 363
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28.
The effect of Eutypella parasitica on the wood decay of three maple species
Ana Brglez, Barbara Piškur, Miha Humar, Jožica Gričar, Nikica Ogris, 2020, original scientific article

Abstract: Eutypella parasitica R.W. Davidson & R.C. Lorenz is the causative agent of Eutypella canker of maple, a destructive disease of maples in Europe and North America. The fungus E. parasitica is known to cause wood stain and decay. However, it is not known how effectively it decomposes the wood of the most widespread maple species in Europe. Wood samples of Acer pseudoplatanus L., A. platanoides L., and A. campestre L. were exposed to four isolates of E. parasitica and nine other fungal species for comparison, according to the modified EN 113 standard. After 15 weeks of incubation, mass loss and microscopical analysis of samples showed evidence of colonization and different wood decay potentials among fungal species. A highly significant positive correlation was found between mass loss and moisture content for all fungal species. Similarly, the measured cell wall thickness correlated well with the calculated mass loss of the samples. On average, the fungal species caused the lowest mass loss in A. pseudoplatanus (10.0%) and the highest in A. campestre (12.6%) samples. Among the samples exposed to E. parasitica isolates, the highest mass loss was recorded in A. pseudoplatanus (6.6%). Statistical analysis showed significant differences in mass loss and moisture content between different E. parasitica isolates. Based on the results of staining, we discuss the type of decay caused by E. parasitica. Although E. parasitica isolates caused smaller mass loss of samples compared to other more effective decay species, we should not disregard its capability of degrading maple wood. Because E. parasitica usually infects the lower portion of the trunk, which is the largest and most valuable part of the tree, any damage can cause significant economic and resource loss.
Keywords: wood decay, mass loss, moisture content, mini-block test, decay test, Acer spp., Eutypella parasitica, fungi, light microscopy, scanning electron microscopy
Published in DiRROS: 13.07.2020; Views: 1761; Downloads: 1204
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29.
Timeline of autumn phenology in temperate deciduous trees
Inge Dox, Jožica Gričar, Lorène Julia Marchand, Sebastien Leys, Paolo Zuccarini, Charly Geron, Peter Prislan, Bertold Mariën, Patrick Fonti, Holger Lange, Josep Peñuelas, Jan Van den Bulcke, Matteo Campioli, 2020, original scientific article

Abstract: Cessation of xylem formation or wood growth (CWG) and onset of foliar senescence (OFS) are key autumn phenological events in temperate deciduous trees. Their timing is fundamental for development and survival of trees, ecosystem nutrient cycling, the seasonal exchange of matter and energy between the biosphere and atmosphere and affect the impact and feedback of forests to global change. A large-scale experimental effort and improved observational methods have allowed us to compare the timing of CWG and OFS for different deciduous tree species in Western Europe, in particularly silver birch, a pioneer species, and European beech, a late-succession species, at stands of different latitudes, of different levels of site fertility, and for two years with contrasting meteorological and drought conditions i.e., the low-moderately dry 2017 and the extremely dry 2018. Specifically, we tested whether foliar senescence started before, after or concurrently with CWG. OFS and CWG occurred generally between late September and early November, with larger differences across species and sites for OFS. Foliar senescence started concurrently with CWG in most cases, except for the drier 2018 and, for beech, at the coldest site, where OFS occurred significantly later than CWG. Behavior of beech in Spain, the southern edge of its European distribution, was unclear, with no CWG, but very low wood growth at the time of OFS. Our study suggests that OFS is generally triggered by the same drivers of CWG or when wood growth decreases in late summer, indicating an overarching mechanism of sink limitation as a possible regulator of the timing of foliar senescence.
Keywords: autumn phenology, xylem formation, foliar senescence, cambium, chlorophyll, radial growth, wood, decidiuous trees, common aspen, common beech, pedunculate oak, silver birch
Published in DiRROS: 10.06.2020; Views: 1874; Downloads: 1122
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30.
Inter-individual variability in spring phenology of temperate deciduous trees depends on species, tree size and previous year autumn phenology
Lorène Julia Marchand, Inge Dox, Jožica Gričar, Peter Prislan, Sebastien Leys, Jan Van den Bulcke, Patrick Fonti, Holger Lange, Erik Matthysen, Josep Peñuelas, Paolo Zuccarini, Matteo Campioli, 2020, original scientific article

Abstract: We explored the inter-individual variability in bud-burst and its potential drivers, in homogeneous mature stands of temperate deciduous trees. Phenological observations of leaves and wood formation were performed weekly from summer 2017 to summer 2018 for pedunculate oak, European beech and silver birch in Belgium. The variability of bud-burst was correlated to previous' year autumn phenology (i.e. the onset of leaf senescence and the cessation of wood formation) and tree size but with important differences among species. In fact, variability of bud-burst was primarily related to onset of leaf senescence, cessation of wood formation and tree height for oak, beech and birch, respectively. The inter-individual variability of onset of leaf senescence was not related to the tree characteristics considered and was much larger than the inter-individual variability in bud-burst. Multispecies multivariate models could explain up to 66% of the bud-burst variability. These findings represent an important advance in our fundamental understanding and modelling of phenology and tree functioning of deciduous tree species.
Keywords: leaf unfolding, wood formation, coloration, Pedunculate oak, European beech, Silver birch
Published in DiRROS: 10.06.2020; Views: 1819; Downloads: 1056
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