1. A single-tree approach to determine climate-growth patterns of European beech and their seasonality in the species southern distribution areaRoberto Serrano-Notivoli, Jernej Jevšenak, Katarina Čufar, Nina Škrk Dolar, Angela Balzano, Jožica Gričar, Maks Merela, Klemen Novak, Peter Prislan, Martin De Luis, 2025, original scientific article Abstract: Dry and warm climate conditions in southern Europe represent clear limits for European beech (Fagus sylvatica) growth near the species southern distribution limit, but it is unclear how aridification and changes in seasonal precipitation regimes will affect these forests at the individual level. We explored climate-growth relationships and the seasonality of peak climate signals in European beech using daily climate data and a large collection of tree-ring width series from southern and southeastern Europe through Generalised Linear Mixed Models (GLMMs). In most cases we found a positive and significant influence of precipitation on tree growth, and a significant negative effect of maximum temperature. Predictions from the GLMMs revealed a positive impact of precipitation during an 88 day window from spring to early summer (mid-April to mid-July), for an average tree across our network. This critical growing time window ranged from 75 days in warmer and drier conditions, and extended up to 100 days in areas with mild temperatures and moderate summer precipitation. Maximum temperatures negatively affected trees for an average of 27 day window in summer (June-July). This period was reduced to <10 days in locations with wetter and colder summers, rising up to 45 days in sites with drier and warmer summers. The positive effect of precipitation on growth was stronger and commenced earlier in larger trees. Similarly, the negative effects of maximum temperatures were more pronounced for larger trees. The use of daily climate data and a tree-centred approach allowed for capturing critical temporal dynamics in climate-growth relationships that are often overlooked by conventional methods. These insights significantly enhance our understanding of climatic factors influencing individual beech growth at the edge of its distribution range and their seasonal variations.
Keywords: European beech, daily climatic variables, precipitation, maximum temperature, tree-ring width, range limit
Published in DiRROS: 06.06.2025; Views: 539; Downloads: 259
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2. Optimizing competitor definitions for the sustainable management of dominant silver fir trees (Abies alba Mill.) in uneven-aged mixed Dinaric forestsMilan Kobal, Tom Levanič, 2025, original scientific article Abstract: Understanding competition between trees is essential for sustainable forest management as interactions between trees in uneven-aged mixed forests play a key role in growth dynamics. This study investigated nine competition indices (CIs) for their suitability to model the effects of neighboring trees on silver fir (Abies alba) growth in Dinaric silver fir-European beech (Fagus sylvatica) forests. Although numerous competition indices have been developed, there is still limited consensus on their applicability in different forest types, especially in mature, structurally complex forest stands. The indices were evaluated using the adjusted coefficient of determination in a linear model wherein the volume growth of the last five years for 60 dominant silver fir trees was modeled as a function of tree volume and competition index. The results demonstrated that distance-dependent indices (e.g., the Hegyi height-distance competition and Rouvinen-Kuuluvainen diameter-distance competition indices), which consider the distance to competitors and their size, perform better than distance-independent indices. Using the optimization procedure in calculating the competition indices, only neighboring trees at a distance of up to 26-fold the diameter at breast height (DBH) of the selected tree (optimal search radius) and with a DBH of at least 20% of that of the target tree (optimal DBH) were considered competitors. Therefore, competition significantly influences the growth of dominant silver firs even in older age classes. The model based solely on tree volume explained 32.5% of the variability in volume growth, while the model that accounted for competition explained 64%. Optimizing the optimal search radius had a greater impact on model performance than optimizing the DBH threshold. This emphasizes the importance of balancing stand density and competition in silvicultural practice.
Keywords: sustainable forest management, Dinaric silver fir-European beech forests, Competition indices, CIs, optimal search distance, optimal diameter at breast height, DBH
Published in DiRROS: 05.06.2025; Views: 480; Downloads: 288
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3. Phenological trends of European beech stands along the Carpathian arc : a 20-year MOD13Q1/MYD13Q1 based analysisM. Švik, O. Brovkina, Tatjana Veljanovski, Matjaž Čater, 2025, original scientific article Abstract: European forests are severely threatened by rapid global climate change. Predicting the effects of climate change on the future performance of tree species can be enhanced by using geographical gradients as space-time proxies. This study focuses on analysing seasonal and inter-annual phenological trends for eight sites of European beech (Fagus sylvatica L.) in the Carpathians along such geographical gradient. Using time series of the Enhanced Vegetation Index (EVI) from 2003 to 2022, derived from 16-day MODIS Terra and Aqua vegetation products, combined with meteorological parameters (temperature and precipitation) interpolated for a grid and Land Surface Temperature (LST) data from Landsat, we compared annual forest development at the study sites and extracted key phenological metrics (start, length, and end of the growing season) using the phenofit software package for R. Our results show varied responses of the studied forest sites to climate change. The end of season extended significantly at Soveja (slope = 0.50, p = 0.023). Spring temperatures had negative correlations with the start of season (r = -0.37) and autumn temperatures positive correlation with the end of season (r = 0.43). Understanding these patterns is crucial for developing adaptive forest management strategies in Carpathians.
Keywords: Carpathians, European beech, vegetation index, MODIS, land surface phenology, time series
Published in DiRROS: 21.05.2025; Views: 547; Downloads: 292
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4. Phenological trends of European beech stands along the Carpathian arc : a 20-year MODIS based analysisM. Švik, O. Brovkina, Tatjana Veljanovski, Matjaž Čater, 2024, published scientific conference contribution abstract Keywords: European beech, phenology, remote sensing, time series, vegetation index
Published in DiRROS: 03.09.2024; Views: 1128; Downloads: 325
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5. Climate growth limitations of European beech and silver fir along the Carpathian arc – the recent state and future prospectsJakub Kašpar, Kamil Král, Tom Levanič, Pia Caroline Adamič, Matjaž Čater, 2024, published scientific conference contribution abstract Keywords: climate-growth limitation, VS model, Carpathians, climate change, silver fir, European beech
Published in DiRROS: 03.09.2024; Views: 891; Downloads: 552
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6. Temporal and spatial variability of phloem structure in Picea abies and Fagus sylvatica and its link to climateJožica Gričar, Jernej Jevšenak, Kyriaki Giagli, Klemen Eler, Dimitrios Tsalagkas, Vladimir Gryc, Hanuš Vavrčík, Katarina Čufar, Peter Prislan, 2024, original scientific article Abstract: Using a unique 8-year data set (2010–2017) of phloem data, we studied the effect of temperature and precipitation on the phloem anatomy (conduit area, widths of ring, early and late phloem) and xylem-ring width in two coexisting temperate tree species, Picea abies and Fagus sylvatica, from three contrasting European temperate forest sites. Histometric analyses were performed on microcores taken from tree stems in autumn. We found high interannual variability and sensitivity of phloem anatomy and xylem-ring widths to precipitation and temperature; however, the responses were species- and site-specific. The contrasting response of xylem and phloem-ring widths of the same tree species to weather conditions was found at the two Slovenian sites generally well supplied with precipitation, while at the driest Czech site, the influence of weather factors on xylem and phloem ring widths was synchronised. Since widths of mean annual xylem and phloem increments were narrowest at the Czech site, this site is suggested to be most restrictive for the radial growth of both species. By influencing the seasonal patterns of xylem and phloem development, water availability appears to be the most important determinant of tissue- and species-specific responses to local weather conditions.
Keywords: wood anatomy, early phloem, European beech, late phloem, Norway spruce, sieve element area, xylem-ring width
Published in DiRROS: 19.01.2024; Views: 1272; Downloads: 777
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7. Radial increment of beech (Fagus sylvatica L.) Is under a strong impact of climate in the continental biogeographical region of CroatiaTom Levanič, Damir Ugarković, Ivan Seletković, Mladen Ognjenović, Mia Marušić, Robert Bogdanić, Nenad Potočić, 2023, original scientific article Abstract: 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.
Keywords: climate change, tree growth, forest productivity, drought, European beech
Published in DiRROS: 28.06.2023; Views: 1406; Downloads: 837
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8. Mode I fracture of beech-adhesive bondline at three different temperaturesJaka Gašper Pečnik, Andreja Pondelak, Michael David Burnard, Václav Sebera, 2022, original scientific article Abstract: Single edge-notched three-point bending tests (SEN-TPB) for mode I were utilized to experimentallyevaluate fracture properties of adhesive bondlines in European beech (Fagus SylvaticaL.). Thebondline was examined at two anatomical planes with TR and RT orientation and at control andtwo elevated temperatures (70°C and 140°C). Among epoxy (EPI), melamine-urea formaldehyde (MUF), and polyurethane (PUR) adhesives, the highest average critical energyGcwith 0.80 N/mmand fracture energyGfwith 1079.4 N/mm were obtained for EPI in the TR plane and understandard climate conditions (20°C/65% relative humidity), followed by MUF (Gc= 0.50 N/mm andGf= 620 N/mm) and PUR (Gc= 0.25 N/mm andGf= 290.9 N/mm), respectively. PUR was leasteffected by elevated temperature, and no significant differences forGcandGfbetween TR and RTbondline orientations were found for MUF and PUR treated at 20°C/65% relative humidity whilecomparisons between other factors varied significantly. Treatment of specimens at elevatedtemperatures resulted in reduced fracture performance regardless of wood grain orientation orthe adhesive system.
Keywords: crack, fracture, grain orientation, temperature, European Beech, odprti dostop
Published in DiRROS: 03.05.2023; Views: 1439; Downloads: 1334
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9. Inter-individual variability in spring phenology of temperate deciduous trees depends on species, tree size and previous year autumn phenologyLorène 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: 2799; Downloads: 1751
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