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European beech is one of the most common tree species in Europe and is generally suggested to play even more of a prominent role in forestry in the future. It seems to have the potential to partially replace Norway spruce, as it is less sensitive to expected warmer and drier conditions. It is, however, not well known in which regions these new plantings would be particularly favourable and if specific provenances may be better adapted to the new conditions than others. Therefore, we estimated the potential early height growth under climate conditions in 2040–2060 for 20 beech provenances across a region covering the Czech Republic and Slovakia. This Central European region is expected to experience considerably drier and warmer conditions in the future. For this exercise, we implemented a new neural network model developed from height growth information obtained from the open-access BeechCOSTe52 database. The simulations are driven by past and future climate data obtained from the WorldClim database of historical climate data and future climate projections. Simulations revealed that provenances originating from drier regions performed on average significantly better than those from regions with good water supply. Moreover, provenances originating from drier regions had a particularly large advantage in the relatively arid regions of Central Czechia and Southern Slovakia. We can also confirm that all provenances showed a high phenotypic plasticity of height growth across the whole investigated region. [ABSTRACT FROM AUTHOR]

During drought, the formation of air bubbles known as embolisms in the water-conducting xylem reduces hydraulic conductivity, which can ultimately result in tree death. Accurately quantifying vulnerability to embolism formation is therefore essential for understanding tree hydraulics. Acoustic emission (AE) analysis offers a non-destructive method to monitor this process, yet the interpretation of captured signals remains debated. In this study, we introduce an improved methodology for constructing acoustic vulnerability curves (VCAE) that minimizes subjectivity and enhances the accuracy of assessing a tree's vulnerability to drought stress. Our approach combines AE signal clustering with an objective method for pinpointing the endpoint (point of 100% embolism) based on the observed correlation between water potential at maximum AE activity and 50% loss of hydraulic conductivity. By applying a refined clustering algorithm to four temperate tree species (Platanus × acerifolia (Aiton) Willd., Betula pendula Roth, Quercus robur L. and Fagus sylvatica L.), we consistently identified natural frequency-based clusters that effectively separate embolism-related AEs from other signals. This focus on embolism-related AE activity allowed us to minimize the influence of non-embolism-related signals and identify the true VCAE endpoint. Our method, by reducing the subjectivity inherent in previous approaches, enhances the accuracy of VCAE construction, offering broader insights into tree hydraulics and expanding its applicability across different species and environmental conditions., (© The Author(s) 2025. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.)

Food-hoarding granivores act as both predators and dispersers of plant seeds, resulting in facultative species interactions along a mutualism-antagonism continuum. The position along this continuum is determined by the positive and negative interactions that vary with the ratio between seed availability and animal abundance, particularly for mast-seeding species with interannual variation and spatial synchrony of seed production. Empirical data on the entire fate of seeds up to germination and the influence of rodents on seed survival is rare, resulting in a lack of consensus on their position along the mutualism-antagonism continuum. Here, we quantified annual seed rain and rodent abundance in an old-growth European beech forest and tracked 639 beechnuts to the seedling stage with 84% of seeds successfully located. Over 4 study years that covered the range of seed-to-rodent ratios, not a single seed successfully germinated after dispersal, illustrating a predominantly antagonistic interaction between rodents and seeds of European beech. Therefore, our findings do not support the predator dispersal hypothesis and partially contradict the predator satiation hypothesis, as the highest number of germinants and intact seeds were found in situ after an intermediate seed crop, not a bumper crop. Our results underline the necessity to track seeds up to germination.

Forest management has a direct influence on the structure and stability of forests. In this study, we used the 3D data from mobile laser scanning in real forest stands dominated by European beech (Fagus sylvatica L.) to simulate different silvicultural treatments and assess their impact on the structural complexity and short-term economic return. For the structural assessment, we used the box-dimension (Db), a holistic measure of structural complexity in forest. The expected net revenues of the silvicultural treatments were used as a proxy for short-term economic gain. We simulated six different treatments in 19 different real-world forest stands. The results showed that each treatment had a negative impact on the structural complexity of the stands but with varying severity. The treatments with the smallest effect on stand structural complexity showed the highest net revenue, indicating no trade-offs if a forest owner strives for small stand structural changes and high economic return. The approach used here allows quantifying the structural and economic consequences of different treatments in forest stands prior to the actual application in the real world. This holds large potential for decision making according to the forest owner's objective.

Leaf cuticular waxes play an important role in reducing evapotranspiration via diffusion. However, the ability of mature trees to regulate the biosynthesis of waxes to changing conditions (e.g., drought, light exposition) remain an open question, especially during the late growing season. This holds also true for one of the most widely distributed trees in Central Europe, the European beech tree (Fagus sylvatica L.). In order to investigate the ongoing formation of wax constituents like alkanes and fatty acids, we conducted a 13CO2 pulse-chase labelling experiment on sun-exposed and shaded branches of a mature beech tree during the late summer 2018. The 13C-label was traced via compound-specific δ13C isotope analysis of n-alkanes and fatty acids to determine the de-novo biosynthesis within these compound classes. We did not observe a significant change in lipid concentrations during the late growing season, but we found higher n-alkane concentrations in sun-exposed compared to shaded leaves in August and September. The n-alkane and fatty acid composition showed ongoing modifications during the late growing season. Together with the uptake and following subsequent decrease of the 13C-label, this suggests ongoing de-novo biosynthesis, especially of fatty acids in European beech leaves. Moreover, there is a high variability in the 13C-label among individual branches and between sun-exposed and shaded leaves. At the same time, sun-exposed leaves invest more of the assimilated C into secondary metabolites such as lipids than shaded leaves. This indicates that the investigated mature beech tree could adjust its lipid production and composition in order to acclimate to changes in microclimates within the tree crown and during the investigated period.

During the particularly severe hot summer drought in 2018, widespread premature leaf senescence was observed in several broadleaved tree species in Central Europe, particularly in European beech (Fagus sylvatica L.). For beech, it is yet unknown whether the drought evoked a decline towards tree mortality or whether trees can recover in the longer term.In this study, we monitored crown dieback, tree mortality and secondary drought damage symptoms in 963 initially live beech trees that exhibited either premature or normal leaf senescence in 2018 in three regions in northern Switzerland from 2018 to 2021. We related the observed damage to multiple climate‐ and stand‐related parameters.Cumulative tree mortality continuously increased up to 7.2% and 1.3% in 2021 for trees with premature and normal leaf senescence in 2018, respectively. Mean crown dieback in surviving trees peaked at 29.2% in 2020 and 8.1% in 2019 for trees with premature and normal leaf senescence, respectively. Thereafter, trees showed first signs of recovery. Crown damage was more pronounced and recovery was slower for trees that showed premature leaf senescence in 2018, for trees growing on drier sites, and for larger trees. The presence of bleeding cankers peaked at 24.6% in 2019 and 10.7% in 2020 for trees with premature and normal leaf senescence, respectively. The presence of bark beetle holes peaked at 22.8% and 14.8% in 2021 for trees with premature and normal leaf senescence, respectively. Both secondary damage symptoms occurred more frequently in trees that had higher proportions of crown dieback and/or showed premature senescence in 2018.Our findings demonstrate context‐specific differences in beech mortality and recovery reflecting the importance of regional and local climate and soil conditions. Adapting management to increase forest resilience is gaining importance, given the expected further beech decline on dry sites in northern Switzerland. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The article reports the AMS (accelerator mass spectrometry) radiocarbon dating results of the historic Emperor’s Beech (Fagul Împăratului) from Muncel, Baia de Arieş, Romania. Two wood samples were collected from the large tree, out of which four segments were extracted and analysed by AMS radiocarbon. The oldest dated sample segment had a radiocarbon date of 233 ± 18 BP, which corresponds to a calibrated age of 365 ± 5 years. This value suggests an age of 420 ± 20 years for the Emperor’s Beech. Thus, the historic beech started growing around the year 1600. [ABSTRACT FROM AUTHOR]

Temperature (T) and vapour pressure deficit (VPD) are important drivers of plant hydraulic conductivity, growth, mortality, and ecosystem productivity, independently of soil water availability. Our goal was to disentangle the effects of T and VPD on plant hydraulic responses. Young trees of Fagus sylvatica L., Quercus pubescens Willd. and Quercus ilex L. were exposed to a cross‐combination of a T and VPD manipulation under unlimited soil water availability. Stem hydraulic conductivity and leaf‐level hydraulic traits (e.g., gas exchange and osmotic adjustment) were tracked over a full growing season. Significant loss of xylem conductive area (PLA) was found in F. sylvatica and Q. pubescens due to rising VPD and T, but not in Q. ilex. Increasing T aggravated the effects of high VPD in F. sylvatica only. PLA was driven by maximum hydraulic conductivity and minimum leaf conductance, suggesting that high transpiration and water loss after stomatal closure contributed to plant hydraulic stress. This study shows for the first time that rising VPD and T lead to losses of stem conductivity even when soil water is not limiting, highlighting their rising importance in plant mortality mechanisms in the future. [ABSTRACT FROM AUTHOR]

Large and severe disturbances may erode the resilience of temperate forest ecosystems and alter their recovery dynamics, especially under global change. We investigated mid-term recovery in mixed mountain forests in Slovenia after three independent severe windstorms in 2008 created large disturbed patches. Across a network of 102 permanent plots and three inventories over the 11-year post-disturbance period, we monitored trends in density, composition, and structure of regeneration, which are key indicators of forest resilience. Ecological drivers of regeneration, including topography, microsites, and biotic interactions, were analysed using linear mixed models. We quantitatively assessed physiognomic recovery by comparing regeneration densities with the restocking target used in forest practice, and compositional recovery by comparison with pre-disturbance stand composition. Regeneration densities and structure tended to converge among post-disturbance treatments (planting vs. natural regeneration) 11 years post-disturbance, as density of natural regeneration substantially dropped between the second and third inventory. Some drivers of recovery (i.e. ground vegetation and distance to the forest edge) varied over time, while the effect of elevation on regeneration density was consistently negative. The results indicate that the forest sites generally show adequate resilience to large-scale wind disturbances, in terms of physiognomic recovery, but not in terms of rapid compositional recovery, as pioneer and light-demanding tree species increased in share compared to the pre-disturbance stands. [ABSTRACT FROM AUTHOR]

Partitioning of evapotranspiration (ET) into transpiration (T) and residual evaporation (E) is a challenging but important task in order to assess the dynamics of increasingly scarce water resources in forest ecosystems. The T/ET ratio has been linked to the ecosystem water use efficiency of temperate forests, and thus is an important index for understanding utilization of water resources under global climate change. We used concurrent sap flow and eddy-covariance measurements to quantify the ET partitioning in pure European beech forest during the 2019–2020 period. The sap flow data were upscaled to stand level T and combined with stand level ET to calculate the T/ET ratio. We analysed intra-annual dynamics, the effect of seasonality and the impact of meteorological conditions on T, ET and T/ET. Annual T/ET of a pure European beech ecosystem was 0.48, falling at the lower end of reported global T/ET values for forest ecosystems. T/ET showed significant seasonal differences throughout spring (T/ET = 0.28), summer (T/ET = 0.62) and autumn (T/ET = 0.35). Air temperature (R2 = 0.45–0.63), VPD (R2 = 0.47–0.6) and PAR (R2 = 0.32–0.63) affected the daily dynamics of T, ET and T/ET; however, soil water content (SWC) had no significant effect. Mature European beech trees showed more anisohydric behaviour and relatively stable T/ET, even under decreasing SWC. The results improve the understanding of ecosystem scale T, ET and T/ET intra-annual dynamics and environmental constraints in anisohydric mature European beech. [ABSTRACT FROM AUTHOR]

In the future, climate change is expected to affect the spatial distribution of most tree species in Europe. The European beech (Fagus sylvatica), a drought-sensitive tree species, is currently distributed throughout Europe, where it is an ecologically and economically important species. In Slovenia, the European beech represents 33% of the growing stock, but such a proportion greatly varies across Europe. Whether such a variation is related to the climate environmental gradients or because of historical or management decisions is an as-yet unexplored question. For this study, we employed the Slovenian Forests Service inventory, where the proportion of beech in the forest stock has been monitored in 341,341 forest stands across the country. Modeled climate data from the SLOCLIM database, calculated for each of the stands, was also used to test the hypothesis that although beech forests have always been influenced by human activity, the dominance of beech trees in forest stands is at least partially dictated by the climate. The results showed the distribution of the main climate variables (annual precipitation, the share of summer and spring precipitation, and annual maximum and minimum temperatures) and how they affect the current dominance of beech trees at the stand level. Due to the large number and variability of forest stands studied, the results should be transferable to better understand and manage the climatic suitability and risks of Fagus sylvatica. The modeled data is publicly available in the web repository Zenodo. [ABSTRACT FROM AUTHOR]

Climate change, specifically the increasing frequency and intensity of summer heat and drought, has severe influences on the performance of beech forests, including decline in growth, reduced nutrient turnover, enhanced mortality, and a shift in spatial distribution northwards and towards higher elevations. The present study aimed to characterize the physiological responses of Croatian beech saplings originating from 10 natural forest stands to experimentally applied water deprivation in a common-garden experiment. The aim was to evaluate the extent to which external factors such as climate, as well as nitrogen (N) and phosphorus (P) availability in the soil of the natural habitats, control the response of beech saplings to water deprivation. For this purpose, beech saplings from 10 forest stands that differed in terms of soil type, chemical soil properties, as well as climate were collected in winter, cultivated in an artificial soil substrate under controlled conditions for one year, and then subjected to 29 days of water deprivation. Responses to water deprivation were observed in the antioxidative system (total ascorbate, reduced ascorbate, oxidized ascorbate, and redox state) in leaves and fine roots. The latter allowed us to categorize saplings as adapted or sensitive to water deprivation. P over N availability in the soil rather than climatic conditions in the natural habitats controlled the response of beech saplings to the water-deprivation event. The categorization of saplings as adapted or sensitive to water deprivation was related to genetic parameters. The results of this multidisciplinary study (tree physiology, climate, and genetic data) are considered to be highly significant and beneficial for the adaptation of European beech forests to changing climatic conditions. [ABSTRACT FROM AUTHOR]

The aim of the study was to analyse the changes in the infection rate development inside the beech stem as a result of browsing by deer (Cervus elaphus). The research materials were collected from three research plots located in the Polanów Forest Inspectorate from March to April 2020. For the study, 80 beech trees were selected, for which the size of the fallow tree, the percentage of the section taken from its centre infected with rot, and the number of years passed since the tree was wounded were determined. The study shows that the infection affects only the rings formed before the tree was injured. The average size of stem rot was 7.75% of its area, and it spread at the rate of 2.52% of the cross-sectional area per year. The analysis of the obtained results proved that both the size of the wound (splits) and the time elapsed since the tree was damaged are significantly correlated with each other. It is also possible to build a model for estimating the size of decay in stunted beech trees based on easy-to-determine predictors, such as maximum wound width and elapsed time since tree damage. [ABSTRACT FROM AUTHOR]

The importance of veteran trees is well recognised nowadays. The sudden breakage of some of these plants in Trentino (Italy), mainly due to Kretzschmaria deusta, prompted a survey of the veteran beeches reported in this area. Visual tree assessment was carried out in 40 sites with either single trees or groups of beeches, for a total of 115 trees evaluated. Most trees showed serious defects or problems in need of management and 19 had a high level of risk of breakage because of the presence of several structural problems. The presence of K. deusta was recorded on 50.4% of the examined trees. The pathogen was also identified in the proximity of investigated trees at 29 sites. Laboratory tests confirmed the identity of K. deusta by microbiological and molecular approaches and also identified Cosmopora berkeleyana as mycoparasite on K. deusta fruiting bodies. Isolates obtained from declining trees and old stumps showed the same pattern of growth at different temperatures. The risk evaluation emphasised how the fungus could affect the survival and safety of these veteran trees; this was confirmed by the collapse of four of the investigated trees in the last years. Therefore, K. deusta, which has been considered as a facultative parasite up to now, could play a more incisive role both in the decline of old beech trees and the natural evolution of aging beech woods.

Wood use in bio-building should be considered as one of the main pillars of sustainability. According to international standards, beech wood (Fagus sylvatica L.) is a rather less durable species as it is subject to degradation due to weathering, though it is abundantly available to a more intense use. Service life of beech products and wood products in general can be enhanced by different methods, such as heat treatments, but new chances are offered by coating technologies. However, to ensure protection from wood-destroying organisms, most commercial coatings include components that could harm human health, other organisms and the environment. Therefore, coating industry has to develop more eco-friendly solutions in order to decrease its impact on human health and environment. The objective of this article was to modify commercial acrylic varnish by adding cellulose nanocrystals (CNC) and lignin (LN) extracted from beech wood and investigate their effect on water sorption, additive dispersion in the coating matrix and coating resistance to bacterial attack. Contact angle, weight gain and colour difference were analysed and FT-IR mapping was applied. The performance of CNC was promising, as it enhanced water sorption of the modified coating. However, protection against bacterial attack was not satisfying. On the other hand, chemically unmodified lignin did not show positive effects as component in the coating formulation. Nevertheless, the currently limited usage of these two renewable and abundant resources urgently calls for their more efficient utilization, in order to create additional value with industry side-streams producing novel bio-based materials. Further experiments are needed in order to obtain better dispersion of the particles and higher resistance to bacterial attacks.

Abstract Background The tick Ixodes ricinus is an important vector of tick-borne diseases including Lyme borreliosis. In continental Europe, the nymphal stage of I. ricinus often has a bimodal phenology with a large spring peak and a smaller fall peak. There is consensus about the origin of the spring nymphal peak, but there are two alternative hypotheses for the fall nymphal peak. In the direct development hypothesis, larvae quest as nymphs in the fall of the same year that they obtained their larval blood meal. In the developmental diapause hypothesis, larvae overwinter in the engorged state and quest as nymphs one year after they obtained their larval blood meal. These two hypotheses make different predictions about the time lags that separate the larval blood meal and the density of questing nymphs (DON) in the spring and fall. Methods Inter-annual variation in seed production (masting) by deciduous trees is a time-lagged index for the density of vertebrate hosts (e.g., rodents) which provide blood meals for larval ticks. We used a long-term data set on the masting of the European beech tree and a 15-year study on the DON at 4 different elevation sites in western Switzerland to differentiate between the two alternative hypotheses for the origin of the fall nymphal peak. Results Questing I. ricinus nymphs had a bimodal phenology at the three lower elevation sites, but a unimodal phenology at the top elevation site. At the lower elevation sites, the DON in the fall was strongly correlated with the DON in the spring of the following year. The inter-annual variation in the densities of I. ricinus nymphs in the fall and spring was best explained by a 1-year versus a 2-year time lag with the beech tree masting index. Fall nymphs had higher fat content than spring nymphs indicating that they were younger. All these observations are consistent with the direct development hypothesis for the fall peak of I. ricinus nymphs at our study site. Our study provides new insight into the complex bimodal phenology of this important disease vector. Conclusions Public health officials in Europe should be aware that following a strong mast year, the DON will increase 1 year later in the fall and 2 years later in the spring. Studies of I. ricinus populations with a bimodal phenology should consider that the spring and fall peak in the same calendar year represent different generations of ticks. Graphical Abstract

Abstract Background Organic carbon stored in forest soils (SOC) represents an important element of the global C cycle. It is thought that the C storage capacity of the stable pool can be enhanced by increasing forest productivity, but empirical evidence in support of this assumption from forests differing in tree species and productivity, while stocking on similar substrate, is scarce. Methods We determined the stocks of SOC and macro-nutrients (nitrogen, phosphorus, calcium, potassium and magnesium) in nine paired European beech/Scots pine stands on similar Pleistocene sandy substrates across a precipitation gradient (560–820 mm∙yr− 1) in northern Germany and explored the influence of tree species, forest history, climate, and soil pH on SOC and nutrient pools. Results While the organic layer stored on average about 80% more C under pine than beech, the pools of SOC and total N in the total profile (organic layer plus mineral soil measured to 60 cm and extrapolated to 100 cm) were greater under pine by about 40% and 20%, respectively. This contrasts with a higher annual production of foliar litter and a much higher fine root biomass in beech stands, indicating that soil C sequestration is unrelated to the production of leaf litter and fine roots in these stands on Pleistocene sandy soils. The pools of available P and basic cations tended to be higher under beech. Neither precipitation nor temperature influenced the SOC pool, whereas tree species was a key driver. An extended data set (which included additional pine stands established more recently on former agricultural soil) revealed that, besides tree species identity, forest continuity is an important factor determining the SOC and nutrient pools of these stands. Conclusion We conclude that tree species identity can exert a considerable influence on the stocks of SOC and macronutrients, which may be unrelated to productivity but closely linked to species-specific forest management histories, thus masking weaker climate and soil chemistry effects on pool sizes.

The majority of studies exploring the ecology of saprotrophic fungi have worked with individual logs as homogenous sampling units, neglecting the presence of microhabitats and inner complexity. Based on close to 7000 sporocarp records of more than 450 fungal taxa from 134 decaying beech logs we investigated microhabitat preferences in macrofungi and linked these to sporocarp traits. The respective microhabitats were defined by the local wood decay stage, vertical position on the fallen log and special habitat features (hollows, fracture surfaces, woody material fallen from the log). We found microhabitat associations to be non-random in relation to fungal community composition and sporocarp morphology, indicating an evolutionary link between dead wood niche and sporocarp morphology. While log-level fungal species richness peaked at intermediate decay stages, taxa with significant indicator values were skewed towards early and late decay stages, when defined at microhabitat decay level. This suggests that the commonly found peak in fungal species richness on dead logs in intermediate decay stages expresses a peak in niche diversity rather than a peak in taxa decay stage preferences. • Wood decay fungi sporocarp-based trait study performed in central European beech forests. • Microhabitat preferences are non-random in relation to species composition and morphology. • Log-level richness peaks at middle decay stage microhabitat preferences are highest at early and late wood decay. • Species richness at middle decay expresses a peak in niche diversity rather than species preferences. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the role of the oomycete Phytophthora× cambivora in the decline affecting European beech (Fagus sylvatica) in the Nebrodi Regional Park (Sicily, southern Italy). In a survey of a beech forest stand in the heart of the park, Phytophthora× cambivora was the sole Phytophthora species recovered from the rhizosphere soil and fine roots of trees. Both A1 and A2 mating type isolates were found. Direct isolation from the stem bark of trees showing severe decline symptoms and bleeding stem cankers yielded exclusively P. gonapodyides, usually considered as an opportunistic pathogen. The mean inoculum density of P.× cambivora in the rhizosphere soil, as determined using the soil dilution plating method and expressed in terms of colony forming units (cfus) per gm of soil, the isolation frequency using leaf baiting, and the percentage of infected fibrous roots from 20 randomly selected beech trees with severe decline symptoms (50 to 100 foliage transparency classes) were 31.7 cfus, 80%, and 48.6%, respectively. These were significantly higher than the corresponding mean values of 20 asymptomatic or slightly declining trees, suggesting P.× cambivora is a major factor responsible for the decline in the surveyed stand. [ABSTRACT FROM AUTHOR]

Two deciduous forest ecosystems, one dominated by Fagus sylvatica and a mixed one with Quercus cerris and Quercus frainetto, were monitored from an ecophysiological perspective during a five-year period, in order to assess seasonal fluctuations, establish links between phenology and ecophysiology, and reveal climatic controls. Field measurements of leaf area index (LAI), chlorophyll content, leaf specific mass (LSM), water potential (Ψ) and leaf photosynthesis (Aleaf) were performed approximately on a monthly basis. LAI, chlorophylls and LSM fluctuations followed a recurrent pattern yearly, with increasing values during spring leaf burst and expansion, relatively stable values during summer and decreasing values during autumn senescence. However, pre-senescence leaf fall and chlorophyll reductions were evident in the driest year. The dynamically responsive Aleaf and Ψ presented considerable inter-annual variation. Both oak species showed more pronounced depressions of Aleaf and Ψ compared to beech, yet the time-point of their appearance coincided and was the same for all species each year. Spring temperature had a positive role in the increasing phase of all ecophysiological processes while rising autumn temperature resulted in retarded senescence. Precipitation showed asymmetric effects on the measured ecophysiological parameters. The between-species differences in responses, climate sensitivity and climate memory are identified and discussed. [ABSTRACT FROM AUTHOR]

Summary: Sunflecks are transient patches of direct radiation that provide a substantial proportion of the daily irradiance to leaves in the lower canopy. In this position, faster photosynthetic induction would allow for higher sunfleck‐use efficiency, as is commonly reported in the literature. Yet, when sunflecks are too few and far between, it may be more beneficial for shade leaves to prioritize efficient photosynthesis under shade.We investigated the temporal dynamics of photosynthetic induction, recovery under shade, and stomatal movement during a sunfleck, in sun and shade leaves of Fagus sylvatica from three provenances of contrasting origin.We found that shade leaves complete full induction in a shorter time than sun leaves, but that sun leaves respond faster than shade leaves due to their much larger amplitude of induction. The core‐range provenance achieved faster stomatal opening in shade leaves, which may allow for better sunfleck‐use efficiency in denser canopies and lower canopy positions.Our findings represent a paradigm shift for future research into light fluctuations in canopies, drawing attention to the ubiquitous importance of sunflecks for photosynthesis, not only in lower‐canopy leaves where shade is prevalent, but particularly in the upper canopy where longer sunflecks are more common due to canopy openness. [ABSTRACT FROM AUTHOR]

This study focuses on the analysis of wood charcoal from Cova del Vidre (Roquetes, Tarragona, Spain). This cave, located at an altitude of 1000 m a.s.l., is a key site for understanding the transition from hunting and gathering to farming in a mountainous region of north-eastern Iberia so far unexplored by archaeobotany. The anthracological study is based on four archaeological levels from the Epipalaeolithic to the Early Neolithic dated between 12.9 and 6.8 kyr cal BP, that is, from the Late Glacial period to the Middle Holocene. During the Younger Dryas, the record is dominated by a little varied spectrum of cryophilous pines (Pinus tp. sylvestris) and thorny shrubs revealing an open landscape where Prunus may prefigure the spread of temperate taxa. In the Early Holocene, a significant change in temperature and precipitation is evidenced, which promoted successional changes in plant communities, with a decline of pine and the sudden rise of temperate/Mediterranean taxa, such as Prunus and Quercus coccifera/ilex. During the Middle Holocene, other temperate taxa appear, such as Quercus deciduous, Buxus sempervirens and Taxus baccata, with yew finally dominating the anthracological record. The appearance and early development of temperate or Mediterranean species as early as the Younger Dryas and the Early Holocene periods, in a mountain context that had long been favourable for Scots pine, allows us to argue the local existence of a glacial refugium. Differences with the nearby sites in the lowlands demonstrate that altitudinal differences in vegetation were already established in the Holocene. Furthermore, the site helps to define the palaeodistribution of Taxus baccata, Abies alba and Fagus sylvatica in southern Europe. [ABSTRACT FROM AUTHOR]

Sustainable Forest Management (SFM) indicators consider the main ecological and socioeconomic functions of forests but do not currently include some key groups widely adopted to assess the effects of forest management, such as herbaceous vascular plants, epiphytic lichens, and wood-decay fungi. Moreover, they are shaped into high forests while in the Mediterranean area the oldest type of forest management is coppice. We investigated the diversity and the relationships of the above-mentioned groups of taxa in three European Forest Types (EFTs) to contribute to the selection of indicator species suitable for monitoring Mediterranean coppice forests. We find only a weak cross-taxon congruence between vascular plants and lichens on considering the whole dataset, while no significant correlations are evident within the three EFTs. Species richness was significantly different among EFTs, being Thermophilous deciduous forests the richest, both considering the groups of taxa separately and the total species richness. As for species composition, significant differences were found both for the whole dataset and also for pairwise comparisons among EFTs. We provided a dwelling-species list of the three key groups of taxa, which could be suitable for monitoring the sustainability characteristics of fragmented and low continuity forests such as coppice stands. [ABSTRACT FROM AUTHOR]

Common beech is a shade-tolerant tree species that can adapt to varying light intensities at the level of whole plants, crown fragments, and individual leaves. The acclimation abilities of the morphological, physiological, and biochemical characteristics of beech leaves were experimentally determined in tree crowns for different levels of light availability. About 24% higher length, width, and area and about 35% higher thickness were recorded in the sun leaves compared with shade leaves. Lower and earlier maximum leaf pigment levels, a faster degradation of leaf pigments during senescence, and a higher chlorophyll a/b ratio were observed in fully sun-grown leaves compared with leaves growing deeper in the canopy. Changes in the intensity of oxidative stress and the differential ability of developing and senescing leaves to defend against this effect under different light conditions were determined. This resulted in a higher redox imbalance and faster senescence in the outer parts of the tree crowns. Due to higher ascorbic acid and glutathione content and slower activity loss of antioxidative enzymes involved in superoxide anion and hydrogen peroxide decomposition, better control over the redox balance, oxidative stress, and senescence induction was noted in the sun leaves. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In the present study, we conduct a floristic and phytosociological analysis of the Fago-Quercetum petraeae R. Tüxen 1955 association identified in the northern part of the Semenic Mountains in southwestern Romania. The aim of this research is to perform a floristic, phytosociological, ecological, conservative, and economic study of the oak (Quercus petraea) and beech (Fagus sylvatica) forests identified in the northern part of the Semenic Mountains. The phytocenoses of these forests have been analyzed in terms of physiognomy, floristic structure, life form spectrum, floristic elements, the synecology expressed mainly through main indexes (soil moisture, temperature, and soil reaction), as well as the polyploidy/diploidy ratio. A total of 19 relevées, described from various locations within the Silvicultural Districts of Reșița and Văliug, have been recorded and analyzed in the association table. [ABSTRACT FROM AUTHOR]

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Fine roots are crucial for water and nutrient acquisition in plants; yet it is unknown how nutrient inputs and soil fertility in forests influence fine root biomass seasonal trajectories. Here, we hypothesized that standing fine root biomass increases with addition of a limited resource and shows different seasonal patterns depending on nutrient availability and phenology. We further hypothesized that the influence of climate is greater in the organic layer, causing larger responses of root biomass to climate in the organic layer and stronger responses to nutrient changes in mineral soil. We conducted our study in three European beech (Fagus sylvatica) forests representing a soil fertility gradient with high, medium, and low phosphorus (P) contents. A fully factorial fertilization regime with N and P was applied at each forest site. To test our hypotheses, we conducted soil coring in spring and fall for 2.5 years. Soil cores were fractionated into organic layer (Oe + Oa layer) and mineral soil (A horizon) and used to determine fine root biomass, soil pH and moisture, total concentrations of soil and root nutrients (basic cations, micronutrients, S, P, N, C), soluble concentrations of soil and root P. Fine root biomass in the mineral soil at the forest site with the lowest soil P content increased in response to P addition. Pheno-seasonal changes caused increases in soil P and N in spring and opposing cycling of biomass and fine root labile P contents at the P-medium and P-high sites. Contrary to our expectation, we observed stronger climatic effects on fine root biomass in the mineral soil, whereas soil moisture was more important in explaining fine root biomass variation in the organic layer. Our results show that seasonal patterns of fine root biomass are dependent on the stratification of environmental factors with soil depth and imply negative consequences for fine root biomass in the organic soil layer due to acute soil water content fluctuations and climate change effects in the mineral horizon due to long-term precipitation changes.

Provenance tests of forest tree species are important experiments in silviculture and tree breeding. Their results provide information about provenances' growth, adaptability, and other features. The research aimed to determine the dynamics of growth and tree shape of common beech plants per provenances in the international provenance test in Bosnia and Herzegovina to choose the best provenances considering wood production and quality. Research was conducted in the provenance test containing eight provenances from Bosnia and Herzegovina, four from Germany, three from Serbia, two each from Croatia, Romania, and Switzerland, and one from Hungary. Provenance test was established in 2007 by planting 2-year-old and 3-year old seedlings. Height and root collar diameter were measured, and tree shape was assessed in 2019. Data were processed in SPSS 26.0. Descriptive statistics, variance analysis, multiple Duncan's test for all traits, and Pearson's coefficient of corelation among morphological traits and tree shape were calculated. Variance for the height and root collar diameter showed statistically significant differences among different ages of plants and among provenances. Provenance from Croatia (Dilj Čaglinski) had the highest, and provenance from Romania (Alba-Iulia) had the lowest average height. The highest average value of root collar diameter had provenance Dilj Čaglinski, and the lowest value had provenance Sihlwald (Switzerland). The highest percentage of category 10 (ideal tree form) had provenance Bad Wildbad (Germany), and categories 1-4 (no silviculture value) had provenance Alba-Iulia (Romania). Pearson's coefficient showed that height, root collar diameter, and tree shape are highly correlated. Considering all the above, when planning forest-breeding works, it is recommended to continue the research and favor provenances with the best growth and tree shape.

Provenance trials are a valuable source of information, especially in species such as European beech (Fagus sylvatica L.), which will likely increase its distribution due to global warming. The current study compares radial increment and wood density of beech provenances in the juvenile development stage from contrasting environments in Europe (Belgium, Slovenia, Czech Republic, Italy) planted at a mesic to wet site in Slovenia and a xeric site in Hungary. Existing data (past measurements of diameters and height) were combined with new measurements of tree height, diameter, dendrochronological and resistance drilling density measurements to assess differences in provenance radial growth. The wood density data were evaluated using a Bayesian general linear model. In order to study the differences in radial increment in more detail, two weather-wise contrasting years (2014 and 2017) were selected from the last decade, based on calculations of the 12-month Standardized Precipitation-Evapotranspiration Index. The differences in average tree-ring width among provenances at each sampled site appeared to be relatively small when averaged over a whole decade of data. However, according to year-to-year data, some provenances grew faster than others, especially in favorable weather conditions. In unfavorable conditions, the differences in tree-ring widths among provenances were smaller. For most provenances, variation in tree-ring widths within the same provenance increased in unfavorable conditions. The difference between the provenances with the highest and lowest wood densities at both locations did not exceed 5%. The model results indicate that the Idrija (Slovenia) provenance probably has a higher median wood density than other studied provenances at both sites. Although the current study confirmed some differences in wood density between provenances and trial locations, the differences are negligible in practice due to their low magnitude and the fact that the analyzed trees were still juvenile. As beech has a diffuse-porous wood, negligible differences in wood density would also be expected in adult trees. Beech provenances for planting in relation to changing weather should probably be chosen for their ability to survive more extreme weather events rather than to improve radial increment or wood density, especially as the differences in wood density of juvenile trees are relatively small. [ABSTRACT FROM AUTHOR]

Summary: European beech (Fagus sylvatica) was among the most affected tree species during the severe 2018 European drought. It not only suffered from instant physiological stress but also showed severe symptoms of defoliation and canopy decline in the following year.To explore the underlying mechanisms, we used the Swiss‐Canopy‐Crane II site and studied in branches of healthy and symptomatic trees the repair of hydraulic function and concentration of carbohydrates during the 2018 drought and in 2019.We found loss of hydraulic conductance in 2018, which did not recover in 2019 in trees that developed defoliation symptoms in the year after drought. Reduced branch foliation in symptomatic trees was associated with a gradual decline in wood starch concentration throughout summer 2019. Visualization of water transport in healthy and symptomatic branches in the year after the drought confirmed the close relationship between xylem functionality and supported branch leaf area.Our findings showed that embolized xylem does not regain function in the season following a drought and that sustained branch hydraulic dysfunction is counterbalanced by the reduction in supported leaf area. It suggests acclimation of leaf development after drought to mitigate disturbances in canopy hydraulic function. [ABSTRACT FROM AUTHOR]

Two provenance tests in North-Eastern Bulgaria have been studied, whose purpose is to test the response of beech provenances from Southern Germany to the drier and warmer climatic conditions in Bulgaria, in order to predict how they would perform in a warming and drying climate. The provenance tests were established in the spring of 2010 in the area of the Varbitza and Kipilovo Forest Services with 2-year-old seedlings in a 2 x 1 m scheme in 3 replications. Four provenances of common beech were studied - 2 German (Silberbach and Ebersdorf) and 2 Bulgarian (Petrohan and Berkovitza). On the 12th year after afforestation, an inventory and measurements of the height and root collar diameter were carried out. The results were processed statistically by applying one and two-factor analysis of variance, as well as Tukey’s test for multiple comparisons. A higher survival rate was found in the provenance test in Kipilovo. The Bulgarian provenances Petrohan and Berkovitza were characterized by better growth in height in both provenance tests, and in root collar diameter - provenance Petrohan. Provenance Ebersdorf could be recommended for use in drier and warmer places in Southern Germany [ABSTRACT FROM AUTHOR]

Purpose: Norway spruce log soaking water (SLSW) is considered a waste in the plywood and veneer industry but has not been characterised, and its possible uses remain unexplored. The purpose of this study is to characterise and test the possibility of using SLSW in wood preservative formulations. Methods: First, the SLSW was characterised, and the presence of carbohydrates in the log soaking water was reduced with a hydrophobic adsorbent to reduce the nutrient availability for fungi in the liquids. Then, the feasibility of using SLSW and the sugar free SLSW (denoted later as EHC solution) as wood preservatives was studied by testing their antifungal and antioxidant activities and performing a mini-block test against Schizophyllum commune, Trametes versicolor, Fibroporia vaillantii and Gloeophyllum trabeum. Results: Several phenolic compounds were found in the SLSW. This water also had high antioxidant activity at 1000 mg/L before and after carbohydrate removal but no antifungal activity. Its impregnation in wood caused a slight reduction in mass loss of the Pinus sylvestris specimens but had no effect on the Fagus sylvatica specimens when exposed against Schizophyllum commune, Trametes versicolor, Fibroporia vaillantii and Gloeophyllum trabeum. Conclusion: The SLSW as a wood preservative is invalid, even after partial carbohydrate removal. However, due to the presence of wood constituents, SLSW could be a resource for other uses requiring high antioxidant activity but specific applications need further investigation. [ABSTRACT FROM AUTHOR]

We studied the associations between the stem quality, phenology, and genetic structure by genotyping the phenotypic variation at 15 genomic SSR makers of 208 mature European beech trees in four artificially established stands in Lithuania. The genetic differentiation among the stands was significant (DEST = 0.029**). The stand NOR1 of Carpathian origin significantly differed from the remaining three stands of Bavarian origin at the highest 0.001 significance level. In most of the stands, the early flushing trees were of significantly worse stem quality. Within each of the stands, the Bayesian clustering identified 2 to 3 genetic groups, among which the differentiation was markedly stronger than between the stands (DEST 0.095*** to 0.142***). The genetic groups differed markedly in stem quality and phenology as well as inbreeding levels. We conclude that (a) the genetic structuring in European beech stands strongly depends on non-random mating owing to phenology variation among the relative groups, (b) due to strong relationship among phenology, adaptedness and stem morphotype, this genetic variation is reflected by the stem morphotype. [ABSTRACT FROM AUTHOR]

The onset of the growing season in temperate forests is relevant for forest ecology and biogeochemistry and is known to occur earlier with climate change. Variation in tree phenology among individual trees of the same stand and species, however, is not well understood. Yet, natural selection acts on this inter-individual variation, which consequently affects the adaptive potential to ongoing environmental changes. Budburst dates of 146 mature individuals of Fagus sylvatica , the dominant natural forest tree of central Europe, were recorded over 12 years in one forest stand of 1 ha in the Müritz National Park, Germany. The tree-specific location, topographical differences, as well as social status, were measured to explain the inter-individual variation in budburst. Furthermore, inter-individual differences in bud dormancy were quantified. Additional phenology and weather data across Germany from 405 sites over a 25-year period was used to put the insights from the single stand into perspective. Consistent phenological ranking over the years with respect to early and late flushing trees was observed within the single forest stand, with 23 trees consistently flushing 3–6 days earlier and 22 trees consistently flushing 3–10 days later than the median. Trees flushing consistently early varied most in their spring budburst dates and were less dormant than late-flushing trees already in mid-winter. The higher variation in earlier flushing trees was best explained by a slower warming rate during their budburst period in the observed stand as well as across Germany. Likewise, years with a lower warming rate during the budburst period were more variable in budburst dates. The rate of warming during spring time is crucial to accurately project future within-species variation and the resulting adaptive potential in spring phenology of dominant forest tree species. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Purpose: The woolly beech aphid thrives on European beech leaves, which has complex direct and indirect impacts on above- and belowground processes. A mechanistic understanding of insect-mediated changes in organic carbon (OC) availability for microbial life and its implications for element cycling is still lacking. This study aims at disentangling aphid-induced effects on phyllosphere and rhizosphere bacterial communities, as well as investigating feedbacks to OC transfer from the canopy to the mineral soil. Methods: Following 2.5 months of infestation, we tracked the fate of OC (13CO2 pulse-labelling) in several compartments of beech sapling – soil mesocosms over 5 days. In ecosystem solutions, water extracts and soil/plant compartments we determined OC and N and solid δ13C. Bacterial community structure (16S rRNA gene targeted amplicon sequencing and quantitative PCR) and metabolite profiles (LC-qTOF-MS) were analysed. Results: We found significantly higher aphid-mediated inputs of OC within throughfall. Honeydew-derived C on infested leaves was inconsequential for total phyllosphere bacterial abundances, but verifiably affected the community structure. In all soil compartments, cold-water extractable OC pools declined significantly by frequent inputs of readily available OC. This pattern might relate to reductions in rhizodepositions and altered microbial processing by accelerated soil C-mineralization. As a result, the abundance of metabolites changed significantly in different ecosystem solutions. Conclusions: Our findings attest that insect infestations induce distinct direct and indirect effects on plant-insect-microbiome interactions leading to marked alterations in C dynamics. This integrated approach improves our understanding on microbial dynamics and biogeochemistry and evaluates the role of insects for ecosystem processes. [ABSTRACT FROM AUTHOR]

We examined the ectomycorrhizal (ECM) mycobiota at three localities that have diff erent distances from the aluminium plant (locality L2: 2 km away, L7: 7 km away and L18: 18 km away). Th e trend of a strong negative impact of air pollution on ECM mycobiota has been confi rmed in submontane beech stands in the vicinity of the aluminium plant in the locality L2, during 30 years of mycological research. Compared to relatively air pollution-cleared beech stands at the locality L18, at the locality L2 there has been observed low species diversity of ECM macromycetes – (6 to 14 species compared to 18 to 33 species) low values of fruitbodies biomass (1.84 to 5.13 versus 15.95 to 115.82 kg.ha-1 fresh weight of fruitbodies) and low values of mycorrhizal potential (0.42 to 0.74 versus 1.45 to 1.97). We found a signifi cant dependence (P=0.0009) from the results of the Spearman correlation (R = 0.8293) between the distance from the emission source and the abundance values of ECM fruiting bodies. Th e negative infl uence of the aluminium plant on the share of ECM species was also confi rmed by Bayesian analysis of the sequences of clones from the soil template nrDNA (decrease from 75% and 72% to 45% in L2). From selected ECM species it is possible to mention fungi that were dominant in research localities, e.g. Hygrophorus eburneus, Lactarius blennius, L. piperatus, Russula cyanoxantha, Xerocomellus chrysenteron. Signifi cant parasites, e.g. Ilyonectria radicicola, Neonectria ditissima and Trichoderma viride were determined from soil monoliths at the locality L2 using molecular genetic methods. It can be concluded that this state of mycobiota in the research sites will not change in the coming years, as long as the residual air pollution in the soil will be a strong stressor for the mycobiota of these forest stands. [ABSTRACT FROM AUTHOR]

The main goal of this paper was to evaluate structure dynamics in the fir-beech, old-growth forest Badínsky prales. Measurements were taken on four permanent research plots (0.5 ha each) between 1970 and 2018, typically in ten-year intervals. In order to assess long-term structure dynamics, this study used basic stand characteristics and selected structural indices - the relative density (RD), coefficient of homogeneity (H), and structural complexity index (SCI). Species composition was quantified by the relative importance value (RIV), and a detrended correspondence analysis was carried out for the visualisation of long-term changes. The long-term mean of the stand volume reached 634 ± 99 m3.ha-1, and the mean of the basal area was 36.6 ± 4.0 m2.ha-1. Calculated values of the coefficient of homogeneity (1.46-2.54) were similar to values in other old-growth forests with a comparable tree species composition. An increasing trend in beech RIV values was observed; on the other hand, fir RIV values fell by approximately 20%-25%. In 2018, maximal values of the basal area, stand volume and relative density were recorded. These high values may indicate better growth conditions due to climate change, as well as fewer disturbance events in the last few decades.

Scientists and society are increasingly becoming aware of loss of insect biodiversity and biomass. The level of biodiversity determines the efficiency of ecological communities to capture essential resources, produce biomass, decompose and recycle nutrients. Relationships between plant and insect diversity can be modified by changes in insect abundance. This study determined the associations between microclimate and diversity of forest plants on overall insect abundance and abundances of different insect orders in the canopy of temperate deciduous forests dominated by Fagus sylvatica L. (European beech; Fagaceae) in Central Germany. Following model selection, a linear mixed model was used to analyse the associations between abiotic factors (air temperature and relative humidity) as well as biotic factors (species richness and cover for the ground, shrub and tree layer) and insect abundance and abundances of insect orders. Within similar strength of evidence, best models were chosen as those with a single explanatory parameter. Significant associations were recorded between abundances of Lepidoptera and Neuroptera and relative air humidity, insect abundance and species richness in the shrub layer, and between abundances of Diptera and Psocoptera and percentage cover of shrubs. Trends in associations were detected between the abundance of Hemiptera and species richness recorded in the shrub layer, and between the abundance of Thysanoptera and the species richness in the ground layer. No significant associations with single explanatory parameters were recorded for the abundances of Coleoptera and Hymenoptera. Phytodiversity, especially that in the shrub layer, were more often associated with the abundances of insect orders than microclimatic factors. The potential importance of the association between shrub layer parameters and the abundance of insects might be based on the shrub layer combining the associations with the ground layer (bottom-up processes) and canopy layer (environmental conditions). In addition, associations between phytodiversity and abundance of insects seem to vary most for Coleoptera and Hymenoptera in which there are markedly different functional groups.

Abstract Background To predict the risk of tick-borne disease, it is critical to understand the ecological factors that determine the abundance of ticks. In Europe, the sheep tick (Ixodes ricinus) transmits a number of important diseases including Lyme borreliosis. The aim of this long-term study was to determine the abiotic and biotic factors driving the annual abundance of I. ricinus at a location in Switzerland where Lyme borreliosis is endemic. Methods Over a 15-year period (2004 to 2018), we monitored the abundance of I. ricinus ticks on a monthly basis at three different elevations on Chaumont Mountain in Neuchâtel, Switzerland. We collected climate variables in the field and from nearby weather stations. We obtained data on beech tree seed production from the literature, as the abundance of Ixodes nymphs can increase dramatically two years after a masting event. We used AIC-based model selection to determine which ecological variables drive annual variation in tick density. Results We found that elevation site, year, seed production by beech trees two years prior, and mean annual relative humidity together explained 73.2% of the variation in our annual estimates of nymph density. According to the parameter estimates of our models, (i) the annual density of nymphs almost doubled over the 15-year study period, (ii) changing the beech tree seed production index from very poor mast (1) to full mast (5) increased the abundance of nymphs by 86.2% two years later, and (iii) increasing the field-collected mean annual relative humidity from 50.0 to 75.0% decreased the abundance of nymphs by 46.4% in the same year. Climate variables collected in the field were better predictors of tick abundance than those from nearby weather stations indicating the importance of the microhabitat. Conclusions From a public health perspective, the increase in nymph abundance is likely to have increased the risk of tick-borne disease in this region of Switzerland. Public health officials in Europe should be aware that seed production by deciduous trees is a critical driver of the abundance of I. ricinus, and hence the risk of tick-borne disease.

In Poland and most of the areas of Europe, the beech, that is, Fagus sylvatica L. is one of the most vital species found in the species composition of forests. A number of the species of foliophages tend to develop on the leaves, which may contribute to the dieback of the tree. The demonstrated results are the effects of the research conducted in 2018 in the Cisów-Orłowiny Landscape Park. Subsequently, 11 species of foliophages were initially discovered there. Such species were inclined to form galls and the miner damages to the beech leaves. Among 4,000 of the analysed leaves, 398 galls and 498 leaf miner damages were found. They were caused by the representatives of insects and mites.

Abstract Many theoretical models predict when genetic evolution and phenotypic plasticity allow adaptation to changing environmental conditions. These models generally assume stabilizing selection around some optimal phenotype. We however often ignore how optimal phenotypes change with the environment, which limit our understanding of the adaptive value of phenotypic plasticity. Here, we propose an approach based on our knowledge of the causal relationships between climate, adaptive traits, and fitness to further these questions. This approach relies on a sensitivity analysis of the process‐based model Phenofit, which mathematically formalizes these causal relationships, to predict fitness landscapes and optimal budburst dates along elevation gradients in three major European tree species. Variation in the overall shape of the fitness landscape and resulting directional selection gradients were found to be mainly driven by temperature variation. The optimal budburst date was delayed with elevation, while the range of dates allowing high fitness narrowed and the maximal fitness at the optimum decreased. We also found that the plasticity of the budburst date should allow tracking the spatial variation in the optimal date, but with variable mismatch depending on the species, ranging from negligible mismatch in fir, moderate in beech, to large in oak. Phenotypic plasticity would therefore be more adaptive in fir and beech than in oak. In all species, we predicted stronger directional selection for earlier budburst date at higher elevation. The weak selection on budburst date in fir should result in the evolution of negligible genetic divergence, while beech and oak would evolve counter‐gradient variation, where genetic and environmental effects are in opposite directions. Our study suggests that theoretical models should consider how whole fitness landscapes change with the environment. The approach introduced here has the potential to be developed for other traits and species to explore how populations will adapt to climate change.

In the last century, a synchronous beech expansion has been observed for many mixed mountain forests in southeastern Europe. This change is associated with the interaction of various disturbances. We analyzed structural changes in the Pecka old-growth forest in Slovenia during the last century, using several inventories of the tree layer, regeneration, and site factors. Throughout the observation period, the density of silver fir in the regeneration layer and in the overstory steadily decreased. In 1893, silver fir accounted for about 60% of the growing stock, whereas in 2013 it accounted for less than 13%. This is likely because of silver fir’s decline in the canopy layer due to air pollution, successive windthrows, and overbrowsing. However, climate change may also have played an important role, as silver fir also declined in southeastern European old-growth forests where air pollution was less pronounced and ungulate densities were low. A gradual decline of silver fir in the overstory resulted in a decrease of overall tree density to 231 trees ha–1, while growing stock remained relatively high at 712 m3 ha–1. Median diffuse light at 1.3 m was 3.7% and regeneration density was 19,954 ha–1. Beech was dominant (94%), followed by silver fir (4%), and sycamore maple (2%). No silver fir seedlings larger than 0.2 m were recorded. Silver fir, sycamore maple, and beech regeneration showed 87, 76, and 45% browsing damage, respectively. Regression models indicated some evidence of niche partitioning between silver fir and beech. However, many processes may be masked by the silver fir’s avoidance strategy. Given current red deer densities, climate change, and existing forest structure, the Pecka old-growth forest will likely reach an alternative stable state dominated by beech in a few decades. This calls for immediate reduction of ungulate populations. Despite the interaction of multiple disturbances, the Pecka old-growth forest has maintained a relatively high overall growing stock, a favorable microclimate, and succession pathway with shade-tolerant beech. This indicates the intrinsic resilience of natural forests. The mechanisms discussed here can be applied to the future governance of old-growth and managed montane mixed forests.

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.

The onset of the growing season in temperate forests is relevant for forest ecology and biogeochemistry and is known to occur earlier with climate change. Variation in tree phenology among individual trees of the same stand and species, however, is not well understood. Yet, natural selection acts on this inter-individual variation, which consequently affects the adaptive potential to ongoing environmental changes. Budburst dates of 146 mature individuals of Fagus sylvatica, the dominant natural forest tree of central Europe, were recorded over 12 years in one forest stand of 1 ha in the Müritz National Park, Germany. The tree-specific location, topographical differences, as well as social status, were measured to explain the inter-individual variation in budburst. Furthermore, inter-individual differences in bud dormancy were quantified. Additional phenology and weather data across Germany from 405 sites over a 25-year period was used to put the insights from the single stand into perspective. Consistent phenological ranking over the years with respect to early and late flushing trees was observed within the single forest stand, with 23 trees consistently flushing 3–6 days earlier and 22 trees consistently flushing 3–10 days later than the median. Trees flushing consistently early varied most in their spring budburst dates and were less dormant than late-flushing trees already in mid-winter. The higher variation in earlier flushing trees was best explained by a slower warming rate during their budburst period in the observed stand as well as across Germany. Likewise, years with a lower warming rate during the budburst period were more variable in budburst dates. The rate of warming during spring time is crucial to accurately project future within-species variation and the resulting adaptive potential in spring phenology of dominant forest tree species.