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Previous studies found that pedunculate oak, one of the most widespread and abundant species in European deciduous forests, regenerates in open habitats and forest edges, but not in closed forest interiors. However, these observations usually come from the core areas of the biome, and much less is known about such processes at its arid boundary, where limiting factors may be different. In a full factorial field experiment, we tested the effects of different habitats (grassland, forest edge, forest interior) and increased growing season precipitation on the early regeneration of pedunculate oak in a forest-steppe ecosystem in Central Hungary, at the arid boundary of temperate deciduous forests. In the grassland habitat, seedling emergence was very low, and no seedlings survived by the fourth year. In contrast, seedling emergence was high and similar at forest edges and forest interiors, and was not affected by water addition. Most seedlings survived until the fourth year, with no difference between forest edge and forest interior habitats in numbers, and only minor or transient differences in size. The lack of oak regeneration in the grassland differs from previous reports on successful oak regeneration in open habitats, and may be related to a shift from light limitation to other limiting factors, such as moisture or microclimatic extremes, when moving away from the core of the deciduous forest biome towards its arid boundary. The similar number and performance of seedlings in forest edges and forest interiors may also be related to the decreasing importance of light limitation. [ABSTRACT FROM AUTHOR]

Intended for human consumption water resources are rapidly decreased due to overuse, global warming and also polluting by pollutants. Metal concentrations are generally removed by precipitation, adsorption, biosorption and some chemical reactions in the receiving water media. Therefore, polluted waters by metals are caused to rarely toxic effects in living things in high concentrations. Metal polluted waters are generally caused to esthetic and cosmetic effects. Adsorption is one of the commonly used methods for metal removal. In recent years, researches about natural low cost adsorbents are increased. Factors such as modification and electricity costs increase the cost of adsorbent. In this study, dry acorn caps of Quercus robur were used as non-modify natural adsorbent. The batch experiments were carried out to removal of copper in water that has initial low concentration by prepared natural adsorbent. It was performed equilibrium, kinetics, thermodynamic studies and moreover adsorbent characterization studies with using SEM + EDX and XRD methods. It was found the removal efficiency was 84%, and adsorption capacity was 0.336 mg/g. This paper is aimed to expressing the affecting factors of adsorption mechanism at the removal of copper in water. This paper is expressing the affecting factors of a non-modify natural adsorbent's adsorption mechanism at the removal of copper in water which has initial low concentration. As a consequence, it has been seen that acorn caps of Quercus robur due to contained tannins highly effects adsorption mechanism, and it may be used of copper removal. [ABSTRACT FROM AUTHOR]

The Kunming-Montreal Global Biodiversity Framework recognised the urgency of taking action to conserve intraspecific genetic diversity (IGD) as an insurance against habitat degradation and environmental change. Recent work suggests that 90–99 % of IGD should be conserved to safeguard viability of future generations. Here, we addressed such a conservation issue in three forest tree species in Italy: silver fir (Abies alba Mill.), Heldreich's pine (Pinus heldreichii H. Christ), and pedunculate oak (Quercus robur L.). We used microsatellite markers to measure IGD of 36 (A. alba), 15 (P. heldreichii) and 25 (Q. robur) natural sites, including several putative glacial refugia. We developed a spatial conservation planning (SCP) analysis to quantify the genetic irreplaceability of each site and identify the minimum set coverage ensuring IGD protection. Finally, we compared SCP results with the contributions to allelic diversity within and between sites, total allelic diversity and private allelic richness. We found that between 44 % and 73 % of sites were required to conserve 90–99 % of the alleles, and that this conservation effort held even when targeting lower percentages of alleles to protect (50–75 %). Glacial refugia were often included in the minimum set coverage, confirming biogeographical expectations. Finally, sites with high genetic irreplaceability were found to have higher private allelic richness on average. These results are discussed in the light of the biogeographic history of the species studied and the current policies for the conservation of forest genetic resources. • Intraspecific genetic diversity (IGD) must be protected to avoid extirpation. • Spatial conservation planning of IGD in forest trees from a multi-refugial area. • ½ to ¾ of sites are to be conserved to achieve adequate protection for IGD. • Setting unambitious conservation targets has limited impact on conservation costs. • Glacial refugia are priority candidates for maximising IGD conservation. [ABSTRACT FROM AUTHOR]

The impact of climate change that comes with a dramatic increase of long periods of extreme summer drought associated with heat is a fundamental challenge for European forests. As a result, forests are expected to shift their distribution patterns toward north-east, which may lead to a dramatic loss in value of European forest land. Consequently, unraveling key processes that underlie drought stress tolerance is not only of great scientific but also of utmost economic importance for forests to withstand future heat and drought wave scenarios. To reveal drought stress-related molecular patterns we applied cross-species comparative transcriptomics of three major European oak species: the less tolerant deciduous pedunculate oak (Quercus robur), the deciduous but quite tolerant pubescent oak (Q. pubescens), and the very tolerant evergreen holm oak (Q. ilex). We found 415, 79, and 222 differentially expressed genes during drought stress in Q. robur, Q. pubescens, and Q. ilex, respectively, indicating species-specific response mechanisms. Further, by comparative orthologous gene family analysis, 517 orthologous genes could be characterized that may play an important role in drought stress adaptation on the genus level. New regulatory candidate pathways and genes in the context of drought stress response were identified, highlighting the importance of the antioxidant capacity, the mitochondrial respiration machinery, the lignification of the water transport system, and the suppression of drought-induced senescence – providing a valuable knowledge base that could be integrated in breeding programs in the face of climate change.

Most of the forest area dominated by pedunculate oak (Quercus robur L.) in Latvia was lost to arable land several centuries ago and the remnant patches of Q. robur stands are small and spatially scattered. We hypothesized that a large part of the present Q. robur stands in the Eastern Baltic area of the hemiboreal forest zone developed around the past manor houses in the period of social and political turmoil and subsequent agricultural land abandonment. Our aim was to determine the relationship of Q. robur stand occurrence with soil properties, climatic conditions and proximity to past manor houses. Our study area was the entire territory of Latvia (64.589 km2), divided into 16 landscape regions. We used the State Forest Inventory database to filter out all stands dominated by Q. robur (n=3746). Spatial aggregation of the stands was tested by multi-distance spatial clustering analysis (Ripley’s K method). Mean stand area and Euclidean nearest-neighbour distance for stands were calculated for landscape regions. Binary logistic regression with the calculation of autocovariates showed that winter temperature, soil texture, carbonate concentration and distance to closest manor house were the independent factors significantly (p

With ongoing climate change, episodes of severe flooding are predicted to become more frequent despite a general trend towards increasing summer drought. We investigated how wood growth of adult trees of two species characteristic of floodplain forests in Central Germany (Fraxinus excelsior L., Quercus robur L.) and two less-typical species (Acer pseudoplatanus L., Carpinus betulus L.) responded to both maximum stream water level and climate, with a special focus on the effects of the extraordinary flood of the Saale River in June 2013 and the extreme drought in summer 1976. Tree-ring widths were measured on wood cores, and standardized ARSTAN tree-ring chronologies were produced. Using variance partitioning as well as linear mixed-effects models, we compared the effects of monthly values for maximum water level, temperature and precipitation sum on tree-ring width. Further, we calculated resistance, resilience and recovery of the tree species to the extreme events of flooding in 2013 and drought in 1976. Wood growth of all species studied, and particularly of F. excelsior, responded positively to the extraordinary flooding in June 2013. However, in the best models for the characteristic floodplain forest species (F. excelsior and Q. robur), mainly precipitation (F. excelsior) or a combination of precipitation and wood growth of the previous year (Q. robur) acted as drivers of wood growth of the current year. In contrast, growth of the less habitat-specific species (A. pseudoplatanus) mainly showed a significant response to the combination of temperature and wood growth of the previous year. C. betulus was the only species studied that benefited from the extreme drought in 1976. However, two years afterwards, only the wood growth of A. pseudoplatanus was still reduced, while F. excelsior and Q. robur fully recovered. In comparison to other regions in Central Europe, the moderate flood regime of the Saale River seems to have the potential to mitigate effects of summer drought in this region, which is one of the driest in Germany. Thus, increased flooding frequency might, to some degree, reduce drought effects brought about by climate change as well.

In this study we derived allometric functions for estimating the belowground biomass (BGB) of Silver Birch (Betula pendula Roth), Pedunculate Oak (Quercus robur L.), Sessile Oak (Quercus petraea (Matt.) Liebl.) and Scots Pine (Pinus sylvestris L.) in Germany. To assess the impact on German greenhouse gas (GHG) reporting, these new functions were further compared with BGB functions currently used in France and Sweden. For developing new BGB functions 48 Silver Birches, 39 Pedunculate and Sessile Oaks and 54 Scots Pines were destructively sampled. The sampled trees spanned a DBH range from 8.2 to 52.9 cm for Silver Birch, from 7.4 to 42.0 cm for Oak and from 7.2 to 53.2 cm for Scots Pine. After fitting the data, the following values of model efficiency were achieved: 0.81 for Silver Birch, 0.98 for Oak and 0.95 for Scots Pine. The model root mean square error varies between 5.2 kg for Oak, 13.7 kg for Scots pine and 26.9 kg for Silver Birch. Comparison with the currently applied BGB functions in the German GHG inventory from France and Sweden showed that the use of these functions results in systematically different estimates for the BGB of Silver Birch and Oak. Thus, our findings indicate that BGB functions recommended for other European countries (in particular France and Sweden) are not appropriate for estimating the BGB for the tree species concerned in Germany. Currently, the derived data-set for BGB of Silver Birch, Oak and Scots Pine is the largest in Germany and the developed functions are thus the best available for estimating national BGB stock and stock change in Germany at the moment.

Abstract Background Environmental change has resulted in changes in forest growth in Europe during the last century. This has consequences for the products and services delivered by forest. Mixing tree species is often proposed as a strategy to deal with the consequences of climate change. Diversifying forests is believed to result in higher productivity and increased growth stability. Tree species diversity is therefore expected to affect long-term trends in tree radial growth. However, this has not yet been studied. In this paper we study the effect of diversity on the radial growth and its long-term trends for beech and oak trees growing along a gradient of tree species diversity in the loamy region of central Belgium (from monocultures to mixed forests patches up to three species). Results We found that beech trees have a higher radial growth whereas oak trees have a lower one when growing in mixtures. The contrasting diversity-productivity relationship observed for beech and oak is in agreement with their ranking in shade tolerance, where oaks suffer increased competition in mixed oak patches. Overall, in monocultures and mixtures, an increasing radial growth trend of + 2% for the period 1927–2015 and 21% for the period 1899–2015 was found for beech and oak, respectively. Tree species diversity did not alter the shape of this detected long-term radial growth trend. Nevertheless, for oak a lower year-to-year variability in radial growth is found in mixtures indicating a higher resilience. Conclusion We conclude that diversity impacts the average radial growth and its variability (only in the case of oak) but not the shape of the long-term trend in radial growth of beech and oak trees growing in the loamy region of central Belgium.

The aim of the present study was to evaluate the effect of one of the most important foliar diseases, powdery mildew, on the leaf physiological traits of Quercus robur L. using chlorophyll a fluorescence parameters in combination with parameters of leaf gas exchange. For this purpose, greenhouse semi-controlled experiment was conducted with 25 one-year-old seedlings kept in optimal conditions, and the same number of seedlings infected with the mentioned pathogen. Measurements were carried out when the coverage of epiphytic micelia visually reached more than 75% of the surface of leaves in the infected seedlings. The results of gas exchange measurement showed that Erysiphe alphitoides (Griffon and Maubl.) U. Braun and S. Takam caused a significant reduction of net photosynthesis (A) and a significant increase in substomatal CO2 concentration (Ci). Furthermore, considering the fast kinetics of chlorophyll a fluorescence, all of the observes parameters were significantly affected by oak powdery mildew. On the other hand, pulse amplitude modulated fluorescence parameters were mildly affected, with only minimal (Fo’) and maximal (Fm’) fluorescence of dark adopted leaves showing significant difference. This study presented the possibility of usage and the effectiveness of chlorophyll a fluorescence parameters in detection the severe stress conditions, on the example of leaves infected with oak powdery mildew over 75%. Some additional studies should be conducted in the future to determine the possibility of usage and the effectiveness of the observed fluorescence parameters of fast kinetics in detection of mild and early stress. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 43002: Biosensing Technologies and Global System for Long-Term Research and Integrated Management of Ecosystems]

The influence of the addition of oak chips and barrel ageing on basic wine parameters and volatile compounds of Chardonnay wines has been studied. Chardonnay wines were obtained by the traditional wine-making process. Oak chips (4 g/L—non-toasted and light toasted) were added at the final stage of the winemaking process for ageing 1, 2 and 3 months, respectively. Also, the control wine was aged in non-toasted barrels for the same period of time. Following Liquid-liquid extraction-gas chromatography-mass spectrometry analysis, alcohols, esters, fatty acids, lactones, and phenolic compounds were identified and quantified. The light toasted wine was clearly separated by phenolic compounds (vanillin, p-vinyl guaiacol and acetovanillone). The floral aroma supplied by 2-phenylethanol was slowly increased by ageing with odor activity values (OAV) higher in aged samples than control wine (1.07). The vanilla scent could be easily perceived in all aged samples, mainly for light toasted chip-treated samples with OAV values between 2.30 and 2.37. After 3 months, the volatile compounds of wine from non-toasted medium (chips and barrels) were almost similar from the volatile profile point of view. This could have economic and vinification management implications since oak barrels are expensive and the wine oak barrel aging is a long process. All wines studied in this research can provide a viable alternative to young varietal wines. [ABSTRACT FROM AUTHOR]

Communities across trophic levels, and the functional roles they play, are vital for the sustained provision of ecosystem services. In forest systems, diversification of overstorey composition has been shown to be a key driver of biodiversity, but its influence on across‐trophic level relationships remains scarcely known. Species across trophic levels in varied overstorey compositions are also differentially susceptible to fragmentation context. We hypothesise that fragmentation will disrupt community relationships associated with particular overstorey compositions.We test this hypothesis using a tree diversity research platform across 53 deciduous woodland plots in central Belgium. We estimate species' abundances within nine, generally taxonomic, community groups across trophic levels: understorey vegetation; leaf miners and gall formers; woodlice, millipedes; carabid beetles, harvestmen, spiders, birds, bats. We use multiple co‐inertia analyses to examine how taxonomic and trophic role community matrices covary across gradients of overstorey composition, via three different tree species diversification pathways, and fragmentation.For all trophic role groups, across all plots, there was at least one significant pairwise comparison. Apart from comparisons involving bats, there was at least one significant pairwise correlation between taxonomic groups too. These results indicate correlated community matrices across trophic levels. Overstorey composition related to community tightness, that is, the level of co‐ordinated change among taxonomic and/or trophic role groups as revealed by multiple co‐inertia analyses. Notably, diversifying woodlands of beech Fagus sylvatica or red oak Quercus rubra with pedunculate oak Quercus robur correlated with increased taxonomic community tightness. Diversifying pedunculate oak forest stands with other overstorey species related to unchanged community tightness. Evidence was lacking for fragmentation affecting community tightness, singly or by interacting with overstorey composition.Synthesis. Overall, changing tree species composition and fragmentation level affected across‐trophic level community relationships differently. Yet, we demonstrated a clear signal that diversifying monoculture stands with particular species correlated with greater community tightness, and co‐ordinated change among sets of community groups, across trophic levels and regardless of fragmentation context. We postulate that having tighter community relationships suggests that measures to improve biodiversity at one trophic level (i.e. trees) could affect other groups, and their associated roles, in a co‐ordinated manner. [ABSTRACT FROM AUTHOR]

Urbanization and climate change are two inevitable megatrends of this century. Knowledge about the growth responses of urban trees to climate is of utmost importance towards future management of green infrastructure with the aim of a sustainable provision of the environmental ecosystem services. Using tree-ring records, this study analyzed growth response to climate by stem diameter at breast height (DBH) of 1178 trees in seven large cities worldwide, including Aesculus hippocastanum L. in Munich; Platanus × hispanica Münchh. in Paris; Quercus nigra L. in Houston; Quercus robur L. in Cape Town; Robinia pseudoacacia L. in Santiago de Chile, Munich, and Würzburg; and Tilia cordata Mill. in Berlin, Munich, and Würzburg. Climate was characterized following the de Martonne aridity index (DMI). Overall, trees showed an 8.3% lower DBH under arid than humid climate at the age of 100. Drought-tolerant tree species were overall not affected by climate. However, R. pseudoacacia showed a lower diameter when growing in semi-dry than humid climate. In contrast, drought-sensitive tree species were negatively affected by arid climate. Moreover, the effect of drought years on annual diameter increment was assessed. P. × hispanica and R. pseudoacacia appeared as the most drought-resistant species. The highest sensitivity to drought was detected in T. cordata and Q. robur. A. hippocastanum and Q. nigra showed a lower diameter growth during drought events, followed by a fast recovery. This study’s findings may contribute to a better understanding of urban tree growth reactions to climate, aiming for sustainable planning and management of urban trees.

To determine the appropriate final use of wood from a particular tree species, it is first necessary to know its properties. Methods that use wood samples taken directly from the trunk of a growing or felled tree are very time-consuming and require a great deal of manual work. Non-destructive methods may be more effective and much faster, thanks to the use of advanced technologies. The resistance drilling can be used to determine the variation in wood density along the radius of the stem. The main aim of the present study was to determine the basic density of the wood on a cross-section of the trunk of oak trees and to investigate the correlation of the results with those obtained by drilling the same trees with the IML RESI-PD 400. The results of Spearman’s correlation test showed strong positive correlations between all examined properties. We observed a trend whereby the density of the wood and Resi amplitude increased in direct proportion to the width of the annual rings. The results of linear regression show a strong relationship between examined properties. This study provide evidence that the Resi is an appropriate tool for non-destructive determination of wood density.

In western Ukraine, forest decline and dieback of several broadleaved tree species have become increasingly evident during recent years, and surveys in some areas have shown symptoms indicative of Phytophthora infections. In this study, we aimed to determine the occurrence and diversity of Phytophthora species associated with several broadleaved tree species (Alnus glutinosa, Betula pendula, Castanea sativa, Fagus sylvatica and Quercus robur) from forest stands where dieback has been observed. Rhizosphere soil samples were collected from 14 forest stands during 2017 and 2018 and tested for the presence of Phytophthora species using morphological and molecular methods. Seven Phytophthora species (P. bilorbang, P. cactorum, P. gallica, P. gonapodyides, P. lacustris, P. plurivora and P. polonica), and two other clade six taxa were detected from the various forest types, several of which are probable agents responsible for decline. Four of the Phytophthora species (P. bilorbang, P. gallica, P. plurivora and P. polonica) have previously never been reported from broadleaf forests in Ukraine. [ABSTRACT FROM AUTHOR]

The phyllosphere is a challenging microbial habitat in which microorganisms can flourish on organic carbon released by plant leaves but are also exposed to harsh environmental conditions. Here, we assessed the relative importance of canopy position—top, mid, and bottom at a height between 31 and 20 m—and tree species identity for shaping the phyllosphere microbiome in a floodplain hardwood forest. Leaf material was sampled from three tree species—maple (Acer pseudoplatanus L.), oak (Quercus robur L.), and linden (Tilia cordata MILL.)—at the Leipzig canopy crane facility (Germany). Estimated bacterial species richness (Chao1) and bacterial abundances approximated by quantitative PCR of 16S rRNA genes exhibited clear vertical trends with a strong increase from the top to the mid and bottom position of the canopy. Thirty operational taxonomic units (OTUs) formed the core microbiome, which accounted for 77% of all sequence reads. These core OTUs showed contrasting trends in their vertical distribution within the canopy, pointing to different ecological preferences and tolerance to presumably more extreme conditions at the top position of the canopy. Co-occurrence analysis revealed distinct tree species-specific OTU networks, and 55–57% of the OTUs were unique to each tree species. Overall, the phyllosphere microbiome harbored surprisingly high fractions of Actinobacteria of up to 66%. Our results clearly demonstrate strong effects of the position in the canopy on phyllosphere bacterial communities in a floodplain hardwood forest and—in contrast to other temperate or tropical forests—a strong predominance of Actinobacteria. [ABSTRACT FROM AUTHOR]

Tuber melanosporum Vittad. (Black or Périgord truffle) is a truffle native to the Mediterranean Southern Europe, popular for its unique flavor, and has great economic importance. The present work focused on assessing the possibility of cultivating T. melanosporum associated with Quercus robur L. in the desert climate of Saudi Arabia. The plantation was initiated in November 2018 by planting 271 oak seedlings in the Al-Qassim desert area and checked for survival and ectomycorrhiza development after 1.5 years of plantation maintenance. Amongst the 271 seedlings planted, 243 plants survived two harsh seasons (2019 and 2020), and the randomly selected and tested seedlings were still mycorrhized with T. melanosporum. The mycorrhization level with T. melanosporum was between 5 and 35% of all fine roots, and the share of contaminant ectomycorrhiza was low. In comparison to other areas where T. melanosporum is successfully cultivated, the Al-Qassim desert area has 10–15 °C higher average summer temperatures and a low total annual precipitation, which necessitates regular irrigation of the plantation. This work opens the avenue for an adapted, yet sustainable cultivation of T. melanosporum-inoculated oak tree in a desert climatic condition and introduces new opportunities of the agro-forest business in Saudi Arabia and GCC region. [ABSTRACT FROM AUTHOR]

Chloroplast DNA variation was investigated in 42 populations of pedunculate oak, Quercus robur L., in the European part of Russia, Belarus, Poland, Ukraine, the Urals, and the Caucasus. Restriction analysis and sequencing, as well as chloroplast DNA microsatellite loci (cpSSR), were used as genetic markers. For successful amplification and sequencing, new oak-specific primers were designed. For the first time for Q. robur, nucleotide sequences of three fragments (psaA-trnS, psbC-trnD, and trnT-trnF) were obtained with the determination of phylogenetic relationships among 13 identified haplotypes. In the eastern part of the range, several divergent chloroplast DNA lineages were identified. The haplotype groups were characterized by a nonrandom geographic distribution, which probably reflected the history of oak colonization in these regions. Sharp population differentiation in terms of haplotype composition and the level of variation was revealed. Specifically, in the eastern part of the Russian Plain and in the Urals, two haplotypes are widespread, which are disappearing in the west (Northwestern Russia, Belarus, Poland, and Western Ukraine), where nine haplotypes are found that are absent in east. Geographic structure of chloroplast DNA variation in pedunculate oak from Eastern Europe is similar to that in small-leaved lime (Semerikova et al., 2020), another representative of European temperate forests, in which, like in oak in this part of the range, sharp differences between western and eastern populations were observed. It seems likely that this is the result of postglacial colonization by both species from different, long isolated refugia, some of which were located in the east of the studied areas. In the Urals, parallel differentiation of oak and lime between the southern part (Ural River and Belaya River basins) and more northern regions (Ufa River basin and Middle Urals) was revealed, which can be explained by different historical colonization patterns of these regions by broad-leaved vegetation. [ABSTRACT FROM AUTHOR]

Premise: Abiotic factors and plant species traits have been shown to drive latitudinal gradients in herbivory, and yet, population‐level factors have been largely overlooked within this context. One such factor is plant density, which may influence the strength of herbivory and may vary with latitude. Methods: We measured insect herbivory and conspecific plant density (CPD) of oak (Quercus robur) seedlings and saplings along a 17° latitudinal gradient (2700 km) to test whether herbivory exhibited a latitudinal gradient, whether herbivory was associated with CPD, and whether such an association changed with latitude. Results: We found a positive but saturating association between latitude and leaf herbivory. Furthermore, we found no significant relationship between CPD and herbivory, and such lack of density effects remained consistent throughout the sampled latitudinal gradient. Conclusions: Despite the apparently negligible influence of plant density on herbivory for Q. robur, further research with other plant taxa and in different types of plant communities are needed to investigate density‐dependent processes shaping geographical variation in plant–herbivore interactions. [ABSTRACT FROM AUTHOR]

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Most existing forests are subjected to natural and human‐mediated selection pressures, which have increased due to climate change and the increasing needs of human societies for wood, fibre and fuel resources. It remains largely unknown how these pressures trigger evolutionary changes. We address this issue here for temperate European oaks (Quercus petraea and Q. robur), which grow in mixed stands, under even‐aged management regimes. We screened numerous functional traits for univariate selection gradients and for expected and observed genetic changes over two successive generations. In both species, growth, leaf morphology and physiology, and defence‐related traits displayed significant selection gradients and predicted shifts, whereas phenology, water metabolism, structure and resilience‐related traits did not. However, the direction of the selection response and the potential for adaptive evolution differed between the two species. Quercus petraea had a much larger phenotypic and genetic variance of fitness than Q. robur. This difference raises concerns about the adaptive response of Q. robur to contemporary selection pressures. Our investigations suggest that Q. robur will probably decline steadily, particularly in mixed stands with Q. petraea, consistent with the contrasting demographic dynamics of the two species. [ABSTRACT FROM AUTHOR]

We used double digest restriction site associated DNA sequencing (ddRAD) to develop new geographically informative nuclear SNP loci in Quercus robur and Quercus petraea. Genotypes derived from sequence data of 95 individuals covering the distribution range of the species were analysed to select geographically informative and polymorphic loci within Russia and Germany. We successfully screened a selected set of 119 loci on a MassARRAY® iPLEX™ platform on 190 individuals from 19 locations in Russia. The newly developed loci will be useful for genetic studies over the whole distribution range of both species. [ABSTRACT FROM AUTHOR]

Invasions by non-native pathogens represent a major threat to managed and natural ecosystems worldwide. Although necessary for adopting preventive strategies, the identification of invasive species before they are introduced is particularly difficult. Indeed, most pathogenic species that have become established in the last decades were first described only after they became invasive. To prevent further biological invasions, not only the early identification of potential new invasive plant pathogens is crucial, but also the assessment of their potential host range. In this study, we determined the pathogenicity and the saprotrophic ability of three Cryphonectria species toward three potential hosts in the family Fagaceae. For this, seedlings and dormant stems of European chestnut (Castanea sativa), pedunculate oak (Quercus robur) and European beech (Fagus sylvatica) were inoculated with different genotypes of C. parasitica (Asian species, invasive in Europe), C. naterciae (European species), and C. japonica (Asian species, not present in Europe). Lesion growth was measured and mortality assessed for 4 months. The highest damage was caused by C. parasitica on European chestnut, while C. japonica and C. naterciae induced significantly smaller lesions on this host species. All three Cryphonectria species did not grow saprophytically on F. sylvatica and Q. robur, but successfully colonized dormant stems of C. sativa. In the context of biological invasions, our study shows that the Asian C. japonica most likely represents a much less severe threat than C. parasitica for the tested European host species. Nonetheless, the ability of C. naterciae and C. japonica to saprotrophically colonize fresh chestnut wood may suggest that they could become established in chestnut forests and eventually infect weakened chestnut trees or other hosts not tested in this study.

The study examined the influence of ultraviolet radiation on the colour of thermo-mechanically modified beech (Fagus sylvatica ) and oak (Quercus robur). The wood colour parameters were measured using the mathematical CIE L*a*b* and L*C*h colour space models. The higher the temperature of thermo-mechanical treatment, the least susceptible beech and oak wood was to a change in L*, a* and b* under the influence of light irradiation. The greatest changes in the colour of non-densified and densified beech and oak wood occurred after 20 h of light irradiation. The higher the temperature of thermo-mechanical treatment, the smaller were the total changes in the colour of beech and oak wood under the influence of ultraviolet radiation. The total changes in the colour of beech densified at temperatures of 100°C and 150°C that took place under the influence of ultraviolet radiation were twice as high as in the case of densified oak wood. The colour of oak wood modified at a temperature of 200°C did not change significantly in 300 h of light irradiation.

Traditional flame retardants often contain halogens and produce toxic gases when burned. Hence, in this study, low-cost, environmentally friendly compounds that act as fire retardants are investigated. These materials often contain nanoparticles, from which TiO2 and SiO2 are the most promising. In this work, pedunculate oak wood specimens were modified with sodium silicate (Na2SiO3, i.e., water glass) and TiO2, SiO2, and ZnO nanoparticles using the vacuum-pressure technique. Changes in the samples and fire characteristics of modified wood were studied via thermal analysis (TA), infrared spectroscopy (FTIR), and scanning electron microscopy, coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). The results of TA showed the most significant wood decomposition at a temperature of 350 °C, with a non-significant influence of the nanoparticles. A dominant effect of sodium silicate was observed in the main weight-loss step, resulting in a drop in decomposition temperature within the temperature range of 36–44 °C. More intensive decomposition of wood treated with water glass and nanoparticles led to a faster release of non-combustible gases, which slowed down the combustion process. The results demonstrated that wood modifications using sodium silicate and nanoparticle systems have potentially enhanced flame retardant properties.

Severe droughts are expected to become more frequent and persistent. However, their effect on autumn leaf senescence, a key process for deciduous trees and ecosystem functioning, is currently unclear. We hypothesized that (I) severe drought advances the onset of autumn leaf senescence in temperate deciduous trees and that (II) tree species show different dynamics of autumn leaf senescence under drought. We tested these hypotheses using a manipulative experiment on beech saplings and three years of monitoring mature beech, birch and oak trees in Belgium. The autumn leaf senescence was derived from the seasonal pattern of the chlorophyll content index and the loss of canopy greenness using generalized additive models and piece-wise linear regressions. Drought did not affect the onset of autumn leaf senescence in both saplings and mature trees, even if the saplings showed a high mortality and the mature trees a high leaf mortality (due to accelerated leaf senescence and early leaf abscission). We did not observe major differences among species. Synthesis: The timing of autumn leaf senescence appears conservative across years and species, and even independent on drought stress. Therefore, to study autumn senescence, seasonal chlorophyll dynamics and loss of canopy greenness should be considered separately. [ABSTRACT FROM AUTHOR]

Background and Aims Highly controlled experiments document that plant genetic diversity and relatedness can shape herbivore communities and patterns of herbivory. Evidence from the field is, however, scarce and inconsistent. We assessed whether a genetic signal underlying herbivory can be detected in oak woodlands when accounting for variation at smaller (within-tree) and larger (among-stand) scales. Methods We tested relationships between tree genetic relatedness, leaf chemical defences and insect herbivory for different canopy layers in 240 trees from 15 pedunculate oak (Quercus robur) forest stands. We partitioned sources of variability in herbivory and defences among stands, individuals and branches. Key Results Leaf defences, insect herbivory and their relationship differed systematically between the upper and the lower tree canopy. When accounting for this canopy effect, the variation explained by tree genetic relatedness rose from 2.8 to 34.1 % for herbivory and from 7.1 to 13.8 % for leaf defences. The effect was driven by markedly stronger relationships in the upper canopy. Conclusions Our findings illustrate that considerable effects of the host plant genotype on levels of leaf chemical defences and associated insect herbivory can be detected in natural tree populations when within-individual variation is properly accounted for. [ABSTRACT FROM AUTHOR]

This paper explores the history of age detection of trees, especially the age history of oak trees, throughout two centuries in Estonia. It was already in the beginning of the 19th century when relations between the size and age of oaks in northern Latvia (previous Livonian province) were described. The paper explains how the species concept of Quercus robur developed over time in the past and points out discussions on the existence of two varieties Q. robur L. var. tardiflora Czern and Q. robur L. var. praecox Czern. It also states that thanks to the use of the increment borer, the first dendrochronological studies were carried out in Estonia in the 1920s. Dendrochronological research in the Soviet Union began in the 1950s with Lithuania being the leading country in the field headed by Teodaras Bitvinskas. In Estonia, research was continued in the 1960s until now. The paper takes a look at the life of Mart Rohtla who introduced the method of determining tree age according to tree bark, presents his standpoints on oaks and critically assesses these. A comparative assessment is given on the ages of oak and lime trees found according to the tree-ring method and bark increment method. The great ages of the oaks and limes found by applying the bark increments method are doubted and considered unreliable. However, the age of the surface layers of the bark of oaks and limes needs clarification in the future. [ABSTRACT FROM AUTHOR]

The paper focuses on the study of composition and species correlation in typical specific communities of nemoral biocenoses with Quercus robur L. Species of various viability levels growing in the southwest of Central Russian Upland have been examined. Three polypore fungi types living on oaks have been found to make up the characteristic combination of species in dendro-trophic pathogenic polypore fungi communities growing on oaks in upland and ravine groves, namely, Fistulina hepatica, Laetiporus sulphureus, Fomitiporia robusta. These ones are constant species in the communities' composition, displaying the highest dominance in terms of population, with 44.9%, 28.8%, 20.4%, respectively, in upland groves, and 45.0%, 26.3%, 20.5%, respectively, in ravine groves. F. hepatica is an indicator species which characterizes the vitality of oak stand: the higher dominance is displayed by the species, the poorer is oak stand condition. [ABSTRACT FROM AUTHOR]

Tree health declines can be caused by interactions between pests and pathogens and many studies have shown a reduction in their damage in mixed species forests compared to monocultures. Yet few authors have considered tree diversity effects on both groups simultaneously. Moreover, it is unclear whether diversity effects on tree pests and pathogens are robust to changes in abiotic conditions, such as drought.We addressed tree diversity effects on foliar insect herbivory, oak powdery mildew and their interaction under contrasting water regimes in a large-scale tree diversity experiment in SW France. Using an irrigation treatment that alleviated drought conditions, we were able to experimentally assess the effects of tree diversity under contrasting abiotic environments. We surveyed plots along a richness gradient from one to four tree species, in which a focal study species of oak (Quercus robur) was mixed with other oak species (Q. pyrenaica and Q. ilex) and a taller, broadleaved species (Betula pendula).Increasing tree species richness lowered leaf miner abundance, leaf chewer damage and oak powdery mildew infection, consistent with a protective effect of resource dilution. However, richness effects on leaf miners were stronger in irrigated compared to non-irrigated blocks, indicating that environmental conditions can modulate diversity effects. Separate from the effect of tree species richness, the presence of birch in a plot increased damage by leaf chewers and powdery mildew, but lowered leaf miner damage, suggesting additional tree neighbour identity effects potentially linked to modulation of microclimate. We found a negative association between leaf miner abundance and oak powdery mildew, consistent with antagonism between oak damage agents.Synthesis. Overall, our study illustrates the importance of considering both tree diversity and composition (neighbour identity) in designing forests more resistant to pest and pathogen damage. [ABSTRACT FROM AUTHOR]

Background: Associations of tree roots with diverse symbiotic mycorrhizal fungi have distinct effects on whole plant functioning. An untested explanation might be that such effect variability is associated with distinct impacts of different fungi on gene expression in local and distant plant organs. Using a large scale transcriptome sequencing approach, we compared the impact of three ectomycorrhizal (EMF) and one orchid mycorrhizal fungi (OMF) on gene regulation in colonized roots (local), non-colonized roots (short distance) and leaves (long distance) of the Quercus robur clone DF159 with reference to the recently published oak genome. Since different mycorrhizal fungi form symbiosis in a different time span and variable extents of apposition structure development, we sampled inoculated but non-mycorrhizal plants, for which however markedly symbiotic effects have been reported. Local root colonization by the fungi was assessed by fungal transcript analysis. Results: The EMF induced marked and species specific effects on plant development in the analysed association stage, but the OMF did not. At local level, a common set of plant differentially expressed genes (DEG) was identified with similar patterns of responses to the three EMF, but not to the OMF. Most of these core DEG were down-regulated and correspond to already described but also new functions related to establishment of EMF symbiosis. Analysis of the fungal transcripts of two EMF in highly colonized roots also revealed onset of a symbiosis establishment. In contrast, in the OMF, the DEG were mainly related to plant defence. Already at short distances, high specificities in transcriptomic responses to the four fungi were detected, which were further enhanced at long distance in leaves, where almost no common DEG were found between the treatments. Notably, no correlation between phylogeny of the EMF and gene expression patterns was observed. Conclusions: Use of clonal oaks allowed us to identify a core transcriptional program in roots colonized by three different EMF, supporting the existence of a common EMF symbiotic pathway. Conversely, the specific responses in non-colonized organs were more closely related to the specific impacts of the different of EMF on plant performance. [ABSTRACT FROM AUTHOR]

Summary: Exotic pathogens cause severe damage in natural populations in the absence of coevolutionary dynamics with their hosts. However, some resistance to such pathogens may occur in naive populations. The objective of this study was to investigate the genetics of this so‐called 'exapted' resistance to two pathogens of Asian origin (Erysiphe alphitoides and Phytophthora cinnamomi) in European oak.Host–pathogen compatibility was assessed by recording infection success and pathogen growth in a full‐sib family of Quercus robur under controlled and natural conditions. Two high‐resolution genetic maps anchored on the reference genome were used to study the genetic architecture of resistance and to identify positional candidate genes.Two genomic regions, each containing six strong and stable quantitative trait loci (QTLs) accounting for 12–19% of the phenotypic variation, were mainly associated with E. alphitoides infection. Candidate genes, especially genes encoding receptor‐like‐kinases and galactinol synthases, were identified in these regions. The three QTLs associated with P. cinnamomi infection did not colocate with QTLs found for E. alphitoides.These findings provide evidence that exapted resistance to E. alphitoides and P. cinnamomi is present in Q. robur and suggest that the underlying molecular mechanisms involve genes encoding proteins with extracellular signaling functions. See also the Editorial on this article by Plomion & Martin, 226: 943–946. [ABSTRACT FROM AUTHOR]

Background and Aims Classic theory on geographical gradients in plant–herbivore interactions assumes that herbivore pressure and plant defences increase towards warmer and more stable climates found at lower latitudes. However, the generality of these expectations has been recently called into question by conflicting empirical evidence. One possible explanation for this ambiguity is that most studies have reported on patterns of either herbivory or plant defences whereas few have measured both, thus preventing a full understanding of the implications of observed patterns for plant–herbivore interactions. In addition, studies have typically not measured climatic factors affecting plant–herbivore interactions, despite their expected influence on plant and herbivore traits. Methods Here we tested for latitudinal variation in insect seed predation and seed traits putatively associated with insect attack across 36 Quercus robur populations distributed along a 20° latitudinal gradient. We then further investigated the associations between climatic factors, seed traits and seed predation to test for climate-based mechanisms of latitudinal variation in seed predation. Key Results We found strong but contrasting latitudinal clines in seed predation and seed traits, whereby seed predation increased whereas seed phenolics and phosphorus decreased towards lower latitudes. We also found a strong direct association between temperature and seed predation, with the latter increasing towards warmer climates. In addition, temperature was negatively associated with seed traits, with populations at warmer sites having lower levels of total phenolics and phosphorus. In turn, these negative associations between temperature and seed traits led to a positive indirect association between temperature and seed predation. Conclusions These results help unravel how plant–herbivore interactions play out along latitudinal gradients and expose the role of climate in driving these outcomes through its dual effects on plant defences and herbivores. Accordingly, this emphasizes the need to account for abiotic variation while testing concurrently for latitudinal variation in plant traits and herbivore pressure. [ABSTRACT FROM AUTHOR]

The area of Quercus robur forest stands in Northern Europe is extremely low due to the legacies of forest management targeted on coniferous tree species and past land conversion on rich soils to agriculture. These stands are characterized by a unique flora and fauna and therefore they are important in the network of protected areas. It is well known that Q. robur will not regenerate under a closed canopy. Thus, these stands are being gradually replaced in succession by shade-tolerant species like Picea abies, which can alter soil conditions. Removal of encroaching trees around Q. robur to maintain the typical habitat conditions is commonly practiced in Northern Europe, but the results of these restoration activities are inconclusive, and not always published when conducted in a practical conservation framework. In Latvia, such restoration of Q. robur stands has commonly been implemented in protected areas, but no publications are available on achieved results. In a restoration project setting, we determined effects of removal of P. abies in the subcanopy and canopy around old Q. robur on tree regeneration and composition of the herb layer. Within a five-year period after management, the created openings were invaded first by generalist species common in open habitats. There was a continuous increase in abundance of the shrub Rubus idaeus, which reached 100% in all plots. There was minimal regeneration of Q. robur, while establishment of Populus tremula occurred. Development of a herb layer was inhibited. However, it is expected that this shrub phase will end in the short- to long-term priod of time. [ABSTRACT FROM AUTHOR]

One of the most important ecosystem processes, especially in temperate and boreal forests, is herbivore browsing. In this study, we tested five hypotheses: (H1) oak tree density would positively affect their height; (H2) despite severe browsing pressure, the height of oaks would increase with the age after planting; (H3) oaks growing among the planted pines would be taller than those among the sown ones; (H4) the growth of single oak saplings or of oak nests would be positively affected by the height of the pines growing in the immediate neighbourhood of the oaks; and (H5) the oak height would be affected by the location within a nest and oaks growing in the central zone would be taller than the others. The study was conducted in the Piska Forest in the north-eastern part of Poland. We established three variants of experiment. In the first variant, oaks were planted individually. In the second and third variants, oaks were planted in small nests. The second and third variants differed in the spacing of the nests: 8 × 8 m and 6 × 6 m, respectively. The division into the sub-variants referred to type of pine regeneration. In the first sub-variant, Scots pine was planted. In the second, pine was sown. In general, oaks growing within nests were significantly taller than those planted individually in the Scots pine rows. Despite heavy browsing, oak height consistently increased during the course of the study. Oak height also depended on the type of pine regeneration, and the mean height of oaks surrounded by planted pines was significantly higher than that of oaks surrounded by sown pines (which, in average, was shorter). That was because the planted pines were taller than the sown ones. We found that Spearman's correlation coefficients were positive and significant between pine and oak heights in variants 2 and 3. Growth of oaks did not depend on their location within a nest. The results of the regeneration method of oak (single vs nest and few vs many nests) are modified by browsing. The best method found in the heavy browsing circumstances was planting oaks in many nests within successful pine regeneration (providing the oaks with protection against the browsing). The pine will provide the most efficient protection if regenerated a few years before the oaks. [ABSTRACT FROM AUTHOR]

Pedunculate oak (Quercus robur L.) is one of the most important forest tree species in Europe, from both economic and ecological perspectives. Several studies indicate the possibility of using different species of the genus Quercus for afforestation of lands affected by industry, including trace-element polluted areas. The main objective of this research was to determine the Cd accumulation patterns of pedunculate oak seedlings subjected to various Cd treatments. Differences in Cd accumulation ability, mineral nutrients concentrations and observed damage upon Cd treatment of plants derived from different regions of origin are discussed. Obtained results suggest the possible use of pedunculate oak in cadmium phytostabilization. [ABSTRACT FROM AUTHOR]

One of the best known ecological consequences of climate change is the advancement of spring phenology. Yet, we lack insights into how changes in climate interact with intraspecific genetic variation in shaping spring and autumn phenology, and how such changes in phenology will translate into seasonal dynamics of tree‐associated organisms. To elucidate the impact of warming and tree genotype on spring and autumn phenology, as well as the consequences for the population dynamics of a fungal pathogen Erysiphe alphitoides and plant‐feeding insect Tuberculatus annulatus, we conducted an active field heating experiment using grafts of five oak genotypes Quercus robur. We found that experimental warming generally advanced oak bud burst in spring and delayed leaf senescence in autumn, while additional variation was explained by tree genotype and warming‐by‐genotype interactions. Warming or tree genotype did not affect disease levels at the beginning of the season, but shaped both disease levels and aphid density during the latter part of the season. Overall, our findings demonstrate that elevated temperature and genetic variation affect spring and autumn phenology, as well as the seasonal dynamics of higher trophic levels. Such effects may be either direct (i.e. temperature affecting tree phenology and attack independently) or indirect (as due to climate‐induced changes in plant traits or the synchrony between trees and their attackers). To achieve a predictive understanding of the ecological responses and potential evolutionary changes of natural food webs in response to climate warming, we should merge the frameworks of global warming and community genetics. [ABSTRACT FROM AUTHOR]

In 2017, the Birmingham Institute of Forest Research (BIFoR) began to conduct Free Air Carbon Dioxide Enrichment (FACE) within a mature broadleaf deciduous forest situated in the United Kingdom. BIFoR FACE employs large‐scale infrastructure, in the form of lattice towers, forming ‘arrays’ which encircle a forest plot of ~30 m diameter. BIFoR FACE consists of three treatment arrays to elevate local CO2 concentrations (e[CO2]) by +150 µmol/mol. In practice, acceptable operational enrichment (ambient [CO2] + e[CO2]) is ±20% of the set point 1‐min average target. There are a further three arrays that replicate the infrastructure and deliver ambient air as paired controls for the treatment arrays. For the first growing season with e[CO2] (April to November 2017), [CO2] measurements in treatment and control arrays show that the target concentration was successfully delivered, that is: +147 ± 21 µmol/mol (mean ± SD) or 98 ± 14% of set point enrichment target. e[CO2] treatment was accomplished for 97.7% of the scheduled operation time, with the remaining time lost due to engineering faults (0.6% of the time), CO2 supply issues (0.6%) or adverse weather conditions (1.1%). CO2 demand in the facility was driven predominantly by wind speed and the formation of the deciduous canopy. Deviations greater than 10% from the ambient baseline CO2 occurred <1% of the time in control arrays. Incidences of cross‐contamination >80 µmol/mol (i.e. >53% of the treatment increment) into control arrays accounted for <0.1% of the enrichment period. The median [CO2] values in reconstructed three‐dimensional [CO2] fields show enrichment somewhat lower than the target but still well above ambient. The data presented here provide confidence in the facility setup and can be used to guide future next‐generation forest FACE facilities built into tall and complex forest stands.The Birmingham Institute of Forest Research (BIFoR) has built and operated a free‐air carbon dioxide enrichment (FACE) facility in deciduous forest in the United Kingdom. BIFoR FACE aims to elevate the local atmospheric carbon dioxide concentrations of a temperate, mature, oak woodland, to mimic those predicted for 30–50 years into the future. The facility target of 150 parts per million (ppm) above ambient (currently ~405 ppm) was reached in 97% of the operation time in the first year of operation (2017). With performance of the facility characterized, researchers can now investigate how this ecosystem responds to elevated CO2. [ABSTRACT FROM AUTHOR]

Urban trees contribute to the regulation of microclimates of cities through transpirational cooling. The main environmental factors determining transpiration are evaporative demand and soil water availability. However, growth conditions in urban areas are often unfavorable and may promote drought stress. The responses of trees to these conditions may vary between species and age classes, and in addition, can be modified by their environment. For a better understanding of water use patterns of urban tree species, these responses were investigated as a function of different meteorological and soil conditions of their urban environments. To identify physiological responses of mature oaks (Quercus robur L.) to contrasting site conditions, sap flow measurements were carried out in two consecutive growing seasons (2013 and 2014) in urban and suburban areas of Hamburg, Germany. Even considering the varying and sometimes challenging local soil and meteorological conditions, the oaks showed predominantly uniform response patterns. At all study sites, sap flow dynamics were characterized by saturation responses to increasing vapor pressure deficits during both daytime and nighttime conditions, reflecting stomatal responsiveness and hence, a stomatal down-regulation of water loss at demanding atmospheric conditions. Accordingly, the water use of oak trees was characterized by an isohydric strategy, which can help to avoid the risk of cavitation. Moreover, the maximum values of nighttime sap flow exceeded 20% of the daily total at all sites, indicating high rates of nocturnal transpiration and thus a relevant cooling effect during the night. Actual sap flow followed potential sap flow at all sites despite decreasing soil water potentials in the upper soil layers. This suggests actual sap flow during both growing seasons was only limited by atmospheric water demand. Accordingly, the studied mature oak trees maintained high rates of transpiration even in times of reduced soil water availability and thus could provide cooling under challenging site conditions. In contrast to suburban areas, however, oaks in the urban site showed reduced absolute sap flow rates, indicating transpiration sensitivity to different situations of water demand and supply. Due to its water use strategy and its ability to cope with moderate drought, Q. robur can be considered a suitable urban tree species in view of current and future demanding urban growth conditions. [ABSTRACT FROM AUTHOR]

The study examined the influence of ultraviolet radiation on the colour of thermo-mechanically modified beech (Fagus sylvatica) and oak (Quercus robur). The wood colour parameters were measured using the mathematical CIE L*a*b* and L*C*h colour space models. The higher the temperature of thermo-mechanical treatment, the least susceptible beech and oak wood was to a change in L*, a* and b* under the influence of light irradiation. The greatest changes in the colour of non-densified and densified beech and oak wood occurred after 20 h of light irradiation. The higher the temperature of thermo-mechanical treatment, the smaller were the total changes in the colour of beech and oak wood under the influence of ultraviolet radiation. The total changes in the colour of beech densified at temperatures of 100°C and 150°C that took place under the influence of ultraviolet radiation were twice as high as in the case of densified oak wood. The colour of oak wood modified at a temperature of 200°C did not change significantly in 300 h of light irradiation. [ABSTRACT FROM AUTHOR]

• Autochthony of Central European oaks has been greatly preserved by management. • Quercus petraea and robur are genetically homogenous, Q. pubescens is structured. • Recent species contacts vs. historic hybridization are genetically identifiable. • Autochthonous relict and old managed study stands are suitable for conservation. • Important to promote the evolutionary potential in conservation and management. Central European white oaks expanded rapidly after the last glacial period and reached their current distribution range during the early Holocene. They have been an important resource of timber, fuelwood and animal feed for humans, who actively promoted their presence in forests and other landscape types at least since the early historical times. Besides stands with intensive management, putatively relict populations of three native oak species can be found on unproductive sites with restricted accessibility. Here, we apply chloroplast and nuclear microsatellite markers in order to address the autochthony of relict and managed stands and compare the spatial distribution of genetic variation between them. Based on data from more than 150 populations, we demonstrate that oak autochthony was preserved throughout historical times which is likely the result of traditional silvicultural treatment. This is supported by the fact that the spatial pattern of chloroplast haplotype distribution still reflects the post-glacial recolonization in both relict and old managed stands. We observed significant admixture of haplotypes only in stands established after the Second World War, which is attributable to the transfer of reproductive material used for afforestation. In terms of nuclear genetic variation, we observed marked differences among species. Quercus pubescens exhibited a pronounced genetic structure. Genetic drift and limited gene flow among its small and isolated populations in our study area might have contributed to this pattern. Varying extent of genetic introgression with other sympatric oak species could offer an additional explanation. On the contrary, the gene pools of Q. petraea and Q. robur are highly homogenous, displaying only weak isolation-by-distance. We found no significant differences of genetic diversity and differentiation between relict and managed stands. This suggests that seed transfer mostly occurred within our study area, even in those stands established in post-war times, verifying previous findings which point out limited human interference. We recommend consideration of population genetic structure for gene conservation, with a finer resolution of gene conservation units needed for Q. pubescens due to its spatial genetic structure. Both relict and old managed stands, species-pure or mixed, are suitable for conservation, as they host autochthonous gene pools. Coppice-with-standard management could contribute to preservation of autochthony. In the face of climate change, it is also important to maintain the evolutionary potential of the stands, by facilitating generative reproduction and allowing for hybridization in mixed stands. [ABSTRACT FROM AUTHOR]

For many species, seed storage protocols are still being improved to provide viable seeds of the highest quality. Seed storage is extremely problematic for short-lived seeds categorized as recalcitrant, including pedunculate oak (Quercus robur L.), for which the optimal seed storage protocol involves a temperature of –3 °C and 40% acorn moisture content recommendations. The sensitivity of pedunculated oak seeds to temperature manipulations under preparation for long-term storage has been poorly investigated, particularly in terms of the production of reactive oxygen species (ROS), which are assumed to be determinants of seed longevity. Thermotherapy, the pathogen elimination procedure, did not increase the level of three types of ROS: hydrogen peroxide (H2O2), superoxide anion radical and hydroxyl radical (•OH). The temporal heat stress of thermotherapy resulted in slightly reduced levels of H2O2, indicating activation of the antioxidant systems in acorn preparation for storage. The effect of constant storage temperatures (−3, −5, −7 °C) and their combinations (−3 → −5 °C or −3 → −5 →−7 °C) on ROS levels and seed viability was investigated in three provenances. The highest ROS levels were detected in acorns stored at −7 °C, whereas three-step cold acclimation was beneficial for reducing ROS levels. Interestingly, the levels of H2O2 were not affected by temperature in thermotherapized acorns. In contrast, decreasing storage temperature caused a linear increase in •OH levels in all provenances. The effect of heat stress and cold stress on ROS levels in relation to long-term seed storage of pedunculate oak is discussed here in relation to the seed viability evidenced via germination rates, seedling emergence and electrolyte leakage. Thermotherapy and cold acclimation of acorns can improve their viability after storage by decreasing ROS levels.

The structure and ultrastructure of two developmental stages of the spangle gall induced by Neuroterus quercusbaccarum (Hymenoptera, Cynipidae) were investigated using light microscopy (LM), fluorescence microscopy (FM), and transmission (TEM) and scanning (SEM) electron microscopy. The general design of the gall structure was typical of Cynipidae, but some structural features distinguished the spangle gall. Previously undescribed, characteristic multicellular epidermal protuberances with large openings were observed in autumn on the surface of galls. These may facilitate the gas exchange between the atmosphere and the inside of the gall, thus assisting larval respiration. The larval chamber is surrounded by both a sclerenchymatous capsule and numerous cells containing calcium oxalate crystals that may both serve as protective barriers. In young galls, the nutritive tissue is a wall-less protoplasmic mass, potentially easily accessible to young larvae with delicate mandibles. Cell walls only develop at a later stage. The nutritive tissue was found to be rich in proteins and lipids, but starch grains were not observed. Cellular topology suggests that spangle galls grow by anticlinal division of marginal epidermal cells and periclinal division of subepidermal cells. Cellular proliferation (hyperplasia) also occurs in the leaf tissue near the connection with the gall peduncle, which eventually lignifies.

We used Double Digest Restriction site associated DNA sequencing (ddRAD) and Miseq to develop new geographically informative nuclear and plastid SNP and indel loci in Quercus robur and Q. petraea. Genotypes derived from sequence data of 95 individuals and two pools of 20 individuals each of Q. robur and Q. mongolica covering the distribution range of the species, were analysed to select geographically informative and polymorphic loci within Germany and Russia. We successfully screened a selected set of 431 nuclear single nucleotide polymorphism (nSNP), six nuclear Indel, six mitochondrial single nucleotide polymorphism (mtSNP) and ten chloroplast single nucleotide polymorphism (cpSNP) loci with a SeqSNP genotyping platform on 100 individuals Quercus petraea from 10 locations in Germany, 100 individuals Quercus robur from ten locations in Germany and 100 individuals Quercus robur from ten locations in Russia. The newly developed loci are useful for species identification and genetic studies on the genetic diversity and genetic differentiation of Quercus robur and Quercus petraea in Europe. [ABSTRACT FROM AUTHOR]

European floodplain forest is facing increasingly frequent and severe drought events related with ongoing climate change. Moreover, this ecosystem type was frequently affected by river regulation, leading to groundwater table lowering; however, river revitalization has, in some locations, achieved some restoration of groundwater levels. In this study, we investigated the growth–climate sensitivity and growth modulation after groundwater-level manipulation for Fraxinus angustifolia Vahl. and Quercus robur L. in one of the most important floodplain forest complexes in Central Europe. We constructed three different types of tree ring chronologies to reflect the high frequency variability, medium-low frequency variability, and basal area increment. We found F. angustifolia to be more sensitive than Q. robur to both drought and groundwater level fluctuations. Moreover, F. angustifolia showed more pronounced short-term and long-term growth decreases after artificial ground water level alteration than did Q. robur. We also found that the groundwater level increase due to river revitalization reduced the climate sensitivity for both F. angustifolia and Q. robur. The decrease in climate sensitivity associated with revitalization was more pronounced for F. angustifolia which, moreover, showed a greater basal growth after river revitalization. Our results suggest that F. angustifolia will be more threatened than Q. robur by the diminution in groundwater availability and increase in drought with ongoing climate change. They also show that river revitalization can be a suitable management tool to help the adaptation to climate change.

Understanding intraspecific genetic variation is one of the principal requirements for the evaluation of tree species capacity to cope with intensive climatic changes, as well as designing long-term conservation programs. Herein, we evaluated the genetic diversity and genetic structure of seven pedunculate oak (Quercus robur L.) populations, located at the southern margin of its distribution range on the Balkan Peninsula (Serbia). The objective of the study was to propose future in situ conservation measures aimed at protection of pedunculate oak adaptive and neutral genetic diversity at the species rear-edge. Genetic diversity and structure were estimated using twelve highly polymorphic simple sequence repeat (SSR) markers. The mean expected heterozygosity (He) was 0.769, allelic richness (AR) 9.63, and private allelic richness (pAR) 0.79, indicating high genetic diversity in the studied populations. Genetic differentiation among the populations was low (Fst = 0.032). Structure analysis, the unweighted pair group method with arithmetic mean (UPGMA) showed the existence of two gene pools unrelated to the populations’ area of occurrence. Taking into consideration the results of the current study and previous conservation activities on the pedunculate oak in Serbia, as well as the importance of rear-edge populations in the long-term conservation of the species genetic diversity, we suggested establishing three additional gene conservation units for securing long-term sustainability of the species.