Beech Seeds Research Articles

Spread of Puumala Hantavirus to New Areas in a Large Croatian Outbreak of Hemorrhagic Fever with Renal Syndrome, 2021.

Background: The largest documented outbreak of hemorrhagic fever with renal syndrome occurred in Primorje-Gorski Kotar County, Croatia, in 2021, marking the first-time cases of hantavirus infection recorded outside of the known endemic region in the north of the county. Aim: To identify the factors contributing to the spread of the outbreak and to compare risk factors for acquiring hantavirus infection in the endemic and newly affected regions. Methods and Results: A total of 189 cases were confirmed by positive Puumala IgM/IgG antibodies (93.6%), and 13 probable cases were identified by clinical and epidemiological data (6.4%) using a structured questionnaire. Of the 179 cases with available clinical data, 59 (33.0%) were hospitalized. Three cases received hemodialysis, and no deaths were reported. Among 170 cases with information on exposures, 66 (38.8%) reported occupational risk. Cases in the northern part of county were more likely to have been infected in early spring (OR 27.1, 95% CI 2.93-250.7), to report seeing a rodent (OR 6.5; 95%CI 2.3-18.4), and to know someone with hemorrhagic fever with renal syndrome (HFRS) (OR 3.0; 95%CI 1.2-8.0) than cases from the southern part of the county. Data from Croatian Forests Ltd. suggested that an unusually good production of beech seeds in 2020 may have contributed to an increased rodent population in 2021. However, average temperature, rainfall, and humidity data from 2021 did not illustrate a significant difference from previous years (Kruskal-Wallis p = 0.837, p = 0.999, p = 0.108). Conclusion: The 2021 HFRS outbreak was likely fueled by an abundant rodent population and virus transmission in rodent hosts. Human activity, environmental factors, and the ensuing animal-human interactions have spread hantavirus infection from Croatia's mountainous region to a previously nonendemic coastal area with a Mediterranean climate.

Forest composition shapes seed‐rodent interactions in a gradient of broadleaves and conifers

Abstract Non‐native tree species and mixed forests have been increasingly employed in forestry practice as a safeguard against climate change and as a tool to foster biodiversity while providing economic benefits. Though these changes in forest composition may affect animal communities and ecosystem processes, they are seldom studied through a plant–animal interaction perspective. Here we investigated how forests with varying proportions of a native broadleaf (Fagus sylvatica) and two conifers (introduced Pseudotsuga menziesii and native Picea abies) affect rodents and their interactions with seeds. We surveyed terrestrial small mammal communities, estimated species' densities, assessed seed preference by rodents, collected data on environmental variables (understory density and tree basal area), measured Fagus sylvatica seed production and tracked 1200 seeds of Fagus sylvatica in 20 different forest plots in northern Germany in a mast and non‐mast year for Fagus sylvatica. Forest composition influenced the interactions between rodents and seeds. In forests with a lower proportion of broadleaves, beech seeds were harvested faster and in greater quantities, had diminished survival and were less often cached. These results are in agreement with three other findings: (a) seed fate responded to the proportion of broadleaves and conifers irrespective of conifer tree identity, (b) rodents preferred nutritious beech seeds over small conifer seeds, and (c) higher proportions of seeds were harvested during the period when beech seeds were scarce (non‐mast year). Synthesis and applications: This work provides evidence of how forest composition can affect plant–animal interactions without necessarily altering animal communities or population densities. Specifically, we found no differences between forests with native and non‐native conifer trees regarding small mammal community, seed‐rodent interactions or seed fate. Furthermore, rodents may provide a service in mixed forests by primarily preying upon seeds of Fagus sylvatica, a superior‐competitive species, and thus mitigate beech dominance over conifer species.

The association of protein-bound methionine sulfoxide with proteomic basis for aging in beech seeds

BackgroundEuropean beech (Fagus sylvatica L.) trees produce seeds irregularly; therefore, it is necessary to store beech seeds for forestation. Despite the acquisition of desiccation tolerance during development, beech seeds are classified as intermediate because they lose viability during long-term storage faster than typical orthodox seeds. In this study, beech seeds stored for short (3 years) or long (20 years) periods under optimal conditions and displaying 92 and 30% germination capacity, respectively, were compared.ResultsAged seeds displayed increased membrane damage, manifested as electrolyte leakage and lipid peroxidation levels. Analyses have been based on embryonic axes, which contained higher levels of reactive oxygen species (ROS) and higher levels of protein-bound methionine sulfoxide (MetO) in aged seeds. Using label-free quantitative proteomics, 3,949 proteins were identified, of which 2,442 were reliably quantified pointing to 24 more abundant proteins and 35 less abundant proteins in beech seeds under long-term storage conditions. Functional analyses based on gene ontology annotations revealed that nucleic acid binding activity (molecular function), ribosome organization or biogenesis and transmembrane transport (cellular processes), translational proteins (protein class) and membranous anatomical entities (cellular compartment) were affected in aged seeds. To verify whether MetO, the oxidative posttranslational modification of proteins that can be reversed via the action of methionine sulfoxide reductase (Msr) enzymes, is involved in the aging of beech seeds, we identified and quantified 226 MetO-containing proteins, among which 9 and 19 exhibited significantly up- and downregulated MetO levels, respectively, in beech seeds under long-term storage conditions. Several Msr isoforms were identified and recognized as MsrA1-like, MsrA4, MsrB5 and MsrB5-like in beech seeds. Only MsrA1-like displayed decreased abundance in aged seeds.ConclusionsWe demonstrated that the loss of membrane integrity reflected in the elevated abundance of membrane proteins had a higher impact on seed aging progress than the MetO/Msr system. Proteome analyses enabled us to propose protein Sec61 and glyceraldehyde-3-phosphate dehydrogenase as potential longevity modulators in beech seeds.

Effects of silver nanoparticles on germination and seedling characteristics of Oriental beech (Fagus orientalis) seeds

Nowadays, the applications of nanotechnology are increasing in various fields such as information technology, energy, the medical sector, and agriculture. Nanotechnology has proved its ability to solve problems in agriculture and related industries. Establishing the impact of nanoparticles on various ecosystems has become a primary research topic, but studies on forest ecosystems and trees are quite limited. This study examined the effects of silver nanoparticles on the germination parameters of oriental beech seeds and established their toxic threshold values. Silver nanoparticles were applied at concentrations of 200, 400, 600, 800, and 1000 mg/L to oriental beech (Fagus orientalis) seeds collected from 10 different populations in order to identify the germination rate, germination percentage, seedling height, root collar diameter, plumula length, radicle thickness, and radicle length parameters. The results revealed that silver nanoparticles have a negative effect on germination and seedling parameters of oriental beech seeds, and that this effect is clearly seen in the germination rate at 20 mg/L levels and in seedling characters starting from 60 mg/L dose, causing a decrease of 13% in germination rate, 24% in germination percentage, 40% in plumula length, and 30% in radicle length. The Kahramanmaras-Andirin population was found to be the most affected by nanoparticles, while the Bursa-Inegol and Ordu-Akkus populations were the least affected.

High phenotypic variation found within the offspring of each mother tree in Fagus sylvatica regardless of the environment or source population

AbstractAimClimate change challenges temperate forest trees by increasingly irregular precipitation and rising temperatures. Due to long generation cycles, trees cannot quickly adapt genetically. Hence, the persistence of tree populations in the face of ongoing climate change depends largely on phenotypic variation, that is the capability of a genotype to express variable phenotypes under different environmental conditions, known as plasticity. We aimed to quantify phenotypic variation of central Europe's naturally dominant forest tree across various intraspecific scales (individuals, mother trees (families), populations) to evaluate its potential to respond to changing climatic conditions.LocationEurope.Time Period2016–2019.Major Taxa StudiedEuropean beech (Fagus sylvatica L.).MethodsWe conducted a fully reciprocal transplantation experiment with more than 9000 beech seeds from seven populations across a Europe‐wide gradient. We compared morphological (Specific Leaf Area), phenological (leaf unfolding) and fitness‐related (growth, survival) traits across various biological scales: within single mother trees, within populations and across different populations under the contrasting climates of the translocation sites.ResultsThe experiment revealed significant phenotypic variation within the offspring of each mother tree, regardless of geographic origin. Initially, seedling height growth varied among mother trees and populations, likely due to maternal effects. However, the growth performance successively aligned after the first year. In summary, we observed a consistent growth response in different beech populations to diverse environments after initial maternal effects.Main ConclusionsThe study strikingly demonstrates the importance of considering intraspecific variation. Given the surprisingly broad spectrum of phenotypes each mother tree holds within its juvenile offspring, we conclude that Fagus sylvatica might have the potential for medium‐term population persistence in face of climate change, provided that this pattern persists into later life stages. Hence, we also suggest further investigating the inclusion of passive adaptation and natural dynamics in the adaptive management of forests.

High-throughput method for Oxygen Consumption Rate measurement (OCR) in plant mitochondria

BackgroundConventional methods to measure oxygen consumption, such as Clark-type electrodes, have limitations such as requiring a large amount of starting material. Moreover, commercially available kits for high-throughput methods are usually optimized for animal cells and mitochondria. Here, we present a novel method to measure the oxygen consumption rate using a high-throughput assay in isolated mitochondria of European beech seeds. To perform the measurements, we adapted the Agilent Seahorse XF Cell Mito Stress Test Kit protocol for measurements on plant mitochondria.ResultsThe optimized protocol for OCR measurement of mitochondria isolated from beech seeds allowed the observation of storage period-dependent gradual decreases in non-phosphorylating respiration, phosphorylating respiration and maximal FCCP-stimulated respiration. The longer the seeds were stored, the greater the impairment of respiratory function.ConclusionsThanks to this method it is possible to minimize the amount of plant material and conduct research to obtain information on the respiratory condition and activity of plant mitochondria, including the efficiency of oxidative phosphorylation and the maximum oxidative capacity of the respiratory chain. We demonstrated that the improved protocol is suitable for study of plant material.

Identification of DNA Methylation Changes in European Beech Seeds during Desiccation and Storage.

Ageing and deterioration of seeds is a major problem for the maintenance of seed quality and viability during long-term storage. Prediction of early stages of seed deterioration in order to point out the plantlets' regeneration time is a major challenge of successful storage. In preserved seeds, damages accumulate within cells at the rate mainly related to their moisture content and temperature of storage. Current research reveals global alterations in DNA methylation in lipid-rich intermediate seeds during desiccation and storage at various regimes covering nonoptimal and optimal conditions. We show for the first time that monitoring of 5-methylcytosine (m5C) level in seeds can be used as a truly universal viability marker regardless of postharvest category of seeds and their composition. For seeds stored up to three years, in varied conditions, moisture content, temperature, and time of storage had significant influence on seedling emergence and DNA methylation (p < 0.05). Similarities among lipid-rich intermediate and orthodox seeds regarding different reactions of embryonic axes and cotyledons to desiccation are newly revealed. Along with previous studies on seeds dramatically different in desiccation tolerance (recalcitrant vs. orthodox), results regarding lipid-rich seeds positioned in-between (intermediate) prove that maintaining global DNA methylation status is crucial for maintaining seed viability.

Living underground: Edible Dormouse (Glis glis) activity in the underground shelters during the active period

The Edible Dormouse (Glis glis) uses different types of shelters at particular times of the year. During hibernation, they are found in underground cavities or sometimes in caves, while during active periods they mostly use above-ground shelters: tree hollows or nest boxes. Selection of such thermally varied shelters is the result of different physiological requirements during both active and non-active periods, choosing a lower and constant temperature during hibernation and higher temperature during mating, gestation, and lactation. However, this species is also observed underground outside of hibernation. It is possible that the Edible Dormouse uses caves as alternative shelters during adverse weather conditions or food shortages. We examined the annual and circadian activity of G. glis in two caves (Czestochowska Upland, southern Poland). Research was conducted for three years (2019 – 2021) using a non-invasive method: camera-traps. We evaluated climatic parameters outside and inside caves and the availability of the main diet (beech seeds, Fagus sylvatica). Our research indicates the year-round presence of G. glis in both caves. Dynamics of their activity vary between seasons (masting vs non-masting), but they are similar in different sites within a year. Dormouse activity in the cave was highest during a full masting season and intermediate and lowest during a mast failure year. Circadian activity varied between phenological periods: from 24-hour activity at the beginning of the season (mating period), to becoming exclusively nocturnal in the remaining period. These results may indicate that, apart from being used for hibernation, caves are also a regular daily shelter for active dormice.

Relationships between climate variables, seed production and reproduction of the Edible Dormouse (Glis glis) in mixed oak forests of the Iberian Peninsula

The Edible Dormouse (Glis glis) is a small arboreal mammal that lives in deciduous forests in much of Europe, the Iberian Peninsula being one of the southern limits of its distribution. Some studies have shown that this species uses the strategy of anticipatory reproduction, which means that it adapts its reproductive effort to seed production, such as beech mast and acorns, which varies greatly from year to year. The Edible Dormouse anticipates future seed availability of the coming autumn and modulates its reproductive effort, as beech mast and acorns are a crucial resource for the young to survive their first hibernation. This work aims to determine the correlations between annual variations in climate and seed production, and their effect on Edible Dormouse reproduction using 9 years of data (2012–2020) in two natural parks in Catalonia (Montseny and Montnegre-Corredor). These are located at the southernmost limit of the distribution of this species in the Iberian Peninsula. The results show that the productivity of Beech trees (Fagus sylvatica) is conditioned by local meteorological conditions and pollen availability, and that the acorn production by oak trees (Quercus sp.) is also affected by local meteorological conditions, but not by pollen availability. Additionally, breeding by the Edible Dormouse in Montseny has shown high synchrony with acorn production and that the presence of beech seeds increases the number of offspring per female. These results encourage us to conduct future studies to predict how Edible Dormouse populations will be impacted by climate change.

Effect of Peat-Perlite Substrate Compaction in Hiko V265 Trays on the Growth of Fagus sylvatica L. Seedlings

The growth of seedlings depends on many factors: the availability of light, water, and minerals, as well as the type and physical properties of the substrate, including its density. The effect of different levels of compaction of the peat-perlite substrate on the growth of European beech (Fagus sylvatica L.) seedlings in container nursery has not been investigated so far. In presented research, nine variants of peat-perlite substrate compaction (in three replications), with the actual bulk density ranging between 0.196 and 0.317 g·cm−3, were prepared in Hiko V265 nursery trays. European beech seeds were sown in the trays, and a seedling was grown in the production field. After the cultivation period, selected parameters were measured. The results reveal that substrate in a wide range of compaction (dry bulk density: 0.078–0.127 g·cm−3) had an impact on the height of seedlings, root dry matter, and the mean length of coarse roots and fine roots. The best shoot-to-root ratio and sturdiness quotient were observed in the seedlings growing on the substrate with the lowest compaction. Based on the results, compaction at the level of 0.196 g·cm−3 is recommended for the cultivation of European beech in Hiko V265 nursery trays.

Nutritional and environmental factors influence small mammal seed selection in a northern temperate forest

AbstractRodents can influence the succession and assembly of plant communities by preying on and dispersing seeds. Using a seed tray experiment with three common seeds, American beech (Fagus grandifolia), red maple (Acer rubrum), and eastern hemlock (Tsuga canadensis), we assessed factors that influence seed selection and foraging time of three rodents: deer mice (Peromyscus maniculatus), white‐footed mice (Peromyscus leucopus), and southern red‐backed voles (Myodes gapperi). All three rodents preferred beech seeds, likely due to its large size and high lipid content. However, when beech availability was low, secondary seed selection differed by rodent species with P. maniculatus equally selecting hemlock and red maple, P. leucopus preferring hemlock, and M. gapperi preferring red maple. Red maple seeds contained high levels of phenolic compounds, which hinder digestion, and the elongated cecum of M. gapperi may allow for better processing of these compounds relative to Peromyscus. Beech seeds were nearly always removed from trays intact, suggesting rodents could be important dispersers compared to the small‐seeded species, which were generally processed on trays. The influence of environmental factors on seed selection was only notable when beech seed availability was low. Beech seed availability was also the primary factor influencing foraging time on trays, with individuals increasing foraging time as beech availability decreased. Consistent with predator avoidance behaviors, denser shrub cover increased foraging time for P. maniculatus, whereas moon luminosity decreased foraging for all three species. Our findings underscore that seed quality drives seed selection but that preferences are context dependent, varying with seed availability and digestive capacity.

NAD(P)H Drives the Ascorbate-Glutathione Cycle and Abundance of Catalase in Developing Beech Seeds Differently in Embryonic Axes and Cotyledons.

European beech is an important component of European lowland forests in terms of ecology, and produces irregular seeds categorized as intermediate due to their limited longevity. Removal of the excess of reactive oxygen species is crucial for redox homeostasis in growing plant tissues. Hydrogen peroxide (H2O2) is detoxified via the plant-specific ascorbate-glutathione cycle, and enzymatically, mainly by catalase (CAT). The reduced and oxidized (redox) forms of ascorbate (AsA, DHA) and glutathione (GSH, GSSG) decreased during maturation as the content of redox forms of nicotinamide adenine dinucleotide (NADH, NAD+) phosphate (NADPH, NADP+), cofactors of ascorbate–glutathione enzymes, declined and limited this cycle. The degree of oxidation of glutathione peaked at approximately 80%, at the exact time when the NADP content was the lowest and the NADPH/NADP+ ratio reached the highest values. The glutathione pool was reflected in changes in the NADP pool, both in embryonic axes (R2 = 0.61) and in cotyledons (R2 = 0.98). A large excess of NADPH was reported in embryonic axes, whereas cotyledons displayed more unified levels of NADP redox forms. As a result, anabolic redox charge and reducing power were higher in embryonic axes. CAT was recognized as two proteins, and the abundance of the 55 kDa protein was correlated with all redox forms of ascorbate, glutathione, NAD, and NADP, whereas the 37 kDa protein was oppositely regulated in embryonic axes and cotyledons. Here, we discuss the role of NAD(P) in the regulation of the ascorbate–glutathione cycle, catalase, and seed longevity concerning a putative role of NAD(P)H as a redox biomarker involved in predefining seed quality, because NAD(P)H-derived redox homeostasis was found to be better controlled in embryonic axes than cotyledons.

High plasticity in germination and establishment success in the dominant forest tree Fagus sylvatica across Europe

AbstractAimDistribution ranges of temperate tree species are shifting poleward and upslope into cooler environments due to global warming. Successful regeneration is crucial for population persistence and range expansion. Thus, we aimed to identify environmental variables that affect germination and seedling establishment of Europe's dominant forest tree, to compare the importance of plasticity and genetic variation for regeneration, and to evaluate the regeneration potential at and beyond the southern and northern distribution margins.LocationEurope.Time period2016–2018.Major taxa studiedEuropean beech (Fagus sylvatica (L.)).MethodsWe investigated how germination, establishment and juvenile survival change across a reciprocal transplantation experiment using over 9,000 seeds of beech from 7 populations from its southern to its northern distribution range margins.ResultsGermination and establishment at the seedling stage were highly plastic in response to environmental conditions. Germination success increased with warmer and declined with colder air temperature, whereas establishment and survival were hampered under warmer and drier conditions. Germination differed among populations and was positively influenced by seed weight. However, there was no evidence of local adaptation in any trait.Main conclusionsThe high plasticity in the early life‐history traits found irrespective of seed origin may allow for short‐term acclimatization. However, our results also indicate that this plasticity might not be sufficient to ensure the regeneration of beech in the future due to the low survival found under dry and hot conditions. The future climatic conditions in parts of the distribution centre and at the rear edge might thus become limiting for natural regeneration, as the likelihood of extreme heat and drought events will increase. By contrast, at the cold distribution margin, the high plasticity in the early life‐history traits may allow for increasing germination success with increasing temperatures and may thus facilitate natural regeneration in the future.

Relationship between mitochondrial changes and seed aging as a limitation of viability for the storage of beech seed (Fagus sylvatica L.)

Aging is one of the most fundamental biological processes occurring in all forms of eukaryotic life. Beech trees (Fagus sylvatica L.) produce seeds in intervals of 5–10 years. Its yearly seed yield is usually very low, so there is a need for long-term seed storage to enable propagation of this species upon demand. Seeds for sowing must be of high quality but they are not easy to store without viability loss. Understanding the mechanism responsible for seed aging is therefore very important. We observed the generation of reactive oxygen species (ROS) in mitochondria of embryonic axes and cotyledons of beech seeds during natural aging. The presence of ROS led to changes in compromised mitochondrial membrane integrity and in mitochondrial metabolism and morphology. In this study, we pointed to the involvement of mitochondria in the natural aging process of beech seeds, but the molecular mechanisms underlying this involvement are still unknown.

Localization and Dynamics of the Methionine Sulfoxide Reductases MsrB1 and MsrB2 in Beech Seeds.

Beech seeds are produced irregularly, and there is a need for long-term storage of these seeds for forest management practices. Accumulated reactive oxygen species broadly oxidize molecules, including amino acids, such as methionine, thereby contributing to decreased seed viability. Methionine oxidation can be reversed by the activity of methionine sulfoxide reductases (Msrs), which are enzymes involved in the regulation of many developmental processes and stress responses. Two types of Msrs, MsrB1 and MsrB2, were investigated in beech seeds to determine their abundance and localization. MsrB1 and MsrB2 were detected in the cortical cells and the outer area of the vascular cylinder of the embryonic axes as well as in the epidermis and parenchyma cells of cotyledons. The abundances of MsrB1 and MsrB2 decreased during long-term storage. Ultrastructural analyses have demonstrated the accumulation of these proteins in protein storage vacuoles and in the cytoplasm, especially in close proximity to the cell membrane. In silico predictions of possible Msr interactions supported our findings. In this study, we investigate the contribution of MsrB1 and MsrB2 locations in the regulation of seed viability and suggest that MsrB2 is linked with the longevity of beech seeds via association with proper utilization of storage material.

Epigenetic anticipation for food and reproduction.

Physiological changes in anticipation of cyclic environmental events are common for the persistence of populations in fluctuating environments (e.g. seasons). However, dealing with sporadic resources such as the intermittent production of seed masting trees may be challenging unless reliable cues also make them predictable. To be adaptive, the anticipation of such episodic events would have to trigger the corresponding physiological response. Epigenetic modifications could result in such physiological anticipatory responses to future changes. The eastern chipmunk (Tamias striatus) is known to adjust its reproductive activity to match juvenile weaning with peak seed availability of masting trees, which are essential for their survival. We therefore expected that epigenetic changes would be linked to spring reproductive initiation in anticipation for beech seed availability in fall. We correlated the variation of DNA methylation profiles of 114 adult chipmunks captured in May with beech seeds abundance in September, over 4 years, for three distinct populations, as well as individuals sampled twice during reproductive and non-reproductive years. The significant correlation between spring epigenetic variation and the amount of food in the fall confirmed the phenotypic flexibility of individuals according to environmental fluctuations. Altogether, these results underlined the key role of epigenetic processes in anticipatory responses enabling organisms to persist in fluctuating environments.

Regulation of thiol metabolism as a factor that influences the development and storage capacity of beech seeds

Seeds are the basis of propagation for the common beech (Fagus sylvatica L.), but the seed set of the beech is unsteady, with 5–10 years between abundant crops. Beech seeds are very difficult to store and lose their viability quickly even in optimum storage conditions. To date, it has not been possible to determine factors indicative of the aging process and the loss of viability of beech seeds during storage. To address this important economic challenge and interesting scientific problem, we analyzed the adjustment of the redox state during the development and storage of seeds. Many metabolic processes are based on reduction and oxidation reactions. Thiol proteins control and react to the redox state in the cells. The level of thiol proteins increased during seed maturation and decreased during storage. Gel-based redox proteomics identified 17 proteins in beech seeds during development. The proteins could be assigned to processes like metabolism and antioxidant functions. During storage, the number of proteins decreased to only six, i.e., oxidoreductases, peptidases, hydrolases and isomerases. The occurrence of peroxiredoxins (PRX) as thiol peroxidases and redox regulators indicates an important role of cytosolic 1CysPRX and PRXIIC, mitochondrial PRXIIF, and plastidic PRXIIE, 2CysPRX, and PRXQ in beech seeds during development and storage. Particularly, 2CysPRX was present in beech seeds during development and storage and may perform an important function in regulation of the redox state during both seed development and storage. The role of thiol proteins in the regulation of the redox state during the development and storage of beech seeds is discussed.

Effect of food availability on the reproduction in edible dormice (Glis glis L., 1766) on the eastern periphery of the range

The edible dormouse (Glis glis) is an example of a mammal with anticipatory reproduction, the mechanism by which animals increase reproductive output before pulsing resources become available, to provide offspring with the maximum abundance of food. In Central Europe, the main pulsing food resources for the edible dormouse are seeds of the European beech and oak. In this location, spermatogenesis occurs only in mast years and most probably depends on the number of beech flowers and buds. The purpose of the study was to determine the mechanism of reproductive regulation of the dormouse in the Zhiguli Mountains (Russia), which are on the eastern periphery of the dormouse range and outside that of beech trees. The main food of dormice here are acorns, hazelnuts, birch seeds and mushrooms, rather than beech seeds. In years, when there is a shortage of acorns, these are replaced by birch seeds and mass resorption of edible dormouse embryos also occurs. Analyses of diet, environmental condition and reproductive success demonstrated that in unfavourable years, the overwhelming majority of females resorb embryos. In consequence, juveniles are born only once in every 2 to 3 years, despite annual mating and pregnancy of most females. Resorption of embryos is observed in most species of mammals under the influence of strong negative factors and usually affects only some of the embryos, whereas in this dormouse population the process exhibits a regular, synchronous pattern and becomes the primary factor of natality regulation. These findings suggest that mass resorption of embryos might be a common regulatory mechanism of reproduction under pulsing food resources.

Effects of charcoal hearth soil on forest regeneration: Evidence from a two-year experiment on tree seedlings

Production of wood charcoal is a traditional form of forest use that lasted for millennia in most temperate regions, vanishing only some decades ago in the Mediterranean countries. Here, the abandoned charcoal hearths form a network of microhabitats with peculiar vegetation and soil conditions. Previous observational studies showed that establishment of woody species at these sites is severely hindered for unknown reasons. To test the effects of charcoal hearth soil on tree growth we used a common garden experiment with three major Euro-Mediterranean forest trees with different traits and ecology, one evergreen (Quercus ilex, holm oak) and two deciduous (Fagus sylvatica, beech, and Quercus cerris, Turkey oak). These were sown on control and charcoal-enriched soil collected in forest hearths abandoned since decades. Seed germination, seedling growth, photosynthetic efficiency and mortality were measured over a period of two years. Some responses were species-specific, while others were possibly associated to key traits such as evergreen vs. deciduous habit. Although charcoal soil effects were mainly positive on growth rate (height increase), they were mostly negative on germination of beech seeds, survival of holm oak seedlings, and photosynthetic efficiency. Although total biomass was not significantly affected, the root:shoot ratio was increased as a possible effect of physiological drought on hearth soil. These results support field-based evidence that the long persistence of charcoal remains in the soil may be not a favourable condition for forest regeneration. Management implications concern the use of biochar practices to promote forest restoration, which should be further tested on a wide range of species in different life-stages before applications in the field, also considering its long-term consequences.

Physicochemical characteristics of the cold-pressed oil obtained from seeds of Fagus sylvatica L.

A physicochemical characteristic of the cold-pressed oil obtained from seeds of common beech (Fagus sylvatica L.) has been presented. This plant may be considered as unconventional oilseeds crops because of relatively high content of fat (27.25%). The analyzed beech seeds oil has been classified as oleic-linoleic acids oil with more than 76% percentage share of those species. Beech seeds oil contains 4.2% of gamma-linolenic acid (GLA). Unique characteristic is the high content of γ-tocopherol (75.4mg/100g) and δ-tocopherol (34.05mg/100g). γ-Tocopherol is effective scavengers of reactive nitrogen species and prevents DNA bases nitration, what makes beech seeds oil interesting raw material in the production of cosmetics. Additionally the content of carotenoids, very effective photooxidation inhibitors, is at high level in comparison with other cold-pressed oils. It was demonstrated that PCA analysis may help to determine the authenticity of oil obtained from beech seeds.