Birch Research Articles

Sámi Literature in Norwegian Language Arts Textbooks

Sámi Literature in Norwegian Language Arts Textbooks

Extractable Compounds in a Birch Tree—Variations in Composition and Yield Potentials

Extractives from silver birch (Betula pendula) can play an important role in the future bioeconomy by delivering the feedstock, for instance, for antioxidative applications. It is, therefore, inevitable to gain knowledge of the distribution of extractive content and composition in the different tissues of the tree for estimating the potential volumes of valuable extractable compounds. This study examines the extractable compound distribution of different tree tissues such as outer and inner bark and wood, respectively, considering the original height of the stem and comparing the yields after Soxhlet and accelerated solvent extraction (ASE). Eleven parts of the model tree (seven stem discs and four branches) were separated into primary tissues and extracted with a ternary solvent system. The investigated extraction methods resulted in a comparable performance regarding yields and the composition of the extractives. The extractives were divided into single compounds such as betulin, lupeol, γ-sitosterol, and lupeone and substance groups such as carbohydrates, terpenes, aromatics, and other groups. The distribution of single substances and substance groups depends on the location and function of the examined tissues. Furthermore, the evidence for the correlation of a single substance’s location and original tree height is stronger for lupeol than for betulin. Primary betulin sources of the calculated betulin output are the outer bark of the stem and the branches. By using small branches, further potential for the extraction of betulin can be utilized. A model calculation of the betulin content in the current birch tree revealed a significant potential of 23 kg of betulin available as a valuable chemical resource after by-product utilization.

Gold of the upper horizons of the Berezovsky ore field

The calculation of gold reserves (14–25 tons) in the upper part of the ore field (to a depth of 20 m) was made in the 30s of the twentieth century. Their diligent development was carried out until the 60s of the twentieth century. When conducting engineering and geophysical survey work for industrial and civilian construction in the Rudny Field (in fact, in the territory of the city of Berezovsky) it is possible to clarify the position of well-known and untouched famous golden berets and quartz veins, as well as detect golden-bearing facilities to the minological service of the mines. Modern legislation prohibits the prey of minerals in the territory of cities. The extraction of gold of the upper part of the ore field can be organized subject to sampling from the volumes of construction boilers of gold-containing birch trees, quartz cores, marshallite kaolinite loams of cortical corticals and granite porpherfires. Such a small enterprise should be organized by the owners of the Berezovsky land: a mine or a municipality

Inconsistent Skin Prick Tests for Allergy to Birch Homologous Trees May Result from Cross-Reacting Allergens or Technical Errors

Introduction: Skin prick tests (SPTs) are the gold standard for diagnosis of allergic rhinitis (AR). A decrease in the number of allergens included in standard SPT panels has recently been debated – particularly regarding the cross-reacting homologous pollen from birch, alder, and hazel trees – but has not yet been implemented in clinical guidelines. Methods: A subgroup of patients with AR (n = 69) who showed inconsistent SPT results among birch, alder, and hazel was investigated in detail. Beyond SPT, patient workup included assessment of clinical relevance and various serological parameters (total IgE, and specific IgE to birch, alder, and hazel and to Bet v 1, Bet v 2, and Bet v 4). Results: More than half the study group had negative SPT results for birch but positive results for alder and/or hazel, and 87% of the study group was polysensitized, showing at least one more positive SPT result for other plants. Whereas 30.4% of patients showed serological sensitization to birch pollen extract, only 18.8% displayed positive specific IgE to Bet v 1. Clinical assessment revealed that most patients with AR were polysensitized and had perennial symptoms or symptoms also occurring during times other than tree flowering times. If the SPT panel is limited to testing birch only, 52.2% of patients in this subgroup would have been overlooked. Conclusion: Inconsistent SPT results in the birch homologous group may result from cross-reacting allergens or technical errors. If patients report convincing clinical symptoms despite negative results from a reduced SPT panel or inconsistent results for homologous allergens, SPT should be repeated, and molecular markers should be added to achieve a correct diagnosis.

Betulin – application in dermatology and cosmetology

Betulin (BN) is a natural lupane-type triterpene extracted from many plant species. Its main source is the outer bark layer of birch trees of the Betulaceae family. BN exhibits a number of biological properties, including anti-inflammatory, antioxidant, anticancer and bacteriostatic effects. The article aimed to present the biological properties of BN and its plausible use in cosmetology and dermatology. BN and its derivatives have significant therapeutic potential, which opens wide possibilities for their use in the treatment of various skin diseases.

A Birch Tree as a Witness in a Murder and Cannibalism Case

Fifteen years after a murder and an act of cannibalism, the police in Szczecin have conducted an investigation, in which neither the time of the murder, nor the victim identity were known, no body was found, and the defendants have not confessed. Due to the circumstantial nature of the investigation and the trial, a number of analyses were performed, and expert opinions were requested as part of the inquiry. A dendrochronological study of a birch tree growing on the shore of Lake Żabie was one of the analyses lending credibility to the testimony of one of the defendants and pointing to the murder site. The aim of this study was to determine the age and size of the birch tree in the 1998–2002 period, and to determine whether the tree was a distinctive feature of the landscape through the period in question. Field work was performed in April 2019, under the supervision of the police. The birch tree was measured and samples collected using a Pressler borer. The measurements and observations revealed that the birch tree, due to its size, and the absence of other trees of this species in this segment of the lake shore, may have been a characteristic landscape element in the late 1990s and early 2000s. According to the police officer and the prosecutor in charge of the case, the results of the dendrological analysis have lent a strong credibility to the testimony of one of the defendants and other findings of the investigation.

Involvement of Mitochondrial Damage and Oxidative Stress in Apoptosis Induced by Betulin Plus Arsenic Trioxide in Neuroblastoma Cells.

Arsenic trioxide (As2O3), a potent toxin in traditional Chinese medicine, has been utilized as an anticancer agent in Chinese culture for over a millennium. Betulin, commonly extracted from the bark of birch trees, has been identified for its pharmacological properties, including antibacterial, anti-inflammatory, antitumor, and antiviral activities. The aim of this study was to determine the efficacy and underlying anticancer signaling cascade induced by As2O3 and betulin in neuroblastoma cells. SK-N-SH cells were treated with As2O3 with or without betulin. Cell viability and apoptotic signaling were assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, measurement of mitochondrial membrane potential (MMP) loss and reactive oxygen species (ROS), and quantitative western blotting analysis. Student's t-test in addition to one- or two-way analysis of variance was used to examine significant differences between comparison groups. The combined treatment of As2O3 plus betulin was more effective than single treatments in suppressing cell viability and induction of apoptosis, which correlated well with elevated ROS levels. The apoptotic signaling cascade of As2O3 plus betulin was revealed as ROS elevation and relative loss of MMP, leading to the cleavage of caspase-3 and -9. As2O3 plus betulin treatment also reduced the expression of BCL2 apoptosis regulator, BH3-interacting domain death agonist, and BCL2-like-1. The novel combination of As2O3 plus betulin has the potential to serve as a practical anti-neuroblastoma drug.

Consistency of phenolic profiles with taxonomic distribution and adaptation of birch species (Betula L.) to environmental conditions

The phenolic compounds in the leaves of 12 species of birch trees of the subgenera Neurobetula, Betulenta, and Betula were biochemically profiled using HPTLC. The duration of the vegetation period was found to be significantly related to the content of total phenols ( r = 0.74) and flavonoids in leaves ( r = 0.65). The correlations for Neurobetula plants were 0.86 and 0.91, respectively. The relationship between the duration of the growing season and the concentration of phenolic compounds in Betula plants was inverse ( r = −0.84). A cluster analysis of phytochemical profiles revealed that the studied birch species form groups that coincide with the subgenera proposed by De Jong due to an affinity with the qualitative composition of phenolic compounds. A multiple correlation analysis confirmed the relationship between the qualitative composition of phenolic compounds and the morphological characteristics of the leaves. The results of phytochemical profiling revealed that the qualitative composition of polyphenols in the leaves of 12 birch species is quite specific, allowing the use of individual compounds as additional differential biochemical characters in identifying species and hybrids and studying their potential role in plant adaptation to habitat conditions.

The size distribution metrics and kinetic energy of raindrops above and below an isolated tree canopy in urban environment

Raindrop impact on bare soils is the initial phase of rainfall-induced soil erosion which is altered under any type of vegetation due to the interactions of rainfall with the canopies. This study examines the drop size distribution (DSD) and kinetic energy (KE) of raindrops above and below the birch tree (Betula pendula Roth.) canopy in a research plot in the city of Ljubljana, Slovenia using a one-year observation of 63 rainfall events and the effect of meteorological variables under moderate continental climate. Simultaneous measurement of the microstructures of open rainfall and throughfall was carried out using an optical disdrometer. The result of our analysis revealed that throughfall DSD showed two distinct major peaks (bimodal) occurring primarily on smaller drop sizes while open rainfall has only one. The cumulative drop number, median drop-volume diameter (D50), and drop fall velocity of throughfall were 16.4%, 26.6%, and 5.0% lower than those of open rainfall, respectively. Also, the relative volume percentage of raindrops > 1.5 mm is 1.5 times higher than those observed in throughfall drops which indicates that the presence of the canopy caused the fractionation of larger drops into smaller droplets. These reductions significantly differ depending on the phenoseasons of the canopy with the leafed state being higher than the leafless state. Similarly, the Kruskal-Wallis H test result revealed that birch tree elicits a statistically significant change in the kinetic energy of open rainfall, thus weakening the mean rainfall KE by 33.7%. On the other hand, KE is positively affected by the phenological condition of the canopy with higher attenuation being observed during its leafed state. Also, the correlation analysis demonstrated that vapor pressure deficit, air temperature, and relative humidity have stronger associations with throughfall kinetic energy among meteorological variables considered. These findings underscore the necessity of an optimized selection of tree species for afforestation programs.

Исследование внутреннего трения натуральной и модифицированной прессованием древесины березы повислой (Betula pendula Roth)

A method is proposed for approximating of the internal friction of wood based on the Boltzmann superposition principle, which describes the complex viscoelastic behavior of the system by a linear combination of components. Prepared samples of natural and modified wood, sawn from the stem part of drooping birch (Betula pendula ROTH) trees growing in the Khlevensky Forestry (52.184130, 39.110463, ASL 157m), were exposed to radial and tangential directions with ultrasound (frequency 24.5 kHz, exposure 0 -20 minutes, step 5 minutes) and pulsed magnetic field (strength - 0.3 T, exposure 0-2 minutes, step 0.5 minutes). Next, the internal friction of the samples was studied on an experimental setup using the logarithmic damping decrement based on free-bending vibrations. The absolute values of the dimensionless viscosity coefficient κ included in the model as the main structural parameter for samples of natural and modified wood were obtained at a significance level of p=0.95: for moisture content from 4.3 to 15; for ultrasound 4.6 to 20; for a pulsed magnetic field from 3.6 to 7.7. The absolute values of the dimensionless scaling factors μ for natural and modified wood samples range from 1.92 to 3.91. The highest approximation value was achieved when testing natural wood samples of silver birch (Betula pendula ROTH): R2=0.98 for the radial direction, the influence of the humidity factor, and R2=0.85 for the tangential direction, the influence of the ultrasonic factor, as well as for a sample of modified wood brand "Destam" in the radial direction R2=0.96, the influence of the factor of the pulsed magnetic field.

Temporal response of urban soil water content in relation to the rainfall and throughfall dynamics in the open and below the trees

Abstract Rainfall interception process is an important part of the biohydrological cycle, in which vegetation plays an important role by regulating the amount and dynamics of rainfall reaching the ground. In this paper, an event-based analysis is performed to discuss the influence of vegetation on dynamic of temporal response of soil volumetric water content (VWC) in the upper soil layer during rainfall events. More specifically, six events that occurred between 19 November 2021 and 30 June 2022, characterized by different hydro-meteorological and vegetation conditions, are analyzed based on continuous measurements of VWC in the open and below groups of two deciduous (Betula pendula Roth.) and two coniferous trees (Pinus nigra Arnold), as well as rainfall in the open and throughfall on an urban experimental plot in Ljubljana, Slovenia. VWC values at the upper depth (16 cm) were the highest under the birch tree, followed by the location in the open and under the pine tree. However, in the lowest depth (74 cm) VWC values were the lowest under the birch tree. VWC responses to rainfall and throughfall showed seasonal patterns related to the pre-event wetness conditions, with a faster occurrence of maximum VWC values in the leafless period. Additionally, rainfall amount and its dynamics during the event significantly affect the response, as VWC in general reaches its peak after the occurrence of more intense rainfall. Such an event-based analysis, offering an insight into the dynamics of the event development, is crucial and very beneficial for understanding of the biohydrological processes.

Crown snow load outage risk model for overhead lines

In the northern hemisphere, snow accumulating on trees and overhead lines causes widespread outages in the electricity distribution networks. Accurate outage risk models are an essential element in improving the resilience of modern distribution networks. In this paper, a Random Forest-based model for estimating the susceptibility of overhead lines to outages caused by tree crown snow loads is proposed. The model uses a novel combination of an aerial inspection outage risk dataset, an advanced forest crown snow load risk map, a canopy height model, and forest characteristics data. All predictor variables used in the study are available as open data. As a result, outage risk probability in 50 m overhead line sections for a distribution network was generated. Cross-validation of the model showed a good predictive performance with a receiver operating characteristic area under curve (ROC AUC) of 0.75 and an accuracy of 0.74. The impact of the predictor variables was investigated by using Shapley additive explanations (SHAP) values. The most impactful variables were the forest crown snow load risk, the number of nearby canopy height model pixels, and the birch tree volume. The outage risk probability model developed in this paper could be similarly applied to assess the crown snow load risk in other distribution networks or even in other types of networks, such as roads and railways.

Palynological characteristics of plant communities in the eastern Arctic during the Early to Middle Calabrian Age

Palynological analysis of Early Pleistocene sediments from Lake El'gygytgyn indicate that climate was warmer than present between c. 1.2860 and 1.6975 Ma (late Gelisian–early Calabrian ages), although variations in the paleovegetation indicate fluctuations between relatively cool and warm conditions. During the coolest intervals, the vegetation on the Anadyr Plateau was a mix of Betula-Salix shrub tundra and Larix forest-tundra. Larix forests, which probably included trees species of Betula and Alnus, characterized the regional vegetation during the warmest times. Slightly cooler interglaciations are indicated by the presence of Larix-forest tundra. Pinus pumila pollen is not consistently present in all interglaciations, indicating that variations in the extent and/or duration of snow cover occurred during these warm intervals. The absence of pollen from this evergreen shrub contrasts with Holocene and Late Pleistocene assemblages, where the taxon is a hallmark of warm conditions. During the Early Pleistocene, Betula pollen indicates the plant's presence during warm and cool intervals, in contrast to Late and Middle Pleistocene spectra where shrub Betula is absent or rare. The pollen data from MIS 55 suggest that it was the coolest of the Pleistocene “super” interglaciations and that the MIS 43 climate was as warm as that of MIS 55. The El'gygytgyn palynological record is a powerful reminder that the distribution of arctic communities can be vastly reduced or eradicated during warm Earth scenarios.

Tree stems are a net source of CH4 and N2O in a hemiboreal drained peatland forest during the winter period

Nutrient-rich northern peatlands are often drained to enhance forest productivity, turning peatland soils into sinks of methane (CH4) and sources of nitrous oxide (N2O). However, further attention is needed on CH4 and N2O dynamics during the winter period to fully understand the spatio-temporal variability of fluxes. Besides soil, tree stems can also emit CH4 and N2O. However, stem contribution is not considered in most biogeochemical models. We determined the temporal dynamics of winter-time CH4 and N2O fluxes in a drained peatland forest by simultaneously measuring stem and soil fluxes and exploring the relationships between gas fluxes and soil environmental parameters. During sampling (October 2020–May 2021), gas samples from Downy Birch (Betula pubescens) and Norway Spruce (Picea abies) trees were collected from different tree heights using manual static chambers and analysed using gas chromatography. Soil CH4 and N2O concentrations were measured using an automated dynamic soil chamber system. Tree stems were a net source of CH4 and N2O during the winter period. The origin of stem CH4 emissions was unclear, as stem and soil CH4 fluxes had opposite flux directions, and the irregular vertical stem flux profile did not indicate a connection between stem and soil fluxes. Stem N2O emissions may have originated from the soil, as emissions decreased with increasing stem height and were driven by soil N2O emissions and environmental parameters. Soil was a net sink for CH4, largely determined by changes in soil temperature. Soil N2O dynamics were characterised by hot moments—short periods of high emissions related to changes in soil water content. Tree stem emissions offset the soil CH4 sink by 14% and added 2% to forest floor N2O emissions. Therefore, CH4 and N2O budgets that do not incorporate stem emissions can overestimate the sink strength or underestimate the total emissions of the ecosystem.

QUALITY OF BEECH, BIRCH AND OAK WOOD FROM STANDS GROWING ON POST-AGRICULTURAL LANDS

This study assessed the quality of birch, beech, and oak for timber production on former agricultural land. All sample plots for the selected species had the same forest habitat type. All measured trees had already reached the age of felling. Thus, beech was over 120 years old, birch was over 70 years old, and oak was over 140 years old. On each plot, the same morphological features were measured for all trees: diameter at breast height, tree height, height of the first dead branch, height of the first live branch, and crown base. Based on collected data the length and percentage of the trunk suitable for industrial purposes were calculated. In general birch and beech trees from former agricultural land were higher, but had thinner trunks, when in oak reverse observation were noticed. Tree trunks from former agricultural lands have app. 7% shorter knots-free trunk section. The bigger different between forest and former agricultural land was noticed in case of the oak – 14%, then beech – 5% and birch – 1%. Considering the morphological characteristics of the trees and quality indicators, we showed that all species could be used for the afforestation of former agricultural lands to produce high-quality wood for future industrial purposes. However, it should be noticed, that in general calculated standing volume was lower on former agricultural land.

Variability of activity concentrations and radial distributions of 137Cs and 90Sr in trunk wood of Scots pine and Silver birch

This study analyzes the variability of 137Cs and 90Sr concentrations in wood and their radial distributions in the trunks of Scots pine and Silver birch trees in the small uniformly contaminated forest stands in the Chornobyl Exclusion Zone. Concentrations of both radionuclides follow a lognormal distribution with a large scatter of values measured in the trees within the stands (GSD ranges from 1.6 to 2.0). No correlation was found between the concentrations of the two radionuclides measured in individual trees, or between their concentrations and tree diameter. The average 137Cs and 90Sr Tag were 8.4 × 10−4 m2 kg−1 and 8.8 × 10−3 m2 kg−1 for pine, respectively, and 9.3 × 10−4 m2 kg−1 and 1.1 × 10−2 m2 kg−1 for birch, indicating a much higher availability of 90Sr for uptake by the studied species. For 137Cs, the Tag values are within the range recommended by the IAEA Handbook (IAEA, 2010), while the values for 90Sr exceed the recommended range for birch and are close to its upper value for pine.The highest concentrations of 137Cs in pine at the height of 1.3 m were measured in the youngest sapwood rings; they were lower in the rest of the sapwood and decreased further in the heartwood, but remained relatively high even in annual rings that were the heartwood at the time of deposition, suggesting sapwood-to-heartwood translocation of the radionuclide by diffusion and/or ray transport. In contrast, 90Sr concentrations increased through the sapwood from the trunk periphery in pine trees up to 80 years old and remained stable through the sapwood in older trees (except for higher concentrations in the young annual rings), but dropped to zero in physiologically inactive heartwood tissues. In most birch trees, regardless of age, 137Cs concentrations demonstrated an increasing trend from the trunk periphery towards the pith, while concentrations of 90Sr were relatively stable in the whole trunk except in the oldest annual rings, where they increased sharply, likely indicating active transport of the radionuclide to senescing tissues.

Preparation of highly porous nitrogen-doped biochar derived from birch tree wastes with superior dye removal performance

Heteroatom doping is a highly effective strategy that can be used to modify carbonaceous adsorbents to improve their chemical reactivity and increase their adsorptive properties. Herein, a simple method is reported for the preparation of nitrogen-doped biochar using a natural and abundant biowaste from birch trees and melamine as a nitrogen dopant for the adsorption of Acid red 18 (AR-18) dye from water. The doped biochars were also characterized for their performance during the treatment of synthetic effluents. The physicochemical characterization results showed that the N-doping process provoked remarkable chances on the biochar morphology, pore structure, and surface functionalities. N-doped biochar showed abundant nitrogen functional groups with 5.4 % of N in its structure while non-doped carbon showed traces with 0.47 %. Moreover, the specific surface area of doped biochar was dominated by mesopores (86.4 %) while non-doped was dominated by micropores (67.8 %). Raman analysis showed that the incorporation of N created more defects in the biochar structure. The adsorption experiments showed that the N-doping boosted the biochar adsorptive performance. The maximum adsorption capacity of the doped biochar was 545.2 mg g−1, while the non-doped exhibited 444.5 mg g−1, i.e., an increase of 22.6 %. The kinetic and equilibrium studies showed that Avrami fractional order and Liu models were the most suitable for describing the experimental AR-18 dye adsorption data. The equilibrium parameters were found to obey a nonlinear relationship with the temperature. Since the biochars are highly porous, pore filling was the main adsorption mechanism, however; AR-18 dye removal suggests that interactions such as electrostatic, hydrogen bonds, Lewis acid-base, and π-π between the adsorbent and the dye are involved. The thermodynamic studies showed that the removal of the AR-18 dye from the solution is dependent on temperature, exothermic, and spontaneous. The N-doped biochar showed excellent removal performances of contaminants from synthetic effluents confirming their high efficiency for color removal. This research shows that N-doping is an efficient strategy to design effective, low-cost, and sustainable adsorbents to remediate dye contamination in wastewater.

Динамика структуры популяции ели под пологом березняков южной тайги и смешанных лесов в европейской части России

A comparative study of a restoration process is conducted in combinational forests of birch and spruce, as a population under the canopy, in the conditions of coniferousdeciduous or subboreal (Moscow region, Mozhayskiy district), and southern taiga or boreal forests (Yaroslavl region, Rybinskiy district) of European Russia. The relevance of investigations in this field is determined by the controversies over the outcomes from the natural course of successional processes in small-leaved forests with spruce growth under the canopy. The permanent trial plots, which were used for examinations, are characterized by the high-density birch forests of the oxalis-blueberry group with a first-class growth quality at the maturity stage, between 60 and 80 years old. The dynamics of age and vertical layers are investigated for the spruce under the canopy and the parcel structure of stand with ages within the 20-year period. It is determined that the main part of the spruce population under the canopy is represented by the generation, which was established in the birch forests until they reach the age of 30. The age composition of the spruce population, the arrangement of renewal periods, and the process of tree falling at the beginning and the end of the birch forests maturity stage are practically similar. In the zone of subboreal forests the vertical structure of the second layer of the spruce population develops earlier, compared to the boreal forests. In the boreal area, the formation of the under canopy second layer of spruce and its development to the first one begins at the aging stage, which is reached by birch trees around 90 years old. It was concluded that there are no fundamental differences in parcel structure of the stand or its fragmentation. In the mixed birch forests under the age of 60–80 years old the following properties are observed: an increase in the monoparcellarity of phytocenoses, in the areas with a closed second layer of spruce rises the occurrence of parcels, the amount of parcel plots declines, while their areas expand. If the birch forests are older than 90 years, monoparcellarity of the phytocenosis structure destroys, the number of parcels increases due to the appearance of gaps in the canopy, spruce renews in the areas the birche group-fall or after the snowfall and gusts of strong wind. For citation: Deryugin A.A., Rybakova N.A., Glazunov Y.B. Dynamics of the Spruce Population Structure Under the Canopy of Birch in Coniferous-Deciduous and Southern Taiga Forests of European Russia. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 2, pp. 15–25. (In Russ.). https://doi.org/10.37482/0536-1036-2023-2-15-25

Tree Biomass and Leaf Area Allometric Relations for Betula pendula Roth Based on Samplings in the Western Carpathians.

Biomass allometric relations are necessary for precise estimations of biomass forest stocks, as well as for the quantification of carbon sequestered by forest cover. Therefore, we attempted to create allometric models of total biomass in young silver birch (Betula pendula Roth) trees and their main components, i.e., leaves, branches, stem under bark, bark, and roots. The models were based on data from 180 sample trees with ages up to 15 years originating from natural regeneration at eight sites in the Western Carpathians (Slovakia). Sample trees represented individuals with stem base diameters (diameter D0) from about 4.0 to 113.0 mm and tree heights between 0.4 to 10.7 m. Each tree component was dried to constant mass and weighed. Moreover, subsamples of leaves (15 pieces of each tree) were scanned, dried, and weighed. Thus, we also obtained data for deriving a model expressing total leaf area at the tree level. The allometric models were in the form of regression relations using diameter D0 or tree height as predictors. The models, for instance, showed that while the total tree biomass of birches with a D0 of 50 mm (and a tree height of 4.06 m) was about 1653 g, the total tree biomass of those with a D0 of 100 mm (tree height 6.79 m) reached as much as 8501 g. Modeled total leaf areas for the trees with the above-mentioned dimensions were 2.37 m2 and 8.54 m2, respectively. The results prove that diameter D0 was a better predictor than tree height for both models of tree component biomass and total leaf area. Furthermore, we found that the contribution of individual tree components to total biomass changed with tree size. Specifically, while shares of leaves and roots decreased, those of all other components, especially stems with bark, increased. The derived allometric relations may be implemented for the calculation of biomass stock in birch-dominant or birch-admixed stands in the Western Carpathians or in other European regions, especially where no species- and region-specific models are available.

Betula pendula trees infected by birch idaeovirus and cherry leaf roll virus: Impacts of urbanisation and NO2 levels

Viruses are frequently a microbial biocontaminant of healthy plants. The occurrence of the infection can be also due to environmental stress, like urbanisation, air pollution and increased air temperature, especially under the ongoing climate change. The aim of the present study was to investigate the hypothesis that worsened air quality and fewer green areas may favour the higher frequency of common viral infections, particularly in a common tree in temperate and continental climates, Betula pendula ROTH.We examined 18 trees, during the years 2015–2017, the same always for each year, in the region of Augsburg, Germany. By specific PCR, the frequency of two viruses, Cherry leaf roll virus (CLRV, genus Nepovirus, family Secoviridae), which is frequent in birch trees, and a novel virus tentatively named birch idaeovirus (BIV), which has been only recently described, were determined in pollen samples. The occurrence of the viruses was examined against the variables of urban index, air pollution (O3 and NO2), air temperature, and tree morphometrics (trunk perimeter, tree height, crown height and diameter). Generalized Non-linear models (binomial logit with backward stepwise removal of independent variables) were employed.During the study period, both CLRV and BIV were distributed widely throughout the investigated birch individuals. CLRV seemed to be rather cosmopolitan and was present independent of any abiotic factor. BIV's occurrence was mostly determined by higher values of the urban index and of NO2. Urban birch trees, located next to high-traffic roads with higher NO2 levels, are more likely to be infected by BIV.Increased environmental stress may lead to more plant viral infections. Here we suggest that this is particularly true for urban spaces, near high-traffic roads, where plants may be more stressed, and we recommend taking mitigation measures for controlling negative human interventions.