Birch Species Research Articles

Betula mcallisteri sp. nov. (sect. Acuminatae, Betulaceae), a new diploid species overlooked in the wild and in cultivation, and its relation to the widespread B. luminifera.

Taxa are traditionally identified using morphological proxies for groups of evolutionarily isolated populations. These proxies are common characters deemed by taxonomists as significant. However, there is no general rule on which character or sets of characters are appropriate to circumscribe taxa, leading to discussions and uncertainty. Birch species are notoriously hard to identify due to strong morphological variability and factors such as hybridization and the existence of several ploidy levels. Here, we present evidence for an evolutionarily isolated line of birches from China that are not distinguishable by traditionally assumed taxon recognition proxies, such as fruit or leaf characters. We have discovered that some wild material in China and some cultivated in the Royal Botanic Gardens Edinburgh, formerly recognized as Betula luminifera, differ from other individuals by having a peeling bark and a lack of cambial fragrance. We use restriction site-associated DNA sequencing and flow cytometry to study the evolutionary status of the unidentified Betula samples to assess the extent of hybridization between the unidentified Betula samples and typical B. luminifera in natural populations. Molecular analyses show the unidentified Betula samples as a distinct lineage and reveal very little genetic admixture between the unidentified samples and B. luminifera. This may also be facilitated by the finding that B. luminifera is tetraploid, while the unidentified samples turned out to be diploid. We therefore conclude that the samples represent a yet unrecognized species, which is here described as Betula mcallisteri.

Differentially Expressed Conserved Plant Vegetative Phase-Change-Related microRNAs in Mature and Rejuvenated Silver Birch In Vitro Propagated Tissues.

In plants, phase change from the juvenile stage to maturity involves physiological and anatomical changes, which are initiated and controlled by evolutionary highly conserved microRNAs. This process is of particular significance for the in vitro propagation of woody plant species, as individuals or tissues that have undergone the transition to vegetative maturity are recalcitrant to propagation. Conserved miRNAs differentially expressed between juvenile (including rejuvenated) and mature silver birch tissues were identified using high-throughput sequencing of small RNA libraries. Expression of some miR156 isoforms was high in juvenile tissues and has been previously reported to regulate phase transitions in a range of species. Additional miRNAs, such as miR394 and miR396, that were previously reported to be highly expressed in juvenile woody plant tissues were also differentially expressed in this study. However, expression of miR172, previously reported to be highly expressed in mature tissues, was low in all sample types in this study. The obtained results will provide insight for further investigation of the molecular mechanisms regulating vegetative phase change in silver birch and other perennial woody plant species, by analysing a wider range of genotypes, tissue types and maturation stages. This knowledge can potentially assist in identification of rejuvenated material at an earlier stage than currently possible, increasing the efficiency of silver birch in vitro propagation.

Palaeobiodiversity of Knyszyn Forest (NE Poland) Mires Based on the Late Glacial and Holocene Histories of Vascular Plant Species

Peat and lacustrine sediments are a valuable source of knowledge about past biodiversity. Plant macrofossil remains were identified in sediments of mires in northeastern Poland’s Knyszyn Forest. Among them, the remains of species currently absent in this area, such as Potamogeton pusillus, P. friesii, P. filiformis, Myriophyllum alterniflorum, and Cladium mariscus, have been found. In addition, the history of Betula humilis and its possible correlations with another species of bush birch—Betula nana—were of interest. Radiocarbon dating allowed the presence of the studied species to be placed within a time frame, and it was thus established that aquatic species existed in the area under study during the Late Glacial and the turn of the Holocene. Cladium mariscus occurred during the Greenlandian and Meghalayan stages of the Holocene and then became intolerant of habitat changes that occurred. The coexistence of two species of birch known to exist since the Late Glacial was interrupted in the Northgrippian. B. nana, then disappeared from the area, and B. humilis continued to occur as it was more resistant to the changing environmental conditions. It must be emphasized, however, that these conclusions were made possible by the researchers’ access to undisturbed deposits. The mires present in the area of study remain in good condition, providing important and relevant materials for palaeoecological research.

Birch establishes anywhere! So, what is there to know about natural regeneration and direct seeding of birch?

We tested three soil scarification approaches of varying intensity (intensive preparation exposing bare mineral soil, medium intensity with a mixture of organic material and mineral soil, and control without site preparation) on six clear-felled sites in two localities in northern and central Sweden between 2018 and 2021. The effect of soil scarification intensity and soil moisture on the occurrence of naturally regenerated birch seedlings was tested one, two and three years after soil scarification, and the density of direct-seeded birch seedlings one year after seeding. In addition, we tested the effect of the annual seed rain, and differences between the two birch species, on the density of direct-seeded seedlings. Soil scarification and its interaction with soil moisture had a significant positive effect on both the occurrence of naturally regenerated birch seedlings and the density of direct-seeded birch seedlings. There was no significant effect of neither annual natural seed rain nor species choice on direct-seeded seedling density. Time since soil scarification had a significant effect on the occurrence of naturally regenerated birch seedlings. In moist soils with high volumetric water content (≥ 28%), birch seeds germinate at high rates and seedlings survive without soil scarification. In mesic soils, birch seeds germinate with higher rates after soil scarification. In dry soils, birch seeds rarely germinate regardless of any disturbance of the humus layer.

Microscopical palynology: Birch woodland expansion and species hybridisation coincide with periods of climate warming during the Holocene epoch in Iceland.

Introgressive hybridisation between arctic dwarf birch (Betula nana) and European downy birch (B.pubescens) is relatively common in natural woodlands in Iceland. As dwarf birch is a diploid species and downy tree birch a tetraploid species, their hybrids are triploid. In the introgression process, triploid hybrids, which are partially fertile, can backcross with the parental species, producing progenies comprising introgressed diploid, triploid and tetraploid plants. Triploid plants produce both normal triporate pollen (with three pores) and abnormal, aborted pollen, due to dysfunctional meiosis. The type of pollen abnormality that can be detected and quantified is non-triporate pollen (with four or more pores in the pollen wall). We therefore used the presence of non-triporate pollen as a marker to trace birch hybridisation in the past. In the current study we examined fossil pollen in samples from Holocene sediments from three locations: Grímsnes (SW), Eyjafjördur (N) and Thistilsfjördur (NE Iceland). All three peat monoliths had the starting age of 10.3cal. ka BP. Ages were calibrated based on known tephra layers and by radiocarbon dating. The size of Betula pollen grains was measured, and the species proportions calculated from size. Non-triporate grains were detected in samples from all three locations and throughout the Holocene, but with different frequencies. The peaks of intense hybridisation followed birch woodland expansion in two major periods of the Holocene, both coinciding with a warming of climate. The first period occurred in the Early Holocene, around 9.5-7cal. ka BP, when the climate warmed rapidly after deglaciation. The second period occurred around 5-3.5cal. ka BP, well within the mid-Holocene Northern Hemisphere warming. A new wave of birch hybridisation appears to have started in the last few decades as the climate has warmed. Birch woodlands are likely to become more widespread. Introgressed shrub birch is likely to be more competitive over dwarf birch.

Relationship between Laboratory Germination and Biometric Parameters of Betula jarmolenkoana Golosk. Aglets

This study evaluates the relationship between laboratory germination and biometric parameters of aglets of the critically endangered birch tree species Betula jarmolenkoana Golosk (Yarmolenko birch). The Yarmolenko birch is a very rare, narrowly endemic species, growing at an altitude of 1,900-2,100 m above sea level and only in the basins of three rivers (Kakpak, Bayynkol, and Tekes) in the Almaty region of Kazakhstan. Therefore, research is currently needed to increase the stability of birch forests and determine the optimal ways to preserve them. The study aimed to establish the nature of the relationship between laboratory germination and biometric parameters of birch aglets. To conduct surveys on the Yarmolenko birch forests, six sampling areas were selected, and five trees of close age (VI-VII age classes) were selected and marked in each sampling area. At the end of summer (August), after the seeds had reached physiological maturity (yellowing of the aglet core), 100 pieces of aglets were collected from trees at a height of 2.0 to 2.5 m and weighed on electronic scales. The data obtained were processed using methods of variational statistics, and the average values, coefficient of variability, and standard error of the average value were calculated. Student's t-test was used to compare features between the areas. The relationship between biometric parameters and seed germination was identified and statistically substantiated. According to three-year observations, in some areas of the forest, especially in areas with young and medium-aged plants, the morphometric parameters of aglets were not the same and did not repeat in different years. This was due to the weather conditions of the year of aglet formation and the growth and development of seeds.

Spatial structure and morpholody of understory in the southern taiga zone of central Siberia

The spatial structure of understory is influenced by various biotic and abiotic factors. The aim of the present study was to reveal the role of spatial distribution of the understory and its influence on the morphological and other forest characteristics in young stands. Visual and instrumental forest measuress were conducted to assess the spatial distribution of understory (forest inventory data for Boguchanskoye, Daurskoye and Manskoye forestries in 1965–1975 were used). In Central Siberia, the spatial structure of understory is significantly influenced by the number of understory trees and the share of conifers in the stand composition. Quality of the understory worsens with increase in its number and age. At the same time, the condition of young trees growing in groups is lower. Competition in groups accelerates growth in height, making trees growing in groups higher than those arranged uniformly after 30 years of age. It was confirmed that the spatial structure of understory changes from a group to a uniform one with age. The analysis of variance showed that group arrangement of the understory significantly influences its quality and the share that dominant forest-forming species (spruce) takes in the young generation. In the case of uniform arrangement, a significant characteristic is the number of understory trees. Group spatial structure significantly influences the quality of understory and its growth rate in the southern taiga zone of South Siberia. In Central Siberia, abandoned agricultural lands are restocked mainly with coniferous (Scots pine) and deciduous (birch) species.

DYNAMICS OF DISTRIBUTION, AMOUNT OF UNDERGROWTH, TYPE OF FOREST VEGETATION CONDITIONS

Peculiarities of natural regeneration of oak and related species in the conditions of the Northern Steppe were studied. According to the conducted surveys, over the course of 4 years, 21.38–58.19 thousand pcs.•ha-1 of natural renewal of undergrowth of various species were found. In seven-year-old crops, this indicator was somewhat lower and amounted to 40.26 thousand pcs.•ha-1. In six- and nine-year crops, the total amount of natural renewal was approximately the same - 24.1 thousand pcs.•ha-1 and 24.19 thousand pcs.•ha-1, respectively. As for the species composition of the undergrowth, the amount of preserved self-sowing varied greatly by year. Thus, common oak had the largest amount of natural renewal in six-year crops (5.23 thousand pcs.•ha-1). Even in seven-year-old crops, its preservation was 2.54 thousand pcs.·ha-1. In the following years, the conservation of this species was less than one thousand pieces.•ha-1. On the other hand, common ash had the lowest preservation in six-year-old and nine-year-old cultures - 3.52 and 3.84 thousand pcs.•ha-1, respectively. In other years, its preservation was much higher than that of oak, with the maximum amount in 7-year cultures – 19.1 thousand pcs.•ha-1. With the help of statistical data processing, it was found that there is a significant difference in reducing its quantity on one- and two-year-old log cabins. In subsequent years, there is a decrease in the amount of self-sowing oak, which over time completely falls out of the undergrowth. The natural regeneration of common ash, hornbeam, and maple has a significant difference in the age of the logs, but the increase or decrease in regeneration is not monitored due to the systematic cutting of natural regeneration during maintenance felling. There are no significant changes in the undergrowth of acacia, field maple, heart-leaved linden, birch and other species. Significant changes in the total amount of natural renewal were found in log cabins of all years.

Molecular Traits for Adaptation to Drought and Salt Stress in Birch, Oak and Poplar Species

Betula spp., Quercus spp., and Populus spp. are the most promising deciduous woody plants in forestry. However, these species were found to be sensitive to climate change that can badly affect their plantations. Thus, a deep understanding of genetic mechanisms of adaptation to adverse environmental conditions plays an important role in preventing the reduction of deciduous forest area. This mini review describes the stress responses of Betula spp., Quercus spp., and Populus spp. to drought and salt stresses. The overall stress response of the reviewed tree species includes ROS scavenging, ABA- and JA-mediated signaling pathways, and antioxidant and chaperone activities. Short-term drought promotes accumulation of proline, indicating the osmotic stress response. In turn, long-term drought stress activates the DNA repair and chromatin remodeling systems aimed at adapting and gene protecting. Furthermore, alternative pathways of carbohydrate production are used under nutrient deficiencies. It should be noted that stomatal movement control and cell wall remodeling are always observed during drought. In turn, the main response to salt stress includes the maintenance of ion homeostasis and the accumulation of osmoprotectant, as well as cell wall remodeling due to the biosynthesis of cellulotic and non-cellulotic cell wall compounds. It should be noted that the described species demonstrate similar molecular traits for adaptation to drought and salt stress, which may be due to their common habitats.

Intraspecific Variation in Three Species of Semudobia (Diptera: Cecidomyiidae) Forming Fruit Galls on Betula (Betulaceae) in the Holarctic Region

We analyzed the Folmer fragment of the mitochondrial COI gene of three closely related species of Semudobia (Diptera: Cecidomyiidae): S. betulae (Winnertz), S. tarda Roskam, and S. skuhravae Roskam. These species form fruit galls on different birch species (Betula, Betulaceae) in the Holarctic Region. In Japan, larvae of S. betulae and S. tarda were collected from the native Japanese birch, B. platyphylla, whereas S. skuhravae was collected from the eastern Palearctic birch, B. ermanii. In the Netherlands, the three species were collected from intermediate forms between the Eurasian endemic birches, B. pendula and B. pubescens. Additional sequences of Canadian and European S. betulae and S. skuhravae were obtained from the Barcode of Life Data system (BOLD). In a maximum likelihood analysis, the individuals of each species formed strongly supported clades, but genetic divergence was high within each clade indicating species complexes. European and Canadian individuals of S. betulae and S. skuhravae each formed a single clade with low intraspecific variation, suggesting that these species were introduced together with their hosts to North America. In contrast, Japanese individuals of the three Semudobia species were remarkably distant from European and Canadian individuals, indicating that they have been isolated genetically for a long period on their native eastern Palearctic and Japanese hosts.

Wood Quality along the Trunk Height of Birch and Aspen Growing in the Restoring Forests of Central Russia

The structure of forests has changed with an increase in soft-wooded broadleaved species over the past decade. The demand for hard-wooded broadleaved species can be met by replacing them with compressed wood of soft-wooded broadleaved species. Existing compressed wood technologies do not fully take into account the density variations that exist along the height of a tree trunk. In this study, we examined the variability of birch and aspen microstructures along the height of the trunk, including vessels per square millimeter and the diameter (tangential and radial) of the vessel lumina. The research was carried out on aspen and birch species growing in Central Russia. The vessels per square millimeter in both species increased from the base to the top of the trunk and their diameters decreased from the base to the top of the trunk. Birch demonstrated greater changes in these values than aspen. There was a strong relationship between the diameter of the vessel lumina and the trunk height. A decrease in the density of the stemwood from the base to the top of the trunk was caused by an increase in the vessels per square millimeter. These results affected the density of the stemwood and determined the degree of compression as well as the initial size of the blanks required to obtain material with uniform quality indicators, regardless of the source location of the raw materials in the tree trunk.

Investigation of the Genotoxicological Profile of Aqueous Betula pendula Extracts.

Betula pendula belongs to the Betulaceae family and is most common in the northern hemisphere. Various birch species have exhibited antimicrobial, antioxidant and anticancer properties. In the present study, we investigated the genotoxic and cytotoxic activity as well as the antigenotoxic potential against the mutagenic agent mitomycin-C (MMC) of two commercial products, i.e., a Betula pendula aqueous leaf extract product (BE) and a Betula pendula product containing aqueous extract of birch leaves at a percentage of 94% and lemon juice at a percentage of 6% (BP) using the cytokinesis block micronucleus (CBMN) assay. The most prevalent compounds and elements of BE and BP were identified using UHPLC-MS and ICP-MS/MS, respectively. All mixtures of BE with MMC demonstrated a decrease in the MN frequencies, with the lowest and highest concentrations inducing a statistically significant antigenotoxic activity. BP lacked genotoxic potential, while it was cytotoxic in all concentrations. Its mixtures with MMC demonstrated statistically significant antigenotoxic activity only at the lowest concentration. UHPLC-MS and ICP-MS/MS showed the presence of various elements and phytochemicals. Our results reveal antigenotoxic and cytotoxic potential of both BE and BP, while the variations observed could indicate the importance of the interactions among different natural products and/or their compounds.

Development of a database of three-dimensional models of
 deciduous forest species of Birch and Aspen for a geoinformation model of the forest ecosystem

The article is a continuation of the authors' cycle of works devoted to the development of geoinformation modeling technology for forest ecosystems. The article deals with the formation of an object-oriented catalog of deciduous woody plants growing on the territory of the Lisinsky educational and Experimental Forestry, a branch of S. M. Kirov SPbGLTU. The main purpose of the work is to form a single 3D database of two forest-forming species of hanging birch (Betula Pendula Roth.) and trembling poplar (Populus Tremula L.) to integrate the generated catalog of tree models into the environment of geoinformation modeling of forest ecosystem

Restoring tree species mixtures mitigates the adverse effects of pine monoculture and drought on forest carabids

Abstract Habitat degradation and climate change are main drivers of insect species loss worldwide, raising concern about natural forest replacement by tree monocultures in a context of more frequent disturbances like drought. Carabid beetles are emblematic species in ecology because they are often used as indicators of biodiversity and they have important functional roles, particularly predation. We used a tree diversity experiment with half of the plots irrigated and the other half under summer water stress to test the combined effects of tree species mixing and drought on carabid species and functional diversity. We observed a qualitative effect of drought on carabid communities, with species turnover mainly due to predator species loss in the drier (non‐irrigated) plots. We also found that species richness and activity density were lowest in pure pine plots and highest in mixture of pine and birch at low tree density. The likely underlying mechanism is the better provision of food and shelter resources in mixed forests. The association of pine with birch species could compensate for the loss of carabid beetles observed between pine monocultures benefiting from the water regime of the last century and those subject to current droughts. This suggests that diversifying plantation forests is a promising way to increase their resilience to the adverse effects of climate change.

White bark in birch species as a warning signal for bark-stripping mammals

Background : Birch species such as Betula pendula have conspicuous white bark and the evolutionary drivers for this colouration remain unresolved. Aims We evaluated our hypothesis that the white bark is a visual warning signal to deter mammals from bark-stripping. Many species of deer (Cervidae) and multiple other mammals consume bark. White birch species’ bark contains betulin and other compounds which likely make the bark unprofitable for herbivores. The white bark has features consistent with a visual signal for mammalian herbivores and could act as a visual aposematic signal of chemical defence. Methods We compared deer bark-stripping between tree species in Scottish woodlands. For Betula pendula, we compared stripping of juvenile brown bark with mature white bark. We also reviewed existing literature to find the tree-species preference for a wide-range of bark-stripping mammals. Results In Scotland, we found that white-barked birch bark was less preferred. We also found mature white birch bark was avoided compared to juvenile brown bark. Existing literature for multiple herbivores showed that white birch species’ bark was often either not preferred or avoided. Conclusion We suggest that the conspicuous white colouration of birch bark may act as an aposematic visual signal to deter bark-stripping mammals.

Revealing the Chemical Composition of Birch Pollen Grains by Raman Spectroscopic Imaging.

The investigation of the biochemical composition of pollen grains is of the utmost interest for several environmental aspects, such as their allergenic potential and their changes in growth conditions due to climatic factors. In order to fully understand the composition of pollen grains, not only is an in-depth analysis of their molecular components necessary but also spatial information of, e.g., the thickness of the outer shell, should be recorded. However, there is a lack of studies using molecular imaging methods for a spatially resolved biochemical composition on a single-grain level. In this study, Raman spectroscopy was implemented as an analytical tool to investigate birch pollen by imaging single pollen grains and analyzing their spectral profiles. The imaging modality allowed us to reveal the layered structure of pollen grains based on the biochemical information of the recorded Raman spectra. Seven different birch pollen species collected at two different locations in Germany were investigated and compared. Using chemometric algorithms such as hierarchical cluster analysis and multiple-curve resolution, several components of the grain wall, such as sporopollenin, as well as the inner core presenting high starch concentrations, were identified and quantified. Differences in the concentrations of, e.g., sporopollenin, lipids and proteins in the pollen species at the two different collection sites were found, and are discussed in connection with germination and other growth processes.

Yield Performance of Woody Crops on Marginal Agricultural Land in Latvia, Spain and Ukraine

Agricultural land abandonment due to biophysical and socioeconomic constraints is increasing across Europe. Meanwhile there is also an increase in bioenergy demand. This study assessed woody crop performance on several relevant types of marginal agricultural land in Europe, based on field experiments in Latvia, Spain and Ukraine. In Latvia, hybrid aspen was more productive than birch and alder species, and after eight years produced 4.8 Mg ha−1 y−1 on stony soil with sandy loam texture, when best clone and treatment combination was selected. In Spain, Siberian elm produced up to 7.1 Mg ha−1 y−1 on stony, sandy soil with low organic carbon content after three triennial rotations. In Ukraine, willow plantations produced a maximum of 10.8 Mg ha−1 y−1 on a soil with low soil organic carbon after second triennial rotation. The productivity was higher when management practices were optimized specifically to address the limiting factors of a site. Longer rotations and lower biomass yields compared to high-value land can be expected when woody crops are grown on similar marginal agricultural land shown in this study. Future studies should start here and investigate to what extent woody crops can contribute to rural development under these conditions.

Modeling of forest fires based on the Bayesian forecast model and geoinformation technologies

Today, a variety of information about forest ecosystems can be obtained using remote sensing methods. The use of space data for forest monitoring is cost-effective because it allows you to quickly obtain the objective information needed by foresters to solve practical problems. Satellite data provide wide coverage of forest lands, high accuracy of results, as well as high frequency of data obtained. Space images of the Ovruch district of the Zhytomyr region of Ukraine in the summer of 2020 were selected for the study. Determination of breed composition was carried out by the methods of controlled classification, namely the Bayesian classifier. It was found that 70 % of forests are pine, less aspen, hornbeam, birch, alder and ash tree species. According to statistics, during 2000-2020, 51.4 thousand hectares of forest plantations in Ukraine were damaged and destroyed by forest fires. Therefore, objective and timely information on the consequences of fires is needed to solve a wide range of applied problems of forestry. An important task in assessing the environmental and economic damage caused to forestry as a result of forest fires is to determine the area of damaged forests. The paper considers technologies for determining the area of the forest where the fire took place, using space images of the Landsat 8 satellite. The normalized NBR fire index before and after the fire and the DNBR index are used to identify areas burned by fire and impression levels. To predict forest fires, a mathematical model based on Bayes' theorem was created and a thematic map with fire hazard classes on a quarterly basis was created. To check the accuracy of the results of the created forecast model, the thematic map was combined with a layer of defined fire areas. This software product is quite flexible and versatile, it can be easily adapted for use not only to identify burned forest lands, but also for other areas.

Spatial patterns and species composition of new forest areas present challenges for forest management in Latvia

Forest area increase has been characteristic to the Eastern Baltic region since the early twentieth century. The emergence of new forest areas in significant amounts changes the visual and ecological character of landscapes and affects forest management decisions. The aim of this study was to investigate how emerging spatial patterns and stand characteristics of new forest areas impact forests in Latvia. Four study areas were selected in Latvia – Skrunda, Bauska, Skujene and Kaunata to analyze new and stable forest areas. Inside these four areas, 27,205 forest compartments were analyzed from new forests and 93,902 compartments in stable forests for reference. New and stable forest areas were mapped for the period of 1967–2017. Latvian State Forest register database provided compartment-level characteristics for new and stable forests. Descriptive statistics was used to analyze differences in tree species composition, ownership structure and management restrictions; and GIS methods – to assess compartment accessibility by roads. Spatial pattern metrics were calculated using Morphological Spatial Pattern Analysis in Guidos Toolbox 2.6. Results show that the majority of new forest areas have emerged from spontaneous afforestation, this was especially pronounced in Kaunata area (only 5% of new forest areas were planted). Scots pine, Norway spruce and two birch species comprised the majority in stable forest areas compared to new forest areas, where the proportions of dominant tree species were more evenly distributed. Spatial pattern analysis showed that the emergence of new forest areas has contributed to the homogenization of forest pattern with increasing Core area, reducing Edge and Islet (isolated patch) proportion. 93–99% of new forest areas identified in this study were not state-owned. Compartment accessibility was very good for all four study areas in Latvia, with 60–80% of stands being located closer than 500 m from roads. This study demonstrated that management of such small, spatially scattered and young forest compartments can be problematic. Since the majority or Latvia’s private forest owners’ holdings are smaller than 50 ha, the lack of resources and education as well physical factors impede successful involvement of these numerous small owners in sustainable management efforts.

Chemical Composition of the Unexplored Volatile Fraction of Betula glandulosa, a Prevalent Shrub in Nunavik, Québec.

The volatile fraction of the leaves of Betula glandulosa Michx. has been investigated for its secondary metabolite composition by GC/MS and GC/FID. The rapid expansion of this shrub species in subarctic landscapes, like the ones found in Nunavik (Northern Québec, Canada), highly impacts ecosystem dynamics. Yet, despite its abundance, few phytochemical investigations have yet been conducted on this species. In this study, we present the first phytochemical investigation of the volatile metabolites of B. glandulosa leaves. Although no essential oil was isolated, volatile compounds were extracted from the hydrosol by steam distillation. The main metabolites observed were linalool (14.6-19.0 %), C6 oxylipins (known as green leaf volatiles, GLV; total of 18.2-40.2 %), eugenol (1.6-8.6 %) and α-terpineol (3.3-4.8 %). Dwarf birch is an important food source for insects and herbivores, so knowledge of its metabolite composition could help understand parts of its functional role in subarctic ecosystems. The composition of the volatile fraction could serve as marker for differentiating B. glandulosa from other dwarf birch species like Betula nana L.