The dynamics of the fatty acid composition and activity of acyl-lipid desaturases contained in the buds of silver birch Betula pendula Roth have been studied. The places of growth of this tree are located in contrasting natural and climatic conditions: at the same latitude – 62° N, but are separated from each other by more than 5 thousand km in the longitudinal direction – 34° E (the vicinity of Petrozavodsk) and 130° E (the vicinity of Yakutsk). It has been found that, regardless of the place of growth, in the spring-winter period, the total lipids of the buds of silver birch have been characterized by a high content of unsaturated fatty acids. At the same time, significant differences have been revealed in the composition of mono-, di- and trienoic fatty acids, the dynamics of which have largely depended on both the phase of winter-spring plant development and the degree of continentality of the climate. It has been shown that in Karelia, during the exogenous dormancy period (January–March), an increased content of dienoic fatty acids is observed in the lipids of the buds of silver birch, and by the beginning of their breaking (April–May) – trienoic fatty acids, whereas in Yakutia in the winter-spring period monoenoic and dienoic fatty acids steadily prevail. At the same time, a high activity of ω6- and ω3-desaturases (responsible for the synthesis of linoleic С18:2 and С18:3 fatty acids) has been detected in the lipids of the buds of silver birch growing in Karelia, and ω9-desaturase (catalyzing the synthesis of oleic С18:1 fatty acid) in Yakutia. It has been suggested that in permafrost conditions there is a relationship between the expression of genes controlling the formation of ω9-acyl-lipid desaturase and the resistance of the tissues of primordial organs during their intra-bud development to negative temperatures not only of the air, but also of the root-inhabited soil layer. The authors believe that the features identified in the composition of total lipids in the buds of silver birch in Yakutia compared to Karelia can be considered as one of the additional mechanisms that increase the adaptive potential of the species in permafrost conditions and allowing the representatives of the genus Betula L. to expand their area to the northern limit of the distribution of woody vegetation.

The article provides a brief overview of the almost century-long history of the largest natural populations of curly, aka Karelian, birch, Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti, which were discovered in Karelia in the 1930s and were in 1984 given the official status of state botanical reserves (BRs), not found elsewhere in our country. The current state of each of the four operating curly birch BRs (Anisimovshchina, Kakkorovsky, Spasogubsky, and Curly Birch Near the Village of Tsarevichi) is described. The article reveals the principal reasons for the changes taking place in the BRs (lack of regular tending, critical age of trees, illegal logging), which entail negative consequences, of them being a marked decline in tree numbers. The more than 15-year-long experience of restoration activities in the Kakkorovsky and Spasogubsky reserves is analyzed. It is emphasized that despite the obviously insufficient scope of protection and tending activities, the curly birch BRs established in Karelia have contributed greatly to the preservation of its gene pool and genetic diversity and continue to play the pivotal role in this matter. Currently, they comprise the greatest and the most valuable part of the gene pool of this unique tree variety, which is an essential element of the natural heritage of Karelia, as well as Russia in general.

A study of the allelic diversity of donor and recipient tissues was conducted and their ploidy was assessed using microsatellite markers in transplant symbionts obtained by grafting or local transplantation. Betula pendula Roth var. carelica (Mercklin) Hamet-Ahti—Karelian (Curly) birch bark tissue, whose patterned texture contrasts well with the normal (straight-grained) wood of the recipients—silver birch Betula pendula Roth and downy birch Betula pubescens Ehrh—was used as a donor. It has been shown that even with local ring transplantation of donor tissues, when all descending and ascending transport pathways along the axis of the recipient’s trunk are completely “cut” around the circumference of the trunk, successful fusion of genetically heterogeneous tissues occurs, which, even years later (9 years), retain their phenotypic and genetic characteristics. Using microsatellite analysis, it was established that, regardless of the method of production, transplant symbionts are characterized by clearly expressed allelic diversity, although microsatellite instability and even genetic chimerism may appear at some loci in the case of a ring transplant. In particular, the allele imbalance in individual chromosomes varied from 22.2 to 37.9

Changes in the fatty acid composition of phospholipids in buds during the winter-spring period (January–May) were studied in silver birch (Betula pendula Roth) growing in Karelia and Yakutia. Phospholipids were isolated from total lipids using column chromatography, while fatty acids were separated through gas chromatography. The metrics for acyl-lipid desaturase activity were represented by the ratios of stearoyl- (SDR), oleoyl- (ODR), and linoleoyl- (LDR) desaturases. Our findings demonstrate that, regardless of geographical location, the predominant phospholipid fraction during the development of primordia within the bud consists of unsaturated fatty acids. During the period of exogenous bud dormancy, dienoic acids were the most prevalent; however, their share declined by the onset of the growing season, while the proportion of trienoic acids increased. These changes were accompanied by a slight rise in the double bond index. Conversely, the unsaturation index nearly doubled by March, with this change being particularly pronounced in Yakutia. Simultaneously, the SDR and ODR values were high, indirectly indicating the active involvement of ω9 and ω6 desaturases in maintaining the liquid-crystalline state of phospholipids. The LDR value in phospholipids was the lowest, yet it nearly tripled by the onset of the growing season in both Karelia and Yakutia. We hypothesize that the liquid state of phospholipids in the cell membranes of meristematic tissue in the buds of silver birch growing in Karelia and Yakutia during the winter-spring period is sustained by high desaturase activity, with the most significant response to temperature changes observed in acyl-lipid ω3 desaturase. Furthermore, through the course of evolution, silver birch in Yakutia has developed an additional mechanism that involves a pronounced reduction in cell and tissue water content, which also contributes to maintaining an ordered state of phospholipids and their functions, particularly when exposed to extremely low air temperatures and permafrost.

Changes in the fatty acid composition of neutral lipids in buds in the winter-spring period (January-May) were studied in silver birch (Betula pendula Roth) growing under the notably different natural and climatic conditions of Karelia and Yakutia. In this period, the apical meristem develops inside the bud. The study showed that irrespective of the geographical location, neutral lipids in silver birch buds contained high levels of unsaturated fatty acids. Their content declined as the air temperature rose, but the double bond index in buds of the trees growing in Karelia remained almost unchanged, whereas in Yakutia it even increased somewhat. At the same time, the prevalent neutral lipid fractions in Karelia were di- and trienoic fatty acids, and in Yakutia it was mono- and dienoic acids. Awakening from exogenous dormancy in the period in question was accompanied by certain changes in the activity of acyl-lipid desaturases: in Yakutia, the oleoyl- and linoleoyl-desaturase ratios in buds increased from January towards May, while in Karelia a minor rise in the ratios was observed only in April. The high stearoyl-desaturase ratios, especially in Yakutia, are probably explained by the functional role of neutral lipids as energy and/or substrate depots, which are utilized not only in the processes of bud adaptation to low temperatures but also in the formation of primordial structures in buds. Our data also indicate that the variation of the indices that represent the specific features of neutral lipids in silver birch buds was mostly controlled by the physiological status and the development phase of embryonic organs formed therein, whereas the timing of the phases, as well as the composition and content of fatty acids – by the local environmental and climatic conditions

В статье кратко изложена история ботанического заказника карельской березы Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti «Спасогубский», который является одним из старейших и наиболее крупных не только на территории Республики Карелия, но и в России. Его история охватывает почти 100 лет, в рамках которых авторами условно выделены четыре временных периода. При этом учитывали не только длительность существования популяций, но и происхождение составляющих их деревьев, поскольку первоначально заказник был представлен естественными насаждениями, а затем - искусственно созданным in situ. Приводятся таксационное описание исходного древостоя, получившего официальный статус заказника, а также характеристики плюсовых деревьев карельской березы, выявленных в его границах. Показано, что к началу 21-го века в результате незаконных рубок и естественных потерь природная популяция на территории данного заказника была практически полностью уничтожена: из 262 деревьев карельской березы осталось всего 4. Анализируются результаты восстановления заказника с использованием семенного потомства, полученного от контролируемого опыления деревьев местного происхождения, которые также оказались намного хуже ожидаемых: из 1600 растений спустя 16 лет сохранилось не более 200, большинство из которых находятся в угнетенном состоянии. Как установлено, к этому прежде всего привело отсутствие лесоводственных уходов, из-за чего карельская береза здесь активно вытесняется другими породами и прежде всего осиной. На основании проведенных исследований и совокупности имеющихся данных сделан вывод, что к началу 21-го века карельская береза в данном заказнике, как и в целом в Карелии, оказалась под угрозой реального исчезновения, а проблема сохранения и восстановления ее генофонда приобрела особую остроту. Поэтому сохранение генетических ресурсов этой уникальной лесной породы является важной государственной задачей, решение которой требует разработки и принятия долговременных программ и значительных финансовых ресурсов, которые легче изыскать в результате объединения средств из регионального и федерального бюджетов. Помимо выделения значительных финансовых средств, необходимы целевая подготовка квалифицированных кадров, разработка и принятие ряда нормативно-правовых актов, а также информационная поддержка со стороны средств массовой информации. The article gives an overview of the history of the Spasogubsky Botanical Reserve (BR, Zakaznik) established to conserve curly (or Karelian) birch, Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti. The reserve is one of the oldest and largest of the kind not just in the Republic of Karelia but also in the whole of Russia. Its almost 100-year-long history is conventionally broken down into four time periods based both on the life span of populations as well as on the provenance of the constituent trees, considering that the original natural stands of the reserve were later replaced by those planted in situ. The valuation parameters of the original stand at the time of official designation as a nature reserve and the characteristics of the curly birch plus trees identified within it are provided. We demonstrate that by the beginning of the 21st century, illegal logging and natural losses have almost totally ruined the natural population within this reserve: only 4 of the original 262 curly birch trees have survived. Analysis is given also for the outcome of restoring the reserve using the seed progeny produced through controlled pollination of trees of local provenance, which proved to be far worse than expected: of the 1600 plants, not more than 200 have survived 16 years after planting, and even these are mostly in a suppressed condition. This was arguably primarily a consequence of the absence of silvicultural tending, which results in an active displacement of curly birch by other species and above all aspen. The conclusion from our studies and other available data is that by the beginning of the 21st century curly birch in this nature reserve, as well as in Karelia at large, found itself on the verge of extinction, and the problem of preserving it and restoring its gene pool has become particularly acute. Thus, preserving the genetic resources of this unique forest tree is an important task for the state, which requires thorough elaboration and adoption of long-term programs and substantial financial resources, which would be easier to find by combining regional and federal funding. In addition to substantial financial allocations, it is also necessary to train qualified personnel, to work out and adopt certain statutory regulations, and to raise awareness using mass media.

Seven microsatellite markers were used in molecular genetic analysis of curly birch and silver birch trunk tissue fragments produced through whip grafting or bark ring transplantation. The analysis showed that whichever grafting method was used, each component steadily retained their genotype upon tissue fusion. It is demonstrated that aberrant cells may be formed at the point of bark and trunk tissue fusion after donor bark ring transplantation, when all the ascending and descending transport pathways along the recipient’s trunk axis have been severed all around the trunk circumference. Even then, however, both curly birch and silver birch retain their phenotypic (figured and straight wood grain, respectively) as well as genotypic (which is expressed in preserving a combination of identified allelic variants) traits.

The article reports the results of studies on the growth and development of curly birch sibs progeny (produced through controlled pollination) aged 35 and 15 years growing in the Zaonezhye forest seed orchard (sites 1 and 2, respectively) in south-eastern Karelia, Medvezhyegorsky District. The number of trees with signs of wood figure in the seed progeny of curly birch in site 1 was 67 % by the age of 20 years, and by the age of 35 years – almost 80 %. This can probably be attributed to the genetic characteristics of the parent (plus) trees on one hand and to the favorable conditions in the forest seed orchard during the first years of the sibs progeny development on the other. Four of the 36 hybrid families (selected to include forward- and backcrossing products) were used for the case study of the growth and development patterns in stands of different age. The sibs progeny of these hybrid families was dominated by high-stemmed plants, but the main trunk shape in the 15-year-old stand was one with necks and muffs, while in the 35-year-old stand – with small protuberances. The rate of height growth in the trees decreased notably with age, whereas radial (stem diameter) growth, on the contrary, accelerated. As the bark grew thicker, however, the formerly bulgy surface “smoothed down”. We have also identified specific features of the ground vegetation formed under the effect of curly birch plantations of different age (15- and 35 years old). A conclusion drawn from the study is that good results from targeted cultivation of curly birch with figured grain (e.g., for sliced veneer) can be achieved already by the age of 20–35 years. Furthermore, considering the number of trees and their origin, this forest seed orchard constitutes an essential part of the valuable gene pool of curly birch, which may turn into a source for expanded reproduction of the resources of this unique member of the European forest tree flora. For citation: Vetchinnikova L.V., Titov A.F., Kostina E.E., Zhigunov A.V. Sibs Progeny of Curly Birch at the Zaonezhye Forest Seed Orchard. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 5, pp. 9–26. (In Russ.). https://doi.org/10.37482/0536-1036-2023-5-9-26

The article briefly recapitulates on and systematizes major results of the studies of curly (or Karelian) birch Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti, mainly from the past two or three decades. Its main biological characteristics are described. Facts regarding curly birch resources are provided; the important role of protected areas in conserving its gene pool is emphasized. Good experience of its introduction and re-introduction is demonstrated. The origin of curly birch, the process of figured grain formation in its wood and the question of its taxonomic status are touched upon. It is pointed out that our knowledge of the nature and characteristics of curly birch as a biological object has advanced substantially over the past two or three decades, but two essential questions remain unresolved: a) origin of the curly birch and b) causes and mechanisms of figured grain formation in its wood. Answers to these questions are of much interest both theoretically and for practical causes as they would help preserve the gene pool of curly birch and contribute to augmented reproduction of its resources.

The article summarizes and systematizes the results of studies by Russian and foreign authors related to the population-genetic features of the main members (silver birch Betula pendula L., downy birch Betula pubescens Ehrh., curly (or Karelian) birch Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti) of the birch genus (Betula L.) growing in the forest zone of Europe. Information is provided about the formation of birch populations in the region and about its migration pathways when recolonizing the territory after the Ice Age. We demonstrate that due to certain geographic and climatic affiliations there appeared zones of hybridization between different birch species, which had an effect on the subsequent evolution of this genus. Attention is given to the role of hybridization in shaping the genetic structure of the birch population in the northwestern part of continental Europe, where introgression has generated unusual genotypes and haplotypes, among which curly birch has probably become differentiated. We argue that the introgressive hybridization of species observed now and then in the birch genus may be of the main reasons for the problems with definite taxonomic identification of silver birch and downy birch. It is also remarked that curly birch, although meeting the conventional biological criteria of a species, is still regarded a variety of silver birch. Having analyzed the population-genetic features of members of the genus Betula L., the authors conclude that the species status of silver birch and downy birch should be retained in spite of the identification difficulties and that instating curly birch as a separate biological species is advisable. We emphasize the importance and relevance of studying the population-genetic features of both common and rare members of the Betula genus to enable the development of efficient methods and practices of their selective breeding and reproduction of the most valuable genotypes as a solid scientific foundation for sustainable forest management.

The paper offers a systematic overview of the results of research regarding reintroduction of curly (Karelian) birch Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti published by Russian and foreign authors over the past few decades. We briefly outline the current situation with its resources and the key causes of their decline in the late 20th – early 21st centuries, such as mass-scope illegal logging, vanishing or substantial alteration of typical curly birch habitats, as well as some biological features (fragmented distribution, low competitive capacity, etc.). The main outcomes of the curly birch introduction activities in the areas lying far beyond its natural distribution (mainly to the south-east from it) are reported. It is shown that the experience of curly birch reintroduction in Russia is mostly based on planting of forests and establishment of specially protected areas. The results of curly birch reintroduction in Finland, Sweden, Norway, Germany, Belarus and other countries are observed. Although reintroduction is not equally effective in all countries (its success depends on many factors), it has made and is making a significant contribution to the preservation and augmentation of the resources of this unique member of the European forest tree flora. Importantly, the curly birch from the reintroductions performed in different years and different edaphic and climatic conditions steadily retains its key biological features, such as figured grain and diversity of growth forms and trunk surface characteristics, which once again confirms the authors’ previously expressed opinion that there are grounds for classifying the curly birch as a separate biological species. Proceeding from the analysis of the data amassed by now, it is suggested that that the efficiency of curly birch reintroduction to its natural habitats can be promoted by mainly using the stocking material of local provenance (when restoring populations) or by transferring it from other populations (for repatriation cases). An important role in the preservation and reproduction of curly birch belongs to the micropropagation technique.

Проведен анализ видового состава живого напочвенного покрова, сформировавшегося под влиянием насаждений карельской березы на двух разновозрастных участках (15-ти и 35-ти лет), расположенных на Заонежской лесосеменной плантации (ЛСП) в Медвежьегорском районе Республики Карелия, где в результате предварительной подготовки территории был существенно поврежден растительный покров и нарушена структура почвы. Установлено, что общее проективное покрытие живого напочвенного покрова в настоящее время составляет в среднем 70%. На обоих участках в целом выявлено 38 видов, из них 32 – сосудистые растения (преимущественно лесные), 4 – лишайники, 2 – мхи. Среди сосудистых растений 94% являются аборигенными и только 6% – адвентивными. Несмотря на значительное сходство в составе напочвенного покрова, выявлены определенные особенности каждого из участков. В частности, на территории 35-летнего насаждения зафиксировано 28 видов сосудистых растений, среди которых преобладают вереск обыкновенный (20% от общего проективного покрытия), вейник тростниковый (20%), ландыш майский (15%), а также овсяночка извилистая (10%). В 15-летнем насаждении обнаружено 19 видов сосудистых растений с доминированием вереска обыкновенного (40%) и брусники обыкновенной (10%). В живом напочвенном покрове травяно-кустарничкового яруса на обоих участках преобладают по отношению: к освещенности – семигелиофиты, к почвенному увлажнению – мезофиты, к почвенному плодородию – мезотрофы. Выявленные особенности живого напочвенного покрова, сформированного под влиянием искусственно созданных насаждений карельской березы, обусловлены прежде всего разной продолжительностью его формирования, количеством поступавшего в почву опада березы (позднее дополняемого опадом травяно-кустарничковой растительности), а также отчасти видовым составом растительности, произрастающей на сопредельной с ними ненарушенной лесной территории, и с неровностью микрорельефа. Сделан вывод, что создание лесных культур плантационного типа является наиболее перспективным способом решения задачи воспроизводства карельской березы, а Заонежская ЛСП представляет собой хороший пример реинтродукции карельской березы in situ. В дальнейшем она может использоваться не только в практическом плане, но и для решения различных научных задач, выступая, в частности, в качестве объекта для проведения ботанических, физиолого-биохимических или молекулярно- генетических исследований. К л ю ч е в ы е с л о в а : карельская береза, лесосеменная плантация, живой напочвенный покров, видовой состав, проективное покрытие. The articles gives an analysis of the species composition of the ground vegetation formed under the effect of curly birch plantations of two ages (15 and 35 years old) in sites situated in the Zaonezhye seed orchard (Medvezhyegorsky District, Republic of Karelia), where pre-planting operations had strongly damaged the plant cover and disturbed the soil structure. Currently, average total ground vegetation cover is 70%. Surveys of both sites revealed a total of 38 species, including 32 vascular plants (chiefly forest-dwelling), 4 lichens, and 2 mosses. Among the vascular plants, 94% are native and only 6% are non-native. Although the sites are quite similar in the ground vegetation composition there are some distinctions too. To wit, the 35-year-old site was found to harbor 28 vascular plant species with Calluna vulgaris (20% of the total cover), Calamagrostis arundinacea (20%), Convallaria majalis (15%), and Avenella flexuosa (10%) prevailing. The 15-year-old stand contained 19 vascular plant species, the dominants being C. vulgaris (40%) and Vaccinium vitis-idaea (10%). The prevalent groups in the herb-subshrub layer were: in relation to light – semiheliophytes, in relation to soil moisture – mesophytes, in relation to soil fertility – mesotrophs. The distinctive features of the ground vegetation formed under the impact of curly birch plantations are primarily due to the different durations of the impact, the amount of birch litter input to the soil (with a later addition of herbaceous-subshrub litterfall), as well as, to some extent, to the species composition of the vegetation growing in the adjacent undisturbed forest area and to microtopographic roughness. It is concluded that forest crop planting is the most promising method for securing curly birch regeneration and that the Zaonezhye seed orchard is a good example of curly birch re-introduction in situ and can be used in the future both for applied purposes and in various sorts of theoretical research, acting, in particular, as an object for botanical, physiological, biochemical, or molecular genetic studies.

The effect of cadmium ions (10−6–10−3 М) on gemmation (formation of buds and subsequent development of axillary shoots out of them) and rhizogenesis (formation of adventitious roots in the basal part of shoots) was separately investigated in in vitro shoot culture of Karelian birch Betula pendula Roth var. carelica (Mercklin) Hamet-Ahti produced from apical meristem of vegetative buds. It was shown that the metal present in the nutrient medium brought about not only its accumulation in the growing shoots but also suppressed gemmation and rhizogenesis with the extent of this inhibition depending on metal concentration. At the same time, the experiments revealed a moderate stimulatory effect of cadmium at low concentrations (10–6 М) on gemmation and lack of stimulation in respect to rhizogenesis. Elevating the metal concentration in the nutrient medium to 10–5 М was accompanied by suppression of shoot growth but without disturbance of setting and formation of new organs. Simultaneously, certain disorders in the operation of the photosynthetic apparatus were revealed, namely, a reduction in the rate of СО2 assimilation and a decrease in the content of photosynthetic pigments. In addition, introduction of cadmium to the nutrient medium considerably affected fatty acid lipid composition in the shoots and activity of acyl-lipid desaturases. In particular, when metal concentration increased from 10−6 to 10−4 М, total content of saturated FA rose, although a decrease in the indices of stearoyl- (SDR), oleoyl- (ODR), and linoleoyl- (LDR) desaturase ratios was observed only at cadmium concentration of 10–4 М. The obtained data suggest that protective mechanisms ensuring gemmation are much more efficient than the mechanisms responsible for rhizogenesis. On the whole, a universal response to cadmium in tissue culture, in vitro organs, and intact plants makes it possible to conclude that tissue culture is a convenient instrument for dealing with many aspects of metal resistance of woody plants.

The article describes the most important and interesting curly birch research results obtained by staff of the Forest Research Institute KarRC RAS over the institute’s more than half-century history. Quantitative indicators of the dynamics of major publications (monographs, articles in Russian and foreign journals, articles in collected volumes, textbooks) and of intellectual property (patents, know-how, databases) produced by scientists working at the Institute are reported. Their analysis shows that interest in this unique member of the forest flora is great and unfailing, as evidenced by the growing number of recent publications. We emphasize that long-term studies in the field and in the laboratory have produced extensive scientific material, substantially enriching our knowledge of the traits and properties of curly birch, its distinctive features. We indicate the research areas of applied as well as theoretical nature where one can potentially expect to obtain the most interesting results providing a deeper insight into the biological nature of curly birch and which, as the authors believe, will very soon help discover adequate approaches to preservation of the plant’s gene pool and to its extended reproduction in the long run.

We introduce an analysis of the experience of curly birch introductions accumulated in Russia and abroad, from which the main means and methods of evaluating introduction prospects were derived. It follows from this analysis that the most important and commonly used approaches and criteria are: comparison of the edaphic and climatic conditions in the prospective introduction site and the location from which the source material is taken (climate analogues method), assessment of the origin and biological characteristics of the source material, assessment of the composition of stand-forming tree species and their companion species in the prospective introduction site. In addition, we suggest the “distance method”, providing information about the distance from the species range boundary to the prospective introduction site, and about the distance over which curly birch has been moved for introduction before relative to the “averaged” distance. The importance of cultural operations, stocking rate and density of the planted trees for the expression of “figured grain” and “figure intensity” features in wood is highlighted. It is concluded that although curly birch has quite high ecological plasticity and, accordingly, a high introduction potential, the prospects for its introduction should be assessed using a widest possible set of indirect criteria and indicators, which will collectively yield a more probable future estimate of the introduction outcome, and generate a premise for improving its efficiency. The lack of the said integrated approach to evaluating the prospects of introduction is a key reason for its underperformance, notably reducing the chances of successfully dealing with the tasks of gene pool preservation and augmented reproduction of this unique member of the forest tree flora by means of introductions