Conifer Species Research Articles

Rapid identification of Ips sexdentatus (Boerner, 1766) (Curculionidae) from adults and frass with real-time PCR based on probe technology

A molecular tool has been developed for the molecular identification of Ips sexdentatus (Börner 1776) (Coleoptera Curculionidae Scolytidae), the well-known six thooted bark beetle, widely distributed in Eurasia, where it infests several species of the genus Pinus and occasionally a few conifer species of the genera Abies, Larix and Picea. The developed test can be useful both in countries where I. sexdentatus is handled as a quarantine species and, to greater reason, in Europe to discriminate biological traces of this commonly found beetle from those produced by regulated pests. The protocol is based on real-time PCR with TaqMan probe technology and has been developed on whole insect bodies (adults) as well as on artificial frass contaminated by DNA of the beetle. The molecular test developed here for both direct and indirect identification of I. sexdentatus has proven effective in terms of analytical specificity, analytical sensitivity, reliability and reproducibility. The recommended protocol is a practical diagnostic tool allowing a rapid identification of the six toothed bark beetle in the presence of any biological trace of other xylophagous pests collected at points of entry during phytosanitary surveys.

Irruptions of crossbills Loxia spp. in northern Europe – patterns and correlations with seed production by key and non‐key conifers

Irruptions by boreal seed‐eating and frugivorous birds are assumed to be driven by the production of seeds and fruits, crops of which are highly variable between years. Using data from Sweden, we tested whether irruptions of Common Crossbills Loxia curvirostra were correlated with low Norway Spruce Picea abies seed production in the same year as the irruption and/or high seed production in the year prior to an irruption. Similar tests were made for Parrot Crossbill Loxia pytyopsittacus irruptions in relation to Scots Pine Pinus sylvestris seed production. In northern Europe, these conifers represent the key food species of the two crossbill species, respectively. Despite differing times that seeds take to mature and asynchronous seed production between the two conifer species, including a 3‐year cycle for Norway Spruce, the two crossbill species often irrupted in the same year as one another. Analyses showed that irruptions into Britain and other parts of western Europe by both crossbill species were correlated with low seed production by Norway Spruce in Sweden. Low seed production by Scots Pine had a marginally non‐significant additive effect on both crossbill species. In a second set of analyses, the best‐fitting model was one in which low seed production by both conifers in a given year and high seed production in the previous year were each correlated with large numbers of irrupting Common and Parrot Crossbills. The models indicate that the incidental co‐occurrence of low seed production of Norway Spruce and Scots Pine in a given year, after a year of high seed production, may result in an irruption. The seed production of Norway Spruce and Scots Pine in Sweden was correlated with production by the same species in Finland, indicating widespread synchrony of cropping across northern Europe.

Effects of nitrogen addition and leaf age on needle traits and the relationships among traits in Pinus koraiensis

Leaf functional traits are essential for the growth and adaptation of trees to environmental changes. However, how needle traits and trait–trait relationships respond to different nitrogen (N) addition rates and leaf ages remain unclear for evergreen coniferous species. Our study aimed to investigate the effects of N addition and leaf age on needle traits and their bivariate correlations. Understanding resource utilization and distribution strategies during tree growth under the background of increased N deposition is important. We conducted a six-year manipulative field experiment in a Pinus koraiensis plantation in northeastern China with variable N addition levels: control (no N addition, CK); 20 kg N ha−1yr−1 (low-N, LN); 40 kg N ha−1yr−1 (medium-N, MN); and 80 kg N ha−1yr−1 (high-N, HN). The needle trait data were collected in September. The morphological traits, i.e., specific leaf area (SLA) and leaf dry matter content (LDMC); and chemical traits, i.e., leaf nitrogen concentration (LNC), leaf phosphorus concentration (LPC), and leaf nonstructural carbohydrates (NSC) concentrations, were measured to investigate the changes in needle traits and their bivariate correlations. We found that N addition and needle age significantly affected needle traits, and the effect of needle age was much stronger than that of N addition. N addition and needle age had no significant interaction effects on any of the traits except for the LNC. Due to the dispersal trait values of current-year needles, there were almost no significant bivariate correlations between traits under different N addition rates. The SLA–LDMC and LDMC–LNC relationships were found to differ among the various N addition rates, and other traittrait relationships may be relatively stable because of the weak plasticity of older needles. Additionally, needle age significantly affected the slope of the SLA–LDMC relationship and the elevation of the LDMC–LPC and NSC–LNC relationships, indicating differences in the ecological strategies of needles at different ages. In summary, our findings emphasize that trait–trait relationships in current-year and older needles were inconsistent in response to N addition and that the optimal allocation of resources in needles was based on their functional needs during leaf aging.

Properties of Forest Tree Branches as an Energy Feedstock in North-Eastern Poland

Tree branches from forest tree harvesting for the timber industry are an important energy feedstock. Solid biofuel in the form of wood chips, produced from branches, is an excellent renewable energy source for generating heat and electricity. However, the properties of wood chips as a solid biofuel produced from forest tree branches can vary greatly depending on the species from which they have been produced. Therefore, this study aimed to assess the thermophysical properties and elemental composition of fresh branches harvested from nine tree species (pedunculate oak, silver birch, European ash, common aspen, grey alder, Norway maple, Scots pine, European larch and Norway spruce) over three consecutive years (2020–2022). The branches of the tree species most commonly found in Polish forests (Scots pine) were characterized by the highest heating value (an average of 20.74 GJ Mg−1 DM), the highest carbon content (an average of 55.03% DM), the lowest ash (an average of 0.60% DM) and nitrogen contents (an average of 0.32% DM), and low sulfur (an average of 0.017% DM) and chlorine contents (an average of 0.014% DM). A cluster analysis showed that the branches of all three coniferous tree species (Scots pine, Norway spruce and European larch) formed one common cluster, indicating similar properties. The branches of the European ash were characterized by the lowest wood moisture content (an average of 37.19% DM) and thus the highest lower heating value (an average of 10.50 GJ Mg−1). During the three years of the study, the chlorine and ash contents of the branches of the tree species under study exhibited the highest variability.

Factors Affecting Radial Increment Dynamics in Lithuanian Populations of Common Juniper (Juniperus communis L.)

Although common juniper (Juniperus communis L.) is a widely spread species and important for the forest biodiversity and economy in many European countries, it remains one of the least studied coniferous species. This research is the first attempt to evaluate the factors affecting the increment of Juniperus communis in Lithuanian populations. The aim of this article is to evaluate the patterns of radial increment in Juniperus communis and to identify the key factors influencing the increment. We collected stem discs from 160 junipers in 8 stands distributed in the different regions of Lithuania and performed the tree-ring analysis. All studied junipers expressed a pronounced eccentricity of the stem. The results of our study revealed four patterns of Juniperus communis’ radial increment, which are strongly dependent on the granulometric properties of the soil and hydrologic conditions. The effect of climatic conditions on the Juniperus communis increment was strongly dependent on the terrain; however, most of the junipers had a positive reaction to the temperatures in April, July, and August and to the precipitation in February.

Functional Characterization of PmDXR, a Critical Rate-Limiting Enzyme, for Turpentine Biosynthesis in Masson Pine (Pinus massoniana Lamb.).

As one of the largest and most diverse classes of specialized metabolites in plants, terpenoids (oprenoid compounds, a type of bio-based material) are widely used in the fields of medicine and light chemical products. They are the most important secondary metabolites in coniferous species and play an important role in the defense system of conifers. Terpene synthesis can be promoted by regulating the expressions of terpene synthase genes, and the terpene biosynthesis pathway has basically been clarified in Pinus massoniana, in which there are multiple rate-limiting enzymes and the rate-limiting steps are difficult to determine, so the terpene synthase gene regulation mechanism has become a hot spot in research. Herein, we amplified a PmDXR gene (GenBank accession no. MK969119.1) of the MEP pathway (methyl-erythritol 4-phosphate) from Pinus massoniana. The DXR enzyme activity and chlorophyll a, chlorophyll b and carotenoid contents of overexpressed Arabidopsis showed positive regulation. The PmDXR gene promoter was a tissue-specific promoter and can respond to ABA, MeJA and GA stresses to drive the expression of the GUS reporter gene in N. benthamiana. The DXR enzyme was identified as a key rate-limiting enzyme in the MEP pathway and an effective target for terpene synthesis regulation in coniferous species, which can further lay the theoretical foundation for the molecularly assisted selection of high-yielding lipid germplasm of P. massoniana, as well as provide help in the pathogenesis of pine wood nematode disease.

Spectral-temporal traits in Sentinel-1 C-band SAR and Sentinel-2 multispectral remote sensing time series for 61 tree species in Central Europe

Tree species maps derived from satellite imagery increasingly support forest administrations and nature conservation authorities with large-scale and up-to-date information. However, many species are often excluded or aggregated in classification tasks due to a limited knowledge of the most suitable predictors. Our study aims to gain a better understanding of optical and polarimetric traits for tree species mapping by examining Sentinel-1 and Sentinel-2 time series from 61 tree species in temperate Europe. For a selection of 32 optical, polarimetric and structural variables, the principal component analysis revealed that Sentinel-2 variables mainly explain the variance in the data by contributing to the “seasonality” and “foliage color” components. Sentinel-1 contribute most to the “texture” component. The Normalized Difference Vegetation Index (NDVI), Tasseled Cap Greenness (TCG) and Radar Vegetation Index (RVI) were chosen as key variables for further analysis. Seasonality was found to be the most dominant aspect in all vegetation indices. Furthermore, the TCG was found to be useful to distinguish between early and late budding species. The RVI showed a large potential to discriminate conifers, which is attributed to the crown volume effect of C-band SAR. Using exploratory data analysis, we further examined the influence of management, biogeographical and meteorological factors on the time series from Fagus sylvatica, Pinus sylvestris, and Picea abies. The NDVI and TCG are relatively robust to different conditions. For the two conifer species however, we found strong spatial variations of the RVI which are presumably caused by different crown conditions across the study area. Using Sentinel-1 data could therefore lead to uncertainties in tree species mapping across large biogeographical gradients. This study contributes to the improvement of tree species mapping based on optical and dual-polarimetric data and thus benefits forest authorities and other stakeholders in their monitoring tasks and decision-making.

Climate sensitivity alteration of the Middle Sikhote-Alin main conifer species

Climate sensitivity alteration of the Middle Sikhote-Alin main conifer species

Drought- and heat-induced mortality of conifer trees is explained by leaf and growth legacies.

An increased frequency and severity of droughts and heat waves have resulted in increased tree mortality and forest dieback across the world, but underlying mechanisms are poorly understood. We used a common garden experiment with 20 conifer tree species to quantify mortality after three consecutive hot, dry summers and tested whether mortality could be explained by putative underlying mechanisms, such as stem hydraulics and legacies affected by leaf life span and stem growth responses to previous droughts. Mortality varied from 0 to 79% across species and was not affected by hydraulic traits. Mortality increased with species' leaf life span probably because leaf damage caused crown dieback and contributed to carbon depletion and bark beetle damage. Mortality also increased with lower growth resilience, which may exacerbate the contribution of carbon depletion and bark beetle sensitivity to tree mortality. Our study highlights how ecological legacies at different time scales can explain tree mortality in response to hot, dry periods and climate change.

Seasonal patterns of nonstructural carbohydrate storage and mobilization in two tree species with distinct life-history traits.

Nonstructural carbohydrates (NSC) are essential for tree growth and adaptation, yet our understanding of the seasonal storage and mobilization dynamics of whole-tree NSC is still limited, especially when tree functional types are involved. Here, Quercus acutissima Carruth. and Pinus massoniana Lamb, with distinct life-history traits (i.e. a deciduous broadleaf species vs an evergreen coniferous species), were studied to assess the size and seasonal fluctuations of organ and whole-tree NSC pools with a focus on comparing differences in carbon resource mobilization patterns between the two species. We sampled the organs (leaf, branch, stem and root) of the target trees repeatedly over four seasons of the year. Then, NSC concentrations in each organ were paired with biomass estimates from the allometric model to generate whole-tree NSC pools. The seasonal dynamics of the whole-tree NSC of Q. acutissima and P. massoniana reached the peak in autumn and summer, respectively. The starch pools of the two species were supplemented in the growing season while the soluble sugar pools were the largest in the dormant season. Seasonal dynamics of organ-level NSC concentrations and pools were affected by organ type and tree species, with above-ground organs generally increasing during the growing season and P. massoniana roots decreasing during the growing season. In addition, the whole-tree NSC pools of P. massoniana were larger but Q. acutissima showed larger seasonal fluctuations, indicating that larger storage was not associated with more pronounced seasonal fluctuations. We also found that the branch and root were the most dynamic organs of Q. acutissima and P. massoniana, respectively, and were the major suppliers of NSC to support tree growth activities. These results provide fundamental insights into the dynamics and mobilization patterns of NSC at the whole-tree level, and have important implications for investigating environmental adaptions of different tree functional types.

Genome-wide identification and expression analysis of ARF gene family in embryonic development of Korean pine (Pinus koraiensis)

BackgroundThe Auxin Responsive Factor (ARF) family plays a crucial role in mediating auxin signal transduction and is vital for plant growth and development. However, the function of ARF genes in Korean pine (Pinus koraiensis), a conifer species of significant economic value, remains unclear.ResultsThis study utilized the whole genome of Korean pine to conduct bioinformatics analysis, resulting in the identification of 13 ARF genes. A phylogenetic analysis revealed that these 13 PkorARF genes can be classified into 4 subfamilies, indicating the presence of conserved structural characteristics within each subfamily. Protein interaction prediction indicated that Pkor01G00962.1 and Pkor07G00704.1 may have a significant role in regulating plant growth and development as core components of the PkorARFs family. Additionally, the analysis of RNA-seq and RT-qPCR expression patterns suggested that PkorARF genes play a crucial role in the development process of Korean pine.ConclusionPkor01G00962.1 and Pkor07G00704.1, which are core genes of the PkorARFs family, play a potentially crucial role in regulating the fertilization and developmental process of Korean pine. This study provides a valuable reference for investigating the molecular mechanism of embryonic development in Korean pine and establishes a foundation for cultivating high-quality Korean pine.

Checklist of Macrofungi Associated with Nine Different Habitats of Taburno-Camposauro Massif in Campania, Southern Italy.

The checklist serves as an informative method for evaluating the diversity, geography, and ecology of established and reproducing macrofungi. Additionally, considering macrofungi as bioindicator species, their census should be incorporated into efforts to monitor the state of health of ecosystems and directly applied to conservation policies. Between 2019 and 2023, a census of macrofungal species was conducted in Taburno-Camposauro Regional Park (Campania, Italy) across nine distinct habitats. A total of 453 fungal taxa were identified, including several new records for the Campania region. The fungal diversity exhibited significant variations based on the dominant plant species in each habitat. Fagacean tree species and Carpinus spp. shared similar fungal communities. Equally, coniferous tree species displayed a comparable fungal composition. In Abies alba and mixed broad-leaved forests, low levels of ectomycorrhizal taxa were observed alongside a concurrent increase in saprotrophs, indicating a disturbed habitat and a reduction in the Gadgil effect. Notably, lower fungal diversity was documented in the grassland habitat, suggesting the potential implications of wildlife imbalance and excessive grazing. The provided checklist constitutes a valuable resource for local management authorities, providing insights to formulate specific management policies.

Regional differences in stem form between southern and northern red spruce (Picea rubens Sarg.) populations

Abstract Red spruce (Picea rubens Sarg.) is a commercially and ecologically important conifer species that primarily exists at northern latitudes of eastern North America and extends southward following the Appalachian Mountains into North Carolina and Tennessee. Due to a warming climate and human-caused disturbances, only fragmented, sky-island populations remain at the highest peaks of the southern Appalachians where their habitat continues to be threatened. While they have been recognized for the rare wildlife habitat they provide in the region, these populations remain understudied. This work aimed to examine differences in stem form between the northern and southern populations of red spruce and to provide additional quantitative methods for managing red spruce stands through providing regionally fitted stem taper models. First, we examined differences in stem form using two methods: a sectional rate of change in diameter and a region variable added to the Kozak (2004) Model 02 taper model. The sectional taper comparison showed significant differences (P < .05) in taper rate throughout the stem that were most pronounced below breast height and above the midpoint. The nested model comparison also showed a significant difference after performing a likelihood ratio test. These results agreed that significant differences in stem form between the two populations exist and supported the idea that localized taper models would provide the best results. Next, we evaluated four stem taper models for their ability to predict upper stem diameters and total volume in southern Appalachian red spruce: a quadratic polynomial, a segmented, a variable exponent, and a geometric model. Fitting data came from a 1992 study across three southern Appalachian spruce-fir sites. Validation data came from a new dataset collected in 2022 at Unaka Mountain, Tennessee. Based on past studies and our results, we found that the Kozak (My last words on taper equations. For Chron 2004;80:507–15. https://doi.org/10.5558/tfc80507-4.) Model 02 variable exponent and the Max and Burkhart (Segmented polynomial regression applied to taper equations. For Sci 1976;22:283–9.) segmented polynomial models performed equally well. The choice of the final model should depend on the users’ objectives and practical limitations (i.e. programming ability, availability of fitting data, error tolerance).

Detecting changes in industrial pollution by analyzing heavy metal concentrations in tree-ring wood from Romanian conifer forests

The impact of air pollution on forests, especially in urban areas, has been increasingly discussed recently. Many pollutants, including heavy metals, are released into the atmosphere from various sources, such as mining, non-ferrous metal processing plants, and fossil fuel combustion. These pollutants can adversely affect not only tree growth but also other species, including humans.This study compared the concentrations of several elements in tree-ring wood from two conifer species (Silver fir, Abies alba; Norway spruce, Picea abies) growing in polluted and unpolluted areas. Two regions in northern Romania (Bicaz and Tarnița) that were subjected to historical pollution changes were selected. Two chemical analyses were used: inductively coupled plasma mass spectrometry (ICP-MS) and X-ray fluorescence spectrometry (XRF).The silver fir trees from the intensively polluted area in the Tarnița region were negatively impacted by industrial pollution: the Mn concentrations were, on average, three times higher in polluted areas than in unpolluted areas (ca. 30 vs. 10 mg kg−1). This finding was consistent for both ICP-MS and XRF analyses. However, in Norway spruce, this difference was found only in the XRF data, which detected Mn concentrations seven times higher in trees from polluted areas than those from unpolluted areas (ca. 700 vs. 100 mg kg−1). In the Tarnița region, Norway spruce accumulated more heavy metals than silver fir, but the most pronounced differences between polluted and unpolluted areas were found in silver fir.The two analytical methods are commonly used to determine metal concentrations in wood, and they complement each other, with ICP-MS having a low detection limit for some elements and XRF having higher detection limits and better accuracy. Each method has its advantages and disadvantages, and the optimal method depends on many factors, such as the type of heavy metal analyzed, its concentration in wood, sample type, cost, analysis time, and sample preparation.

Postfire reproduction of a serotinous conifer, the giant sequoia, in the Nelder Grove, California.

The giant sequoia, a serotinous conifer naturally occurring in mixed-conifer forests of the southern and central Sierra Nevada, California, USA, is the world's largest tree species. Giant sequoia reproduction has been severely lacking over the past century, due to fire exclusion, creating a significant conservation threat. Previous research on postfire sequoia reproduction in high-severity fire areas, relative to low- and moderate-severity areas, is limited. At 6 years postfire, we investigated giant sequoia reproduction in a high-severity fire area, and nearby low-/mixed-severity fire areas, in the Nelder Grove, which burned in 2017 in the Railroad fire. Postfire giant sequoia reproduction was positively correlated with fire severity in terms of density, height (growth), and proportion (relative to other conifer species), and sequoia seedling/sapling density was positively correlated with percent shrub cover. There was no correlation between distance to live sequoia seed source and density of sequoia reproduction. More research is needed in other mixed-severity fire areas, with larger high-severity fire patches, to determine whether a similar postfire response occurs elsewhere.

Assessing the Relationship between Tree Growth, Crown Size, and Neighboring Tree Species Diversity in Mixed Coniferous and Broad Forests Using Crown Size Competition Indices

Competition among trees for limited resources (e.g., sunlight, water, and nutrients) impacts their growth differently. Crown plays a crucial role in resource access for trees. However, uncertainties persist regarding crown size differences, tree growth, and tree competition levels between coniferous and broadleaf trees in mixed-age forests. We conducted a study on 3008 live trees across 28 plots in Hunan Province to measure individual crown size and tree growth increment. Introducing a new metric, the Crown Size Competition Index (CSCI), we assessed competition pressure among coniferous and broadleaf species in mixed-age forests. We examined the correlation between competition indices and tree growth increment while also investigating the influence of neighboring species diversity on tree competition. Our results revealed a significant negative correlation between the tree growth of Cunninghamia lanceolata (Lamb.) Hook.(CL) and Phoebe bournei (Hemsl.) Yang (PB) and the competition index. Increased competitive pressure on the focal tree corresponded to a decline in the growth of focal tree volume, with a more pronounced impact observed in PB compared to CL. The diversity of neighboring species contributed to variations in competition for the focal tree, with broadleaved species (PB) exerting a greater influence on the focal tree than coniferous species (CL). These findings underscore the competitive potential of PB in mature coniferous stands and advocate for the restoration of stratified mixes in CL broadleaf forests. Furthermore, our findings support the management strategies for the valuable tree species PB.

Seasonal dynamics of photosynthetic pigments (chlorophylls a, b and carotenoids) in woody plants of the Altai Botanical Garden

This article reflects the results of studies of photosynthetic pigments (chlorophylls a, b and carotenoids) in 14 species of deciduous plants (trees and shrubs) and one coniferous Juniperus sabina L. in the Altai Botanical Garden during two growing seasons. The following species have a high accumulation of pigments: Acer tataricum L., Juglans cinerea L., Tilia cordata L., Corylus avellana L., Cotoneaster lucidus Schlecht., Lonicera tatarica L. For the coniferous species Juniperus sabina L. low levels of chlorophylls a, b and carotenoids are characteristic. Berberis thunbergii DC is also distinguished by a low accumulation of photosynthetic pigments. Minor differences between the species were noted in the content of carotenoids, twelve species were included in the group with low and medium content of this pigment. There is no definite pattern in the accumulation of carotenoids, and the data on the types and number of yellow pigments do not differ significantly. As a result of the conducted studies, a correlation was revealed between the content of carotenoids and the content of chlorophyll a in most species. The data obtained indicate the presence of species specificity in the content of chlorophylls a, b and carotenoids. Also, the photosynthetic apparatus of woody plants is sensitive to light and water conditions

Long-Term Successional Subculture Dynamics and Their Effects on the Proliferation Efficiency, Embryogenic Potential, and Genetic Stability of Embryogenic Tissues in Larix principis-rupprechtii Mayr

Larix principis-rupprechtii Mayr, a coniferous species indigenous to Northern China, possesses significant ecological and economic value. Somatic embryogenesis offers a pathway with significant potential for large-scale propagation, long-term germplasm conservation, and genetic transformation in L. principis-rupprechtii Mayr. However, it remains unclear whether significant variations occur in embryogenic tissues during long-term successive subculturing, which could impact the productivity of somatic embryos. This is a pivotal concern that lacks comprehensive understanding. In this study, three embryogenic cell lines were used to explore the dynamics and relationships among proliferation rate, pre-treatment proliferation rate, and embryogenic capabilities across a series of 32 subculturing cycles. Proliferation rate, pre-treatment proliferation rate, and somatic embryo maturation rate showed no significant correlation with subculturing cycles. However, there was a positive correlation between subculturing cycles and pre-treatment proliferation rate and a negative correlation with somatic embryo maturation rate in the BFU1 cell line. In addition, we utilized ten SSR molecular markers to investigate the genetic stability in embryogenic tissues during long-term subculturing. No genomic variations were detected in any of the three embryogenic cell lines, which suggests that the observed phenotypic dynamics during subculturing may not be primarily driven by genomic alterations. This study provides novel insights into the dynamics of the long-term culture of embryogenic tissues, laying a foundation for the optimization and application of somatic embryogenesis techniques in L. principis-rupprechtii Mayr and potentially other coniferous species.

ПИРОГЕННАЯ МОДИФИКАЦИЯ СОСНОВОГО ДРЕВОСТОЯ В ЗАПОВЕДНИКЕ «ДЕНЕЖКИН КАМЕНЬ»

The features of the implementation of the initial stage of restoration of mossy pine after the passage of a grass-roots fire below average intensity are considered. The research was conducted three years later, after the fire occurred. Fires are not uncommon in the “Denezhkin Kamen” Nature Reserve, but there is a tendency to decrease the intensity of fires and the size of burned areas due to improved fire protection. The fire made minor changes to the structure of the stand. First of all, the changes affected the undergrowth and the thin layer of dark coniferous species. Quantitative indicators of the whole stand (before the fire) and the preserved one are given. The complete disappearance of the thin layer of fir and its younger generations is noted. The loss of spruce, which was actively introduced into the composition of the stand, was very significant, especially there were a lot of its thin-gauge and shoots. Also, like all dark conifers, there is a significant decrease in cedar. It is shown that the total loss of the stand is small, 88.5 % of the number of trees of the past (before the fire) stand has been preserved from the former stand. It was found that the natural generation of the stand of the trial area is taking place with the active participation of new species (Willow) and aspen, which replaced fir, which was previously in the minority. There was no renewal of larch. Pine remained the dominant species on the permanent trial area, it has not lost its importance as the main forest-forming breed, but its serious competition with aspen is expected in the future. It is also supposed to introduce dark coniferous species into the stand, which in the process of ontogenesis will influence the course of the forest formation process with their possible sodomination with light coniferous and deciduous species in the long absence of fires. Such a transformation of plantings is characteristic of poorly destroyed communities with preserved dominants and a liberated ecotope.

Environmental changes in the Eastern Arctic during the Early Gelasian Age: Palynological Data from Lake El'gygytgyn

The 2.373-2.510 Ma BP (isotopic stages 92-99; Early Gelasian Age) interval of the palynological record from Lake El'gygytgyn, northern Chukotka, includes 9 pollen zones characterizing interglacial, interstadial, and glacial plant communities. The boundaries of pollen zones and isotope stages in some cases do not correspond, indicating that the age model developed for the El'gygytgyn core requires revision. Between 2.373 and 2.510 Ma, the warmest climate occurred during MIS93, when larch forests, which included dark coniferous species, spread across the region. Alnus hirsuta (Spach) Turcz. ex Rupr., Chosenia arbutifolia (Pall.) A. K. Skvortsov, and Populus suaveolens Fish. dominated the gallery forests of the river valleys. The development of grass-shrub tundra and larch forest-tundra is associated with periods of climatic cooling, with the coolest conditions occurring at the beginning of MIS97. The consistent presence of Larix pollen throughout the Early Gelasian indicates that even in harsher climatic conditions, larch forest-tundra persisted in the areas of the Anadyr Plateau and Lake El'gygytgyn.