Climatic variation is inherently linked with tree phenology; however, phenological triggers depend on species and habitat. We analyzed key climatic factors for the onset of secondary growth for Scots pine (Pinus sylvestris L.) at the southern limit of its distribution in Siberia. From direct observations of developing tree rings, seasonal curves of the number of cells in the cambial zone, in the cell-expansion zone, and the total number of xylem tracheids were developed over seven years with a wide variety in the phenological dates. We found that later and shorter intervals of these stages of xylogenesis were compensated by higher maximums of kinetics curves, probably due to higher temperatures and daylengths during the respective phenophases. Air temperature and soil temperature at a depth of 20 cm converged to values (mean ± SE) 6.6 ± 0.9 °C (air) and 3.7 ± 0.4 °C (soil) for a 15-day interval prior to cambial activity onset. Date of Tsoil ≥ 3.5 °C was most closely related to cambial activity onset (r = 0.99) and preceded it by 9.6 ± 1.1 days. Cumulative temperature sums were less reliable. Apparently, both air and soil temperature thresholds have to be reached for cambial division to start in this species-habitat combination. Late abundant snowfall can yield divergence between air and soil temperatures and delay the onset of xylogenesis.

Long-term observations of the seasonal growth of Scots pine (Pinus sylvestris L.) tree rings in the arid conditions of the Khakass-Minusinsk Basin (southern Siberia) revealed that in 2024, trees had formed a tree ring with a typical intra-annual density fluctuation (IADF) in the transition wood. An analysis of the timing and causes of this wood structure anomaly was conducted using a combination of three approaches: (1) analyzing images of cross-sections of the forming tree ring throughout the season; (2) comparing the timing of anomalous cells’ differentiation with daily climate data; (3) comparing seasonal growth observations with calculated characteristics of the modeled growth rate and its derivatives: soil moisture and transpiration. We found that during the most severe heat wave and drought (from 22 June to 9 July), the last normal earlywood cells were yet expanding, IADF cells were being produced in the cambial zone, and the first of them began expansion, while normal cells began being produced again immediately after the subsiding of environmental stress. Apparently, low soil moisture and very high temperatures mainly impacted cells in the cambial zone, marking it as the primary target of external factors influencing tree-ring formation and structure, which is important for dendroclimatology and digital wood anatomy. This result is supported by both indirect and limited direct evidence from other sources.

Chromium (Cr) and nickel (Ni) are different from many other elements, having a strong and consistent association in the xylem of Scots pine. On average, one atom of Ni corresponds to 2–3 atoms of Cr. This association cannot be explained by the content of the elements in mobile chemical forms in the soil. This study examined possible explanations of the observed phenomenon. The research materials included soil samples in the research area and at the places of wood sampling in two populations of Scots pine. Chemical analysis was performed with the help of atomic emission spectral analysis. The results show no anomalies in Cr and Ni contents in the soils. Despite an even level of Cr and Ni, their variations among trees are quite wide. The association of Cr and Ni in xylem is reversed with respect to their content in mobile (bioavailable) forms. The association is consistent between the pine populations. Two hypotheses evaluated included: (1) a possible negative correlation between the rate of stem growth and the lignin content, and (2) an ability of Cr and Ni atoms to bond in the xylem. As of yet, no single plausible explanation can fully account for the observation. Disentangling this association will require more penetrating approaches such as electron microscopy and structural analysis.

The response of trees to extreme events, including volcanic eruptions, varies depending on environment, species and tree-ring trait analyzed. We recently reported severe and long-lasting growth suppression and wood-anatomical anomalies in Pinus sibirica Du Tour and to the lesser degree Larix sibirica Ledeb. from the Altai-Sayan mountainous region, likely linked to tropical volcanic eruption in 1695 CE. In this study, we examine a broader range of species and tree-ring markers to climate impacts of volcanic events. We compare tree-ring data of various conifers and environmental proxies obtained from open repositories and test a hypothesis that among them, P. sibirica and similar pine species from Strobus subsection are particularly vulnerable to such events. Comparison of tree-ring, earlywood and latewood width and wood density of several species and a wide range of habitats in continental temperate Asia after the volcanic eruption in 1695 CE supports our hypothesis, and anatomical measurements of sensitive P. sibirica demonstrate this reaction at the cell scale. A similar tree-ring reaction was found in Pinus cembra L. from the European Alps after the Tambora eruption in 1815 CE, and contrasted with a milder reaction in Larix decidua Mill. We found different patterns of wood growth and structure in moisture-limited stands of P. sibirica and Pinus armandii Franch., which highlights the habitat-conditional nature of such tree-ring reactions to volcanic events.

Stand density is one among a multitude of factors impacting the growth of trees and their responses to climatic variables, but its effect on wood quality at the scale of anatomical structure is hardly investigated. Therefore, we analyzed the radial growth and wood structure of Siberian spruce (Picea obovata Ledeb.) and Scots pine (Pinus sylvestris L.) in an experimental conifer plantation with a wide gradient of stand density in the Siberian southern taiga. The measured and indexed chronologies of the tree-ring width (TRW), number of tracheid cells per radial row in the ring produced in the cambial zone (N), cell radial diameter (D), and cell wall thickness (CWT) demonstrated the influence of the planting density. The TRW and N have a negative allometric dependence on the stand density (R2 = 0.75–0.88), likely due to competition for resources. The consistent negative dependence of the D on the stand density (R2 = 0.85–0.97) is log-linear and also seems to be related to tree size, while the CWT is not significantly dependent on the stand density. These findings can be used as insights in regulating cellular structure and procuring desired wood quality by silvicultural means. Both conifer species have similar climatic reactions. We observed significant suppression of TRW and D related to water deficit in May–July (both species), as well as frosty (more for pine) and low-snow (for spruce) conditions in winters, as shown by both dendroclimatic correlation and pointer year analysis. Temporal shifts in the climatic responses indicate later transition to latewood and growth cessation in sparse stands, especially in spruce. Better performance was observed in sparce and medium-density stands for both species.

Tree-ring width chronologies of Pinus sibirica Du Tour from near the upper treeline in the Western Sayan, Southern Siberia are found to have an exceptional (below mean–3SD) multi-year drop near 1700 CE, highlighted by the seven narrowest-ring years in a 1524–2022 regional chronology occurring in the short span of one decade. Tree rings are sometimes applied to reconstruct seasonal air temperatures; therefore, it is important to identify other factors that may have contributed to the growth suppression. The spatiotemporal scope of the “nosedive” in tree growth is investigated with a large network of P. sibirica (14 sites) and Larix sibirica Ledeb. (61 sites) chronologies, as well as with existing climatic reconstructions, natural archives, documentary evidence (e.g., earthquake records), and climate maps based on 20th-century reanalysis data. We conclude that stress from low summer temperatures in the Little Ice Age was likely exacerbated by tree damage associated with weather extremes, including infamous Mongolian “dzuds”, over 1695–1704. A tropical volcanic eruption in 1695 is proposed as the root cause of these disturbances through atmospheric circulation changes, possibly an amplified Scandinavia Northern Hemisphere teleconnection pattern. Conifer tree rings and forest productivity recorded this event across all of Altai–Sayan region.

Tree xylem formation is highly dependent on non-structural carbohydrates content and microenvironments. However, it is still less well understood how the key variables regulate cambial activity and xylem formation under different environmental conditions, or the specific contribution of each variable to the number of cells in different stages of xylogenesis. Here, we monitored the xylogenesis and xylem non-structural carbohydrates dynamics of Picea crassifolia during the growing seasons of 2021 and 2022 along an altitude gradient in the Qilian Mountains. We found that the date of maximum cell production rate was about a week later in 2021 than in 2022, and that was later at 2950 and 3200 m than at 2700 m. High altitude sites developed significantly more cambial cells, driving substantially higher cell production rates. Notably, non-structural carbohydrates remained stable early in the growing season before accumulating to peak levels in 2021, whereas 2022 showed a pronounced decrease followed by recovery. The altitude-independent contrast reveals seasonal non-structural carbohydrates dynamics, as the 2022 decline connects stored carbohydrates to sustained xylem formation under drought stress. Linear mixed-effects models showed that, in 2021, cambium cells were predominantly influenced by soil water content and tree individuality, enlargement cells primarily by air temperature (AT), wall-thickening cells by both air and soil temperatures, and the rates of cell production were most significantly affected by AT, soil temperature, and tree individuality. However, in 2022, the cambium cells enlargement cells, and cell production rates were constrained by starch and soluble sugars, while the wall-thickening cells were limited primarily by soluble sugars. Our findings demonstrate that drought triggers a physiological transition from environmental to non-structural carbohydrates mediated control of xylogenesis, highlighting the critical role of carbon reserves for tree resilience in arid regions.

In this study we analyzed the tree growth and the wood anatomical parameters of Picea obovata Ledeb. in an even-aged plantation in the southern taiga, Central Siberia. The samples were collected from six plots having planting densities from 750 to 96,000 trees/ha. Cell radial diameter (CRD) and cell wall thickness (CWT) were measured for the years 2000-2020. The chronologies of maximum and mean CRD and CWT were compared with the number of cells per radial row in the ring (N), tree-ring width (TRW) and basal area increment (BAI). Porosity of the wood was also calculated from CRD and CWT. A significant (p < 0.05) log-linear decrease in CRD with planting density was recorded. In the dense stands, calculated theoretical optimal values of CRD (average CRD for wide rings) were lower, and narrow rings (N < 50 cells) with suppressed CRD occurred frequently. An increase in optimal CWT with planting density was not significant. Suppressed CWT occurred only in the narrowest rings (N < 20 cells). This pattern was considered to be driven by: (1) hydraulic requirements to CRD being related to stand density through tree height, (2) requirements to CWT for safety of water conduction not depending on stand density; (3) legacy effect under stress, i.e., growth suppression at the stage of cell production impacting further cell differentiation. The positive relationship of latewood ratio with planting density, and the formation of less porous wood in dense stands as result of the variation in the anatomical structure has also been observed in previous studies. A more detailed analysis of tracheidograms (intra-seasonal curves of anatomical parameters) is suggested for further research to resolve ambiguity in relationships between stand density and wood anatomy.

For dendrochemical research, it may be important to be aware of the effects of stem asymmetry and the intra-ring structure because these may introduce unwanted dispersion in the results. In dendrochemical studies, separate analysis of the elemental content of early- and latewood is rare. Also, explanations of how the elemental content may relate to stem asymmetry originating from conditions at the edges of contrasting environments are largely lacking in these studies. The purpose of the current study was to estimate the impact of the seasonal tree ring structure and stem asymmetry on the distribution of elements in tree stems. The study population was a plantation of Scots pine (Pinus sylvestris L.) at an afforestation experiment area, with the sample trees being at the edge of the stand, causing strong crown asymmetry. Six pine trees were cored through the thickness from the maximal crown side (max-side) to the minimal crown side (min-side), and the cores were subsequently scanned through an Itrax Multiscanner unit. The count rates of aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), chlorine (Cl), calcium (Ca), iron (Fe), copper (Cu), zinc (Zn), and strontium (Sr) in the tree rings from 1990 to 2022 were analyzed. A group of elements (Al, Si, P, S, and Cl) tended to consistently concentrate on the min-side, both in early- and latewood, the difference being most significant for S and Cl. Regarding early- vs. latewood, Al, Si, P, S, Cl, Cu, and Zn always had lower concentration in earlywood than in latewood, while others (Ca, Fe, and Sr) had lower concentrations in latewood, the relations being consistently significant. Overall, the role of the min- or max-side of the stem in allocation of elements appears to have been weaker that the intra-ring structure (early- and latewood). Some elements such as Al, Si, P, S, Cl, and Ca (in latewood) were often more abundant on the min-side; other elements such as Fe and Sr (in latewood) were often more abundant on the max-side, but these relations were significant only on rare occasions. Intra-ring heterogeneity (in early- and latewood) appears to be more decisive than the asymmetry of the tree stem in regard to the distribution of elements in Scots pine xylem. Nevertheless, tree stems with high and obvious asymmetry should be more extensively explored because a possibility remains that extreme asymmetry does impact the allocation of elements.

Radial growth of trees is highly sensitive to environmental changes, but the effect of climate on tree rings in Qinghai spruce (Picea crassifolia), a widely distributed endemic conifer in western China, is more complex than in many other conifers. A comprehensive understanding of the spatiotemporal climatic responses of its rings is needed to develop theoretical basis for designing strategies for its conservation and management. Here, our synthesis of the literature on responses of radial growth of Qinghai spruce to monthly climate variables in different environmental conditions by meta-analysis showed that precipitation and drought severity are the main limiting factors for Qinghai spruce radial growth in the semiarid region of northwestern China. In warmer and drier areas, radial growth of Qinghai spruce is mainly limited by drought. In the areas north of the 600-mm annual precipitation isoline, the tree-ring width (TRW) was significantly positively correlated with precipitation and significantly negatively correlated with temperature during the growing season (June–August). The limiting effect of drought on Qinghai spruce is also gradually increasing from southeast to northwest, to the west of 103° E and within 37° N–39° N.

Understanding why elements are distributed in tree xylem in a particular way is a significant challenge in dendrochemistry. This study explored a hypothesis that metal elements in the xylem interact due to differences in physical properties such as ionic radius and ionization potential. Scots pine in an even-aged stand established during the early 1970s in eastern Siberia was the study species. Increment cores were taken from the north and south sides of trees and scanned with an X-ray fluorescent multi scanner. With the help of X-ray scanning, the following elements were analyzed: aluminum (Al), potassium (K), calcium (Ca), titanium (Ti), manganese (Mn), iron (Fe), copper (Cu), strontium (Sr) and zinc (Zn). Scanning data on the elements were split into early-wood and late-wood data for each year of growth. The following ratios were analyzed: Ca/Sr, Fe/Ca, Fe/Sr, Al/Cu, Al/Zn, Ti/Mn, and Mn/K. Among these, ones having a consistent pattern across tree rings, the ratios show a more or less dependable relationship: that an element shows a larger decrease (relative another element) that has a larger ionic radius and lower ionization potential. Hypothetically, this may be due to the advantage of an ion with smaller ionic radius and higher ionization potential under a deficit of accommodation centers in organic molecules. An experiment approach should be applied to clarify the relationships.

We propose an improved exponential equation for the nonlinear dependence of cell measurements on the seasonal cell production in conifer wood. These changes shall simplify the model towards ease in understanding, interpretation and analysis. With methodological development, quantitative parameters of wood cellular structure have featured as dendroclimatic indicators in various studies. But to disentangle climatic impacts in different wood anatomical characteristics, relationships between them have to be described quantitatively and extricated. This study investigates exponential description of the non-linear dependences of conifer wood cell measurements on their seasonal production in cambial zone. Improvement to the equation of exponential model was suggested, simplifying the interpretation and analysis and providing biological meaning to all numerical parameters of the model. This new equation was demonstrated for 630 tree rings from 20 to 40-year-old trees of Siberian spruce (Picea obovata Ledeb.) in Siberia, collected at the experimental plantation, as well as for its subsets from plots of various planting density, demonstrating plausible value of the new proposed numerical parameter of model and dependence of the other parameter on the stand density, probably based on the tree height. Limitation for successful fitting of this exponential model was demonstrated, based on representativity of wide and narrow rings within sample; we proposed possible way to overcome it in certain cases.

In mountains, the reactions of trees to climatic fluctuations and changes depend on various factors, including ecological gradients and species. This study investigates the radial growth of Siberian stone pine ( Pinus sibirica Du Tour), a widespread key conifer in the Siberian taiga, across its elevational range in the Western Sayan Mountains of Southern Siberia. Wood samples were gathered along three latitudinal-elevational transects spaced ca. 80-100 km apart from each other, spanning from west to east across the Western Sayan region. The midpoint of these transects coincided with a large reservoir on the Yenisei River. Each transect encompassed three distinct sites: the lower limit of species growth at 400-500 m a.s.l., a site located at 1700-2050 m a.s.l. near the upper forest line, and an intermediary site falling between these boundaries. A spectacular synchronicity was observed in TRW residual chronologies ( R =0.56-0.78 over 1936-2010) and their climatic responses across all sites near the upper forest line and 200-300 m below it. In these areas, temperatures showed a predominantly positive impact from the previous July-August to the current August, except for the end of March-April. The negative influence of excess precipitation during these seasons decreased from west to east, whereas early spring precipitation exhibited a positive correlation with TRW. At the lower limit of growth, the TRW chronologies of species showed lower correlation values between each other ( R =0.26-0.36). Here, the species exhibited a positive impact of annual precipitation and a negative influence of temperature, particularly in the previous August and current May-June, albeit of varying intensities. At the mid-montane site, located at 300-500 m above the lower limit of species growth, a mixed climatic influence was observed with a positive response to annual temperatures and June precipitation. Further, the pointer years of the maximum or minimum indexed TRW also occurred much more synchronously in highland forests. The observed shifts in climatic responses indicated that climate warming has advanced the onset of vegetation and delayed the dormancy in these regions. The majority of the Siberian stone pine stands under consideration showed a positive response to warming. Interestingly, an absence of steady growth decline, even in the foothills, indicated a non-climatic range border. The study approach allowed us to recognize with daily resolution annual and seasonal climatic variables impacting stone pine growth that can be probably reconstructed on a local (precipitation) or regional (temperature) scale. This study enhanced the understanding of climate-growth relationships in P. sibirica , offering insights into the species' resilience and vulnerability across ecological gradients in response to changing climatic conditions.

An understanding of how boreal forest composition responds to global environmental changes is an important challenge to predicting the future global carbon balance. Boreal forests are the most significant sink for atmospheric carbon dioxide; however, their sequestration capacity is highly sensitive to ongoing climate changes. The combination of the hydrothermal conditions of a territory strongly regulates its biogeochemical processes. The carbon fluxes in boreal forests are strongly mediated by the ground vegetation cover, composed of mosses (mesic) and lichens (xeric). Despite the concurrence of xeric and mesic vegetation types, their responses to climate variations varies significantly. Soil emission is an informative indicator of ecosystem functioning. In this study, we focused on the soil CO2 dynamics during frost-free seasons with different precipitation regimes in the xeric and mesic boreal ecosystems of Central Siberia. Seasonal measurements of soil CO2 emissions were conducted during frost-free seasons using the dynamic chamber method. Our findings reveal that the precipitation regimes of each year may control the seasonal soil emission dynamics. The soil moisture is the most important driver of emissions growth in the water-limited lichen pine forest (R2adj. = 18%). The soil temperature plays the largest role in the feather moss pine forest during the dry (R2adj. = 31%) seasons, and in the lichen pine forest during the wet (R2adj. = 41%) seasons. The cumulative efflux for the xeric and mesic sites is mostly related to the hydrothermal conditions, and not to the differences in ground vegetation cover. During the dry seasons, on average, the soil CO2 emissions are 45% lower than during the wet seasons for both sites. These findings emphasize the need for estimating and including the hydrothermal characteristics of the growing season for detailed emission assessments.

Boreal forests nowadays act as a sink for atmospheric carbon dioxide; however, their sequestration capacity is highly sensitive to weather conditions and, specifically to ongoing climate warming. Extreme weather events such as heavy rainfalls or, conversely, heat waves during the growing season might perturb the ecosystem carbon balance and convert them to an additional CO2 source. Thus, there is an urgent need to revise ecosystem carbon fluxes in vast Siberian taiga ecosystems as influenced by extreme weather events. In this study, we focused on the soil CO2 pulses appearing after the rainfall events and quantification of their input to the seasonal cumulative CO2 efflux in the boreal forests in Central Siberia. Seasonal measurements of soil CO2 fluxes (both soil respiration and net soil exchange) were conducted during three consecutive frost-free seasons using the dynamic chamber method. Seasonal dynamics of net soil exchange fluxes demonstrated positive values, reflecting that soil respiration rates exceeded CO2 uptake in the forest floor vegetation layer. Moreover, the heavy rains caused a rapid pulse of soil emissions and, as a consequence, the release of additional amounts of CO2 from the soil into the atmosphere. A single rain event may cause a 5–11-fold increase of the NSE flux compared to the pre-rainfall values. The input of CO2 pulses to the seasonal cumulative efflux varied from near zero to 39% depending on precipitation patterns of a particular season. These findings emphasize the critical need for more frequent measurements of soil CO2 fluxes throughout the growing season which capture the CO2 pulses induced by rain events. This approach has inevitable importance for the accurate assessment of seasonal CO2 soil emissions and adequate predictions of response of boreal pine forests to climatic changes.

Recent methodological advances in quantitative wood anatomy have provided new insights into the climatic responses of radial growth at the scale of cell structure of tree rings. This study considered long-term chronologies of tracheid measurements, indexed by a novel approach to separate their specific climatic responses from signal recorded in cell production (closely reflected in tree-ring width). To fill gaps in understanding the impact of climate on conifer xylem structure, Scots pine ( Pinus sylvestris L.) trees > 200 years old were selected within the forest-steppe zone in southern Siberia. Such habitats undergo mild moisture deficits and the resulting climatic regulation of growth processes. Mean and maximum values of cell radial diameter and cell wall thickness were recorded for each tree ring. Despite a low level of climatogenic stress, components of cell chronologies independent of cambial activity were separated to obtain significant climatic signals revealing the timing of the specific stages of tracheid differentiation. Cell expansion lasted from mid-April to July and was impacted similarly to tree-ring width (stimulated by precipitation and stressed by heat), maximum cell size formed late June. A switch in the climatic responses of mean anatomical traits indicated transition to latewood in mid-July. Secondary wall deposition lasted until mid-September, suppressed by end of season temperatures. Generally, anatomical climatic responses were modulated by a less dry May and September compared with summer months.

This methodological study describes the adaptation of a new method in digital wood anatomy, pixel-contrast densitometry, for angiosperm species. The new method was tested on eight species of shrubs and small trees in Southern Siberia, whose wood structure varies from ring-porous to diffuse-porous, with different spatial organizations of vessels. A two-step transformation of wood cross-section photographs by smoothing and Otsu’s classification algorithm was proposed to separate images into cell wall areas and empty spaces within (lumen) and between cells. Good synchronicity between measurements within the ring allowed us to create profiles of wood porosity (proportion of empty spaces) describing the growth ring structure and capturing inter-annual differences between rings. For longer-lived species, 14–32-year series from at least ten specimens were measured. Their analysis revealed that maximum (for all wood types), mean, and minimum porosity (for diffuse-porous wood) in the ring have common external signals, mostly independent of ring width, i.e., they can be used as ecological indicators. Further research directions include a comparison of this method with other approaches in densitometry, clarification of sample processing, and the extraction of ecologically meaningful data from wood structures.

The development of the tree ring is a process occurring under limitations caused by a complex of environmental factors and intrinsic regulatory mechanisms. Its understanding is of interest in many scientific fields, but most quantitative models trying to describe its details meet several issues stemming from the difficulty of its verification. This study attempted to combine several observational and modeling approaches to verify intermediate details of the description of xylogenesis, aiming to restore the tree-ring seasonal growth kinetics on the basis of dendrochronological and wood anatomical data. It was carried out for Scots pine in two semiarid habitats in South Siberia. The Vaganov-Shashkin model was used jointly with tree-ring width chronology and climatic data to model the tree radial growth rate with daily precision. The Band-model was then used to calculate the kinetics of tracheid production from the growth rate and actual final number of cells per radial file in the ring. Seasonal observations of cell population and final measurements of cell sizes were used to fit model parameters and verify the numbers of developing tracheids produced by the Band-model. The patterns of modeled seasonal kinetics for six seasons and two sites were found to repeat the actual drought-derived deviations in tree growth and observations (R2 = 0.70–0.84). Further research is required to test other climatic limitations and species-specific ecophysiological mechanisms of growth regulation.

Siberian pine (Pinus sibirica Du Tour) is a widespread and long-lived species in the northern hemisphere, which makes it a good potential proxy for climatic data. However, the tree-ring growth of this species weakly correlates with climatic conditions, which prevents its use in dendroclimatic reconstruction. It was proposed to use the measurements of tracheid characteristics as model predictors to reconstruct the smoothed temperature of the key periods in tree growth. In this study, algorithms for preprocessing tracheids and temperature data, as well as for model cross-validation, were developed to produce reliable high-resolution (weekly-based) temperature reconstructions. Due to the developed algorithms, the key time periods of Siberian pine growth were identified during the growing season—early June (most active cell development) and mid-July (setting new buds for the next growing season). For these time periods, reliable long-term temperature reconstructions (R2 > 0.6, p < 10−8) were obtained over 1653–2018. The temperature reconstructions significantly correlated (p < 10−8) with independent reanalysis data for the 19th century. The developed approach, based on preprocessing tracheid and temperature data, shows new potential for Siberian pine in high-resolution climate reconstructions and can be applied to other tree species that weakly respond to climate forcing.

Soils of boreal forests are crucial carbon reserves. The response of soil carbon emission to climate change significantly affects the concentration of carbon dioxide in the atmosphere. Soil carbon emission models frequently show a nonlinear response to temperature, but soil moisture is an important limiting factor, often overlooked in energy limited ecosystems. We suggest a statistical model of soil CO2 emission constrained by soil moisture and temperature for different ecosystems in the boreal zone. We tested this modelling strategy using direct measurements of seasonal soil CO2 emission near the research observatory ZOTTO near the Bor settlement, Central Siberia, Russia, in 2012-2017. Soil moisture explained a significant amount of variability of soil emission: the adjusted R2 was twice higher than in the baseline model. Although the temperature-only model describes the annual variability of carbon dioxide emissions quite well, the addition of moisture measurement significantly refines the quality of prediction of the seasonal component dynamics. Models including both temperature and soil moisture could serve as a promising tool to analyze the carbon cycle in boreal forest ecosystems.