Global warming is most pronounced at high latitudes where temperatures increase twice as fast as the global average. Boreal forest growth is generally limited by low temperatures, so elevated temperature is supposed to enhance biomass production and carbon sequestration. A large amount of evidence has recently shown inconsistent responses of tree growth derived from annual tree rings to increasing temperature. We studied Siberian spruce growth in the remote and isolated Putorana Mts, Western Siberia in populations at its natural distribution limit. Tree ring cores were sampled along vertical transect in 100, 200 and 350 m a.s.l. as the aim was to identify the tree growth rate at different altitudes. Detailed sampling site descriptions served to identify possible factors controlling the growth rate in extremely heterogeneous environments. Monthly climate data for the period 1900–2020 were extracted from the gridded CRU database. Tree ring chronologies confirmed long-lasting limited growth, and despite high year-to-year ring width variability, synchronous growth at vertical study sites dominantly controlled by climate. The positive tree ring growth response to summer temperature was significant for most of the 20th century but dramatically changed in recent decades, when unusually warm summers were reported. There was no, or even a negative growth rate correlation with precipitation, which indicates a sufficient water supply at the study sites. Elevated temperature in this region with a continental climate might turn the study localities to water-limited areas with many negative consequences on tree growth and related ecosystem services.

Transpiration and sap flow are physiologically interconnected processes that regulate nutrient and water uptake, controlling major aspects of tree life. They hold special relevance during drought, where wrecked sap flow can undermine overall tree growth and development. The present study encompasses five-year (2012–2015 and 2017) sap flow datasets on European beech (Fagus sylvatica). Four different techniques were used for sap flow modeling, namely, a linear model (LM), random forest (RF), extreme gradient boosting machine (XGBM), and neural networks (NN). We used six variants (Variants 1–6) differing in the captured conditions and the dataset size. The ‘prediction power’ was the ratio of the predicted and observed sap flow. We found the LM had the maximum prediction power for the overall sap flow in beech trees with 1 h shift of global radiation. In the reaming variants, the LM provided comparable prediction power to RF and XGBM. At the same time, NN exhibited relatively poor prediction power over other machine learning models. The study supports an easier-to-apply and computationally simpler approach (LM) to assess sap flow over more sophisticated machine learning approaches (RF, XGBM, and NN).

Natural disturbances (windthrow, bark beetle, and fire) have reduced forest cover in the Tatra National Park (Slovakia) by 50% since the year 2004. We analyzed carbon fluxes and streamflow ten years after the forest destruction in three small catchments which differ in size, land cover, disturbance type and post-disturbance management. Point-wise CO₂ fluxes were estimated by chamber methods for vegetation-dominated land-use types and extrapolated over the catchments using the site-specific regressions with environmental variables. Streamflow characteristics in the pre- and post-disturbance periods (water years of 1965–2004 and 2005–2014, respectively) were compared to identify changes in hydrological cycle initiated by the disturbances. Mature Norway spruce forest which was carbon neutral, turned to carbon source (330 ± 98 gC m⁻² y⁻¹) just one year after the wind disturbance. After ten years most of the windthrow sites acted as carbon sinks (from −341 ± 92.1 up to −463 ± 178 gC m⁻² y⁻¹). In contrast, forest stands strongly infested by bark beetles regenerated much slowly and on average emitted 495 ± 176 gC m⁻² year⁻¹. Ten years after the forest destruction, annual carbon balance in studied catchments was almost neutral in the least disturbed catchment. Carbon uptake notably exceeded its release in the most severely disturbed catchment (by windthrow and fire), where net ecosystem exchange (NEE) was −206 ± 115 gC m⁻². The amount of sequestered carbon in studied catchments was driven by the extent of fast-growing successional vegetation cover (represented by the leaf area index LAI) rather than by the disturbance or vegetation types. Different post-disturbance management has not influenced the carbon balance yet. Streamflow characteristics did not indicate significant changes in the hydrological cycle. However, greater cumulative decadal runoff, different median monthly flows and low flows and the greater number of flow reversals in the in the first years after the windthrow in two severely affected catchments could be partially related to the influence of the disturbances.

In recent decades, large-scale forest disturbances such as windthrow and bark beetle infestations have significantly impacted Earth’s carbon balance and forest ecosystems. This impact alters soil respiration (SR), along with decreased gross primary productivity. To investigate the impact of bark beetle (Ips typographus L.) infestations in mountain spruce forests on SR, we measured SR at sites infested by bark beetles and adjacent undisturbed stands in the Tatra National Park (Slovakia) during the vegetation period (May–September) in 2016–2017 five to six years after the initial bark beetle attack. The measurements were taken along an altitudinal gradient (1100–1400 m a.s.l.). The highest rates of SR were observed during the summer months in both years (from June to August). However, yearly SR from May to September at infested sites showed significantly higher rates than uninfested ones in both years. SR showed a decreasing pattern with elevation gain in 2016 at infested sites, but this pattern was not observed in 2017. This study provides important insights into the impact of bark beetle infestations on SR and emphasizes the need for further research on the long-term effects of forest disturbances on carbon cycling. It also underscores the importance of determining the effect of different components of SR on the changed environment due to bark beetle attacks on mountain spruce forests.

The high ambient ozone concentrations cause impairing effects on vegetation leading to plant injuries. The potential ozone uptake to vegetation through open stomata can be quantified using stomatal conductance measurements under the local environmental conditions. This study compares the ozone stomatal conductance to vegetation obtained with a modified Jarvis formula adopted from the Vegetation Manual of United Nations Economic Commission for Europe, and experimental field measurements’ data. The stomatal conductance was measured by a portable photosynthesis and gas exchange analyzer system LiCOR6400. The measurements were performed in the submontane environment of the High Tatra Mountains in Slovakia on Swiss pine (Pinus cembra), as a native species of the local flora. According to previous studies, Swiss pine is considered as an ozone-sensitive species. The modified Jarvis model for the ozone stomatal conductance is compared with the field measurements. The suitable parameterization of the modified Jarvis model for Swiss pine is obtained. The parameterization of stomatal conductance for Swiss pine in the local environment would help understand its specificity and similarity to other conifer species. In the case of using parameterization for a boreal coniferous from the Vegetation Manual of the International Cooperative Programme on Effects of Air Pollution on Natural Vegetation and Crops, validation of the model with the measurements without temperature adjustment of the conifer chamber achieved a coefficient of determination of $R^2=0.75$. This result is not in contradiction with the previous researches. With the optimal set of parameters, obtained in this paper, the Jarvis model reaches $R^2=0.85$. The data suggest that Jarvis-type models with appropriate parameterization are applicable for stomatal conductance estimation for Pinus cembra when the measurements do not modify the temperature regime.

Heavy metals accumulate in forest soils worldwide, yet their effects on greenhouse gas dynamics remain poorly understood. Mycorrhizal fungi lie at the heart of this issue. These symbiotic organisms regulate carbon and nutrient flow between trees and soil, positioning them to influence fluxes of CO₂, N₂O, and CH₄. However, research on mycorrhizal ecology, metal toxicology, and greenhouse gas biogeochemistry has proceeded largely in isolation. This review bridges these fields through a conceptual framework built on three contamination scenarios and four mechanistic pathways. Our confidence in these mechanisms varies by gas: well-established for CO₂, developing for N₂O, and mostly inferential for CH₄. Critical gaps remain. Studies measuring mycorrhizal communities, metal availability, and gas emissions simultaneously are rare. Comparisons between ectomycorrhizal and arbuscular mycorrhizal systems are virtually absent. This framework establishes a basis for understanding how metal-contaminated forests regulate greenhouse gas exchange and identifies priority areas for future investigation.