Climate change occurs more rapidly at high latitudes, making polar ecosystems highly vulnerable to environmental changes. Plants respond to these conditions by altering the fluxes of water vapor (H2O) and carbon dioxide (CO2). This study analyzed the seasonal variability of the Net Ecosystem Exchange (NEE) of CO2, as well as the sensible (H) and latent (LE) heat fluxes, in two ecosystems in north-central Siberia: a subarctic palsa mire near Igarka, and a mature larch forest near Tura. The flux responses to variations in atmospheric parameters were also assessed. Experimental data were collected from 2019 to 2023 using eddy covariance methods. The results showed that both permafrost ecosystems consistently served as net atmospheric CO2 sinks during the growing seasons, despite significant year-to-year meteorological variations. From 2019 to 2023, summer NEE ranged from -62.9 to -120.2 gC m-2 in the Igarka palsa mire and from -63.5 to -83.6 gC m-2 in the Tura larch forest. During summer periods characterized by prolonged insufficient soil moisture, higher air temperatures, and limited precipitation, the palsa mire exhibited reduced CO2 uptake (i.e., less negative NEE) and Gross Primary Production (GPP) compared to the larch forest. These results suggest that larch forests may be more resilient to climate change than palsa mires. This resilience is primarily linked to deep-rooted water access and conservative stomatal control in larch, whereas palsa mire vegetation depends strongly on surface moisture availability. H and LE fluxes exhibited significant interannual variations, primarily due to variations in incoming solar radiation and precipitation. No significant LE decrease occurred during periods of low precipitation in 2019 and 2020 when drought conditions were observed at both stations during the summer. Maximum H and LE flux rates occurred in June and July when net radiation values were at their maximum for both ecosystems. These findings underscore the urgent need for ecosystem-specific climate strategies, as differential resilience could significantly impact future carbon dynamics in the rapidly warming Arctic.

Permafrost is increasingly vulnerable to thaw and collapse because of Arctic climate warming and wildfire activity. Arctic permafrost holds one third of global soil carbon (C) and large nitrogen (N) pools. A majority of permafrost organic matter is in the Russian Yedoma Domain. Soils in this remote region have high mineral soil C and N concentrations and massive, patterned ice wedges susceptible to degradation after disturbance. Yet, how Yedoma C and N pools will respond to the interaction of climate warming, wildfire, and permafrost thaw remains unknown. Here, we examined fire and permafrost thaw impacts in the Yedoma Domain of far northeast Siberia forests burned in 2001. We measured C and N pools, soil characteristics, and foliar chemistry and productivity. We found burning reduced soil organic layer depth, promoted active layer deepening, and initiated ground subsidence. Active layer permafrost thaw resulted in a 50% reduction in soil C pools in the top 125 cm, supported by evidence of increased decomposition from soil C isotope signatures and declining C:N. Burning and subsidence similarly diminished total soil N pools 50%, labile N pools 75%, and foliar N. Foliar N isotope signatures became more depleted after disturbance, suggesting greater reliance on mycorrhizal uptake and/or NO3-. Collectively, permafrost thaw mobilized soil organic matter, reducing soil C storage, N pools, and overall nutrient capital. Permafrost collapse is not only a significant atmospheric C source but N cycle restrictions could further diminish long-term C sequestration potential which balances permafrost C loss as the ecosystem recovers from disturbance.

Siberia occupies vast areas underlain by permafrost, and understanding its land cover changes is important for ecological environmental protection in a warming climate. Based on the land cover and climate datasets, we analyzed the land cover changes and their drivers in Siberia from 1992 to 2020. The results show that (1) From 1992 to 2020, the areas of evergreen needleleaf trees and deciduous needleleaf trees in Siberia decreased by 9% and 2.5%, and the areas of grassland, shrub, cropland, and construction land increased by 1.5%, 14.2%, 2.8%, and 39.2%, respectively. Cropland expansion had the fastest rate of 1.85% in the continuous permafrost zone, and construction land expansion had the fastest rate of 3.07% in the non-permafrost zone. (2) The center of gravity of agricultural land continues to migrate to the northeast, and the center of gravity of construction land continues to migrate to the southwest. (3) The primary drivers for the land cover changes were temperature and precipitation, and active layer thickness also affected grassland, cropland, and deciduous needleleaf trees. The correlation coefficient between active layer thickness and cropland area is 0.74 in the continuous permafrost zone. The interaction between factors is mostly manifested as a two-factor enhancement, with the highest q-value of the interaction of temperature and precipitation for explanatory power. Our results suggest that climate change and permafrost degradation significantly changed land cover in Siberia. This finding deepens our understanding of the mechanisms of land cover change under the influence of permafrost degradation and provides a new perspective on the land cover changes in permafrost regions.

Siberian wildrye (Elymus sibiricus) is a xero-mesophytic forage grass with high nutritional quality and stress tolerance. Among its numerous germplasm resources, some possess superior drought resistance. In this study, we firstly investigated the physiological differences between the leaves of drought-tolerant (DT) and drought-sensitive (DS) genotypes under different field water contents (FWC) in soil culture. The results showed that, under drought stress, DT maintained a lower leaf water potential for water absorption, sustained higher photosynthetic efficiency, and reduced oxidative damage in leaves by efficiently maintaining the ascorbic acid-glutathione (ASA-GSH) cycle to scavenge reactive oxygen species (ROS) compared to DS. Secondly, using RNA sequencing (RNA-seq), we analyzed the gene expression profiles of DT and DS leaves under osmotic stress of hydroponics induced by PEG-6000. Through differential analysis, we identified 1226 candidate unigenes, from which we subsequently screened out 115/212 differentially expressed genes (DEGs) that were more quickly induced/reduced in DT than in DS under osmotic stress. Among them, Unigene0005863 (EsSnRK2), Unigene0053902 (EsLRK10) and Unigene0031985 (EsCIPK5) may be involved in stomatal closure induced by abscisic acid (ABA) signaling pathway. Unigene0047636 (EsCER1) may positively regulates the synthesis of very-long-chain (VLC) alkanes in cuticular wax biosynthesis, influencing plant responses to abiotic stresses. Finally, the contents of wax and cutin were measured by GC-MS under osmotic stress of hydroponics induced by PEG-6000. Corresponding to RNA-seq, contents of wax monomers, especially alkanes and alcohols, showed significant induction by osmotic stress in DT but not in DS. It is suggested that limiting stomatal and cuticle transpiration under drought stress to maintain higher photosynthetic efficiency and water use efficiency (WUE) is one of the critical mechanisms that confer stronger drought resistance to DT. This study provides some insights into the molecular mechanisms underlying drought tolerance in E. sibiricus. The identified genes may provide a foundation for the selection and breeding of drought-tolerant crops.

The present world faces a new threat of ancient microbes and resistomes that are locked in the cryosphere and now releasing upon thawing due to climate change and anthropogenic activities. The cryosphere act as the best preserving place for these microbes and resistomes that stay alive for millions of years. Current reviews extensively discussed whether the resurrection of microbes and resistomes existing in these pristine environments is true or just a hype. Release of these ancient microorganisms and naked DNA is of great concern for society as these microbes can either cause infections directly or they can interact with contemporary microorganisms and affect their fitness, survival, and mutation rate. Moreover, the contemporary microorganisms may uptake the unlocked naked DNA, which might transform non-pathogenic microorganisms into deadly antibiotic-resistant microbes. Additionally, the resurrection of glacial microorganisms can cause adverse effects on ecosystems downstream. The release of glacial pathogens and naked DNA is real and can lead to fatal outbreaks; therefore, we must prepare ourselves for the possible reemergence of diseases caused by these microbes. This study provides a scientific base for the adoption of actions by international cooperation to develop preventive measures.

Lakes on the Qinghai-Tibet Plateau (QTP) have notably expanded over the past 20 years. Due to lake water level rise and lake area expansion, the permafrost surrounding these lakes is increasingly becoming submerged by lake water. However, the change process of submerged permafrost remains unclear, which is not conducive to further analyzing the environmental effects of permafrost change. Yanhu Lake, a tectonic lake on the QTP, has experienced significant expansion and water level rise. Field measurement results indicate that the water level of Yanhu Lake increased by 2.87 m per year on average from 2016 to 2019. Cold permafrost, developed in the lake basin, was partially submerged by lake water at the end of 2017. Based on the water level change and permafrost thermal regime, a numerical heat conduction permafrost model was employed to predict future changes in permafrost beneath the lake bottom. The simulated results indicate that the submerged permafrost would continuously degrade because of the significant thermal impact of lake water. By 2100, the maximum talik thicknesses could reach approximately 7, 12, 16, and 19 m under lake-bottom temperatures of +2.0, +4.0, +6.0, and +8.0 degrees C, respectively. Approximately 291 years would be required to completely melt 47 m of submerged permafrost under the lake-bottom temperature of +4 degrees C. Note that the permafrost table begins to melt earlier than does the permafrost base, and the decline in the permafrost table occurs relatively fast at first, but then the process is attenuated, after which the permafrost table again rapidly declines. Compared to climate warming, the degradation of the submerged permafrost beneath the lake bottom occurred more rapidly and notably.

Western Siberia is exposed to extreme wind events caused by severe convective storms. However, our knowledge on such storms in Siberia is still fragmentary compared to other parts of the world primarily due to the lack of weather radar data. These storms cause substantial damage, which signifies the need for comprehensive assessment of their characteristics and predictability even on the basis of existing data. In this paper, we present a case study analysis of a severe weather outbreak that occurred on 25-26 May 2020 in Western Siberia, during a record six-month heatwave that lasted in Siberia from January to June. The outbreak resulted in six fatalities and substantial economic losses. Using various satellite data and damage reports we found that two consecutive mesoscale convective systems (MCSs) developed within the outbreak having an exceptionally long total track about 2000 km and causing large-scale forest damage with a total area of 64.5 km(2). Such an exceptionally long path was supported by a strong mid-tropospheric jet, which settled extremely high values of wind shear that fostered the development of the outbreak. To analyze the accuracy of the forecast of the MCS and three asso-ciated windstorms on 26 May, we performed a set of simulations with the COSMO and ICON numerical weather prediction models launched with convection-permitting resolution (2.2 km) with different forecast lead times. Both models successfully predicted the most severe windstorm with the 24 h lead time, this emphasized the predominant role of large-scale dynamics and the minor role of local factors in the outbreak formation and development. In particular, the intrusion of the upper tropospheric high potential vorticity streamer along the blocking periphery induced strong deep convection and determined the severe character of the outbreak. Specifically, the studied outbreak had an exceptional longevity compared to other long-lived windstorms observed in Northern Eurasia at the blocking periphery.

Invasions of dendrophagous insects pose major threats to forest ecosystems and to the timber industry. The alien species bark beetle Polygraphus proximus Blandf. of Far Eastern origin has caused Siberian fir dieback in vast areas within several regions of Russia. Rapid spread of the pest and its outbreaks raise the issue of preserving the most important functions, including carbon sequestration, by the damaged forests. In this study, monitoring of carbon pool dynamics was carried out during 2012-2023 on four sample plots showing various degrees of damage in the southern taiga zone of Western Siberia in the Larinsky Landscape Reserve. Dynamics of the forest stands' vitality were reflected in a rapid decline of the number of viable trees and an increase in amounts of deadwood, debris, and soil composition, resulting in a transformation of the natural biological carbon cycle in the native dark coniferous ecosystems.

Permafrost regions are under particular pressure from climate change resulting in wide-spread landscape changes, which impact also freshwater chemistry. We investigated a snapshot of hydrochemistry in various freshwater environments in the lower Kolyma river basin (North-East Siberia, continuous permafrost zone) to explore the mobility of metals, metalloids and non-metals resulting from permafrost thaw. Particular attention was focused on heavy metals as contaminants potentially released from the secondary source in the permafrozen Yedoma complex. Permafrost creeks represented the Mg-Ca-Na-HCO3-Cl-SO4 ionic water type (with mineralisation in the range 600-800 mg L-1), while permafrost ice and thermokarst lake waters were the HCO3-Ca-Mg type. Multiple heavy metals (As, Cu, Co, Mn and Ni) showed much higher dissolved phase concentrations in permafrost creeks and ice than in Kolyma and its tributaries, and only in the permafrost samples and one Kolyma tributary we have detected dissolved Ti. In thermokarst lakes, several metal and metalloid dissolved concentrations increased with water depth (Fe, Mn, Ni and Zn - in both lakes; Al, Cu, K, Sb, Sr and Pb in either lake), reaching 1370 mu g L-1 Cu, 4610 mu g L-1 Mn, and 687 mu g L-1 Zn in the bottom water layers. Permafrost-related waters were also enriched in dissolved phosphorus (up to 512 mu g L-1 in Yedoma-fed creeks). The impact of permafrost thaw on river and lake water chemistry is a complex problem which needs to be considered both in the context of legacy permafrost shrinkage and the interference of the deepening active layer with newly deposited anthropogenic contaminants.

The northernmost margin of the East Asian summer monsoon (NMEASM) is the northernmost position that the East Asia summer monsoon (EASM) can reach. NMEASM has obvious multi-scale variability, and well reflects the wet/dry climate variability in northern China. Predicting the location change of the NMEASM is important for understanding future East Asian climate change. However, the variability of the NMEASM has not been studied extensively, and its underlying mechanisms have not been clarified. To explore the movement of the NMEASM and its causes, we use reanalysis datasets to evaluate the NMEASM index from 1979 to 2018. The NMEASM indicates a decreasing trend over 40 years and a significant abrupt point in 2000, which is positively correlated with the Tibetan Plateau snow cover before 2000 and the Siberian snow cover after 2000 in spring. The decreased Siberian snow cover increases the soil temperature and decreases the atmospheric baroclinicity over Mongolia and northern China after 2000. The decreased atmospheric baroclinicity induces the dipole mode of anticyclonic anomaly over Mongolia and northern China and the cyclonic anomaly over the Sea of Japan by modulating the wave activity flux (WAF). The WAF's southeastward propagation strengthens the anticyclonic anomaly over Mongolia and northern China and the cyclonic anomaly over the Sea of Japan, which weakens the upward movement and water vapor transport, respectively. Hence, the decreased Siberian snow cover in spring modulates the precipitation over Mongolia and northern China and the southward movement of NMEASM by turbulent westerly circulation.