Search Results (154)

Heterogeneous ice nucleation is a key process for ice cloud formation, snowfall, and freezing of water bodies. Ice nucleating particle (INP) cloud feedbacks are one of the largest sources of uncertainties in Earth’s Energy Budget. Although INPs are essential in the development of mixed-phased and glaciated clouds, their composition, sources, and cloud feedbacks remain poorly constrained. Previous studies have shown mixed results on the potential of light-absorbing particles (LAP), such as black carbon (BC) and high latitude dust (HLD), serving as INPs. However, many of these studies use laboratory or model-generated particles that may not represent the complex morphology and behaviors of ambient light-absorbing particles sufficiently. Here, we use in situ surface snow samples, collected during Spring 2018 in Svínafellsjökull, Iceland. The samples were analyzed by an immersion freezing mechanism for their ice nucleation activity (INA). Portions of the filtered samples were concentrated by lyophilization to observe the potential enhancement of INA. We investigated environmental samples of deposited aerosols to better understand the role activity of HLD and BC in ice nucleating activity in mixed-phase clouds in Iceland. We found concentrations of 16 ± 27 ng g⁻¹ and 33 ± 66 × 10⁶ ng g⁻¹ for BC and HLD, respectively. However, we found that isolated methanol-soluble organic aerosols have a more prominent role than BC and HLD in Iceland. We conclude that BC and HLD are insignificant INP but that they can inhibit INA from other INP. Full article

Animal manure application is widely recognized for its agronomic benefits in enhancing soil fertility and crop productivity through organic matter enrichment and nutrient supply, but the critical application time governing its greenhouse gas emission trade-offs remains unresolved. The objective of this study was to investigate the effects of pig manure compost application timing on nitrous oxide (N₂O) emissions and maize yields in Northeast China through a four-year field experiment. The treatments included: (1) inorganic fertilizers (NPK); (2) NPK plus pig manure compost applied in spring (NPK-MS); and (3) NPK plus pig manure compost applied in autumn (NPK-MA). The N₂O fluxes, NH₄⁺-N contents, NO₃⁻-N contents, and maize yields were analyzed. The results showed that compared with NPK, NPK-MA increased N₂O emissions by 44.4%. Applying pig manure compost in autumn promotes N₂O emissions during the freeze–thaw period. However, there was no significant effect of NPK-MS on N₂O emissions compared with NPK (p > 0.05). Spring-applied manure compost (NPK-MS) resulted in an 11.9% increase in maize yield compared to NPK. In contrast, autumn-applied manure compost (NPK-MA) did not significantly affect maize yield (p > 0.05). Furthermore, yield-scaled N₂O emissions were significantly increased in NPK-MA (p < 0.05). Overall, spring application of pig manure compost is recommended for increasing maize yield without significantly increasing N₂O emissions while in Northeast China. Full article

Late spring frosts represent a major threat to grapevine (Vitis vinifera L.), a risk increasingly exacerbated by climate change-driven shifts in phenology. To explore sustainable strategies for frost mitigation, this study investigated the effect of a natural polysaccharide-based biogel, derived from carob (Ceratonia siliqua L.), on the molecular response of grapevine buds exposed to severe cold stress. To this aim, a preliminary RNA-Seq analysis was carried out to compare the transcriptomes of biogel-treated frozen buds (BIOGEL), untreated frozen buds (NTF), and unstressed controls (TNT). The transcriptomic analysis revealed extensive reprogramming of gene expression under freezing stress, highlighting the involvement of pathways related to membrane stabilization, osmotic adjustment, and metabolic regulation. Interestingly, the biogel treatment appeared to attenuate the modulation of several cold-responsive genes, particularly those associated with membrane functionality. Based on these preliminary transcriptomic data, twelve candidate genes, representative of the functional classes affected by biogel treatment, were selected for qRT-PCR validation. The expression patterns confirmed the RNA-Seq trends, further suggesting that biogel application might mitigate the typical transcriptional activation induced by frost, while supporting genes involved in cellular protection and integrity maintenance. The overall analyses suggest that the biogel may act through a dual mechanism: (i) providing a physical barrier that reduces cold-induced cellular damage and stress perception, and (ii) promoting a selective adjustment of gene expression that restrains excessive defense activation while enhancing membrane stability. Although further field validation is required, this natural and biodegradable formulation represents a promising and sustainable tool for mitigating late frost injuries in viticulture. Full article

The ability of Ribes species to survive the fluctuating winter and early spring conditions, relies on the regulation of transcription factors (TFs) and other key genes involved in the abiotic stress response. In this study, we developed specific primers for 33 stress-responsive genes, which may facilitate future functional studies in Ribes and other less-characterized lineages within the Saxifragales order. These genes were selected based on a comparative transcriptomic analysis of R. nigrum cv. Aldoniai and are known to function in cold acclimation and stress signaling pathways. We analyzed expression profiles of these 33 genes in R. aureum, R. hudsonianum, and R. nigrum microshoot cultures exposed to controlled cold stress, deacclimation and reacclimation treatments. Our results revealed species-specific genetic responses across acclimation cycles of varying durations (24–96 h). Cold stress induces molecular changes in three Ribes spp.; however, deacclimation triggered by transient warming significantly reduced freezing tolerance in R. nigrum, had a moderate effect on R. hudsonianum, and minor impact on R. aureum. Gene expression profiling revealed distinct, species-specific regulatory patterns among species during different stress cycles, highlighting conserved and specific genes in acclimation mechanisms within the Ribes spp. These findings contribute to a deeper understanding of transcriptional regulation under acclimation cycles in currants and provide molecular tools that may support breeding strategies aimed at enhancing cold tolerance in Ribes crops amid increasing climate variability. Full article

River ice is a common feature in most Canadian rivers and streams during the cold season. River channel hydraulics under ice conditions may cause higher water levels at a relatively lower discharge compared to the open-water flood events. Elevated water levels resulting from river ice processes throughout fall freeze-over, mid-winter, and spring break-up are important hydrologic events with diverse morphological, ecological, and socio-economic impacts. This study analyzes the timing of maximum water levels (occurring during freeze-over, spring break-up, and open-water periods) and the typology of maximum ice-related events (at freeze-over, mid-winter, and spring break-up) using data from the Canadian River Ice Database. The study also compares annual maximum water levels during the river ice and open-water periods at selected hydrometric stations from 1966 to 2015, divided into two 25-year windows: 1966–1990 and 1991–2015. A return period classification method was applied to define ice-influenced, open-water, and mixed-regime conditions. The results indicate that the majority of ice-influenced maximum water levels occurred during spring break-up (~79% in 1966–1990 and ~69% in 1991–2015), followed by fall freeze-up (~13% and ~23%) and mid-winter break-up (~8% and ~7%) for the two periods, respectively. Among 15 stations analyzed for 1966–1990 and 42 stations for 1991–2015, the proportion of annual maximum water levels dominated by open-water conditions increased from 47% to 55%, while ice-dominated events decreased from 13% to 12%, and mixed-regime events dropped from 40% to 33%. However, a focused comparison of eight common stations revealed minimal change in the distribution of water level-generating events between the two periods. The findings offer valuable insights into the spatial distribution of maximum water level-generating mechanisms across Canada. Full article

Walnuts (Juglans regia L.) are an economically important woody crop, but spring frost poses a serious threat to their growth and productivity. However, the molecular mechanisms underlying walnut responses to freezing stress remain largely unknown. In this study, transcriptome analyses were performed on cold-tolerant and cold-sensitive walnut varieties subjected to freezing stress. A total of 9611 differentially expressed genes (DEGs) responsive to freezing stress were obtained, of which 2853 were common up-regulated and 2880 were common down-regulated in both varieties. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed 15 significantly enriched pathways in both varieties, including flavonoid biosynthesis. A simplified walnut flavonoid biosynthesis pathway was constructed, encompassing 36 DEGs encoding 13 key enzymes, demonstrating that flavonoid biosynthesis in walnut is significantly activated under freezing stress. Furthermore, weighted gene co-expression network analysis (WGCNA) identified a regulatory network centered on the JrCBF genes and uncovered 34 potential interacting genes. Collectively, these findings provide novel insights into the molecular responses of walnut to freezing stress and establish a foundation for elucidating the mechanisms underlying walnut cold tolerance. Full article

The Republic of Korea, with 64% forest coverage, is increasingly vulnerable to large-scale wildfires. This study employed electrical resistance tomography (ERT) to diagnose internal damage in Pinus densiflora trees following a surface fire in spring 2023. Of the 30 monitored trees, 5 died in 2023 and 6 more had died by 2024. Dead trees showed a 41% higher Bark Scorch Index (BSI) and a 10%–15% lower DBH and circumference than survivors. From July, ERT detected significant increases in high- (ERT_R) and medium-resistance (ERT_Y) areas, while low-resistance (ERT_B) regions declined. By September, ERT_R and ERT_Y were 2.2 and 1.9 times higher in dead trees. Maximum resistivity (Rs_max) rose 6.1-fold to 3724 Ωm. One year post-fire, healthy areas in dead trees dropped below 18%. These findings indicate that internal defects develop gradually and accelerate in summer and winter, correlating with thermal and freeze–thaw stress. Early diagnosis within two months post-fire was unreliable, while post-summer assessments better distinguished trees at mortality risk. This study demonstrates ERT’s utility as a non-destructive tool for tracking post-fire damage and guiding forest restoration under increasing wildfire threats. Full article

Understanding the spatiotemporal dynamics of runoff and its drivers is essential for water resources management in mid–high latitude basins. This study investigates runoff changes in the Songhua River Basin, Northeast China, during 1980–2022 using the Budyko framework, combined with Mann–Kendall trend analysis, Pettitt tests, Hurst index, and wavelet analysis. Results indicate significant climatic shifts, with basin-wide warming, heterogeneous precipitation changes, and declining relative humidity, leading to intensified cold-season drying. Temperature and evapotranspiration showed strong persistence, while precipitation exhibited high variability and periodicities linked to ENSO and East Asian monsoon anomalies. Runoff increased significantly in the mainstream Songhua and Nenjiang basins, especially in autumn, with abrupt changes clustered between 2009 and 2015. The Second Songhua Basin displayed weaker variability, largely influenced by reservoir regulation and land-use change. Attribution analysis confirmed precipitation as a primary driver, with elasticity coefficients exceeding 3 in the Nenjiang Basin during some summers, indicating extreme sensitivity. Evapotranspiration suppressed runoff under high temperatures, while freeze–thaw processes and human interventions became critical in spring and autumn. The aridity index revealed persistent winter deficits and rising spring–autumn drying trends after 2000, posing risks for snowmelt runoff and baseflow sustainability. Overall, runoff evolution reflects a shift from gradual to threshold-triggered regime changes driven by both climate variability and human regulation. These findings provide a basis for adaptive, basin-specific water management and climate resilience strategies in Northeast China. Full article

Under tropical conditions, seasonal variations may also influence the sperm characteristics of Bos indicus. The objective was to evaluate the motility of thawed sperm of bulls from the Peruvian tropics throughout the year. Over 24 months, 129 ejaculates were evaluated based on semen quality and subjected to slow horizontal freezing in 0.5 mL straws. After thawing, the individual, seasonal period, and season effect on motility and kinetic parameters were analyzed using a Sperm Class Analyzer^® (Microptic S.L.U., Barcelona, Spain). There was an individual effect on volume, motility, fresh concentration, and kinetic parameters when thawed. In the dry period, higher straight-line velocity (VSL) (p < 0.05) and beat cross frequency (BCF) were found than in the rainy period (p < 0.01). In summer and autumn, there was greater total motility, fast, circular routes, curvilinear velocity, average path velocity, VSL, amplitude of lateral displacement of the head, and BCF (p < 0.01). Greater volume and motility were found in winter and spring, but in summer and autumn, greater speed and vigor of movement were obtained in thawed sperm. The variation in annual climate patterns influences the seminal quality of bulls, and its effect needs to be assessed to propose adaptation strategies to climate change in tropical areas. Full article

Peat soil is a significant global carbon storage pool, accounting for one-third of the global soil carbon pool. Its greenhouse gas emissions have a significant impact on climate change. Seasonal freeze–thaw cycles are common natural phenomena in high-latitude and high-altitude regions. They significantly affect the mineralization of soil organic carbon and greenhouse gas emissions by altering the physical structure, moisture conditions, and microbial communities of the soil. In this study, through the construction of an indoor simulation experiment of the typical freeze–thaw cycle models in spring and autumn in the Greater Xing‘an Range region of China and the Jinchuan peatland of Jilin Longwan National Nature Reserve, the physicochemical properties, greenhouse gas emission fluxes, microbial community structure characteristics, and key metabolic pathways of peat soils in permafrost and seasonally frozen ground areas were determined. The characteristics of greenhouse gas emissions and their influencing mechanisms for peat soil in northern regions under different freeze–thaw conditions were explored. The research found that the freeze–thaw cycle significantly changed the chemical properties of peat soil and significantly affected the emission rates of CO₂, CH₄, and N₂O. It also clarified the interaction relationship between soil’s physicochemical properties (such as dissolved organic carbon (DOC), dissolved organic nitrogen (DON), ammonium nitrogen (NH₄⁺), soil organic carbon (SOC), etc.) and the structure and metabolic function of microbial communities. It is of great significance for accurately assessing the role of peatlands in the global carbon cycle and formulating effective ecological protection and management strategies. Full article

To address the freezing damage to tunnel lining caused by frost heaving of the surrounding rock in water-rich tunnels in cold regions, a numerical thermo-mechanical coupling model for tunnel-surrounding rock that considers the anisotropy of frost heave deformation was established by examining overall frost heaves in a freeze–thaw cycle. Using a COMSOL Multiphysics 6.0 platform and the sequential coupling method, the temperature field evolution of tunnel-surrounding rock, freezing cycle development, and distribution characteristics of the frost heaving force of a tunnel lining under different minimum temperatures, numbers of negative temperature days, frost heave ratios, and anisotropy coefficients of frost heave deformation were systematically simulated. The results revealed that the response of the temperature field of tunnel-surrounding rock to the external temperature varies spatially with time lags, the shallow surface temperatures and the area around the lining fluctuate with the climate, and the temperature of the deep surrounding rock is dominated by the geothermal gradient. The extent of the freezing cycle and the frost heaving force increase significantly when lowering the minimum temperature. The maximum frost heaving force usually occurs in the region of the side wall and the spring line, and tensile stress is prone to be generated at the spring line; the influence of slight fluctuations in the minimum temperature or the short shift in the coldest day on the frost heaving force is limited. A substantial increase in frost heaving force is observed with higher frost heave ratios; for example, an increase from 0.25% to 2.0% results in a 116% rise at the sidewall. Although the increase in the anisotropy coefficient of frost heave deformation does not change the overall distribution pattern of frost heaving force, it can exacerbate the directional concentration of frost heave strain, which can increase the frost heaving force at the periphery of the top arch of the lining. This study revealed the distribution pattern and key influencing factors of the freezing cycle and frost heaving force for tunnels, providing a theoretical basis and data reference for the frost resistance design of tunnels in cold regions. Full article

Climate warming leads to earlier onset and shortened duration of the freeze–thaw period in the eastern Tibetan Plateau, which has complex effects on vegetation growth. We assessed the spatiotemporal changes in the freeze–thaw period, evaluated its relationship with Normalized Difference Vegetation Index (NDVI from remotely sensed data), used the Panel Smooth Threshold Regression (PSTR) model to quantify the nonlinear impacts and identify critical thresholds, and applied ridge regression to explore the dominant mechanisms under different climatic conditions. The results showed the following: (1) The duration of the freeze–thaw transition period showed strong latitudinal zonality, with stronger spring disturbances than autumn ones. The trend of soil freeze–thaw status in high-altitude areas is the most significant, with a significant increase in the complete thaw period (CTP) and a significant decrease in the complete freeze period (CFP). (2) The earlier onset of the spring freeze–thaw period (SFTTP) and the CTP benefits vegetation growth in both early and late seasons. The delayed autumn freeze–thaw period (AFTTP) benefits early-season vegetation growth but is less favorable for late-season growth. The delayed CFP is beneficial for vegetation growth throughout the year. (3) The CTP’s boost to NDVI collapses at an onset date of 110 days and duration of 190 days. The AFTTP’s benefit peaks at an onset date of 300 days. (4) Temperature and the CTP are key drivers of NDVI changes, especially in the mid-to-late growing season. Arid areas respond strongly to freeze–thaw disturbances, while moderate precipitation areas are less affected. This study is the first to quantitatively analyze the nonlinear mechanism of the freeze–thaw–vegetation relationship, offering a new theoretical basis. Full article

We present a model evaluation of road weather forecasts in Norway with the METRo model in a quasi-operational setting. The road weather forecasts are initialized with measurements made by road weather stations and driven by mesoscale weather forecast data from the Norwegian Meteorological Institute. One important source of hazardous driving conditions in Norway are freezing road-surface temperatures. We quantify the skill of our model setup to predict such conditions by computing the hit rates and false-alarm rates for incidences of freezing temperatures, relative to the climatological rates of occurrence. The METRo forecasts consistently add skill in wintertime and the crucial transitional seasons of spring and fall. Our study illustrates a successful proof-of-concept for novel, operational road weather forecasts in Norway, that could easily be realized with an open-source prediction model and readily available input data. Full article

The abiotic stresses associated with spring/fall freezes and extreme winter cold cause significant economic losses in blueberry production. These problems are exacerbated by climate change and increasingly erratic weather patterns. Developing freeze-tolerant blueberry cultivars with optimized cold hardiness, chilling requirement, and flowering and fruiting phenology holds promise for mitigating the risk of these weather-related damages. These weather-resilient cultivars will ensure the long-term productivity and sustainability of the blueberry industry. The focus of this review is to present the current understanding of the major components of genetic breeding for blueberry freeze tolerance, i.e., phenotyping, genotyping, genetic association analysis, and marker development. The advancement in gene regulation and corresponding proteomic changes upon cold acclimation, dormancy, de-acclamation, and flowering and fruiting aids in the understanding of the adaptive stress response in blueberries. A wide range of genetic diversity in freeze tolerance and phenological traits has been identified among cultivated and wild blueberry relatives. Significant efforts have been made to phenotype freeze tolerance, chilling requirement, and flower and fruit development in both field and controlled environmental conditions. Recent studies emphasize the need for high-throughput, image-based phenotyping of blueberry flower development to improve the precision and efficiency of selecting freeze-resilient genotypes. In addition, advancements in blueberry genomics and pangenome resources expanded the potential of variant calling and high-density linkage map construction. Genetic association studies have identified QTL regions linked to freeze tolerance in blueberries, providing valuable targets for selection. The implementation of these advanced genomic tools and high-throughput phenotyping methodology will accelerate the development of weather-resilient blueberry cultivars. Full article

Understanding plant phenology dynamics is essential for ecosystem health monitoring and climate change impact assessment. This study generated 4-day, 500 m land surface phenology (LSP) in Northeast China (NEC) from 2001 to 2021 using interpolated and Savitzky–Golay filtered kernel normalized difference vegetation index (kNDVI) derived from MODIS. Spatial patterns, trends, and climate responses of phenology were analyzed across ecoregions and vegetation. Marked spatial heterogeneity was noted: forests showed the earliest start of season (SOS, ~125^th day) and longest growing season (LOS, ~130 days), while shrublands had the latest SOS (~150^th day) and shortest LOS (~96 days). Grasslands exhibited strong east–west gradients in SOS and EOS. From 2001 to 2021, SOS of natural vegetations in NEC advanced by 0.23 d/a, EOS delayed by 0.12 d/a, and LOS extended by 0.38 d/a. Coniferous forests, especially evergreen needle-leaved forests, exhibited opposite trends due to cold-resistant traits and an earlier EOS to avoid leaf cell freezing. Temperature was the main driver of SOS, with spring and winter temperatures influencing 48.8% and 24.2% of the NEC region, respectively. Precipitation mainly affected EOS, especially in grasslands. Drought strongly influences SOS, while precipitation affects EOS. This study integrates high-resolution phenology utilizing the kNDVI with various seasonal climate drivers, offering novel insights into vegetation-specific and ecoregion-based phenological dynamics in the context of climate change. Full article