Seasonal Changes Research Articles

Ecological patterns of benthic foraminiferal communities driven by seasonal and spatial environmental gradients in an Arctic fjord

AbstractArctic fjords, being transitional areas between glacier‐covered land and the ocean, are characterized by strong environmental gradients. The seasonal melting of glaciers generates strong turbidity and primary production antagonist gradients, which can affect benthic habitats. Two sampling campaigns were carried out in Kongsfjorden (Svalbard, Arctic Ocean) in May and August 2021 to investigate seasonal changes in benthic foraminifera spatial distribution and ecosystem functioning along a longitudinal transect of 10 km from the Kronebreen tidewater glacier front. Concurrently, organic matter quantity and biochemical composition, sediment grain size, and physical parameters of the water masses were investigated as possible driving factors of benthic ecosystem responses. In a previous study, three statistically determined foraminiferal biozonations (glacier proximal, medial, and distal) were observed on the basis of their species content within the closest 10 km from the glacier front, presenting similar assemblages in both seasons. Our results indicate that foraminiferal distribution at the local scale is mainly driven by physical and geochemical gradients induced by melting waters and sediment discharges from the tidewater glacier occurring during summer. Due to the climate change, the melting season is expected to last longer and increasing global temperature will much probably accelerate the melting processes. Our findings strongly support the use of foraminifera as bioindicators to monitor the effects of ongoing climate change on the benthic ecosystems of Arctic fjords and, accessorily, as proxies for reconstructing glacier front positions in the recent past.

Seasonal Comparison of Pre-Adolescent Soccer Players' Physical Performance Using an Objective Physical Test Battery.

Soccer is a multifactorial sport, requiring physical, psychological, technical, and tactical skills to succeed. Monitoring and comparing physical characteristics over time is essential to assess players' development, customize training, and prevent injury. The use of wearable sensors is essential to provide accurate and objective physical data. In this longitudinal study, 128 male adolescent soccer players (from Under 12 to Under 19) were evaluated at two time points (pre- and post-season). Participants completed the Euleria Lab test battery, including stability, countermovement and consecutive jumps, agility, and quick feet tests. A single Inertial Measurement Unit sensor provided quantitative data on fifteen performance metrics. Percentage changes were compared to the Smallest Worthwhile Changes to assess significant changes over time. The results showed significant improvements in most variables, including a 19.7% increase in quick feet, 10.9% in stability, and 9.6% in countermovement jumps. In principal component analysis, we identified four principal components-strength-power, balance, speed-agility, and stiffness-that explained over 80% of the variance. These findings align with previous studies assessing seasonal changes in adolescent soccer players, showing that the proposed test battery seems to be adequate to highlight physical performance changes and provide coaches with meaningful data to customize training and reduce injury rates.

Persistent high-latitude ionospheric response to solar wind forcing

The solar wind continuously transfers energy into the Earth’s thermosphere-ionosphere system and variations in the solar wind properties modify the state of the system. The modifications are best visible during storm conditions when the ingestion of extreme amounts of solar wind energy into the thermosphere-ionosphere system causes global changes in thermosphere as well as large deviations in the ionospheric electron density from its quiet conditions. This study shows that there exists a persistent impact of the solar wind on the high-latitude electron density. A data set of 22 years of Total Electron Content (TEC) and 15 years of ionosonde data (critical frequency foF2 and height of maximum electron density hmF2) at Tromsø (70°N, 19°E) are used for correlation analyses with different solar wind parameters derived from measurements of the Advanced Composition Explorer (ACE). The results show that the ionospheric parameters systematically respond with an increase or decrease depending on local time, season and solar cycle. TEC and foF2 increase with solar wind energy during winter night conditions and decrease with increasing solar wind energy during summer daytime. The summer negative ionospheric response is more intense during solar maximum conditions, while the winter positive ionospheric response is stronger during solar minimum. An anomaly is observed around 10 UT (noon), when TEC and foF2 respond with an increase during solar minimum conditions. Cross polar cap plasma convection, particle precipitation and Joule heating are considered to be the main drivers of the electron density changes at Tromsø. Local time, season and solar cycle changes in the background ionosphere-thermosphere conditions lead to different effects of theses driving processes. The results help to better understand the variability of the high-latitude electron density and show that solar wind forcing causes a systematic and persistent response of the ionosphere which alternates depending on local time, season and solar cycle.

Seasonal Variability and Hydrological Patterns Influence the Long-Term Trends of Nutrient Loads in the River Po

This study investigates the long-term trends (1992–2022) of nitrogen and phosphorus loadings exported by the River Po to the Adriatic Sea, to better analyse how changes in hydrology are affecting the timing and magnitude of river nutrient loads. We used 30 years of monitoring data in order to (a) identify the main temporal patterns and their interactions at a decadal, annual and seasonal scale, (b) estimate precipitation effects on load formation and evaluate whether and to which extent the hydrological regime affects nutrient export across the years and (c) analyse the nutrient export regime at a monthly scale and the main transport dynamic of N and P chemical species (hydrological vs. biogeochemical control). The long-term analysis shows a general decrease of both P and N loadings, but the trends are different between the elements and their chemical species, as well as undergoing different seasonal variations. We found a statistically significant relationships between precipitation and loads, which demonstrates that precipitation patterns drive the exported load at the intra- and interannual time scales considered in this study. Precipitation-induced load trends trigger seasonal changes in nutrient deliveries to the sea, peaking in spring and autumn. The nitrogen decrease is mainly concentrated in the summer dry period, while total phosphorus diminishes mainly in spring and autumn. This mismatch of N and P results in variable molar N:P ratios within the year. The effects of extreme drought and flood events, along with the progressive decrease in the snowmelt contribution to water fluxes, are expected to exacerbate the variability in the N and P loadings, which in turn is expected to perturbate the biodiversity, food webs and trophic state of the Northern Adriatic Sea.

Application of Electrical Prospecting Methods for Monitoring the Condition of Earth Dam in the Almaty Region of Kazakhstan

This article deals with the issue of diagnostics of the physical condition of earthen dams, taking into account seasonal changes in the water level of hydraulic structures using electrical exploration methods. The simplicity of the method, the accuracy of measurements of geophysical parameters, and the availability of software packages for the processing, interpretation, and visualization were the basis for the choice of method. The method of electrical resistivity and self-potential was chosen. The methodology, technique, technology of field surveys, processing, and geological interpretation of the study results are given. A comparative analysis of the obtained geophysical parameters of seasonal measurements is given. The research results are given in the form of sections of the resistivity model and self-potential isolines.

Nitrogen Fixation, Carbohydrate Contents, and Bacterial Microbiota in Unelongated Stem of Manure Compost-Applied Rice at Panicle Initiation

In rice, symbiotic N2 fixation via nodule bacteroids does not take place naturally. Although N2 fixation by endophytic and associative diazotrophs has been reported in rice, the main organs and seasonal regulation for the N2 fixation have not been elucidated. In this study, seasonal changes in nitrogenase (acetylene reduction) activity and carbohydrate contents in elongated culm (EC), unelongated stem (US), and crown root (CR) were investigated in manure compost (MC)- and chemical fertilizer (CF)-applied rice. Nitrogenase activity increased after rooting (June) and reached the highest activity in US of MC-applied rice at panicle initiation (August). The sucrose content in EC continued to increase after rooting regardless of the applied materials, whereas the glucose content in US increased after rooting only in CF-applied rice, suggesting higher consumption of glucose in US of MC-applied rice. There were significant differences among bacterial microbiota in EC, US, and CR at panicle initiation. In addition, Clostridia class anaerobes were more abundant in US of MC-applied rice than in EC and CR of MC-applied rice. Such difference was not observed in US of CF-applied rice. These results suggest the suitability of US of MC-applied rice at panicle initiation as a site of N2 fixation under anaerobic conditions.

Seasonal Abundance and Diversity of Culicoides Biting Midges in Livestock Sheds in Kanchanaburi Province, Thailand.

Culicoides biting midges were collected using UV light traps from nine livestock farms in Kanchanaburi Province, Thailand. Collections were made one night per month from June 2020 to May 2021 to determine the seasonal changes and spatial distribution of the Culicoides assemblage. The influence of four environmental factors (temperature, rainfall, humidity, and wind speed), types of animals in each shed (cattle, pigs, and avians), and neighboring animals (those in the other sheds and their proximity) were assessed. A subsample of 130,670 out of a total of 224,153 specimens collected was identified and counted. The collections were predominantly female (76.9%), though males were also commonly collected (23.1%). The dominant species included C. peregrinus (97,098 individuals; 43.0%), C. oxystoma (55,579; 24.6%), C. arakawae (45,996; 20.4%), and C. imicola (15,703; 7.0%), while other species accounted for the remaining 9777 individuals (4.4%). Trap captures were strongly influenced by seasons and animal sheds. Cattle exhibited the greatest effect on the community, likely due to their large biomass. Humidity and temperature had a positive effect on trap captures, whereas wind speed exhibited a negative effect. Cattle positively influenced all major species, except for C. arakawae, which showed a positive association with avians. A "neighboring effect" was also observed. Additionally, the lowest dispersal ability of C. arakawae was suggested.

Carbohydrate accumulation patterns in mangrove and halophytic plant species under seasonal variation

This study investigates the impact of carbohydrate accumulation in mangrove and halophytic plants on their response to abiotic stress. Using soil analysis and FT-IR spectroscopy, key species (Sueda nudiflora, Aeluropus lagopoides, Avicennia marina) were examined for seasonal changes in sugar content (reducing sugars, total soluble sugars, starch). The elevated carbohydrate levels may serve as an indication of the plant’s ability to adapt to different environmental conditions throughout the year. This accumulation enables plants to adapt to variations in their environment, assuring their survival and functionality during periods of environmental fluctuation. Halophytic plants’ sugar content peaked during the monsoon, suggesting biotic adaptations. The mangrove Avicennia marina had year-round sugar levels. PCA and Hierarchical Cluster Analysis revealed sugar accumulation trends across species and seasons. Partial Least Squares (PLS) analysis revealed correlations between soil characteristics and sugar content, suggesting plant-microbe interactions. K-means clustering and correlation analysis of FT-IR data revealed sugar composition and resource allocation trade-offs. These findings shed light on the role of carbohydrate metabolism in enabling coastal plants to endure stress. Gaining insight into these mechanisms can enhance sustainable agriculture in challenging environments and shed light on plant adaptations to evolving environmental conditions, especially biotic interactions.

Priority Organic Pollutant Monitoring Inventory and Relative Risk Reduction Potential for Solid Waste Incineration.

Incineration is a promising sustainable treatment method for solid waste. However, the ongoing revelation of new toxic pollutants in this process has become a controversial issue impeding its development. Thus, identifying and regulating high-risk pollutants emerge as pivotal strides toward reconciling this debate. In this study, we proposed a workflow aimed at establishing priority monitoring inventories for organic compounds emitted by industries involving full-component structural recognition, environmental behavior prediction, and emission risk assessment, specifically focusing on solid waste incineration (SWI). A total of 174 stack gas samples from 29 incinerators were first collected. Nontarget full organic recognition technology was then deployed to analyze these samples, and 646 organic compounds were identified. The characteristics, i.e., toxicity effects, toxicity concentrations, persistence, and bioaccumulation potential, of these compounds were assessed and ranked based on the TOXCAST database from the US Environmental Protection Agency and structural effect models. Combined with consideration of changes in seasons and waste types, a priority control inventory consisting of 28 organic pollutants was finally proposed. The risks associated with SWI across different regions in China and various countries were assessed, and results pinpointed that by controlling the priority pollutants, the average global emission risk attributed to SWI was anticipated to be reduced by 71.4%. These findings offer significant guidance for decision-making in industrial pollutant management, emphasizing the importance of targeted regulation and monitoring to enhance the sustainability and safety of incineration processes.

Trend, disparities, and projection analysis of public data on shoulder fractures in Sweden: a retrospective analysis of two hundred and sixty two thousand, four hundred and forty four fractures.

We aimed to identify temporal trends, seasonal changes and regional differences in shoulder fractures in Sweden during 2008-2022. Data from the Swedish National Board of Health and Welfare were used to assess incidence rates per 100,000 people, categorized by sex, age, and month. Results showed an average of 17,496 fractures annually, with a decline in 2020 followed by a resurgence in 2021-2022. Elderly women, especially those over 65, had higher rates. Winter months exhibited increased incidence. Projection analysis indicated a gradual decrease in fractures over the next 15 years. Understanding these patterns can inform preventive strategies and resource allocation for shoulder fractures in Sweden.

Process-based forecasts of lake water temperature and dissolved oxygen outperform null models, with variability over time and depth

Near-term iterative ecological forecasting has great potential for providing new insights into our ability to predict multiple ecological variables. However, true, out-of-sample probabilistic forecasts remain rare, and variability in forecast performance has largely been unexamined in process-based forecasts which predict multiple ecosystem variables. To explore how forecast performance varies for water temperature and dissolved oxygen, two freshwater variables important for lake ecosystem functioning, we produced probabilistic forecasts at multiple depths over two open-water seasons in Lake Sunapee, NH, USA. Our forecasting system, FLARE (Forecasting Lake And Reservoir Ecosystems), uses a 1-D coupled hydrodynamic-biogeochemical process model, which we assessed relative to both climatology and persistence null models to quantify how much information process-based FLARE forecasts provide over null models across varying environmental conditions. We found that FLARE water temperature forecasts were always more skillful than FLARE oxygen forecasts. Specifically, temperature forecasts outperformed both null models up to 11 days into the future, as compared to only two days for oxygen. Across different years, we observed variable forecast skill, with performance generally decreasing with depth for both variables. Overall, all temperature forecasts and surface oxygen, but not deep oxygen, forecasts were more skillful than at least one null model >80 % of the forecasted period, indicating that our process-based model was able to reproduce the dynamics of these two variables with greater reliability than the null models. However, process-based oxygen forecasts from deeper waters were less skillful than both null models during a majority of the forecasted period, which suggests that deep-water oxygen dynamics are dominated by autocorrelation and seasonal change, which are inherently captured by the null forecasts. Our results highlight that forecast performance varies among lake water quality metrics and that process-based forecasts can provide important information in conjunction with null models in varying environmental conditions. Altogether, these process-based forecasts can be used to develop quantitative tools which inform our understanding of future ecosystem change.

The variation in exposure to ambient formaldehyde at different times of the year in various countries: A systematic review and meta-analysis

Exposure to ambient formaldehyde can be associated with hazardous consequences. It can be affected by seasonal and meteorological parameters. This study was performed to investigate the variation in exposure to ambient formaldehyde at different times of the year in various countries. A literature search was performed in five databases of Scopus, PubMed, Web of Science, Medline, and Embase. The search strategy was based on PRISMA protocols. The pooled values of ambient exposure to formaldehyde were computed by meta-analysis for all seasons. 44 articles were evaluated in this study. Based on the results, the concentrations of exposure to this substance in 13 of 20 studies in spring (65.00 percent), 29 of 38 studies in summer (76.32 percent), 12 of 17 studies in autumn (70.59 percent), and 15 of 37 studies in winter (40.54 percent) were higher than permissible value recommended by Texas Commission on Environmental Quality (3.3 µg/m³) for long exposure. The highest concentration of exposure to ambient formaldehyde was observed in Iran (23.93 µg/m3) in spring, in China (26.38 µg/m3) in summer, in China (15.0 µg/m3) in autumn, and in China (45.56 µg/m3) in winter. The pooled concentrations (μg/m3) of formaldehyde in spring, summer, autumn, and winter seasons were estimated as 5.78 (95 % CI: 4.82–6.75), 6.57 (95 % CI: 5.85–7.29), 6.07 (95 % CI: 4.76–7.39), and 3.59 (95 % CI: 3.17–4.01), respectively. The concentrations of formaldehyde in environmental settings tend to be mostly higher during the summer compared to other seasons. Perception of the fluctuations in formaldehyde concentration due to seasonal and meteorological changes is beneficial for air quality management.

Cost-based performance optimization of a single system under a hierarchical imperfect maintenance policy

Abstract Due to the influence from external factors such as repair sites and seasonal climate change, it is difficult to restore the system performance to any intermediate level between perfect maintenance and minimal maintenance through imperfect maintenance. This article first categorizes the states of the system just before repair into three classes based on its internal degradation level: failure, major defect, and minor defect, with three corresponding thresholds. Subsequently, the corresponding repairs are carried out to dwindle the system’s degradation to different levels. In detail, if the internal degradation level of the system just before repair is recognized as minor defect, an imperfect repair, termed as type I imperfect repair, is implemented to scale down the degradation level below the minor defect threshold. If the degradation level is identified as major defect, an upgraded imperfect repair, termed as type II imperfect repair, is executed to only lower the degradation to the level between the minor defect threshold and major defect threshold. Otherwise, if the degradation before repair is beyond the failure threshold, replacement will be carried out instead of these imperfect repairs. Thus, a novel hierarchical imperfect maintenance structure is introduced. Then, a multi-variable repair cost model is constructed when considering the related costs incurred from inspection, type I imperfect repair, type II imperfect repair, replacement, and even system downtime. Finally, with the aid of the stationary law of Markov chains and the semi-regenerative process, the cost-based performance optimization with three parameters, including the inspection interval, minor defect threshold, and major defect threshold, is explored through a numerical experiment, and the closed expression of the optimal cost rate is provided.

Algal diversity and its relationship with seasonal variation of water quality in Gajedi Lake, Rupandehi District (Nepal)

The current study focuses on the algal diversity of Gajedi Lake in different seasons in connection to the lake's water quality indicators. Algae and water samples were collected from eight peripheral sites of the lake in summer, rainy, and winter seasons in 2021. The water temperature, conductivity, total dissolved solids, hardness, alkalinity, phosphorus, free CO2, and dissolved oxygen were recorded as high during the summer season while water pH was high during the rainy season. Altogether 93 species of algae were reported under 52 genera, 30 families, 7 classes and 6 phyla in this study. The largest phylum was Bacillariophyta (44.08%) followed by Chlorophyta (17.20%), Euglenozoa (10.97%), Cyanobacteria (12.90%), Charophyta (10.75%) and Miozoa (1.07%). The Shannon-Weiner diversity index indicated high abundance during the summer season, with more evenly distributed algal species. More algal species were recorded in the winter season. Trachelomonas, Navicula, and Nitzschia were dominant genera during summer; Anagostidinema, Desmodesmus, and Pinnularia were dominant during rainy; and Trachelomonas, Tetradesmus, and Gomphonema were dominant during winter. The redundancy analysis ordination showed that the algal composition varied along with the seasonal changes in physico-chemical parameters. Temperature, pH, and conductivity were thus identified as significant factors influencing species richness.

The effects of Pinus sylvestris L. geographical origin on the community and co-occurrence of fungal and bacterial endophytes in a common garden experiment.

This study advances our understanding of how plant ecotype and seasonal changes influence root endophytic communities in Scots pine (Pinus sylvestris). By examining trees from various origins grown in a common garden, it highlights the role of tree origin and season in shaping fungal and bacterial community and co-occurrence networks. Importantly, this research demonstrates that tree origin impacts the composition and interaction networks of root endophytes and depends on the season. The study's findings suggest that root biochemical traits and climatic conditions (e.g., temperature, precipitation) associated with tree origin are crucial in determining the assembly of endophytic communities. This understanding could lead to innovative strategies for enhancing plant health and adaptability across different environments, contributing to forestry and conservation efforts. The research underscores the complexity of plant-microbe interactions and the need for a comprehensive approach to studying them, highlighting the interplay between tree origin and microbial ecology in forest ecosystems.

Geographical, Seasonal, and Growth-Related Dynamics of Gut Microbiota in a Grapevine Pest, Apolygus spinolae (Heteroptera: Miridae)

A number of insects are associated with gut symbiotic microorganisms, wherein symbiotic partners play pivotal metabolic roles for each other such as nutrient supplementation, diet degradation, and pesticide detoxification. Despite the ecological and evolutionary importance of gut microbial communities in insects, their diversity and dynamics remain unclear in many species. The green plant bug Apolygus spinolae, a notorious grapevine pest in Japan, damages grape shoots and severely reduces grape berry yield and quality. The plant bug possesses a simple tubular gut housing ~ 104 bacteria. Here, we investigated geographic, seasonal, and growth-related dynamics of gut microbiota by high-throughput sequencing in 82 individuals (11 nymphs and 71 adults) from five locations in Hokkaido, Japan. In plant bugs, gut microbiota changed dynamically depending on region, season, and developmental stage. Among the gut bacteria, Serratia was consistently and abundantly detected and was significantly affected by seasonal changes. In addition, Caballeronia, known as a specific symbiont in some stinkbug species, was abundantly detected, especially in insects collected in late summer despite A. spinolae complete lack of midgut crypts known as symbiotic organ harboring Caballeronia in other stinkbug species. Considering their prevalence among host bug populations, it is possible these gut microorganisms play a pivotal role in the adaptation of the green plant bug to grapevine fields, although further confirmation through rearing experiments is needed.

Seasonal piRNA Expression Profile Changes in the Testes of Plateau Zokor (Eospalax baileyi).

Seasonal reproduction is a mammalian behavior that has developed over an extended evolutionary period and requires animals to respond to external environmental changes to facilitate reproduction. In this study, we investigated the role of PIWI-interacting RNA (piRNA) in the seasonal reproduction of plateau zokors (Eospalax baileyi). piRNA expression profiles in plateau zokor testes during both breeding and non-breeding seasons were examined. The piRNAs had a distinctive ping-pong signature and ranged from 27 to 32 nt with a peak at 30 nt. Testicular piRNAs predominantly aligned to specific genomic regions, including repeat and gene regions. Analysis of the piRNA-mRNA interaction network and functional enrichment of differentially expressed piRNAs targeting mRNAs revealed their association with testicular development and spermatogenesis. Significantly, PIWIL4 is an mRNA gene that interacts with piRNA and exhibits high expression levels within the testes during the non-breeding phase. This study provides a foundation to improve our understanding of piRNA regulatory mechanisms during testicular development and spermatogenesis in seasonally reproducing animals and, specifically, in the plateau zokor.

The Yangtze River Delta experienced strong seasonality and regular summer upwelling during the warm mid-Holocene

The mid-Holocene climate optimum saw warm temperatures in large parts of China, but its impact on seasonal environmental changes is not fully understood yet. Here, we use high-resolution geochemical analyses of 7000 to 6000 year-old oyster shells from the Yangtze River Delta to reconstruct climatic and oceanographic patterns. The stable isotope (δ18O, δ13C) and clumped isotope data reflect prominent seasonal changes in temperature, precipitation, and river discharge. Summer months experienced warm temperatures and a distinct increase in rainfalls and river discharge. In contrast, winter months were characterized by a dry season, which might have been longer than today. Stable isotope data also indicate regular summer upwelling in the study area. These results partly disagree with available climate models raising doubts on the models’ reliability. Thus, our palaeo-proxy data offers the possibility to evaluate and correct climate models and thereby improve predictions for the future considering on-going global warming.

Characterization of the Ecological Niche and Interspecific Connectivity of Plankton in Baiyangdian Lake by Combining Ecological Networks

To understand the structure of the plankton community and the ecological niche characteristics of their dominant species, sampling surveys of plankton were conducted in Baiyangdian Lake in the spring （March）, summer （July）, and autumn （September） of 2022. The changes in the plankton community during the three seasons were analyzed by constructing ecological network diagrams, non-metric multidimensional scaling analysis （NMDS）, and the ecological niche width. The niche overlap of zooplankton dominant species was evaluated by the improved Levins' formula and Petraitis' index. The interspecific connectivity of dominant species was judged using the chi-square test and interspecies connectivity coefficients. The results showed that the niche width of plankton in the whole area was low. Zooplankton was dominated by rotifers, and phytoplankton was dominated by diatoms, cyanobacteria, and green algae. There were significant seasonal changes in the community structures of plankton. Compared with that in summer and autumn, there were fewer species of plankton in spring and lower interspecies connectivity. The overlap of dominant species of zooplankton was high in summer, and the interspecific competition was intensified, whereas the interspecific overlap of phytoplankton was at a low level in all three seasons. There was a significant positive correlation （W > χ20.05） between phytoplankton in summer and autumn, and the community structure was stable. The interdomain ecological network of zooplankton and phytoplankton showed a high negative correlation ratio in autumn, especially between copepods and cladoceras of zooplankton and chlorophyta and cyanophyta of phytoplankton. The plankton species in Baiyangdian Lake were abundant, with obvious seasonal differences. The dominant species were mainly a narrow ecological niche. The plankton community was generally in a stable state, and there was a strong predation relationship between copepods and cladoceras and green algae and cyanobacteria.

Changes in the spatiotemporal distribution of the timing and duration of the soil freeze–thaw status from 1979 to 2018 over the Tibetan Plateau

AbstractChanges in the soil freeze–thaw status will inevitably affect the thermal conditions and properties of the Tibetan Plateau (TP), thereby affecting its upper atmosphere, and further afield in East Asia and even globally. In this study, using the soil temperature simulated by the Community Land Model Version 5.0 (CLM5.0), the timing and duration of the soil freeze–thaw status were divided into freeze start‐date, freeze end‐date and freeze duration. Then, using linear trend estimation, correlation analysis and other methods, the changes in the spatiotemporal distribution of the timing and duration of the soil freeze–thaw status from 1979 to 2018 over the TP were analysed, and the relationships between them and surface temperature, altitude and latitude were analysed. The results obtained were as follows: (1) The soil temperature simulated by CLM5.0 can reasonably reproduce the seasonal changes in multilayer soil temperature, and correlated well with observations. Simulated by CLM5.0 of the time and duration of the soil freeze–thaw status also correlated well with observations. (2) The spatial distribution of the soil freeze–thaw status is characterized by a trend of delayed freezing, advanced thawing and shortened freeze duration from northwest to southeast over the TP. From 1979 to 2018, the freeze start‐date postponed by 7.3 days and became delayed at a rate of 1.9 days per decade, while the freeze end‐date advanced by 6.4 days at a rate of 1.7 days per decade, and the freeze duration shortened by 13.7 days at a rate of 3.6 days per decade. The timing and duration of the soil freeze–thaw status vary across different regions of the TP. The freeze start‐date in all areas of the TP has been delayed in the past 39 years. Except for the subcold zone and arid regions of the TP, the freeze end‐date has occurred earlier and the freeze duration has shortened, with the most significant changes in the subcold zone and humid regions, while the freeze end‐date has advanced at a rate of 3.6 days per decade and the freeze duration has shortened at a rate of 6.3 days per decade. (3) The timing and duration of the soil freeze–thaw status are significantly correlated with surface air temperature, elevation and latitude, exceeding the 99% confidence level. The correlation between the timing and duration of the soil freeze–thaw status and surface temperature is strongest, followed by altitude, and correlation with latitude is weaker. The correlation between surface air temperature and the timing and duration of the soil freeze–thaw status in the western TP is stronger than that in the eastern TP. The rate of change in the soil freeze–thaw status increases with altitude to 3000 m above sea level, while this rate decreases with elevation above 3000 m. The rate of change in the soil freeze–thaw status is greatest at 29°N, while the rate of delay in the freeze start‐date is minimal at 33°N and the rates of advancement in the freeze end‐date and shortening of the freeze duration are minimal at 35°N.