Qinghai-Tibet Plateau Region Research Articles

Phase-change pavement structures with gradient low-thermal conductivity for permafrost protection

Currently available permafrost protection techniques do not pay enough attention to the properties of asphalt pavement, and the problem of strong heat-absorbing asphalt pavement and permafrost constraining each other is a global challenge that needs to be urgently addressed. Phase change materials (PCMs) can regulate the operating temperature of pavement structures by storing and releasing large amounts of heat during phase changes. In this paper, composite shaped phase change material (CSPCM) was applied to the permafrost region of Qinghai-Tibetan Plateau, and a new method of phase-change pavement structures with gradient low-thermal conductivity was proposed to reduce the heat absorption of the pavement and realize the active protection of permafrost. The structures were designed based on finite element software, and the heat flux and temperature distribution within the structure were analyzed and verified with indoor and outdoor thermal regulation tests. Results showed that the preferred gradient low-thermal conductivity structure reduced the annual net heat absorption at the top of the pavement by 8.18 %, the heat absorption in summer by 7.65 %, and the heat release in winter by 6.75 % compared with the control group. The heat flux and the temperature distribution within the pavement structures were significantly altered by the phase-change asphalt pavement structures with gradient low-thermal conductivity, and the simulation results of the finite element model agreed well with the results of the indoor and outdoor thermal regulation tests. The temperature regulation factor (RT) was proposed as an evaluation index to quantitatively analyze the temperature regulation performance of CSPCM on the pavement structure, and the results showed that the flexible base layer had the greatest influence on the temperature regulation performance of the pavement structure. The phase-change asphalt pavement structures with gradient low-thermal conductivity proposed in this paper is a structure that has an efficient cooling effect on the interior of the pavement, and provides a new idea for improving the stability of permafrost subgrade and the integrated design of materials and structures in permafrost regions.

Analysis of Atmospheric Aerosol Changes in the Qinghai-Tibetan Plateau Region during 2009–2019 Using a New Fusion Algorithm

Analysis of Atmospheric Aerosol Changes in the Qinghai-Tibetan Plateau Region during 2009–2019 Using a New Fusion Algorithm

A Transcriptomic and Metabolomic Study on the Biosynthesis of Iridoids in Phlomoides rotata from the Qinghai-Tibet Plateau.

Phlomoides rotata is a traditional Chinese herbal medicine that grows in the Qinghai-Tibet Plateau region at a 3100-5000 m altitude. Iridoid compounds are the main active compounds of the P. rotata used as medical ingredients and display anti-inflammatory, analgesic, and hepatoprotective properties. To better understand the biological mechanisms of iridoid compounds in this species, we performed a comprehensive analysis of the transcriptome and metabolome of P. rotata leaves from four different regions (3540-4270 m). Global metabolome profiling detected 575 metabolites, and 455 differentially accumulated metabolites (DAMs) were detected in P. rotata leaves from the four regions. Eight major DAMs related to iridoid metabolism in P. rotata leaves were investigated: shanzhiside methyl ester, 8-epideoxyloganic acid, barlerin, shanzhiside, geniposide, agnuside, feretoside, and catalpin. In addition, five soil physical and chemical indicators in P. rotata rhizosphere soils were analyzed. Four significant positive correlations were observed between alkaline nitrogen and geniposide, exchangeable calcium and geniposide, available potassium and shanzhiside, and available phosphorus and shanzhiside methyl ester. The transcriptome data showed 12 P. rotata cDNA libraries with 74.46 Gb of clean data, which formed 29,833 unigenes. Moreover, 78.91% of the unigenes were annotated using the eight public databases. Forty-one candidate genes representing 23 enzymes involved in the biosynthesis of iridoid compounds were identified in P. rotata leaves. Moreover, the DXS1, IDI1, 8-HGO1, and G10H2 genes associated with iridoid biosynthesis were specifically expressed in P. rotata. The integration of transcriptome and metabolome analyses highlights the crucial role of soil physical and chemical indicators and major gene expression related to iridoid metabolism pathways in P. rotata from different areas. Our findings provide a theoretical foundation for exploring the molecular mechanisms underlying iridoid compound accumulation in P. rotata.

Remote sensing estimation of dissolved organic carbon concentrations in Chinese lakes based on Landsat images

Long-term estimation of dissolved organic carbon (DOC) dynamics based on satellite data provides important information to comprehensively understand the lake carbon cycle, climate change, and sustainable water resource management. Here, we proposed a novel DOC concentration estimation model based on water classification using a large field dataset (n = 1929) collected from 123 Chinese lakes. We divided water into terrestrial-DOM-dominated and endogenous-DOM-dominated water bodies using the optimal spectral slope ratio (SR) threshold determined by setting the classification scenario. Then, we calibrated the optimal DOC estimation model using stepwise quadratic polynomial regression for the different types of water and determined the final DOC estimation model. The final DOC estimation model performed well in both the calibration and validation datasets, with R2 ≥ 0.78, RMSD ≤ 0.78 mg/L, and MAPD ≤ 16.51 %. Subsequently, we mapped the spatiotemporal dynamics of DOC concentrations in Chinese lakes with surface area greater than 1 km2 (n = 2621) between 1986 and 2021 using the Landsat data. Spatially, we observed obvious spatial heterogeneity in the DOC concentrations in the Chinese lakes, with the highest DOC concentration occurring in the Northeast Region (NER) (4.39 ± 0.21 mg/L) and the lowest DOC concentration occurring in the Qinghai-Tibet Plateau Region (QTR) (3.76 ± 1.12 mg/L). Temporally, the average DOC concentration in Chinese lakes generally decreased at a rate of − 0.09 mg/L decade−1 from 1986 to 2021, during which 56.5 % of the lakes experienced a decrease, 29.6 % of the lakes experienced no obvious change, and 13.9 % of the lakes experienced an increase. We also revealed that human activities are the main drivers of DOC increases in lakes, while vegetation and climate change are the main drivers of DOC decreases in lakes. Our results contribute to improving the accuracy of organic carbon estimations in lakes worldwide and provides meaningful insights into the lake carbon cycle..

Spatial-temporal heterogeneity of ecological quality changes across the Qinghai-Tibet Plateau under the influence of climate factors and human activities

Over the last few decades, the ecological quality of the Qinghai–Tibet Plateau (QTP) has significantly changed due to climate warming, humidification, and increasing human activities. Thus, evaluating this region's ecological quality and dominant factors is crucial for sustainable development. In this study, the changes in the ecological quality on the QTP from 2000 to 2020 were evaluated based on aggregated indices and Sen–MK trend analyses, and the dominant factors affecting the ecological quality of the QTP were quantitatively analyzed using decision tree classification. The results revealed that (1) the ecological quality of the QTP exhibited an overall high trend in the east and a low pattern in the west; (2) the ecological quality of the QTP significantly increased from 2000 to 2020, and human activities were the dominant factors causing this change; and (3) the changes in the ecological quality and dominant factors exhibited obvious spatiotemporal heterogeneity. The area with an improved ecological quality occurred mainly in the northern QTP region. It was governed by human activities and precipitation. In contrast, the area with a deteriorated ecological quality occurred largely in the southern QTP region and was dominated by human activities and temperature. The 2000–2010 period was the most significant period of heterogeneity regarding of ecological quality and its driving factors. (4) The change in the ecological quality was mainly affected by the synergistic relationship between human activities and climate change in this region, which encompassed multiple dominant factors. This study provides important information on the spatiotemporal heterogeneity of ecological quality change and its dominant factors on the QTP and offers systematic guidance for the planning and implementation of ecological protection projects.

Snow Disaster Risk Assessment Based on Long-Term Remote Sensing Data: A Case Study of the Qinghai–Tibet Plateau Region in Xizang

The risk analysis and assessment of snow disasters are essential foundational tasks in natural disaster management and profoundly impact the scientific and precise formulation of disaster prevention, preparedness, and mitigation strategies. Employing the theory and methodology of snow disaster assessment, this research focuses on historical and potential snow disasters in the Qinghai–Tibetan Plateau (QTP) Region. Utilizing a long-time-series snow depth remote sensing dataset, we extracted six assessment indicators for historical snow disaster risk factors and potential snow disaster risk factors. We determined the weights of these six assessment indicators using the entropy weight method. Subsequently, we established a snow disaster assessment model to evaluate the grade distribution of snow disasters in the study area. This method can effectively solve the problem of the sparse data distribution of meteorological stations and reflect degrees of snow disaster risk on a large spatial scale. The findings reveal that areas with a relatively high snow disaster risk are primarily concentrated in the western part of the Ali Region, the central part of Chamdo, and near the border in Southern Xizang. Additionally, regions with a high frequency of snow disasters are predominantly located at the junction of Nagchu, Chamdo, and Nyingchi in the eastern part of Xizang. These results contribute valuable insights into the risk assessment of snow disasters and facilitate the development of effective strategies for disaster management in the region.

Dynamic change of a typical surging glacier in the Qinghai tibet plateau based on satellite remote sensing

With global climate change, some mountain glaciers in the Qinghai–Tibet Plateau region are experiencing rapid melting, retreating, and acceleration. Surge-type glaciers are important objects for glacier dynamics research in this region, as sudden surge may threaten human activities and lives. This study focuses on the Shahrek Glacier. Based on multi-source remote sensing images from 2000 to 2023, we generated long-term ice flow velocity maps of the glacier using image template matching technology. Together with its terminus position over this period, the surge dynamics of Shahrek Glacier were analyzed. The glacier surge commenced in September 2016 and terminated in November 2018, reaching a maximum ice velocity of almost 1,200 m/a, which is 9–10 times its ice velocity in the quiescent phase. A substantial change in the magnitude of the ice flow before and after the onset of the Shahrek Glacier surge was observed; the surge comprised five main phases: pre-surge stable, accelerated, surge, decelerated, and stabilized periods. The Shahrek Glacier was retreating from the position of the glacier-terminal ablation zone prior to the onset of leapfrogging. We analyzed the relationship between Shahrek Glacier dynamics and climate and the surge mechanism surge, considering data from meteorological stations in neighboring regions.

Climate change impairs the effects of vegetation improvement on soil erosion control in the Qinghai-Tibetan Plateau

Water erosion is a wide ecosystem degradation threat for the Qinghai-Tibetan Plateau (QTP) region and surrounding areas. Climate wetting and vegetation greening in the QTP could have complex impacts on water erosion. However, there is limited information about the erosion dynamics under climate change and the effects of vegetation improvement on erosion control in this alpine region. By calibrating the Revised Universal Soil Loss Equation (RUSLE) model, we estimated water erosion in the QTP and simulated future changes using different Shared Socioeconomic Pathway-Representative Concentration Pathway (SSP) scenarios. We showed intensified erosion and that the benefits of vegetation improvement to erosion control was impaired under climate change. Under the SSP585 scenario, annual water erosion in the QTP was predicted to increase by 0.35 t∙ha−1∙yr−1 and be dominated by an accelerative rise of rainfall erosivity (R factor of RUSLE). Compared with historical observations, the C factor of RUSLE under the SSP585 scenario was believed to reduce by 4.35 % on average during the 2081–2100 period, but predicted soil loss will increase by more than 90 %. Although more considerable vegetation improvement could occur under high climate forcing, there may also be more intensified rainfall erosivity and water erosion across the QTP than those under SSP126 and SSP245 scenarios. Our results suggest that mitigating climate change rather than vegetation improvement is essential to address climate-dominated ecosystem degradation threats such as water erosion in the QTP.

The impact of mixed planting of Poaceae species in the Qinghai-Tibet plateau region on forage yield, soil nutrients, and soil microbial communities.

Establishing cultivated grassland in the Qinghai-Tibet Plateau region is an effective method to address the conflict between vegetation and livestock. However, the high altitude, low temperature, and arid climate in the region result in slow regeneration and susceptibility to degradation of mixed cultivation grassland containing perennial legumes and gramineous plants. Therefore, we aim to through field experiments, explore the feasibility of establishing mixed cultivation grassland of Poaceae species in the region by utilizing two grass species, Poa pratensis L. and Puccinellia tenuiflora. By employing a mixture of P. pratensis and P. tenuiflora to establish cultivated grassland, we observed significant changes in forage yield over time. Specifically, during the 3rd to 6th years of cultivation, the yield in the mixed grassland was higher than in monocultures. It exceeded the yield of monoculture P. tenuiflora by 19.38% to 29.14% and surpassed the monoculture of P. pratensis by 17.18% to 62.98%. Through the analysis of soil physicochemical properties and soil microbial communities in the cultivated grassland, the study suggests that the mixed grassland with Poaceae species can enhance soil enzyme activity and improve soil microbial communities. Consequently, this leads to increased soil nutrient levels, enhanced nitrogen fixation efficiency, and improved organic phosphorus conversion efficiency. Therefore, establishing mixed grasslands with Poaceae species in the Qinghai-Tibet Plateau region is deemed feasible.

Geographical division of terrestrial mammals in China based on species composition characteristics

China has complex natural conditions and is rich in biodiversity. Based on the geographical distribution and species composition of terrestrial mammals, we explored the characteristics and geographic partitioning of mammal populations in different regions of China. We used a clustering algorithm, combined with the spatial distribution data and taxonomic characteristics of mammals, to geographically partition the terrestrial mammals in China. We found 10 zoogeographic regions of terrestrial mammals in China: Northeast region, North China region, Eastern grassland region, Western region, Northwest region, Qiangtang plateau region, Eastern Qinghai-Tibet Plateau region, Himalayan region, South China region, and Taiwan-Hainan region. We found a new geographical zoning pattern for terrestrial mammals in China, examined the variability and characteristics of species composition among different regions, and quantified the association between species distribution and environmental factors. We proposed a method of incorporating taxonomic information into cluster analysis, which provided a new idea for zoogeographic region studies, a new perspective for understanding species diversity, and a scientific basis for animal conservation and habitat planning.

Reliability risk modelling of asphalt pavement structure performance under the impact of freeze-thaw cycles

This paper delivers an in-depth risk analysis of asphalt pavement structural strength in the cold Qinghai-Tibet Plateau region. It encompasses a wide range of risk factors, including environmental conditions, traffic dynamics, pavement structures and materials, and various human-related factors. These risk factors are quantified using probability distributions, with emphasis on the changes in their mean and variance to simulate the effects of risk. A novel risk metric, termed “CVall”, is introduced to encapsulate the cumulative risk associated with each random variable. The paper describes the risk in the load and resistance equations, which govern the asphalt pavement strength, using the probability density function distribution. This approach takes into account the variation coefficient of each parameter. The study highlights that the risk related to the pavement structure number following freeze-thaw cycles significantly influences the reliability of pavement structural strength. These insights are particularly crucial for highway design, construction, and maintenance in cold regions, where the durability and longevity of pavement are paramount.

Effect of Orientation and Skylight Area Ratio on Building Energy Efficiency in the Qinghai–Tibet Plateau

The Qinghai–Tibet plateau, with an average altitude of over 4000 m, has low annual average temperatures and a high demand for building heating. This region’s abundant solar energy resources hold substantial practical significance for improving the indoor heat environment and reducing building energy consumption. This paper investigates the impact of orientation and skylight area ratio on building heat load and indoor temperature, using both actual measurement and simulation methods, with a case study of the comprehensive building at Beiluhe Observation and Research Station of Frozen Soil Engineering and Environment (Beiluhe Station), located in the Qinghai–Tibet Plateau region. Initially, a model was established using the EnergyPlus 9.4 software, with orientation variables set from east to west in 15° increments, to simulate the variations in building heat load resulting from orientation changes; simulations were then conducted for three different skylight area ratios under the optimal orientation to evaluate their influence on heat load and indoor temperature. The results show that for the architectural style examined in this paper, the optimal building orientation within the region is 30° south by east, with the optimal orientation range spanning from 45° south by east to due south. Heating load is negatively correlated with the skylight area ratio, and beyond a certain threshold, the rate of decrease in heat load diminishes or even stabilizes. The conclusions of this paper offer guidance for the orientation and skylight design of new buildings on the Qinghai–Tibet Plateau.

A global dataset on species occurrences and functional traits of Schizothoracinae fish

The Schizothoracinae fish are a natural group of cyprinids widely distributed in rivers and lakes in the Qinghai-Tibetan Plateau (QTP) and adjacent regions. These fish parallelly evolved with the QTP uplift and are thus important for uncovering geological history, the paleoclimatic environment, and the mechanisms of functional adaptation to environmental change. However, a dataset including species occurrences and functional traits, which are essential for resolving the above issues and guiding relevant conservation, remains unavailable. To fill this gap, we systematically compiled a comprehensive dataset on species occurrences and functional traits of Schizothoracinae fish from our long-term field samplings and various sources (e.g., publications and online databases). The dataset includes 7,333 occurrence records and 3,204 records of 32 functional traits covering all the genera and species of Schizothoracinae fish (i.e., 12 genera and 125 species or subspecies). Sampling records spanned over 180 years. This dataset will serve as a valuable resource for future research on the evolution, historical biogeography, responses to environmental change, and conservation of the Schizothoracinae fish.

Molecular phylogenetics of the Ophiocordyceps sinensis-species complex lineage (Ascomycota, Hypocreales), with the discovery of new species and predictions of species distribution

Ophiocordyceps sinensis is a famous traditional Chinese medicine adapted to the alpine environment of the Qinghai-Tibet Plateau and adjacent regions. Clarification of the species diversity of Ophiocordyceps sinensis and its relatives could expand the traditional medicinal resources and provide insights into the speciation and adaptation. The study is prompted by the discovery of a new species, O. megala, described here from a biodiversity hotspot in the Hengduan Mountains, China. Combined morphological, ecological, and phylogenetic evidence supports its distinctiveness from O. sinensis, O. xuefengensis, and O. macroacicularis. Additionally, based on the phylogenetic construction of Ophiocordyceps, a special clade was focused phylogenetically on the more closely related O. sinensis complex, which was defined as the O. sinensis- species complex lineage. A total of 10 species were currently confirmed in this lineage. We made a comprehensive comparison of the sexual/asexual morphological structures among this species complex, distinguishing their common and distinctive features. Furthermore, using the method of species distribution modelling, we studied the species ocurrences in relation to climatic, edaphic, and altitudinal variables for the eight species in the O. sinensis-species complex, and determined that their potential distribution could extend from the southeastern Qinghai-Tibet Plateau to the Xuefeng Mountains without isolating barrier. Thus, the biodiversity corridor hypothesis was proposed around the O. sinensis-species complex. Our study highlights the phylogeny, species diversity, and suitable distribution of the O. sinensis-species complex lineage, which should have a positive implication for the resource discovery and adaptive evolution of this unique and valuable group.

Research on Ecological Restoration Evaluation Index System for Construction Projects in Qinghai Tibet Plateau

In the “Ecological Protection Law of the People’s Republic of China on the Qinghai Tibet Plateau” released in April 2023, it is stipulated that “the state strengthens the ecological protection and restoration of the Qinghai Tibet Plateau, adheres to the integrated protection and restoration of mountains, rivers, forests, fields, lakes, grasses, sands, and ice, and implements a systematic governance that focuses on natural restoration and combines natural restoration with artificial restoration.” Currently, there is relatively little research on the ecological restoration evaluation index system in high-altitude areas represented by the Qinghai Tibet Plateau in China. This article studies the climate and soil characteristics of the Qinghai Tibet Plateau region and selects ecological restoration evaluation index systems suitable for high-altitude areas, including biological and community evaluation, soil and water conservation function evaluation, soil and water physical and chemical property evaluation, and landscape pattern evaluation.

Changes of Surface Water Resources in China's Mountains in the Past 50 Years

Mountains, provide crucial water resources for the development of human society, are the water towers of the world. However, mountain water resources have undergone marked changes in recent decades, posing a threat to sustainable human development. Based on long-term hydrological, meteorological, and related environmental data, this study analyzes the evolving patterns of water resources in China's mountains over the past 50 years using trend analysis methods. The results indicate that surface water resources in China's major mountains have undergone noticeable changes over the past 50 years, with varying trends among different mountains. The Qinghai-Tibet Plateau and Tianshan regions show an overall increasing trend in surface water resources, while the Hengduan Mountains, Taihang Mountains, Qinling Mountains, Changbai Mountains, and Yunnan-Guizhou Plateau have witnessed decreasing trends to varying degrees. Furthermore, there are differences in the primary processes influencing surface water resource changes across various mountains. For example, climate change plays a predominant role in driving surface water resource changes in the high-altitude Qinghai-Tibet Plateau and Tianshan region, while human-related activities exert a stronger impact on surface water resource changes in other mountains. To address the challenges brought about by changes in China's mountain surface water resources, it is crucial to take into full consideration the unique natural environments and social systems of each mountain.

Spatiotemporal Variability in Rainfall Erosivity and Its Teleconnection with Atmospheric Circulation Indices in China

Rainfall erosivity (RE) is a critical factor influencing soil erosion, and soil erosion is closely related to land ecosystem health and long-term sustainable utilization. To ensure regional stable food supply and ecological balance, it is crucial to study the spatiotemporal distribution and influencing factors of RE. This study focuses on China and its three natural regions using daily precipitation data from 611 stations from 1960 to 2020. The study analyses the spatiotemporal changes in RE. Rainfall events were classified as moderate, large, and heavy based on rainfall intensity. The RE contribution from different rainfall levels to the total RE was analyzed, and the key climatic drivers closely linked to RE were identified using random forest. The results demonstrate that (1) on a national scale, RE shows a significant increasing trend, marked by an 81.67 MJ·mm·ha−1·h−1/decade. In the subregions, the Eastern Monsoon Region (EMR) and Qinghai–Tibet Plateau Region (QTR) show a significant increasing trend, with a greater change rate in EMR of 108.54 MJ·mm·ha−1·h−1/decade, and the Northwest Arid Region (NAR) shows a nonsignificant upwards trend. (2) The average RE increases northwest–southeast nationwide, ranging from 60.15 MJ·mm·ha−1·h−1 to 31,418.52 MJ·mm·ha−1·h−1. The RE contribution generated by different rainfall levels to the total RE exhibits spatial variations. The dominant types show that EMR is influenced by heavy RE, NAR is dominated by large RE, and QTR is affected by moderate RE. (3) The REs are associated with teleconnection indices, but the impact of these indices varies in different regions. The Western Hemisphere Warm Pool has the greatest impact on the EMR, while the North Atlantic Oscillation and Atlantic Multidecadal Oscillation are the factors influencing RE in NAR and QTR, respectively. (4) On a national scale, for every 1 mm increase in annual total rainfall, the RE increased by 8.54 MJ·mm·ha−1·h−1, a sensitivity of 8.54 MJ·mm·ha−1·h−1/mm. For the three subregions, there are differences in the sensitivity of RE to changes in annual precipitation. The highest sensitivity is found in EMR, at 8.71 MJ·mm·ha−1·h−1/mm, which is greater than the sensitivity indices in NAR (6.19 MJ·mm·ha−1·h−1/mm) and QTR (3.60 MJ·mm·ha−1·h−1/mm). This study can provide theoretical references for future regional soil erosion prediction and sustainable agricultural development in China.

Surface oxygen concentration on the Qinghai-Tibet Plateau (2017–2022)

For the ecologically vulnerable Qinghai-Tibet Plateau (QTP), hypoxia is increasingly becoming an extremely important environmental risk factor that significantly affects the health of both humans and livestock in the plateau region, as well as hindering high-quality development. To focus on the problem of hypoxia, it is especially urgent to study the surface oxygen concentration (i.e., oxygen concentration). However, the existing research is not sufficient, and there is a lack of oxygen concentration data collected on the QTP. In this study, through the Second Tibetan Plateau Scientific Expedition and Research and field measurements, the oxygen concentration data and corresponding geographic environmental data were collected at 807 measurement points on the QTP from 2017 to 2022, and the spatiotemporal oxygen concentration patterns were estimated. This work filled the gaps in the measurement and research of oxygen concentrations on the QTP while providing data support for analyses of the influencing factors and spatiotemporal characteristics of oxygen concentrations, which is of great significance for promoting the construction of ecological civilization in the QTP region.

Research on Missing Value Imputation to Improve the Validity of Air Quality Data Evaluation on the Qinghai-Tibetan Plateau

In the Qinghai-Tibet Plateau region, operational deficiencies and limited maintenance capacities often impair automatic air quality monitoring stations. This results in frequent data omissions, compromising the reliability of environmental assessment data. Therefore, an effective data imputation method is required to address the gaps in observational records. Utilizing a Sequence-to-Sequence framework, we introduce a model termed Bidirectional Recurrent Imputation for Time Series-Attention-based Long Short-Term Memory (BRITS-ALSTM). The encoder of BRITS-ALSTM applies BRITS to integrate single-station historical characteristics with multi-station correlation features. Concurrently, the decoder employs LSTM within an attention mechanism to capitalize on previously observed data, thereby generating hourly imputations for missing air quality data values. The model was trained using six types of air quality data from 16 stations across Qinghai Province. Through localized testing and parameter optimization, BRITS-ALSTM achieved a reduction in mean relative error (MRE) by 74.88% compared to the baseline mean-filling approach. Additionally, ablation studies demonstrated an improvement in the coefficient of determination R-squared (R2) from 0.67 to 0.76, outperforming the standalone BRITS. Consequently, BRITS-ALSTM enhances the accuracy of air quality data evaluations in the Tibetan Plateau and offers an efficacious strategy for data imputation in elevated terrains.

Reduced contribution of microbial necromass carbon to soil organic carbon following tunnel construction in the eastern Qinghai-Tibet Plateau

Microbial necromass carbon (MNC) is one of the primary sources of stable soil organic carbon (SOC), playing a crucial role in global carbon cycling. Despite its significance, the impact of tunnel construction, a commonly adopted human activity in railway development, on MNC and its underlying mechanisms remains underexplored. To address this gap, a field survey was conducted in shrubland ecosystems on the eastern edge of the Qinghai-Tibet Plateau. Our study aimed to investigate the influence of tunnel construction on MNC and its contribution to SOC along an altitudinal gradient (3240 m, 3420 m, and 3600 m) and at two soil depths (0–10 cm and 10–30 cm). Results indicated that tunnel construction did not exert a significant impact on SOC and MNC. However, it led to a substantial decrease in the contribution of MNC to SOC (15.6%–19.9% in tunnel-affected areas) compared to the control areas (19.04%–30.97%). This outcome was likely attributed to the decreased bacterial necromass carbon (BNC) and the increased input of underground plant-derived carbon. MNC at 10–30 cm was significantly lower than that at 0–10 cm, and it exhibited a notable decrease at 3420 m compared to both 3240 m and 3600 m. These observations were closely related to reduced carbon input and microbial necromass stability. Principal component structural equation modeling revealed that soil microbial activities were the most important for MNC and SOC accumulation. Consequently, tunnel construction influenced SOC formation by altering the relative contributions from plant and microbial sources. This study provides valuable evidence for assessing the impacts of engineering construction on SOC and its sources in the context of climate change. Moreover, it offers scientific support for ecosystem conservation and sustainable development in the Qinghai-Tibet Plateau region during engineering construction.