How many people can the Qinghai-Tibet Plateau hold, and how large cities can be built in recent hundred years?

The Qinghai-Tibet Plateau (QTP) serves as a vital barrier for both national security and ecological preservation. Overpopulation and urban sprawl pose threats to its ecological security, while underpopulation and small urban cities also undermine national security. Hence, optimizing population distribution and urban development on the QTP is crucial for bolstering the national security perimeter and ensuring basic modernisation across China. Nonetheless, understanding the population carrying capacity (CC) of the QTP and how large cities can safeguard both national security and ecological stability remains limited. To address this research gap, we utilised various model algorithms and methodologies to assess the population CC and urban scale of the QTP from seven different perspectives. The results indicate that the permanent population CC of the QTP in 2050 will be 26.2 million people, with an urbanisation level of 57.25 %, thereby allowing 15 million people to enter cities. Thus, the QTP can add 13.07 million people to its permanent population in the future, with a newly added urban population of 8.75 million, increasing the urbanisation level by 9.67 %. The future permanent population will mainly be distributed in the Xining, Lhasa, and Qaidam metropolitan areas. Combined, the permanent and urban populations will account for 38.54 % and 49.84 % of the QTP, respectively. Moreover, these populations will be moderately dispersed in 11 important node cities and more widely dispersed in key border towns. These findings provide a scientific basis for the sustainable development and high-quality urbanisation of the QTP, which have important implications for achieving sustainable development goals, offering crucial references for governments to formulate resource management policies and achieve sustainable resource utilisation.

Leaf ecological stoichiometry and anatomical structural adaptation mechanisms of Quercus sect. Heterobalanus in southeastern Qinghai-Tibet Plateau

BACKGROUND

With the dramatic uplift of the Qinghai-Tibet Plateau (QTP) and the increase in altitude in the Pliocene, the environment became dry and cold, thermophilous plants that originally inhabited ancient subtropical forest essentially disappeared. However, Quercus sect. Heterobalanus (QSH) have gradually become dominant or constructive species distributed on harsh sites in the Hengduan Mountains range in southeastern QTP, Southwest China. Ecological stoichiometry reveals the survival strategies plants adopt to adapt to changing environment by quantifying the proportions and relationships of elements in plants. Simultaneously, as the most sensitive organs of plants to their environment, the structure of leaves reflects of the long-term adaptability of plants to their surrounding environments. Therefore, ecological adaptation mechanisms related to ecological stoichiometry and leaf anatomical structure of QSH were explored. In this study, stoichiometric characteristics were determined by measuring leaf carbon (C), nitrogen (N), and phosphorus (P) contents, and morphological adaptations were determined by examining leaf anatomical traits with microscopy.

RESULTS

Different QSH life forms and species had different nutrient allocation strategies. Leaves of QSH plants had higher C and P and lower N contents and higher N and lower P utilization efficiencies. According to an N: P ratio threshold, the growth of QSH species was limited by N, except that of Q. aquifolioides and Q. longispica, which was limited by both N and P. Although stoichiometric homeostasis of C, N, and P and C: N, C: P, and N: P ratios differed slightly across life forms and species, the overall degree of homeostasis was strong, with strictly homeostatic, homeostatic, and weakly homeostatic regulation. In addition, QSH leaves had compound epidermis, thick cuticle, developed palisade tissue and spongy tissue. However, leaves were relatively thin overall, possibly due to leaf leathering and lignification, which is strategy to resist stress from UV radiation, drought, and frost. Furthermore, contents of C, N, and P and stoichiometric ratios were significantly correlated with leaf anatomical traits.

CONCLUSIONS

QSH adapt to the plateau environment by adjusting the content and utilization efficiencies of C, N, and P elements. Strong stoichiometric homeostasis of QSH was likely a strategy to mitigate nutrient limitation. The unique leaf structure of the compound epidermis, thick cuticle, well-developed palisade tissue and spongy tissue is another adaptive mechanism for QSH to survive in the plateau environment. The anatomical adaptations and nutrient utilization strategies of QSH may have coevolved during long-term succession over millions of years.

Escalating Carbon Export from High-Elevation Rivers in a Warming Climate

High-elevation mountains have experienced disproportionately rapid warming, yet the effect of warming on the lateral export of terrestrial carbon to rivers remains poorly explored and understood in these regions. Here, we present a long-term data set of dissolved inorganic carbon (DIC) and a more detailed, short-term data set of DIC, δ13CDIC, and organic carbon from two major rivers of the Qinghai-Tibetan Plateau, the Jinsha River (JSR) and the Yalong River (YLR). In the higher-elevation JSR with ∼51% continuous permafrost coverage, warming (>3 °C) and increasing precipitation coincided with substantially increased DIC concentrations by 35% and fluxes by 110%. In the lower-elevation YLR with ∼14% continuous permafrost, such increases did not occur despite a comparable extent of warming. Riverine concentrations of dissolved and particulate organic carbon increased with discharge (mobilization) in both rivers. In the JSR, DIC concentrations transitioned from dilution (decreasing concentration with discharge) in earlier, colder years to chemostasis (relatively constant concentration) in later, warmer years. This changing pattern, together with lighter δ13CDIC under high discharge, suggests that permafrost thawing boosts DIC production and export via enhancing soil respiration and weathering. These findings reveal the predominant role of warming in altering carbon lateral export by escalating concentrations and fluxes and modifying export patterns.

Distribution characteristics of soil carbon density and influencing factors in Qinghai-Tibet Plateau region

The Qinghai-Tibet Plateau has low anthropogenic carbon emissions and large carbon stock in its ecosystems. As a crucial region in terrestrial ecosystems responding to climate change, an accurate understanding of the distribution characteristics of soil carbon density holds significance in estimating the soil carbon storage capacity in forests and grasslands. It performs a crucial role in achieving carbon neutrality goals in China. The distribution characteristics of carbon and carbon density in the surface, middle, and deep soil layers are calculated, and the main influencing factors of soil carbon density changes are analyzed. The carbon density in the surface soil ranges from a minimum of 1.62 kg/m2 to a maximum of 52.93 kg/m2. The coefficient of variation for carbon is 46%, indicating a considerable variability in carbon distribution across different regions. There are substantial disparities, with geological background, land use types, and soil types significantly influencing soil organic carbon density. Alpine meadow soil has the highest carbon density compared with other soil types. The distribution of soil organic carbon density at three different depths is as follows: grassland > bare land > forestland > water area. The grassland systems in the Qinghai-Tibet Plateau have considerable soil carbon sink and storage potential; however, they are confronted with the risk of grassland degradation. The grassland ecosystems on the Qinghai-Tibet Plateau harbor substantial soil carbon sinks and storage potential. However, they are at risk of grassland degradation. It is imperative to enhance grassland management, implement sustainable grazing practices, and prevent the deterioration of the grassland carbon reservoirs to mitigate the exacerbation of greenhouse gas emissions and global warming. This highlights the urgency of implementing more studies to uncover the potential of existing grassland ecological engineering projects for carbon sequestration.

Maintaining the native gut microbiota of bharal (Pseudois nayaur) is crucial in ex situ conservation

As wildlife protection continue to strengthen, research on the gut microbiota of wildlife is increasing. Carrying out conservation and research on endangered species in the Qinghai Tibet Plateau plays an important role in global biodiversity conservation. This study utilized 16S rRNA sequencing of fecal samples to investigate the composition, function, and changes of the gut microbiota of bharal in different environments, seasons, and genders. The results showed that Firmicutes and Bacteroidota were the dominant phyla and UCG-005, Bacteroides, UCG-010 were the dominant genera of bharal. In the wild, the abundance of Firmicutes increased which was conducive to the decomposition and utilization of cellulose, hemicellulose, and carbohydrate. Due to the variety of food types and nutrition in different seasons, the composition and function of gut microbiota were obviously different between genders. Compared with zoo, higher alpha diversity, a more complex gut microbiota network structure, and stronger metabolic function were conducive bharal to adapting to the wild environment. In the zoo, captive bharals were fed foods rich in high fat and protein, which increased the abundance of Bacteroidota and reduced the alpha diversity of gut microbiota. A fixed diet unified the gut microbiota between genders of bharal. It is very important to pay attention to the impact of captive environments and maintain the native gut microbiota of wildlife.

Modeling the effect of grazing on carbon and water use efficiencies in grasslands on the Qinghai-Tibet Plateau

BACKGROUND

Carbon and water use efficiencies (CUE and WUE, respectively) are vital indicators of the adaptability of plants to environmental conditions. However, the effects of grazing and climate change on the spatiotemporal changes in CUE and WUE in Qinghai-Tibet Plateau grasslands (QTPG) are still unclear.

RESULTS

Using the enhanced Biome-BGCMuSo model in combination with observed data, we estimated and analyzed the spatiotemporal variations in CUE and WUE and their responses to grazing in QTPG from 1979 to 2018. The mean annual CUE was 0.7066 in QTPG from 1979 to 2018 under the actual climate scenario. In general, the grassland CUE was low in the southeast and high in the northwest. Grazing generally decreased CUE in QTPG from 1979 to 2018, and there was an increasing trend in the difference in CUE between the grazing and nongrazing scenarios. The difference in CUE was generally greater in the northwest than in the southeast. The mean annual WUE was 0.5591 g C/kg H2O in QTPG from 1979 to 2018 under the actual climate scenario. After 2000, the grassland WUE exhibited a fluctuating upward trend. In general, the grassland WUE was greater in the southeast than in the northwest. Grazing generally decreased WUE in QTPG from 1979 to 2018, and there was an increasing trend in the difference in WUE between the grazing and nongrazing scenarios. The difference in WUE was generally greater in the northwest than in the southeast.

CONCLUSIONS

The findings of this study suggested that the spatiotemporal changes in CUE and WUE in QTPG were closely related to changes in the natural environment and grazing management.

Spatio-temporal variation in soil thermal conductivity during the freeze-thaw period in the permafrost of the Qinghai-Tibet Plateau in 1980-2020

The Qinghai-Tibet Plateau (QTP) has the largest amount of permafrost in the low and middle latitudes, making it highly susceptible to the effects of global warming. In particular, the degradation of permafrost can be intensified by anomalous amplified warming. To accurately model the hydrothermal dynamics of permafrost and its future trends, the accumulation of high-precision, long-term data for the soil thermal conductivity (STC) in the active layer is crucial. However, no previous research has systematically investigated the spatio-temporal variation in the STC on the QTP over an extended period. Therefore, this study aims to fill this gap using the XGBoost model to analyze the STC in the permafrost on the QTP from 1980 to 2020. The findings of this study provide some preliminary insights. First, areas with high variation in the STC between the freeze-thaw periods over the 40 years gradually migrated from the western region to the central region. Second, since 2015, STC in more than 90 % of the permafrost region in the thawing period has shown positive growth. While, during the freezing period, the STC also exhibited an increase over most regions of the QTP, though the western region and parts of the northeastern region exhibited a decrease. Third, the spatial center of gravity for the STC during the freezing and thawing periods from 1980 to 2020 shifted. The mean STC was larger in the eastern and northeastern regions during the freezing period and larger in the western region during the thawing period. Fourth, both alpine swamp meadow and alpine meadow exhibited a gradual increase in the STC during the freeze-thaw period from 1980 to 2020. The conclusions and data products from this study are expected to support spatiotemporal modeling of the permafrost on the QTP and assist in the prognosis for its future.

Dynamic Response of the cbbL Carbon Sequestration Microbial Community to Wetland Type in Qinghai Lake

The soil carbon storage in the Qinghai-Tibet Plateau wetlands is affected by microbiota and wetland types, but the response mechanisms of carbon sequestration microorganisms on the Qinghai-Tibet Plateau to different wetland types are still poorly described. To explore the differences in carbon sequestration microbial communities in different wetlands and the main influencing factors, this study took a marsh wetland, river source wetland and lakeside wetland of Qinghai Lake as the research objects and used high-throughput sequencing to study the functional gene, cbbL, of carbon sequestration microorganisms. The results showed that the dominant bacterial group of carbon sequestration microorganisms in marsh and river source wetlands was Proteobacteria, and the dominant bacterial group in the lakeside wetland was Cyanobacteria. The alpha diversity, relative abundance of Proteobacteria and total carbon content were the highest in the marsh wetland, followed by the river source wetland, and they were the lowest in the lakeside wetland. In addition, the physical and chemical characteristics of the three wetland types were significantly different, and the soil temperature and moisture and total carbon content were the most important factors affecting the community structures of carbon-sequestering microorganisms. There was little difference in the total nitrogen contents between the marsh wetland and river source wetland. However, the total nitrogen content was also an important factor affecting the diversity of the carbon sequestration microbial community. In summary, the wetland type significantly affects the process of soil carbon sequestration. Compared with the riverhead and lakeside wetlands, the marsh wetland has the highest carbon storage.

The Influences of Rainfall Intensity and Timing on the Assemblage of Dung Beetles and the Rate of Dung Removal in an Alpine Meadow

Changes in precipitation patterns, including rainfall intensity and rainfall timing, have been extensively demonstrated to impact biological processes and associated ecosystem functions. However, less attention has been paid to the effects of rainfall intensity and rainfall timing on the assembly of detritivore communities and the decomposition rate of detritus such as animal dung. In a grazed alpine meadow on the eastern Qinghai-Tibet Plateau, we conducted a manipulative experiment involving two levels of rainfall intensity (heavy rainfall, 1000 mL/5 min; light rainfall, 100 mL/5 min) and five levels of rainfall timing (0, 2, 4, 24, and 48 h after yak dung deposition). The aim was to determine the effects of rainfall intensity, timing, and their interaction on the assemblage of dung beetles and dung removal rate during the early stage (i.e., 96 h after yak dung deposition) of dung decomposition. Light rainfall significantly increased species richness in the treatment of 48 h after dung pats were deposited. Heavy rainfall significantly decreased beetle abundance in both the 0 h and 48 h treatments while light rainfall had no effect on beetle abundance. Dung mass loss was significant lower in the 2 h treatment compared to other treatments regardless of rainfall intensity. The structural equation model further revealed that the species richness of dung beetles and dung mass loss were significantly affected by rainfall timing but not by rainfall intensity. However, no significant relationships were observed between any variables examined. These findings suggest that changes in precipitation patterns can influence both the structure of dung beetles and the rate of dung decomposition but may also decouple their relationship under a certain circumstance. Therefore, it is crucial to pay greater attention to fully understand local variability between the biological processes and ecosystem functions within a global climate change scenario.

Current status of research on endophytes of traditional Tibetan medicinal plant and their metabolites

The Qinghai-Tibet Plateau, known as the "Third Pole of the World," has a rich variety of medicinal plants that play an important role in the field of medicine due to its unique geographical environment. However, due to the limited resources of Tibetan medicinal plants and the fragility of the ecological environment of the Qinghai-Tibet Plateau, more and more Tibetan medicinal plants are on the verge of extinction. As a reservoir of biologically active metabolites, endophytes of medicinal plants produce a large number of compounds with potential applications in modern medicine (including antibacterial, immunosuppressive, antiviral, and anticancer) and are expected to be substitutes for Tibetan medicinal plants. This paper reviews 12 Tibetan medicinal plants from the Qinghai-Tibet Plateau, highlighting the diversity of their endophytes, the diversity of their metabolites and their applications. The results show that the endophytes of Tibetan medicinal plants are remarkably diverse, and the efficacy of their metabolites involves various aspects, such as antioxidant, anti-disease and anti-parasitic. In addition, conservation measures for the resources of Tibetan medicinal plants are summarised to provide a reference for an in-depth understanding of the endophytes of Tibetan medicinal plants and to stimulate the scientific community to bioprospect for the endophytes of Tibetan medicinal plants, as well as to provide ideas for their rational exploitation.

Himalayan Marmot (Marmota himalayana) Redistribution to High Latitudes under Climate Change

Climate warming and human activities impact the expansion and contraction of species distribution. The Himalayan marmot (Marmota himalayana) is a unique mammal and an ecosystem engineer in the Qinghai-Tibet Plateau (QTP). This pest aggravates grassland degradation and is a carrier and transmitter of plagues. Therefore, exploring the future distribution of Himalayan marmots based on climate change and human activities is crucial for ecosystem management, biodiversity conservation, and public health safety. Here, a maximum entropy model was explored to forecast changes in the distribution and centroid migration of the Himalayan marmot in the 2050s and 2070s. The results implied that the human footprint index (72.80%) and altitude (16.40%) were the crucial environmental factors affecting the potential distribution of Himalayan marmots, with moderately covered grassland being the preferred habitat of the Himalayan marmot. Over the next 30-50 years, the area of suitable habitat for the Himalayan marmot will increase slightly and the distribution center will shift towards higher latitudes in the northeastern part of the plateau. These results demonstrate the influence of climate change on Himalayan marmots and provide a theoretical reference for ecological management and plague monitoring.

Effects of turning frequency on fermentation efficiency and microbial community metabolic function of sheep manure composting on the Qinghai-Tibet Plateau

This study explored the effects of turning frequency on fermentation efficiency and microbial metabolic function of sheep manure composting on the Qinghai-Tibet Plateau (QTP). Five treatments with different turning frequencies were set up in this study: turning every 1 day (T1), 2 days (T2), 4 days (T3), 6 days (T4), and 8 days (T5). Results showed that the high temperature period for T1 and T5 lasted only 4 days, while that for T2-T4 lasted more than 8 days. The germination index of T1 and T5 was lower than 80%, while that of T2-T4 was 100.6%, 97.8%, and 88.6%, respectively. This study further predicted the microbial metabolic function of T2-T4 using the bioinformatics tool PICRUSt2 (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) and determining the activities of various functional enzymes. The results showed that carbohydrate metabolism, protein metabolism, and nucleotide metabolism were the main metabolic pathways of microorganisms, and that T2 increased the abundance of functional genes of these metabolic pathways. The activities of protease, cellulase, and peroxidase in T2 and T3 were higher than those in T4, and the effect of T2 was more significant. In conclusion, turning once every 2 days can improve the quality of sheep manure compost on the QTP.

Impacts of future climate on the distribution of 4 bumblebee species in the Qinghai-Tibet Plateau

Climate warming threatens dozens of bumblebee species across the world, including alpine areas. In plateaus with vast and continuous high-altitude areas, bumblebees' response to climate warming may be relatively optimistic. To study the species' responses to future climate in the Qinghai-Tibet Plateau, we quantified the suitable areas for 4 local bumblebee indicator species under current and future climate scenarios (Shared Socio-economic Pathway 126, 245, 370, and 585 in 2,100) using MaxEnt models. Suitable areas of indicator species were stacked to obtain the species richness layer. According to the acreage and connectivity of suitable areas and the acreage of the high richness area, a warmed climate will be more suitable for bumblebees' distribution compared to the current climate. The SSP 126 and SSP 245 scenario will be the 2 most suitable. Meanwhile, with climate warming, suitable areas and the high richness areas will move to high altitudes and their altitude range will decrease. The greater suitability in warmed climates may be caused by the topography of plateaus, which provides an opportunity for bumblebees to migrate to cooler areas. However, mitigation of warming is still necessary because an excessively warm climate will decrease bumblebees' habitat suitability. In plateaus, species in lower altitudes will migrate to higher altitudes, conservation in high altitudes should pay attention to not only original species, but also immigrated species. In lower altitudes, many species will migrate to higher altitudes, then local bumblebee diversity will decrease. Local conservation should be focused on these lower altitude areas.

Suitability evaluation and potential estimation of photovoltaic power generation and carbon emission reduction in the Qinghai-Tibet Plateau

The expansion of power development industry is facing enormous pressure to reduce carbon emissions in the context of global decarbonization. Using solar energy instead of traditional fossil energy to adjust energy structure is one of the important means for reducing carbon emissions. Existing research focuses on the evaluation of the generation potential of centralized or distributed photovoltaic power plants, rather than the comprehensive evaluation of multi-type power plants. Based on multi-source remote sensing data for information extraction and suitability evaluation, this paper develops a method to comprehensively evaluate the construction potential of multi-type photovoltaic power stations and determine the potential of photovoltaic power generation and carbon emission reduction on the Qinghai-Tibet Plateau (QTP). The results showed that estimating the power generation potential of only single-type photovoltaic power stations cannot accurately reflect the photovoltaic power generation potential of QTP. It is also demonstrated that the emission reduction effect of the photovoltaic power generation in all prefecture-level cities of QTP can meet national emission reduction targets, showing high annual power generation potential, of which 86.59% is concentrated in Qinghai province's Guoluo, Yushu, and Haixi. An accurate estimation of the photovoltaic power generation potential in QTP can provide a useful theoretical basis for developing carbon-saving and emission reduction strategies for clean energy in China.

Grass-Legume Mixture with Rhizobium Inoculation Enhanced the Restoration Effects of Organic Fertilizer

The establishment of artificial grassland is crucial in restoring degraded grassland and resolving the forage-livestock conflict, and the application of organic fertilizer and complementary seeding of grass-legume mixture are effective methods to enhance grass growth in practice. However, its mechanism behind the underground is largely unclear. Here, by utilizing organic fertilizer in the alpine region of the Qinghai-Tibet Plateau, this study assessed the potential of grass-legume mixtures with and without the inoculation of Rhizobium for the restoration of degraded grassland. The results demonstrated that the application of organic fertilizer can increase the forage yield and soil nutrient contents of degraded grassland, and they were 0.59 times and 0.28 times higher than that of the control check (CK), respectively. The community composition and structure of soil bacteria and fungi were also changed by applying organic fertilizer. Based on this, the grass-legume mixture inoculated with Rhizobium can further increase the contribution of organic fertilizer to soil nutrients and thus enhance the restoration effects for degraded artificial grassland. Moreover, the application of organic fertilizer significantly increased the colonization of gramineous plant by native mycorrhizal fungi, which was ~1.5-2.0 times higher than CK. This study offers a basis for the application of organic fertilizer and grass-legume mixture in the ecological restoration of degraded grassland.

The genome sequence and demographic history of Przewalskia tangutica (Solanaceae), an endangered alpine plant on the Qinghai-Tibet Plateau

To adapt to high-altitude habitats, many alpine plants develop self-compatible breeding systems from outcrossing. The genetic bases for this shift and the resulting demographic consequences remain largely unexplored. Here, we present a high-quality, chromosome-level genome assembly of the monotypic and endangered alpine perennial Przewalskia tangutica (Solanaceae) occurring on the Qinghai-Tibet Plateau (QTP). Our assembled genome is approximately 3 Gb, with a contig N50 size of 17 Mb, and we identified one lineage-specific whole-genome duplication. We found that the gametophytic self-incompatibility (GSI) syntenic locus to the other obligate outcrossing Solanaceae species was broken by the inserted the long terminal repeats, and changes in the flower-specific expression of the homologous genes, and the linked GSI genes in this species. Such changes may have led to its self-compatibility. We identified three deeply diverged lineages in the central distribution of this species, and the gene flow between them was weak but continuous. All three lineages diverged and decreased their population sizes since the largest glaciations occurred in the QTP approximately 720-500 thousand years ago. In addition, we identified one obvious hybrid population between two lineages, suggesting that genetic exchanges between and within lineages still occur. Our results provide insights into evolutionary adaptation through facultative self-pollination and demographic consequences of this alpine rare species in arid habitats.

Vis-NIR Spectroscopy Combined with GAN Data Augmentation for Predicting Soil Nutrients in Degraded Alpine Meadows on the Qinghai-Tibet Plateau

Soil nutrients play vital roles in vegetation growth and are a key indicator of land degradation. Accurate, rapid, and non-destructive measurement of the soil nutrient content is important for ecological conservation, degradation monitoring, and precision farming. Currently, visible and near-infrared (Vis-NIR) spectroscopy allows for rapid and non-destructive monitoring of soil nutrients. However, the performance of Vis-NIR inversion models is extremely dependent on the number of samples. Limited samples may lead to low prediction accuracy of the models. Therefore, modeling and prediction based on a small sample size remain a challenge. This study proposes a method for the simultaneous augmentation of soil spectral and nutrient data (total nitrogen (TN), soil organic matter (SOM), total potassium oxide (TK₂O), and total phosphorus pentoxide (TP₂O₅)) using a generative adversarial network (GAN). The sample augmentation range and the level of accuracy improvement were also analyzed. First, 42 soil samples were collected from the pika disturbance area on the QTP. The collected soils were measured in the laboratory for Vis-NIR and TN, SOM, TK₂O, and TP₂O₅ data. A GAN was then used to augment the soil spectral and nutrient data simultaneously. Finally, the effect of adding different numbers of generative samples to the training set on the predictive performance of a convolutional neural network (CNN) was analyzed and compared with another data augmentation method (extended multiplicative signal augmentation, EMSA). The results showed that a GAN can generate data very similar to real data and with better diversity. A total of 15, 30, 60, 120, and 240 generative samples (GAN and EMSA) were randomly selected from 300 generative samples to be included in the real data to train the CNN model. The model performance first improved and then deteriorated, and the GAN was more effective than EMSA. Further shortening the interval for adding GAN data revealed that the optimal ranges were 30-40, 50-60, 30-35, and 25-35 for TK₂O, TN, TP₂O₅, and SOM, respectively, and the validation set accuracy was maximized in these ranges. Therefore, the above method can compensate to some extent for insufficient samples in the hyperspectral prediction of soil nutrients, and can quickly and accurately estimate the content of soil TK₂O, TN, TP₂O₅, and SOM.

Arthrobacter caoxuetaonis sp. nov., Arthrobacter zhangbolii sp. nov. and Arthrobacter gengyunqii sp. nov., isolated from Marmota himalayana faeces from Qinghai-Tibet Plateau

Six aerobic or facultative anaerobic, motile, Gram-stain-positive, catalase-positive and oxidase-negative strains (zg-Y453^T, zg-Y324, zg-Y462^T, zg-Y411, zg-Y809^T and zg-Y786) were isolated from different faecal samples of Marmota himalayana from the Qinghai-Tibet Plateau. Pale yellow, round, raised and moist colonies appeared 48 h after incubation at 28 °C on brain-heart infusion plates supplemented with 5 % defibrinated sheep blood. According to the 16S rRNA gene sequence alignment, two strain pairs (zg-Y453^T/zg-Y324 and zg-Y462^T/zg-Y411) shared the highest similarities to Arthrobacter luteolus (99.5 and 99.2 %), and the other one (zg-Y809^T/zg-Y786) to Arthrobacter citreus (99.5 %). Results of phylogenetic analysis based on the 16S rRNA gene and genome sequences showed that these six strains represented three separate species within the genus Arthrobacter. The average nucleotide identity and digital DNA-DNA hybridization values between the three novel type strains (zg-Y453^T/zg-Y462^T/zg-Y809^T) and other known species in this genus were all below respective thresholds (70.2-81.5/19.6-24.2 %, 70.6-81.8/19.8-25.0 %, and 70.4-88.2/19.9-35.3 %). Although phylogenetically related, there were obvious chemotaxonomic and phenotypic differences: strain pair zg-Y462^T/zg-Y411 had anteiso-C_15 : 0 as the only major fatty acid; the three novel species had different dominant quinones, MK-8(H₂) in strains zg-Y462^T/zg-Y809^T (74.8/81.1 %) and MK-8(H₂)/MK-9(H₂) (43.1/53.0 %) in zg-Y453^T; similarly, the ability to reduce nitrate in strains zg-Y453^T and zg-Y462^T could differentiate them from zg-Y809^T. All strains had diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol, but differed slightly in the types of unidentified glycolipids, phospholipids and lipids. Based on the results of these polyphasic taxonomic analyses, three novel species within the genus Arthrobacter are proposed, namely Arthrobacter caoxuetaonis sp. nov. (type strain, zg-Y453^T=GDMCC 1.2809^T=JCM 35173^T), Arthrobacter zhangbolii sp. nov. (type strain, zg-Y462^T=GDMCC 1.2880^T=JCM 35170^T) and Arthrobacter gengyunqii sp. nov. (type strain, zg-Y809^T=GDMCC 1.2808^T=JCM 35168^T).

Tropical volcanic eruptions reduce vegetation net carbon uptake on the Qinghai-Tibet Plateau under background climate conditions

The vegetation carbon uptake plays an important role in the terrestrial carbon cycle on the Qinghai-Tibet Plateau (QTP), while it is extremely sensitive to the impact of natural external forcings. Until now, there is limited knowledge on the spatial-temporal patterns of vegetation net carbon uptake (VNCU) after the force that caused by tropical volcanic eruptions. Here, we conducted an exhaustive reconstruction of VNCU on the QTP over the last millennium, and used a superposed epoch analysis to characterize the VNCU response of the QTP after the tropical volcanic eruptions. We then further investigated the divergent changes of VNCU response across different elevation gradients and vegetation types, and the impact of teleconnection forcing on VNCU after volcanic eruptions. Within a climatic background, we found that VNCU of the QTP tends to decrease after large volcanic eruptions, lasting until about 3 years, with a maximum decrease value occurring in the following 1 year. The spatial and temporal patterns of the VNCU were mainly driven by the post-eruption climate and moderated by the negative phase trends of El Niño-Southern Oscillation and the Atlantic multidecadal oscillation. In addition, elevation and vegetation types were undeniable driving forces associated with VNCU on QTP. Different water-heat conditions and vegetation types contributed to significant differences in the response and recovery processes of VNCU. Our results emphasized the response and recovery processes of VNCU to volcanic eruptions without the strong anthropogenic forcings, while the influence mechanisms of natural forcing on VNCU should receive more attention.

The phylogeny and divergence time of Ophiocordyceps sinensis and its host insects based on elongation factor 1 alpha

Ophiocordyceps sinensis Berk. is a fungal parasite that parasitizes the larvae of Hepialidae and is endemic to the Qinghai-Tibet Plateau (QTP). The phylogeny and divergence time of O. sinensis and its host insects were analyzed for 137 individuals from 48 O. sinensis populations based on the elongation factor 1 alpha (EF-1α) gene. Lower nucleotide variation, with only 7 and 16 EF-1α haplotypes, was detected in O. sinensis and its host insects, respectively. The isolated and broad distribution patterns coexisted in both O. sinensis and its host insects on the QTP. The divergence time estimates show that O. sinensis and its host insects originated later than 14.33 million years (Myr) and earlier than 23.60 Myr in the Miocene period, and the major differentiation occurred later than 4 Myr. Their origin and differentiation match well with the second and third uplifts of the QTP, respectively. The host insects from the O. sinensis populations distributed around Qinghai Lake are inferred as an ancient and relict species that has survived various geological events of the QTP. It is suitable to estimate the divergence times of both O. sinensis and its host insects from the same individuals using one gene: EF-1α. Our findings of the origin, phylogeny, and evolution of the endemic species also support the epoch of geological events on the QTP.

Spatiotemporal Changes in Frost-Free Season and Its Influence on Spring Wheat Potential Yield on the Qinghai-Tibet Plateau from 1978 to 2017

Accurately assessing the variation in the frost-free season (FFS) can provide decision support for improving agricultural adaptability and reducing frost harm; however, related studies were inadequate in terms of the Qinghai-Tibet Plateau (QTP). This study analyzed the spatiotemporal changes in the first frost day in autumn (FFA), last frost day in spring (LFS), FFS length and effective accumulated temperature (EAT) during the 1978-2017 period, and their influences on spring wheat potential yield on the QTP, based on daily climatic data and the methodology of Sen's slope and correlation analysis. The results showed that the annual average FFA and LFS occurred later and earlier from northwest to southeast, respectively, and both the FFS length and EAT increased. From 1978 to 2017, the average regional FFA and LFS were delayed and advanced at rates of 2.2 and 3.4 days per decade, and the FFS and EAT increased by 5.6 days and 102.7 °C·d per decade, respectively. Spatially, the increase rate of FFS length ranged from 2.8 to 11.2 days per decade throughout the QTP, and it was observed to be larger in northern Qinghai, central Tibet and Yunnan, and smaller mainly in eastern Sichuan and southern Tibet. Correspondingly, the increase rate for EAT ranged from 16.2 to 173.3 °C·d per decade and generally showed a downward trend from north to south. For a one-day increase in the FFS period, the spring wheat potential yield would decrease by 17.4 and 9.0 kg/ha in altitude ranges of <2000 m and 2000-3000 m, but decrease by 24.9 and 66.5 kg/ha in the ranges of 3000-4000 m and >4000 m, respectively. Future studies should be focused on exploring the influence of multiple climatic factors on crop production using experimental field data and model technologies to provide policy suggestions.

Diagnostic strategy for the combined effects of microplastics and potentially toxic elements on microbial communities in catchment scale

Combined effects of potentially toxic materials (PTMs) released from production activities on microbial communities in environmental flimsy area are poorly recognised. Microplastics (MPs) and potentially toxic elements (PTEs) were investigated in soils and river sediments in a headwater catchment from the Qinghai-Tibet Plateau. Their co-effects on microbial communities and the controlling factors affecting communities were further explored. Results showed that MPs and PTEs significantly accumulated in soils and sediments. Among which fragment-shaped MPs and copper (Cu) dominated, with mean contents of 1.11 × 10⁴ and 1.81 × 10⁴ items kg^-1 and 13.80 and 7.33 mg kg^-1 in soils and sediments, respectively. Distribution index (0.54) suggested that fiber-shaped MPs preferred to transport into rivers and deposited in sediments. The film mulching contributed significantly to the occurrence of fragment-shaped MPs, while Cu may be derived from industrial wastewater. The antagonistic effect between fiber-shaped MPs and zinc (Zn) on soil microbial structure was found based on their obtuse angle in canonical correlation analysis. While the synergistic effect between total phosphorus (TP) and Cu on diversity was detected by interaction detector model (q(TP ∩ Cu) >q(TP) >q(Cu), p < 0.05). Soil TP and Cu were identified as controlling factors influencing diversity through random forest model and factor detector (q(TP) = 0.49, q(Cu) = 0.36, p < 0.05), which may be related to direct nutrient supply and microbial resistance, respectively. The negative effects of MPs on structure might be counteracted by increasing Zn content, while the co-existence of TP and Cu further increased diversity. A diagnostic framework, which involves background data collection, sampling analysis, characterisation and relationship investigation, was proposed to explore the co-effects of complex pollution and factors on communities. This study may provide strategies to mitigate the negative effects on microorganisms in the environment.

Evaluation of the Protection Effectiveness of Natural Protected Areas on the Qinghai-Tibet Plateau Based on Ecosystem Services

Evaluating the protection effectiveness of natural protected areas is an important step in successful management. Adopting 330 natural protected areas on the Qinghai-Tibet Plateau as research subjects, the regional dominant ecosystem service function was selected, and various temporal and spatial analysis methods were employed to analyze the evolution characteristics and influencing factors of ecosystem service patterns from 2000 to 2020. Our results indicated that (1) the water conservation function stabilized after fluctuation and decline, the soil conservation function fluctuated upward, and the windbreak and sand fixation function exhibited an increase after a decreasing fluctuation. (2) The protection effectiveness of25 protected areas significantly improved, that of 151 protected areas improved, that of 84 protected areas stabilized, that of 56 protected areas worsened, and that of 14 protected areas significantly worsened. (3) The top three influencing factors in descending order were precipitation change > altitude > mining area density. (4) Remarkable protection results were achieved in national protected areas, established management institutions, earlier established areas (before 2000), and areas exhibiting alow built-up area density (<0.75%) and low mining density (<1%). Our study provides technical support for the construction and management of protected areas and improvement in ecosystem service functions on the Qinghai-Tibet Plateau.

Spatial-temporal evolution of pumped hydro energy storage potential on the Qinghai-Tibet Plateau and its future trend under global warming

Global warming has brought extensive and far-reaching impacts on human life and production. A pumped hydro energy storage contributes to the large-scale development of renewable energy and serves as an important measure to mitigate climate change. Despite considerable efforts in estimating the potential of the pumped hydro energy storage, research gaps in response to global warming remain. In this regard, this study conducts a novel assessment of the pumped hydro energy storage's potential from a dynamic perspective, taking the Qinghai-Tibet Plateau as the study area. The spatiotemporal evolution of the pumped hydro energy storage's potential over the past few decades (the 1970s-2017) is analyzed, and its response to precipitation is identified innovatively. On this basis, the trend in the future period is further predicted for the first time, which is divided into near, short, medium, and long terms. Results show that the pumped hydro energy storage potential has a generally upward but not monotonic trend, decreasing from the 1970s to 1995 and then rising more dramatically, with slopes of 5548.5 ± 69.2 GWhyr^-1 and -238.1 ± 90.4 GWhyr^-1. In the majority (68.6 %) of lake basins (68.6 %), changes in precipitation positively contribute to the pumped hydro energy storage potential, resulting in a noticeable growth in the future. Under the representative concentration pathway of 8.5, the mean potential density is projected to rise by 23.4 %, 25.2 %, 28.3 %, and 30.6 % in the near, short, medium, and long terms, respectively. This result indicates that high-intensity greenhouse gas emissions under this scenario will lead to a greater potential for the pumped hydro energy storage in the future.

Pollution and Distribution of Microplastics in Grassland Soils of Qinghai-Tibet Plateau, China

Microplastics (MPs) are plastic fragments with particle sizes smaller than 5 mm that have potentially harmful effects on ecosystems and human health. The soil environment is not only the source but also the sink of MPs. Thus, it is necessary to fully understand the pollution and distribution of MPs in soils. In this study, Qinghai Province, northeast of the Qinghai-Tibet Plateau, was selected as the research area, and 22 soil samples were collected and analyzed to study the levels and distribution characteristics of MPs in grassland soils. MPs were obtained from the soils by using density separation, and a laser confocal micro Raman spectrometer was used for MP identification. The results showed that MPs were detected in all of the soil samples. The total abundances of MPs ranged from 1125 to 1329 items/kg, with a mean abundance of 1202 items/kg. Various types, shapes, sizes, and colors of MPs were observed. Polyethylene terephthalate (PET) was the dominant polymer in all the grassland soil samples. The size range of 10-50 μm accounted for 50% of all identified MPs. Pellets were the dominant MP shape, and colored MPs accounted for 64% of all MPs. The results revealed the presence of large quantities of MPs in the grassland soils of remote areas as well. This study can act as a reference for further studies of MPs in terrestrial systems. At the end of the paper, the prospects and suggestions for pollution control by soil MPs are given.

Soil diazotrophic abundance, diversity, and community assembly mechanisms significantly differ between glacier riparian wetlands and their adjacent alpine meadows

Global warming can trigger dramatic glacier area shrinkage and change the flux of glacial runoff, leading to the expansion and subsequent retreat of riparian wetlands. This elicits the interconversion of riparian wetlands and their adjacent ecosystems (e.g., alpine meadows), probably significantly impacting ecosystem nitrogen input by changing soil diazotrophic communities. However, the soil diazotrophic community differences between glacial riparian wetlands and their adjacent ecosystems remain largely unexplored. Here, soils were collected from riparian wetlands and their adjacent alpine meadows at six locations from glacier foreland to lake mouth along a typical Tibetan glacial river in the Namtso watershed. The abundance and diversity of soil diazotrophs were determined by real-time PCR and amplicon sequencing based on nifH gene. The soil diazotrophic community assembly mechanisms were analyzed via iCAMP, a recently developed null model-based method. The results showed that compared with the riparian wetlands, the abundance and diversity of the diazotrophs in the alpine meadow soils significantly decreased. The soil diazotrophic community profiles also significantly differed between the riparian wetlands and alpine meadows. For example, compared with the alpine meadows, the relative abundance of chemoheterotrophic and sulfate-respiration diazotrophs was significantly higher in the riparian wetland soils. In contrast, the diazotrophs related to ureolysis, photoautotrophy, and denitrification were significantly enriched in the alpine meadow soils. The iCAMP analysis showed that the assembly of soil diazotrophic community was mainly controlled by drift and dispersal limitation. Compared with the riparian wetlands, the assembly of the alpine meadow soil diazotrophic community was more affected by dispersal limitation and homogeneous selection. These findings suggest that the conversion of riparian wetlands and alpine meadows can significantly alter soil diazotrophic community and probably the ecosystem nitrogen input mechanisms, highlighting the enormous effects of climate change on alpine ecosystems.

Canibacter zhuwentaonis sp. nov. and Canibacter zhoujuaniae sp. nov., isolated from Marmota himalayana

Four Gram-stain-positive, facultatively anaerobic, non-motile, non-spore-forming and rod-shaped bacteria (lx-72^T, lx-45, ZJ784^T and ZJ955) were isolated from the respiratory tract or faeces of marmot (Marmota himalayana) from the Qinghai-Tibet Plateau in China. Analysis of the 16S rRNA gene sequences showed that all strains belong to the genus Canibacter and are more related to Canibacter oris CCUG 64069^T (95.1-97.4 % similarity) than to the genus Leucobacter. Both strain pairs grew well at pH 6-9 and 15-42°C, and ZJ784^T/ZJ955 could tolerate slightly higher NaCl (0.5-4.5 %, w/v) than lx-72^T/lx-45(0.5-3.5 %). Based on whole-genome sequences, the average nucleotide identity and digital DNA-DNA hybridization values between our four isolates and their closest relative were below the species delineation thresholds of 70 % and 95-96 %. The common major fatty acids (>10 %) of our four strains were anteiso-C_15 : 0 and anteiso-C_17 : 0. For both new type strains, MK-8(H₄) and MK-9(H₄) were the major isoprenoid quinones, and diphosphatidylglycerol and phosphatidylglycerol were the main polar lipids. The genomic DNA G+C content of all strains was 53.9 mol%. Based on results from the genomic comparison, phylogenetic analysis, and physiological and biochemical characteristics, the four isolates represent two novel species in the genus Canibacter, for which the names Canibacter zhuwentaonis sp. nov. (type strain lx-72^T=KCTC 49658^T=GDMCC 1.2569^T) and Canibacter zhoujuaniae sp. nov. (type strain ZJ784^T=KCTC 49507^T=GDMCC 1.1997^T) are proposed.

Cell line derived from muscle of Gymnocypris przewalskii, a species of Schizothoracinae in Qinghai Lake, Qinghai-Tibet Plateau

Gymnocypris przewalskii (naked carp), a native teleost, plays an important role in the ecosystem of Qinghai Lake (altitude, 3.2 km) on the Qinghai-Tibet Plateau in China. We developed a new cell line from the muscle of G. przewalskii using the explant technique and named the cell line GPM. This cell line was maintained in DMEM medium (high glucose) supplemented with 15% fetal bovine serum (FBS). The cell line was successfully subcultured up to 32 passages and was authenticated by immunofluorescence assay, sequencing the mitochondrial cytochrome C oxidase subunit I (COI) and 16S rRNA genes, and by chromosome analysis. In the medium containing 15% FBS, the cell line could be passaged stably at 25 °C. The GPM cell line could express green fluorescent protein (GFP) with a CMV promoter with about 5% transfection efficiency. MTT tests showed that Clostridium botulinum toxin (BTX) was toxic to the cell line. The cell line could be successfully cryopreserved in liquid nitrogen with a revival efficiency of over 70%. This study demonstrated that the GPM cell line can be used as an important tool for understanding the physiological characteristics of G. przewalskii, and it can provide a resource for studying gene function and toxicological reactions in vitro.

Spatial Response of Ecosystem Service Value to Urbanization in Fragile Vegetation Areas Based on Terrain Gradient

The contradiction between urban expansion and ecological protection in fragile vegetation areas has become increasingly prominent with regional development. Revealing the relationship between urbanization and ecosystem services will help to provide solutions to this problem. In order to clarify the impact of urbanization on typical mountain areas with fragile vegetation on the Qinghai Tibet Plateau, we built an ecosystem service value (ESV) evaluation index system. We also evaluated the ESV and its spatial response to the urbanization of Shannan Prefecture in Tibet from 1990 to 2015 based on different terrain gradients (TGs) using vegetation biophysical data obtained from remote sensing platforms. The results show that ESV in Shannan increased first and then declined as the TG increased, reaching a maximum value at the third TG. ESV showed a decreased trend during the study period, with a significant decline at the second and third TGs, which were the main distribution areas of vegetation in Shannan. Through spatial correlation analysis, we observed that urbanization and ESV showed a significant spatial aggregation effect. Among them, the high-low type accounted for the largest proportion in the grid with the agglomeration effect, mainly concentrated at the lower TG in the southern of Shannan, where ESV decreases with the increasing urbanization. We highlight the need for targeted, sustainable development policies to rationally organize the urbanization process in the different-gradient plateau regions with fragile vegetation. These results can provide a reference for applying ESV to vegetation restoration and ecological protection in ecologically fragile mountain areas.

Symptom Structure of Depression in Older Adults on the Qinghai-Tibet Plateau: A Network Analysis

Previous studies have confirmed that depression among residents in high-altitude areas is more severe, and that depression may be more persistent and disabling in older adults. This study aims to identify the symptom structure of depression among older adults on the Qinghai-Tibet Plateau (the highest plateau in the world) from a network perspective. This cross-sectional study enrolled 507 older adults (ages 60-80 years old) from the Yushu Prefecture, which is on the Qinghai-Tibet Plateau, China. Depressive symptoms were self-reported using the shortened Center for Epidemiological Studies-Depression Scale (CES-D-10). Then, a Gaussian graphical model (GGM) of depression was developed. Poor sleep, fear, and hopelessness about the future exhibited high centrality in the network. The strongest edge connections emerged between unhappiness and hopelessness about the future, followed by hopelessness about the future and fear; hopelessness about the future and poor sleep; fear and unhappiness; and then poor sleep and unhappiness in the network. The findings of this current study add to the small body of literature on the network structure and complex relationships between depressive symptoms in older adults in high-altitude areas.

Effects of Regular Water Replenishment on Enzyme Activities and Fungal Metabolic Function of Sheep Manure Composting on the Qinghai-Tibet Plateau

The dry climate characteristics of the Qinghai-Tibet Plateau will seriously affect microbial metabolism during composting. In this study, we aimed to investigate the effects of regular water supplementation on the fungal and enzymatic activities of sheep manure composting in the Qinghai-Tibet Plateau. The experiment set up the treatments of water replenishment once every 7 days(T2) and 3.5 days (T3) days, and no water supplementation was used as the control (T1). The results showed that regular water supplementation increased the activities of various enzymes during composting, and the activities of protease, cellulase, peroxidase and polyphenol oxidase in T3 were higher than those in T2. Regular water supplementation increased the relative abundance of Remersonia and Mycothermus, which were significantly positively correlated with the germination index, and degradation of organic components. Regular water supplementation could enrich fungi carbohydrate, protein, and nucleotide metabolisms, and T3 had a better effect. A redundancy analysis showed that environmental factors could significantly affect the fungal community; among them, moisture content (76.9%, p = 0.002) was the greatest contributor. In conclusion, regular water supplementation can improve the key enzyme activities and fungal metabolic function of sheep manure composting, and water replenishment once every 3.5 days had the best effect.

Testing the Functional and Phylogenetic Assembly of Plant Communities in Gobi Deserts of Northern Qinghai-Tibet Plateau

The mechanism governing plant community assembly across large-scale Gobi deserts remains unclear. Here, we inferred the roles of different assembly processes in structuring plant communities in the Gobi deserts of the Qinghai-Tibet Plateau by using a phylogenetic tree, and leaf and root traits. The functional and phylogenetic structures of 183 plant communities were assessed, and their distributions were linked with environmental gradients. Our results demonstrated that functional convergence was prevalent in most functional traits (75% of the traits) and accentuated when all traits were combined. The phylogenetic structure exhibited significant divergence. We observed the contrasting response of functional and phylogenetic assembly structures to environmental gradients. More importantly, we found that the shifts in the functional assembly along environmental gradients were trait-specific, with dominant roles of local factors, such as gravel coverage and soil attributes, in determining the distribution patterns of most traits. However, the distribution patterns of leaf P concentration (LPC), root N concentration (RNC), and root P concentration (RPC) were mainly driven by climatic factors. These results reveal that niche-based processes, such as abiotic filtering and weaker competitive exclusion, are the major drivers of species co-occurrence, which results in the widespread coexistence of phylogenetically distinct but functionally similar species within the Gobi plant community. Our findings could improve the understanding of plant community assembly processes and biodiversity maintenance in extremely harsh drylands.

Bacterial communities in surface and basal ice of a glacier terminus in the headwaters of Yangtze River on the Qinghai-Tibet Plateau

BACKGROUND

On the front lines of climate change, glacier termini play crucial roles in linking glaciers and downstream ecosystems during glacier retreat. However, we lack a clear understanding of biological processes that occur in surface and basal ice at glacier termini.

METHODS

Here, we studied the bacterial communities in surface ice and basal ice (the bottom layer) of a glacier terminus in the Yangtze River Source, Qinghai-Tibet Plateau.

RESULTS

Surface and basal ice harbored distinct bacterial communities but shared some core taxa. Surface ice communities had a higher α-diversity than those in basal ice and were dominated by Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, and Cyanobacteria while basal ice was dominated by Firmicutes and Proteobacteria. The bacterial communities were also substantially different in functional potential. Genes associated with functional categories of cellular processes and metabolism were significantly enriched in surface ice, while genes connected to environmental information processing were enriched in basal ice. In terms of biogeochemical cycles of carbon, nitrogen, phosphorus, and sulfur, bacterial communities in surface ice were enriched for genes connected to aerobic carbon fixation, aerobic respiration, denitrification, nitrogen assimilation, nitrogen mineralization, sulfur mineralization, alkaline phosphatase, and polyphosphate kinase. In contrast, bacterial communities in basal ice were enriched for genes involved in anaerobic carbon fixation, fermentation, nitrate reduction, 2-aminoethylphosphonic acid pathway, G3P transporter, glycerophosphodiester phosphodiesterase, and exopolyphosphatase. Structural equation modeling showed that total nitrogen and environmental carbon:phosphorus were positively while environmental nitrogen:phosphorus was negatively associated with taxonomic β-diversity which itself was strongly associated with functional β-diversity of bacterial communities.

CONCLUSIONS

This study furthers our understanding of biogeochemical cycling of the mountain cryosphere by revealing the genetic potential of the bacterial communities in surface and basal ice at the glacier terminus, providing new insights into glacial ecology as well as the influences of glacier retreat on downstream systems.

The Plant Interspecific Association in the Revegetated Alpine Grasslands Determines the Productivity Stability of Plant Community Across Restoration Time on Qinghai-Tibetan Plateau

Grassland cultivation is the key measure for restoring "Black Beach," the extremely degraded alpine meadow in the Three River Headwater Area of the Qinghai-Tibetan Plateau. In this study, we examined the inter-specific relationship in the vegetation community of cultivated grasslands with different restoration times through the network analysis method. The results showed that with the extension of restoration time, the development of cultivated grassland would lead to increasing neutral interactions among the plant species. The proportion of species with positive and negative associations in the community decreased, while the number of species-independent pairs increased significantly. The complexity of plant interspecific association (species network density) had more influence on community stability with the extension of recovery time, which can be used to quantify the characteristics of community structure.

A Preliminary Study of Necrophagous Flies (Insecta: Diptera) in the Lhasa Region (Qinghai-Tibet Plateau), China

Lhasa is located on the Qinghai-Tibet Plateau, with an altitude of 3,650 m, and a unique geography. Its climate is dry and cold all year round. Forensic entomological studies of the region are scarce. In this study, the diversity and seasonality of necrophagous flies in eight counties among Lhasa region were determined, and succession of necrophagous flies colonizing on rabbits in the Chengguan area of Lhasa was studied, so as to provide reference data for estimating postmortem interval (PMI) and location of death. In total, 22 species of necrophagous flies, belonging to six families were identified in Lhasa. Protophormia terraenovae (Robineau-Desvoidy, 1830) (Diptera: Calliphoridae) was the dominant species throughout the year, the diversity index (4.5834) indicated that the study on necrophagous flies in the Lhasa region is representative.

Multivariate statistical analysis of potentially toxic elements in soils under different land uses: Spatial relationship, ecological risk assessment, and source identification

The Qinghai-Tibet Plateau is one of the most fragile and susceptible areas to climate change and human disturbances in the world. Here, a total of 48 soil samples were obtained from areas of different land uses within a typical basin in eastern Qinghai-Tibet, China. The selected potentially toxic elements (PTEs, including Cd, Cr, Cu, Pb, and Zn) contents were analyzed to explore their spatial patterns, ecological risks, and then the effects of land use types on these elements were assessed by self-organizing map (SOM) and random forest regression (RFR) models, and the main sources were revealed using positive matrix factorization (PMF) model. Results showed that mean concentrations of selected PTEs in surface soils were higher than local background values and those of subsurface soils. The low-degree ecological risk was obtained with comparatively high risks in the north and south of the study area. The results of the SOM and RFR models revealed that land use types affected the redistribution of PTEs in surface soil. The PMF model demonstrated that these PTEs were mainly derived from natural sources (46.7%), traffic emissions (31.2%), and industrial and agricultural inputs (22.1%). Natural sources were the essential contributors for these soil PTEs, especially for Cr. In addition to natural sources, traffic sources made great contributions for Cd, Pb, and Zn elements, while the enrichment of Cu was mainly related to industrial and agricultural activities.

MaxEnt Modeling to Predict the Current and Future Distribution of Pomatosace filicula under Climate Change Scenarios on the Qinghai-Tibet Plateau

As an important Tibetan medicine and a secondary protected plant in China, Pomatosace filicula is endemic to the country and is mainly distributed in the Qinghai-Tibet Plateau (QTP). However, global climate change caused by greenhouse gas emissions might lead to the extinction of P. filicula. To understand the potential spatial distribution of P. filicula in future global warming scenarios, we used the MaxEnt model to simulate changes in its suitable habitat that would occur by 2050 and 2070 using four representative concentration pathway (RCP) scenarios and five global climate models. The results showed that the QTP currently contains a suitable habitat for P. filicula and will continue to do so in the future. Under the RCP2.6 scenario, the suitable habitat area would increase by 2050 but shrink slightly by 2070, with an average reduction of 2.7%. However, under the RCP8.5 scenario, the area of unsuitable habitat would expand by an average of 54.65% and 68.20% by 2050 and 2070, respectively. The changes in the area of suitable habitat under the RCP4.5 and RCP6.0 scenarios were similar, with the unsuitable area increasing by approximately 20% by 2050 and 2070. Under these two moderate RCPs, the total suitable area in 2070 would be greater than that in 2050. The top three environmental factors impacting the habitat distribution were altitude, annual precipitation (BIO12) and annual temperature range (BIO7). The cumulative contribution rate of these three factors was as high as 82.8%, indicating that they were the key factors affecting the distribution and adaptability of P. filicula, P. filicula grows well in damp and cold environments. Due to global warming, the QTP will become warmer and drier; thus, the growing area of P. filicula will move toward higher elevations and areas that are humid and cold. These areas are mainly found near the Three-River Region. Future climate change will aggravate the deterioration of the P. filicula habitat and increase the species' survival risk. This study describes the distribution of P. filicula and provides a basis for the protection of endangered plants in the QTP.

Changes in the Mitochondrial Dynamics and Functions Together with the mRNA/miRNA Network in the Heart Tissue Contribute to Hypoxia Adaptation in Tibetan Sheep

This study aimed to provide insights into molecular regulation and mitochondrial functionality under hypoxia by exploring the mechanism of adaptation to hypoxia, blood indexes, tissue morphology, mRNA/miRNA regulation, mitochondrial dynamics, and functional changes in Tibetan sheep raised at different altitudes. With regard to blood indexes and myocardial morphology, the HGB, HCT, CK, CK-MB, LDH, LDH1, SOD, GPX, LDL level, and myocardial capillary density were significantly increased in the sheep at higher altitudes (p < 0.05). The RNA-seq results suggested the DEmRNAs and DEmiRNAs are mainly associated with the PI3K-Akt, Wnt, and PPAR signaling pathways and with an upregulation of oncogenes (CCKBR, GSTT1, ARID5B) and tumor suppressor factors (TPT1, EXTL1, ITPRIP) to enhance the cellular metabolism and increased ATP production. Analyzing mRNA−miRNA coregulation indicated the mitochondrial dynamics and functions to be significantly enriched. By analyzing mitochondrial dynamics, mitochondrial fusion was shown to be significantly increased and fission significantly decreased in the heart with increasing altitude (p < 0.05). There was a significant increase in the density of the mitochondria, and a significant decrease in the average area, aspect ratio, number, and width of single mitochondrial cristae with increasing altitudes (p < 0.05). There was a significant increase in the NADH, NAD+ and ATP content, NADH/NAD+ ratio, and CO activity, while there was a significant decrease in SDH and CA activity in various tissues with increasing altitudes (p < 0.05). Accordingly, changes in the blood indexes and myocardial morphology of the Tibetan sheep were found to improve the efficiency of hemoglobin-carrying oxygen and reduce oxidative stress. The high expression of oncogenes and tumor suppressor factors might facilitate cell division and energy exchange, as was evident from enhanced mitochondrial fission and OXPHOS expression; however, it reduced the fusion and TCA cycle for the further rapid production of ATP in adaptation to hypoxia stress. This systematic study has for the first time delineated the mechanism of hypoxia adaptation in the heart of Tibetan sheep, which is significant for improving the ability of the mammals to adapt to hypoxia and for studying the dynamic regulation of mitochondria during hypoxia conditions.

Community Assembly and Co-Occurrence Patterns of Microeukaryotes in Thermokarst Lakes of the Yellow River Source Area

Thermokarst lakes are important aquatic ecosystems in cold regions, experiencing several changes due to global warming. However, the fundamental assembly mechanisms of microeukaryotic communities in thermokarst lakes are unknown. In this study, we examined the assembly processes and co-occurrence networks of microeukaryotic communities in sediment and water of thermokarst lakes in the Yellow River Source Area. Sediment microeukaryotic communities had a significantly lower α-diversity but higher β-diversity than water microeukaryotic communities. pH, sediment organic carbon, and total phosphorus significantly affected taxonomic and phylogenetic diversity of sediment communities, while conductivity was a significant driver for water communities. Both sediment and water microeukaryotic communities were strongly governed by dispersal limitation. However, deterministic processes, especially homogenous selection, were more relevant in structuring microeukaryotic communities in water than those in sediment. Changes in total nitrogen and phosphorus in sediment could contribute to shift its microeukaryotic communities from homogeneous selection to stochastic processes. Co-occurrence networks showed that water microeukaryotic communities are more complex and interconnected but have lower modularity than sediment microeukaryotic communities. The water microeukaryotic network had more modules than the sediment microeukaryotic network. These modules were dominated by different taxonomic groups and associated to different environmental variables.

Mycolicibacterium baixiangningiae sp. nov. and Mycolicibacterium mengxianglii sp. nov., two new rapidly growing mycobacterial species

Four bacterial strains (LJ126^T/S18 and Z-34^T/S20) recovered from faecal samples of Tibetan antelopes on the Qinghai-Tibet Plateau of China were analysed using a polyphasic approach. All four isolates were aerobic, short rod-shaped, non-motile, Gram-stain-positive, acid-fast and fast-growing. Phylogenetic analyses based upon 16S rRNA and whole-genome sequences showed that the two pair of strains formed two distinct branches within the evolutionary radiation of the genus Mycolicibacterium. Strains LJ126^T/S18 and Z-34^T/S20 were most closely related to Mycolicibacterium austroafricanum CCUG 37667^T, Mycobacterium aurum NCTC 10437^T, Mycobacterium pyrenivorans DSM 44605^T, Mycobacterium monacense JCM 15658^T, Mycolicibacterium sarraceniae JCM 30395^T, Mycolicibacterium tokaiense JCM 6373^T and Mycobacterium murale JCM 13392^T, but readily distinguished from the known species by a combination of chemotaxonomic and phenotypic features and by low average nucleotide identity values (74.4-84.9 %). Consequently, the two strain pairs are considered to represent different novel species of Mycolicibacterium for which the names Mycolicibacterium baixiangningiae sp. nov. and Mycolicibacterium mengxianglii sp. nov. are proposed, with LJ126^T (=CGMCC 1.1992^T=KCTC 49535^T) and Z-34^T (=CGMCC 1.1993^T=DSM 106172^T) as the respective type strains.

Pollinator individual-based networks reveal the specialized plant-pollinator mutualism in two biodiverse communities

Generalization of pollination systems is widely accepted by ecologists in the studies of plant-pollinator interaction networks at the community level, but the degree of generalization of pollination networks remains largely unknown at the individual pollinator level. Using potential legitimate pollinators that were constantly visiting flowers in two alpine meadow communities, we analyzed the differences in the pollination network structure between the pollinator individual level and species level. The results showed that compared to the pollinator species-based networks, the linkage density, interaction diversity, interaction evenness, the average plant linkage level, and interaction diversity increased, but connectance, degree of nestedness, the average of pollinator linkage level, and interaction diversity decreased in the pollinator individual-based networks, indicating that pollinator individuals had a narrower food niche than their counterpart species. Pollination networks at the pollinator individual level were more specialized at the network level (H'2) and the plant species node level (d') than at the pollinator species-level networks, reducing the chance of underestimating levels of specialization in pollination systems. The results emphasize that research into pollinator individual-based pollination networks will improve our understanding of the pollination networks at the pollinator species level and the coevolution of flowering plants and pollinators.

Phylogeography of Iris loczyi (Iridaceae) in Qinghai-Tibet Plateau revealed by chloroplast DNA and microsatellite markers

Quaternary climate oscillations and complex topography have tremendous effects on current distribution and genetic structure of species, and hence the Qinghai-Tibet Plateau (QTP), the largest plateau in the world, has become a hotspot for many phylogeographic studies. However, little is known about the phylogeographic pattern of herbaceous plants in QTP. Here, we investigate the genetic diversity, population structure and historical dynamics of Iris loczyi, using five chloroplast DNA (cpDNA) fragments and seven microsatellite markers. A total of 15 populations, and 149 individuals were sampled throughout the QTP. High genetic diversity was detected both in cpDNA (H _d = 0.820) and SSR (H _o = 0.689, H _e = 0.699). Ten cpDNA haplotypes and 163 alleles were identified. AMOVA and clustering analyses revealed obvious differentiation between regions. The N _st, G _st and Mantel test showed significant phylogeographic structure of I. loczyi. The neutrality test and mismatch distribution analyses indicated that I. loczyi could not have undergone a historical population expansion, but population XS from the Qilian Mountain area could have experienced a local expansion. Bottleneck analyses indicated that I. loczyi had not experienced bottleneck recently. Based on cpDNA and SSR results, the Qilian Mountain area was inferred as a potential glacial refuge, and the southern Tibet valley was considered as a 'microrefugia' for I. loczyi. These findings provided new insights into the location of glacial refuges for the species distributed in QTP, and supplemented more plant species data for the response of QTP species to the Quaternary climate.

Impact process and mechanism of summertime rainfall on thermal-moisture regime of active layer in permafrost regions of central Qinghai-Tibet Plateau

Rainfall can potentially change upper thermal-moisture boundary conditions and influence the hydrological and thermal state of the active layer in permafrost regions. Studying the relationship between rainfall and ground temperature represents an emerging issue in permafrost engineering and environment but the interactive mechanisms of rainfall and the active layer are not well understood. This study aims to analyze the effects and mechanisms of summertime rainfall on the thermal-moisture dynamics of the active layer by field observations and simulation. The observation data demonstrated that frequent light rainfall events had a minor impact on the active layer, whereas consecutive rainfall events and heavy rainfall events had significant effects on soil temperature and water content. Moreover, the soil temperatures were more susceptible to summertime rainfall events. These rapidly cooled the shallow ground and delayed the temperature rise. Summertime rainfall significantly increased the surface latent heat flux, but decreased the net radiation, sensible heat flux, and soil surface heat flux. Rainfall also enhanced the amount of downward liquid water and water vapor, but the impact of rainfall on the increase in the convective heat transfer of the liquid water was lower than the decreases in the heat conduction flux, latent heat flux by vapor diffusion, and heat flux by convection of vapor. Thus, the reduction in the total soil heat flux caused by rainfall directly leads to a cooling effect on the soil temperature and delays the increase in soil temperature. The cooling effect of rainfall events may mitigate the warming rate and maintain the active layer at a relatively low temperature. The results provide new insights into understanding the inner mechanisms of the effect of rainfall on the active layer and on the possible long-term change trends of permafrost under increasing precipitation in the central Qinghai-Tibet Plateau.

Characterization of the spatial distribution of plateau pika burrows along an alpine grassland degradation gradient on the Qinghai-Tibet Plateau

Plateau pika burrows are common feature of degraded grassland in the Qinghai-Tibet Plateau (QTP) and serve as an important indicator of pika activity and grassland degradation. However, the current understanding of the spatial pattern changes of pika burrows and their critical thresholds across a degradation gradient in alpine grassland is deficient. In this study, we investigated and quantified changes in the spatial pattern of plateau pika burrows under typical degraded alpine shrub meadows in the northeastern QTP using an unmanned aerial vehicle and landscape pattern metrics. The degradation of the alpine shrub meadow leads to a change in landscape pattern from a two-layered structure of alpine shrub and alpine meadow to a mosaic of alpine meadow and bare soil, with plateau pika burrows scattered throughout. Moderate degradation is the tipping point for changes in surface landscape patterns, followed by the disappearance of alpine shrub, the retreat of alpine meadows and the encroachment of bare soil, and the increasing density and size of pika burrows. The area characteristics of alpine meadows have influenced changes in the spatial pattern of pika burrow, and maintaining its proportional area is a vital measure to control the threat of pika burrows to pastures. The results of this paper provide a methodological reference and guidance for the sustainable utilization of grassland on the QTP.

Food and Grain Consumption Per Capita in the Qinghai-Tibet Plateau and Implications for Conservation

Background: Grain security is crucial for social stability and ecosystem conservation regionally and globally, and it is particularly concerned widely in the Qinghai-Tibet Plateau (QTP) due to its high altitude and harsh climate for agriculture. Method: In this paper, we calculated and analyzed per capita food and grain consumption, including direct grain consumption, grain for fodder, industry consumption, seeds consumption, and wastage consumption and its changes in the QTP during 1995–2019. Results: The results showed that (1) in 2019, the average food consumption per capita was 333.35 kg, was stable since 1995. The dietary structure of residents was composed of direct grain consumption (44.15%), meat (10.72%), and milk (6.94%). The consumption of meat and milk was higher than the national average. (2) The average daily intake of energy and protein, animal protein, and the ratio of high-quality protein and fat energy were 2156.21 kcal·d⁻¹, 73.53 g·d⁻¹, 23.06 g·d⁻¹, 38.32%, and 27.77% in 2019. Their changes were −342.98 kcal·d⁻¹, −8.91 g·d⁻¹, 11.16 g·d⁻¹, 18.37%, and 11.08%, respectively. (3) The corresponding grain consumption per capita was 284.90 kg·a⁻¹ in 1995, 262.19 kg·a⁻¹ in 2010, and then remained stable until 2019. Conclusion: The study suggested that food consumption per capital was guaranteed at the well-off level since 2010, and food and dietary structure of residents were corresponding to physical geographic and climatic environment in the QTP. The conflict between food security and the ecosystem conservation can be managed without scarifying nature as the total grain consumption was stable since 2010, and the yield per unit area and total grain yield were both increasing since 2003 for agricultural condition improved in the QTP.

Genomic Features and Molecular Function of a Novel Stress-Tolerant Bacillus halotolerans Strain Isolated from an Extreme Environment

Simple Summary

The Qinghai–Tibet Plateau is known as the “third pole of the world”. Due to the extreme geographical location, Qinghai–Tibet Plateau has unique ecosystems characterized by oxygen deficiency, low temperature, high salinity and alkalinity. We carried out the current study to explore the excellent extremophilic Bacillus strains via potential stress resistance as well as biocontrol properties in the Qinghai–Tibet Plateau. We found a Bacillus halotolerans strain with a promising ability to withstand harsh environments and which also exhibits an optimistic biocontrol activity against plant pathogens. We revealed the whole genome sequencing and its taxonomic position and elucidated its molecular functions that were responsible for enhancing stress tolerance as well as suppressing plant pathogens at the genetic level. Lastly, we identified this strain harbored the specific genes associated with stresses resistance, biocontrol function, and can be used as a biological agent in the agriculture field.

Abstract

Due to its topographical position and climatic conditions, the Qinghai–Tibet Plateau possesses abundant microorganism resources. The extremophilic strain KKD1 isolated from Hoh Xil possesses strong stress tolerance, enabling it to propagate under high salinity (13%) and alkalinity (pH 10.0) conditions. In addition, KKD1 exhibits promising biocontrol activity against plant pathogens. To further explore these traits at the genomic level, we performed whole-genome sequencing and analysis. The taxonomic identification according to the average nucleotide identity based on BLAST revealed that KKD1 belongs to Bacillus halotolerans. Genetic screening of KKD1 revealed that its stress resistance mechanism depends on osmotic equilibrium, membrane transportation, and the regulation of ion balance under salt and alkaline stress. The expression of genes involved in these pathways was analyzed using real-time quantitative PCR. The presence of different gene clusters encoding antimicrobial secondary metabolites indicated the various pathways by which KKD1 suppresses phytopathogenic growth. Moreover, the lipopeptides surfactin and fengycin were identified as being significant antifungal components of KKD1. Through comparative genomics analysis, we noticed that KKD1 harbored specific genes involved in stress resistance and biocontrol, thus providing a new perspective on the genomic features of the extremophilic Bacillus species.

Phylogenetic and functional structures of succession in plant communities on mounds of Marmota himalayana in alpine regions on the northeast edge of the Qinghai-Tibet Plateau

Few studies have examined the succession of plant communities in the alpine zone. Studying the succession of plant communities is helpful to understand how species diversity is formed and maintained. In this study, we used species inventories, a molecular phylogeny, and trait data to detect patterns of phylogenetic and functional community structure in successional plant communities growing on the mounds of Himalayan marmots (Marmota himalayana) on the southeast edge of the Qinghai-Tibet Plateau. We found that phylogenetic and functional diversities of plant communities on marmot mounds tended to cluster during the early to medium stages of succession, then trended toward overdispersion from medium to late stages. Alpine species in early and late stages of succession were phylogenetically and functionally overdispersed, suggesting that such communities were assembled mainly through species interactions, especially competition. At the medium and late stages of succession, alpine communities growing on marmot mounds were phylogenetically and functionally clustered, implying that the communities were primarily structured by environmental filtering. During the medium and late stages of succession the phylogenetic and functional structures of plant communities on marmot mounds differed significantly from those on neighboring sites. Our results indicate that environmental filtering and species interactions can change plant community composition at different successional stages. Assembly of plant communities on marmot mounds was promoted by a combination of traits that may provide advantages for survival and adaptation during periods of environmental change.

Nocardioides dongkuii sp. nov. and Nocardioides lijunqiniae sp. nov., isolated from faeces of Tibetan antelope (Pantholops hodgsonii) and leaves of dandelion (Taraxacum officinale), respectively, on the Qinghai-Tibet Plateau

In the present study, four bacterial strains, two (S-713^T and 406) isolated from faecal samples of Tibetan antelopes and the other two (S-531^T and 1598) from leaves of dandelion collected on the Qinghai-Tibet Plateau of PR China, were analysed using a polyphasic approach. All four isolates were aerobic, rod-shaped, non-motile, oxidase-negative, Gram-stain-positive and catalase-positive. According to four phylogenetic trees, strain pairs S-713^T/406 and S-531^T/1598 form two independent branches belonging to the genus Nocardioides, and are closest to Nocardioides lianchengensis, Nocardioides dokdonensis, Nocardioides salarius, Nocardioides marinisabuli, Nocardioides psychrotolerans and Nocardioides szechwanensis. Although sharing MK8-(H₄) as their major isoprenoid quinone, strains S-713^T and S-531^T contained C_18 : 1  ω9c (24.64 and 16.34 %) and iso-C_16 : 0 (9.74 and 29.38 %), respectively, as their main fatty acids, with remarkable differences in their biochemical profiles but only slight ones in their optimal growth conditions. The chromosomes of strains S-713^T and S-531^T were 4 207 844 bp (G+C content, 73.0 mol%) and 4 809 817 bp (G+C content, 72.5 mol%), respectively. Collectively, the two strain pairs represent two separate novel species of the genus Nocardioides, for which the names Nocardioides dongkuii sp. nov. and Nocardioides lijunqiniae sp. nov. are proposed, with S-713^T (=JCM 33698^T=CGMCC 4.7660^T) and S-531^T (=JCM 33468^T=CGMCC 4.7659^T) as the respective type strains.

Severe Case of Rickettsiosis Identified by Metagenomic Sequencing, China

A case of Rickettsia sibirica subspecies sibirica BJ-90 infection in China was identified by metagenomic analysis of an eschar biopsy specimen and confirmed by nested PCR. Seroprevalence of spotted fever group Rickettsia was ≈17.4% among the local population. This report highlights the threat of rickettsioses to public health in the Qinghai–Tibet Plateau.

Corynebacterium lizhenjunii sp. nov., isolated from the respiratory tract of Marmota himalayana, and Corynebacterium qintianiae sp. nov., isolated from the lung tissue of Pseudois nayaur

Four Gram-stain-positive, non-motile and asporous bacilli (strains ZJ-599^T, ZJ-621, MC1420^T and MC1482), isolated from animal tissue and environmental samples collected on the Qinghai-Tibet Plateau, PR China, were taxonomically characterized. Based on the results of 16S rRNA gene sequence analyses, the closest relatives of strains ZJ-599^T and ZJ-621 were Corynebacterium endometrii LMM-1653^T (97.5 %), Corynebacterium phocae M408/89/1^T (96.5 %) and Corynebacterium flavescens OJ8^T (96.3 %), whereas strains MC1420^T and MC1482 were closest to Corynebacterium sanguinis CCUG 58655^T (98.9 %), Corynebacterium mycetoides DSM 20632^T (98.4 %) and Corynebacterium lipophiloflavum DSM 44291^T (97.9 %). The results of rpoB gene sequence similarity analysis indicated that C. phocae M408/89/1^T and C. sanguinis CCUG 58655^T were closest to strains ZJ-599^T/ZJ-621 (83.5 %) and MC1420^T/MC1482 (91.8 %), respectively. The two novel type strains shared a similarity of 95.2 % in 16S rRNA and 81.3 % in rpoB gene sequences. The TAP-PCR DNA fingerprint and MALDI-TOF MS spectrum patterns clearly differentiated the novel isolates within and between each pair of strains. Strain ZJ-599^T had 21.9-22.4 % digital DNA-DNA hybridization (dDDH) scores with C. endometrii LMM-1653^T, C. phocae M408/89/1^T and C. flavescens OJ8^T, and 72.3-72.9 % of average nucleotide identity (ANI) with them. Similarly, strain MC1420^T had 22.9-23.7 % dDDH values with C. sanguinis CCUG 58655^T, C. mycetoides DSM 20632^T and C. lipophiloflavum DSM 44291^T, and 80.4-81.3 % ANI scores with them. Strain ZJ-599^T had a 23.1 % dDDH value and 70.5 % ANI score with strain MC1420^T, both below the corresponding thresholds for species delineation. Strains ZJ-599^T and MC1420^T both contain mycolic acids and have MK-8(H₂) and MK-9(H₂) as the predominant respiratory quinones, meso-diaminopimelic acid as the diagnostic diamino acid, and C_18 : 1  ω9c as the main fatty acid. C_17 : 1  ω8c and C_15 : 1  ω8c were predominant in strain ZJ-599^T in contrast to C_17 : 1  ω7c being predominant in strain MC1420^T. The main polar lipids in strain ZJ-599^T were diphosphatidylglycerol, phosphatidylinositol and one unidentified glycolipid, while strain MC1420^T had diphosphatidylglycerol, phosphatidylglycerol and one unidentified lipid as the major components. Since the two pairs of novel strains (ZJ-599^T/ZJ-621, MC1420^T/MC1482) distinctly differ from each other and from their nearest relatives, two novel species of the genus Corynebacterium are proposed, namely Corynebacterium lizhenjunii (type strain ZJ-599^T=GDMCC 1.1779^T=JCM 34341^T) and Corynebacterium qintianiae (type strain MC1420^T=GDMCC 1.1783^T=JCM 34340^T), respectively.