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Soil carbon isotopes (δ13C) provide reliable insights for studying soil carbon turnover at a long-term scale. The Tibetan Plateau (TP), often referred as "the third pole of the earth", is highly sensitive to global climate change, and exhibits an early warning signal of global warming. Although many studies detected soil δ13C variability at site scales, there is still a knowledge gap existing in the spatial pattern of soil δ13C across the TP. In this study, we compiled a database of 198 topsoil δ13C observations from published literatures and used a modified multi-layer perceptron (MLP) neural network algorithm to predict the spatial pattern of topsoil δ13C and β (indicating the decomposition rate of soil organic carbon (SOC), calculated as δ13C divided by logarithmically converted SOC) at 500m resolution. Results showed that MLP model effectively predicted topsoil δ13C with a model efficiency of 0.72 and a root mean square error of 1.16‰. Topsoil δ13C varied significantly across different ecosystem types (p < 0.001) with a mean δ13C of –25.89 ± 1.15‰ (mean ± standard deviation) for forests, –24.91 ± 1.03‰ for shrublands, –22.95 ± 1.44‰ for grasslands, and –18.88 ± 2.37‰ for deserts. Furthermore, there was an increasing trend of predicted δ13C from the southeastern to the northwestern TP, likely linked to vegetation type and climatic conditions. β values were low in the eastern TP and higher in the northern and northwestern TP, indicating faster SOC turnover rate in the east TP compared to the north and northwest. This study represents the first effort to develop a fine resolution product of topsoil δ13C and β across the TP, which could provide an independent, data-driven benchmark for biogeochemical cycling models to study SOC turnover and terrestrial carbon-climate feedback over the TP under climate change. [ABSTRACT FROM AUTHOR]

• Land suitability evaluation assessed the suitability of land for urban development. • Intensive development of 3 urban growth boundary scenarios were simulated for 2040. • Landscape pattern of three urban growth scenarios were generated. • Intensive scenario is an ideal development mode. In designing national parks, it is important to balance land use with ecological protection and local socio-economic development. In the past decades, the national park has undergone landscape fragmentation and degradation of ecological functions due to climate change and land use change, especially in national parks with urban areas. Therefore, ecological environmental protection projects should include the assessment of land use when planning urban area development in the national park region. Consequently, we used the Land Suitability Evaluation (LSE) method, with 13 indicators for natural, social and ecological variables, to assess the suitability of the newly created national park for urban land use on the Tibetan Plateau. Combining results of the suitability assessment and the Cellular Automata (CA) method, three urban intensification scenarios were simulated for 2040: (1) unplanned, (2) intensified, and (3) strictly regulated urban growth boundaries (UGBs). The impact of land use on the normalized difference vegetation index (NDVI) was analyzed by remote sensing and GIS tools, and the landscape patterns of the three urban growth scenarios were calculated. Close to 87 % of the area was basically suitable, nearly 13 % was unsuitable, and only 0.06 % (43.4 km2–also included in the basically suitable) was suitable for urban land use. In 2040, the built-up areas are predicted to be 3.38, 2.71 and 2.32 times greater than in 2020 under the unplanned (without considering ecological restrictions), the intensive development (emphasizing the driving force of transportation and tourism on the expansion of built-up areas) and the strict control (maximizing ecological restrictions) scenarios, respectively. An ideal development model was used to balance ecological protection and population growth and economic development. The NDVI analysis revealed that the impact of land use on vegetation cover in the intensive development scenario was ranked as winter pastures > tourist development zones > summer pastures. It is concluded that the intensification scenario, with transport and tourism as the main spatial drivers, is the most desirable for the future coordination of ecological conservation and socio-economic development in the national park. This scenario may alleviate the current environmental pressure of livestock grazing on winter pastures in the national park on the Tibetan Plateau. However, realizing this model requires appropriate engineering design for town development. Future research should assess the impacts of urban growth on the ecological environment, with the aim to achieve sustainable urban development tailored to the various geographic regions. [ABSTRACT FROM AUTHOR]

Toxocara vitulorum has been rarely reported in yaks at high altitudes and remote areas of Sichuan Province of Tibetan Plateau of China. The current study was designed to investigate the prevalence, associated risk factors, and phylogenetic characteristics of T. vitulorum in yak calves on the Qinghai Tibetan plateau. Fecal samples were collected from 891 yak calves and were examined for the presence of T. vitulorum eggs by the McMaster technique. A multivariable logistic regression model was employed to explore variables potentially associated with exposure to T. vitulorum infection. T. vitulorum specimens were collected from the feces of yaks in Hongyuan of Sichuan Province, China. DNA was extracted from ascaris. After PCR amplification, the sequencing of ND1 gene was carried out and phylogenetic analyses was performed by MEGA 6.0 software. The results showed that 64 (20.1%; 95% CI 15.8-24.9%), 75 (17.2; 13.8-21.1), 29 (40.9; 29.3-53.2), and 5 (7.6; 2.5-16.8) yak calves were detected out to excrete T. vitulorum eggs in yak calve feces in Qinghai, Tibet, Sichuan, and Gansu, respectively. The present study revealed that high infection and mortality by T. vitulorum is wildly spread on the Qinghai Tibetan plateau, China by fecal examination. Geographical origin, ages, and fecal consistencies are the risk factors associated with T. vitulorum prevalence by logistic regression analysis. Molecular detection and phylogenetic analysis of ND1 gene of T. vitulorum indicated that T. vitulorum in the yak calves on the Qinghai Tibetan plateau are homologous to preveiously studies reported. [ABSTRACT FROM AUTHOR]

Climate change has significant impacts on species' distributions and diversity patterns. Understanding range shifts and changes in richness gradients under climate change is crucial for conservation. The Tibetan Plateau, home to wild yak, chiru, and kiang, contains a biome with many endemic ungulates. It is highly sensitive to climate change and a region that merits particular attention with regard to the impacts of global climate change on its biomes. Maximum entropy approaches were used to estimate current and future potential distributions, in response to climate change, for 22 ungulate species. We used three general circulation (MK3, HADCM3, MIROC3_2-MED) and three emissions scenarios (B1, A1B, A2) to derive estimated future measurements of 14 environmental variables over three time periods (2020, 2050, 2080), and then modeled species distributions using these predicted environmental measurements for each time period under two dispersal hypotheses (full and zero, respectively). This resulted in a total of 6160 prediction models. We found that these ungulates, on average, may lose 30-50% of their distributional areas, depending on the dispersal scenarios. In addition, 55-68% of the ungulate species were predicted to become locally endangered under the different dispersal assumptions, 23-32% to become locally critically endangered, and 4-7 endemic species to become globally endangered. Furthermore, ungulate species ranges may experience average poleward shifts of ~300 km. We also predict west-to-east reductions in species richness: southeastern mountainous areas currently have the highest species richness, but are predicted to face the greatest diversity losses, whereas the northern areas are predicted to see increasing numbers of ungulate species in the 21st century. Our study indicates much more severe range reductions of ungulates on the Tibetan Plateau than those anticipated elsewhere in the world, and species richness patterns will change dramatically with climate change. For conservation, we suggest (1) securing existing protected areas, and (2) establishing new nature reserves to counterbalance climate change impacts. [ABSTRACT FROM AUTHOR]

Background Hemoglobin concentration at high altitude is considered an important marker of high altitude adaptation, and native Tibetans in the Qinghai-Tibetan plateau show lower hemoglobin concentrations than Han people who have emigrated from plains areas. Genetic studies revealed that EPAS1 plays a key role in high altitude adaptation and is associated with the low hemoglobin concentration in Tibetans. Three single nucleotide polymorphisms (rs13419896, rs4953354, rs1868092) of noncoding regions in EPAS1 exhibited significantly different allele frequencies in the Tibetan and Han populations and were associated with low hemoglobin concentrations in Tibetans. Methods To explore the hereditary basis of high altitude polycythemia (HAPC) and investigate the association between EPAS1 and HAPC in the Han population, these 3 single nucleotide polymorphisms were assessed in 318 male Han Chinese HAPC patients and 316 control subjects. Genotyping was performed by high resolution melting curve analysis. Results The G-G-G haplotype of rs13419896, rs4953354, and rs1868092 was significantly more frequent in HAPC patients than in control subjects, whereas no differences in the allele or genotype frequencies of the 3 single nucleotide polymorphisms were found between HAPC patients and control subjects. Moreover, genotypes of rs1868092 (AA) and rs4953354 (GG) that were not observed in the Chinese Han in the Beijing population were found at frequencies of 1.6% and 0.9%, respectively, in our study population of HAPC patients and control subjects. Conclusions Carriers of this EPAS1 haplotype (G-G-G, rs13419896, rs4953354, and rs1868092) may have a higher risk for HAPC. These results may contribute to a better understanding of the pathogenesis of HAPC in the Han population. [ABSTRACT FROM AUTHOR]

Dating of quartz by optically stimulated luminescence (OSL) has been revolutionized with introduction of the test dose (TD) in development of a measurement sequence known as the single-aliquot regenerative-dose (SAR), whereby a valid sensitivity correction for the luminescence signal is provided in the measurement cycle. However, the size of the TD used in the SAR protocol remains controversial. Previous studies show that the TD has little effect on the equivalent dose (D e) for young samples in luminescence dating in which the applicability of different deposits varies greatly in different regions. However, detailed studies are lacking on how TD size affects SAR–OSL results of samples with a relatively high D e range. In this study, typical loess samples with high D e values (∼60 Gy–∼250 Gy) from the eastern Tibetan Plateau were selected to investigate the effects of variation in TD size on the quartz SAR–OSL protocol. Dose recovery tests show that a known dose could be recovered successfully by applying different TDs. Test dose size has an effect on shapes of regenerated dose–response curves (DRCs) and has different influences on D e s and characteristic saturation doses for quartz samples with a high dose range. A TD size of 20%–30% D e is a good compromise for Tibetan loess with D e of ∼60–120 Gy in the quartz SAR protocol, and a TD size larger than 30% should be considered for samples with a larger D e. The results of this study highlight the importance of TD size in the SAR–OSL protocol for quartz samples with a high dose range. • Test dose size effect on the quartz SAR for high dose range is investigated. • Successful dose recovery test can be obtained by applying different test doses. • Test dose size has different influences on D e s and D 0 s. • A 20%–30% test dose size is a good compromise for D e of ∼60–120 Gy. [ABSTRACT FROM AUTHOR]

Abstract: The Tibetan Plateau and surrounding mountains represent one of the largest ice masses of the Earth. The region, referred to by scientists as the Third Pole, covering 5 million km2 with an average elevation of >4000m and including more than 100,000km2 of glaciers, is the most sensitive and readily visible indicator of climate change. The area also demonstrates considerable feedbacks to global environmental changes. The unique interactions among the atmosphere, cryosphere, hydrosphere and biosphere on the Third Pole ensure permanent flow of Asia''s major rivers, thus significantly influencing social and economic development of China, India, Nepal, Tajikistan, Pakistan, Afghanistan and Bhutan where a fifth of the world''s population lives. Like Antarctica and the Arctic, a series of observations and monitoring activities in the Third Pole region have been widely implemented. Yet for a comprehensive understanding of the Third Pole, current observational resources need to be integrated and perfected, and research goals and approaches need to be updated and identified. The Third Pole Environment (TPE) program aims to attract relevant research institutions and academic talents to focus on a theme of ‘water–ice–air–ecosystem–human’ interactions, to reveal environmental change processes and mechanisms on the Third Pole and their influences on and responses to global changes, and thus to serve for enhancement of human adaptation to the changing environment and realization of human–nature harmony. [Copyright &y& Elsevier]

The effects of experimental warming on the growth and physiology of grass Elymus nutans and forb Potentilla anserina were studied by using open-top chambers (OTCs) in an alpine meadow of the eastern Tibetan Plateau. The warming treatment increased mean air and soil surface temperatures by 1.53°C and 0.50°C, respectively, but it reduced soil relative water content in the surface layer. Experimental warming enhanced the growth and gas exchange of E. nutans, while it reduced those of P. anserina. Experimental warming resulted in an increased efficiency of photosystem II (PSII) in E. nutans, while decreasing it in P. anserina; significantly stimulated non-photochemical quenching, antioxidative enzymes and non-enzymes in both species; and significantly reduced malondialdehyde content in E. nutans, while promoting it in P. anserina. The results of this study indicated that the two species showed different growth responses to experimental warming and their different physiological performances further indicated that experimental warming alleviated the negative effect of low temperature on the growth and development of E. nutans, but limited the competitive ability of P. anserina in the study region. [ABSTRACT FROM AUTHOR]

Abstract: A brick-red-pigmented strain (XTM003T) isolated from the Qinghai–Tibet plateau was investigated using a polyphasic taxonomy approach. Phylogenetic analyses based on 16S rRNA gene sequence indicated that the organism belonged to the genus Hymenobacter. The predominant menaquinone was MK7. The major fatty acids included iso-15:0, 16:1w5c and summed feature 3 (C16: 1 ω7c and/or C16: 1 ω6c). The G+C content of the DNA was 55.8%. In addition, DNA–DNA hybridization studies demonstrated that strain XTM003T had a relatedness value of 50.7% with the phylogenetically most closely related species Hymenobacter norwichensis DSM 15439T. Based on the results of phenotypic characteristics and DNA–DNA hybridization studies, strain XTM003T is considered to represent a novel species, for which the name Hymenobacter tibetensis sp. nov. is proposed. The type strain is XTM003T (=CCTCC AB 207089T=NRRL B-51271T). [Copyright &y& Elsevier]

Abstract: Plant species have been shown to have significant effects on soil nutrient pools and dynamics. Stellera chamaejasme L., a toxic perennial weed, has established and is now abundant in the alpine meadow on the eastern Tibetan Plateau of China since the 1960s. We quantified the effects of Stellera on carbon and nitrogen cycling in two topographic habitats, a flat valley and a south-facing slope, where Stellera was favored to spread within the study area. Aboveground litter biomass and tissue chemistry of aboveground litter and root were measured to explain the likely effects of Stellera on soil carbon and nutrient cycling. The sizes of various soil pools, e.g. nitrate, ammonium, inorganic phosphorus, microbial biomass, soil respiration and turnover rates including net mineralization, gross nitrification and denitrification were determined. The results showed that Stellera produced more aboveground litter than each of the co-occurring species. Aboveground litter of Stellera had higher tissue N and lower lignin:N than the other species. Stellera significantly increased surface soil (0–15cm) organic matter, whereas no significant differences were found for organic C and total P in subsoil (15–30cm) within and between patches of Stellera. Soil extractable nitrate concentrations in Stellera surface soil were 113% and 90% higher on the flat valley and on the south-facing slope, respectively. Both microbial biomass C and N were significantly higher in Stellera surface soil. Gross nitrification and microbial respiration were significantly higher in Stellera surface soil both on the flat valley and on the south-facing slope, whereas significant differences of denitrification were found only on the flat valley. The differences in the quantity and quality of aboveground litter are a likely mechanism responsible for the changes of soil properties. [Copyright &y& Elsevier]

The article discusses on the nitrification and denitrification of an alpine meadow soil in the eastern Tibetan Plateau in China. It states that nitrification and denitrification represent two of the main biological processes involved in the nitrogen cycle, which contribute to the regulationof nitrogen trioxide.

The article discusses the impact of the increase of atmospheric carbon dioxide concentration to the climate change in Tibetan Plateau. It highlights the involvement of emission to the carbon sequestration in forests and the ecosystem. Also cited the development of species and ecosystems in the region along with the distribution patterns of vegetation.

The production of high-resolution and accurate age models for lake sediments in the Tibetan Plateau (TP) is a prerequisite for subsequent paleoclimatic studies. However, Holocene lake sedimentary records with high-quality age controls from the TP are extremely scarce. Here we present the results of a comparative study of the results of the application of multiple dating techniques (14C, 210Pb, 137Cs) and a paleomagnetic secular variation (PSV) study of the sediments of Angrenjin Co in the southern central TP, during the last 3600 years. The PSV data are verified by comparison with a stacked PSV record from East Asia and with a global geomagnetic field model. The results of 14C-dating, validated by independent 210Pb, 137Cs and PSV dating, together with Bacon age modeling, indicate that the reservoir has an age range of ~2287 ± 58–6434 ± 165 years; in addition, the median offset ages estimated by the Bacon age-depth model range from ~1330 ± 428 to 3102 ± 513 years. This cross-dating approach effectively reduces dating uncertainties for lake sediments in the TP, and it can accommodate a variable reservoir effect. Comparison of the paleomagnetic inclination record from Angrenjin Co with previously published records from Tangra Yumco, Taro Co and Nam Co indicates an overall high degree of similarity, suggesting that the paleomagnetic data from different lakes in the TP are reproducible. In addition, the similar inclination patterns across this large region indicate a common geomagnetic origin. • Multiple dating techniques produce an improved age model for the sediments of Angrenjin Co. • 14C dates are evaluated by the 210Pb CRS model, paleomagnetic secular variation, and Bacon modeling. • Reservoir effect in the Angrenjin Co sediments may range from 2287 to 6434 years. • Inclination records are reproducible between lakes across the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

The spatial distribution of montane forest biomass and C pools along altitudinal gradients and the role of the climate gradient on the Tibetan Plateau are not well-understood. To determine how live biomass and C pools in montane forests vary along an elevation gradient, the biomass and C content of fir trees (Abies georgei), the most widespread forest type on the Tibetan Plateau, were measured from 3100 m asl to 4400 m asl. The total live biomass of the forest nonlinearly declined by 66.2% with the elevation gradient, with most of the biomass reduction (covering almost 94% of the total reduction) occurring at altitudes lower than 3400 m asl and at altitudes above 3900 m asl, and the C concentration of the aboveground components (stems, leaves and branches) of A. georgei were positively correlated with the biomass variation along an elevation gradient. The total C pool of A. georgei (stand and root C) decreased from 259.73 ± 11.75 t C/ha at 3100 m asl to 87.29 ± 8.21 t C/ha at 4300 m asl, whereas the biomass C pool allocation in the roots increased by 2.5% at the same altitude. A possible explanation for these marked shifts in the biomass and C allocation from above to belowground along an increasing elevation gradient is discussed, including the limitation of the N supply and the effect of lower temperatures. The annual air temperature and precipitation were positively correlated with the live biomass and C stocks along an elevation gradient. The live biomass C is allocated more to aboveground components with increasing temperature and precipitation. [ABSTRACT FROM AUTHOR]