Tibet Research Articles

Effects of plant community and altitude on food composition of Cervus elaphus wallichii during the withered grass period on the Tibetan Plateau, China.

How Tibetan red deer (Cervus elaphus wallichii) acclimates to high altitude environment during the withered grass period is one of the challenges in maintaining their nutrient intake. It is an important basis to study the nutritional ecology of wild large ungulates in alpine ecosystems by investigating the changes in plant communities with altitude during the withered grass period and how these changes affect the food composition of Tibetan red deer. In this study, we selected the Tibetan red deer in Sangri County, Shannan region of Tibet as the research subject. We carried out field surveys on the altitude, plant communities, and feeding traces of the Tibetan red deer in March of 2021 and 2022 during the withered grass period on the Tibetan Plateau. Detrended correspondence analysis and canonical correspondence analysis were used to study altitudinal variations in plant communities and the regularity of food composition. The results showed that during the period of withered grass, Tibetan red deer ate primarily Salix daltoniana, Rosa macrophylla var. glandulifera and Dasiphora parvifolia. S. daltoniana accounted for more than 50% of the food composition, as the main food resources for red deer in withered grass period. In the low altitude area (4100-4300 m), plant community included Caragana versicolor, R. macrophylla and Berberis temolaica, and Tibetan red deer mainly ate R. macrophylla, C. versicolor and Artemisia wellbyi. In higher altitude area (4300-4600 m), plant community consisted of Rhododendron nivale, Rhododendron fragariiflorum, and Sibiraea angustata, and Tibetan red deer mainly fed on S. daltoniana, Salix obscura, and Carex littledalei. At different altitudes, the dominant plant species were the main food of Tibetan red deer. It is suggested that the changes of plant community composition with altitude directly affected food composition of Tibetan red deer, indicating different food composition patterns with altitude gradients.

Osteoporosis Screening Values of Osteoporosis Self-Assessment Tool for Asians Index and Body Mass Index in Middle-Aged and Elderly Tibetan Population in Tibet

To analyze the screening value of osteoporosis self-screening tool for Asia (OSTA) and body mass index (BMI) for osteoporosis (OP) in middle-aged and elderly Tibetan population in the Tibetan region. Data on demographic information, bone mineral density (BMD), and other information of 627 middle-aged and elderly people were collected. Analysis of the correlation between OSTA index, BMI and BMD, and receiver operating characteristic (ROC) curve was performed to evaluate the OP screening effects. OSTA index and BMI were correlated with BMD in both female and male populations ( P<0.05). In both male and female populations, OSTA index screening results for OP yielded higher area under the curve ( AUC) than BMI did, with the AUC for female OSTA index being 0.886 and that for female BMI being 0.785, while that for male OSTA index being 0.957 and that for male BMI being 0.834. When comparing the different age groups, the AUC of OSTA index and BMI of the middle-age group was higher than those of the quasi-elderly group and the elderly group, with the AUC of OSTA index and BMI of the middle-age being 0.939 and 0.858, those of the quasi-elderly group being 0.860 and 0.813, and those of the elderly group being 0.750 and 0.650, respectively. When the optimal cut-off value of diagnosis with OSTA index was －2.20, the sensitivity and specificity were both 100%. When the optimal cut-off value for diagnosis with BMI was 17.512 kg/m2, the sensitivity and specificity were both 100%. OSTA index and BMI have different OP screening effects in different middle-aged and elderly Tibetan populations, and OSTA index shows better effects for OP screening than BMI does.

Limits of oxygen isotope palaeoaltimetry in Tibet

Measurements of stable water isotopes (oxygen and hydrogen) are commonly used to estimate palaeoelevation and quantify past changes in surface height across Tibet. Isotope palaeoaltimetry is often based on simple Rayleigh fractionation of a “parcel of air”, but must make a considerable number of approximations and assumptions. In this paper, we elaborate on the practicability of oxygen water isotopes in palaeoaltimetry, and evaluate a recent challenge to the palaeoaltimetry community. First, we examine the isotopic composition of oxygen (δ18O) versus altitude relationship in a set of five topographic realisations of Tibet using an isotope-enabled palaeoclimate model for the mid-Eocene, a period where a variety of topographic ‘uplift’ models have been proposed, and compare it to modern relationships. Second, we investigate whether isotopic composition is a good predictor of more modest changes in topography, such as the introduction of a valley system or uplift of only part of the Tibetan region. The aim of the paper is not to perform a direct comparison to data, but to use the model to further refine knowledge of the strengths and limitations of using oxygen isotopes in palaeoaltimetry. We find that oxygen isotope palaeoaltimetry works surprisingly well, with the exception that it could not identify low elevation valley systems bounded by high elevations because the isotopic composition of the water in the air becomes depleted at the first high elevation that an air parcel passes over and does not recover when it descends into the valley. Hence, isotope-based elevations are biased towards mountain range peaks. Overall, the application of oxygen isotope palaeoaltimetry does have value, but would be further strengthened when employed together with isotope-enabled models. In conjunction with other techniques such as terrestrial thermal lapse rates and energy conservation approaches, over a wide spatial region, a more accurate and fully three-dimension view of complex palaeo-topography is increasingly possible, which will in turn improve the precision of these palaeoaltimeters.

The co-production of disasters: how the nexus of climate change, tourism, and COVID-19 increases socioeconomic vulnerability in Mustang, Nepal

ABSTRACT How do high mountain communities, facing the grave effects from climate change and economic impacts of the COVID-19 pandemic on the local tourism industry, perceive and navigate multiple protracted disasters? This article takes up this question from the perspective of a specific mountain community, that of Mustang, a culturally Tibetan region of Nepal bordering the Tibet Autonomous Region (TAR), China. Our findings stem from collective ethnographic research conducted with Mustangi communities in Nepal and among the diaspora in New York City to investigate the nexus between high mountain livelihoods, particularly tourism, and the consequences of two distinct yet interlocking disasters: climate change and the global health crisis of the COVID-19 pandemic. We argue that the pandemic has undermined elements of Mustang’s economic future and simultaneously prompted a resurgent appreciation for and reliance on more traditional modes of community governance and social support. The fact that these dynamics are unfolding amidst ever-present concerns over the effects of climate change in the Himalayas, against the backdrop of labor- and education-driven outmigration, adds a profound layer of complexity to thinking about the future of tourism but also of Himalayan lives, from built infrastructures to the community resilience needed to sustain both.

Study on the correlation between maternal serum uric acid and foetal birth weight in Naqu, Tibet

In high-altitude regions, low birth weight is mainly caused by hypoxia. We aimed to determine whether maternal serum uric acid (SUC) level was associated with decreased foetal birth weight. The relevant data of individual pregnant women who delivered between 37 and 40 weeks in the People’s Hospital of Naqu City, Tibet were retrospectively collected. The correlation between maternal SUC and birth weight was examined using multivariate linear regression analysis and subgroup analysis. The results showed that there was a significant negative correlation between SUC and birth weight in pregnant women with proteinuria, female foetuses, and primiparas. Fitting smoothing curve analysis showed that there was a negative linear correlation between SUC and birth weight in primiparas and female foetuses. Maternal SUC is negatively associated with foetal birth weight in a single pregnancy with proteinuria, primipara, or female foetuses in the Naqu region of Tibet, China. IMPACT STATEMENT What is already known on this subject? Preeclampsia associated with hyperuricaemia can affect foetal birth weight, foetal birth weight in plains area is negatively correlated with maternal hyperuricaemia. What do the results of this study add? Maternal SUC was negatively correlated with foetal birth weight, especially in primipara, mothers with proteinuria, and pregnant girls. What are the implications of these findings for clinical practice and/or further research? The results suggest that attention should be paid to SUC in pregnant women, especially in primipara, mothers with proteinuria, and pregnant girls, in the prevention of low birth weight infants in Naqu Plateau area of Tibet.

Sichen Formula Ameliorates Lipopolysaccharide-Induced Acute Lung Injury via Blocking the TLR4 Signaling Pathways.

Sichen (SC) formula is a classic prescription of Tibetan medicine. Due to its potential anti-inflammatory effect, the SC formula has been clinically used to treat respiratory diseases for many years in the Chinese Tibet region. The present study aimed to investigate the anti-inflammatory effect of SC and explore the underlying mechanisms. SC formula was characterized by HPLC analysis. The acute lung injury (ALI) mouse model was induced by direct intratracheal lipopolysaccharide (LPS) instillation, and bronchoalveolar lavage fluid (BALF) and lung tissues were collected. Meanwhile, RAW264.7 macrophages were stimulated by LPS. The contents of inflammatory mediators in the culture medium were determined by ELISA. Protein levels were determined by immunohistochemical staining or Western blotting. Nuclear localization of NF-κB, AP-1, and IRF3 was performed using immunofluorescence and Western blotting. In the LPS-induced ALI mouse model, SC treatment suppressed the secretion of inflammatory mediators (TNF-α, IL-6, IL-1β, MCP-1, MIP-1α, and RANTES) in BALF. SC treatment hindered the recruitment of macrophages. SC treatment also inhibited the expression of CD68, p-p65, and TLR4 in the lung tissue. In the LPS-exposed RAW264.7 cells, the cell viability was not changed up to 400 μg/mL of SC. SC concentration-dependently suppressed the production of nitric oxide, prostaglandin E2, TNF-α, IL-6, MCP-1, MIP-1α, and RANTES in LPS-challenged RAW264.7 cells. The expression levels of iNOS, COX-2, p-p38, p-JNK, p-ERK, p-TBK1, p-IKKα/β, p-IκB, p-p65, p-c-Jun, and p-IRF3 were decreased after SC treatment. Moreover, the nuclear translocation of p65, c-Jun, and IRF3 was also blocked by SC treatment. SC treatment inhibited the inflammatory responses in LPS-induced ALI mouse model/RAW264.7 macrophages. The underlying mechanism of this action may be closely associated with the suppression of TLR4 signaling pathways. These research findings provide further pharmacological justifications for the medicinal use of SC in the management of respiratory diseases.

Establishment of Tibetan-Sheep-Specific SNP Genetic Markers

Tibetan sheep are one of the three major coarse sheep breeds in China, and they possess a long history of formation. However, few studies have been conducted on the identification of Tibetan sheep breeds at the molecular level. In this study, a total of 448 individuals from 24 Tibetan sheep populations in the 5 regions of Tibet, Qinghai, Gansu, Yunnan, and Sichuan were analyzed using the Affymetrix Ovine SNP 600K high-density chip to construct specific single-nucleoside polymorphism (SNP) genetic marker sets of Tibetan sheep breeds. Firstly, the genetic structure analysis showed that Yunnan–Tibetan sheep (NL, Ninglang; JC, Jianchuan), Zuogong (ZG), Heizang (HZ), Gongga (GG,) and Tao sheep (TS) can be clearly distinguished from other Tibetan sheep populations. Next, based on the population differentiation index FST, the PCA and NJ tree results showed that only 60 specific SNPs can successfully separate Tibetan sheep in the Yunnan region from Tibetan sheep in other regions, and the distinguishing effect on Yunnan–Tibetan sheep reached 100%. Using the same method, we found that 4 Tibetan sheep breeds, including Zuogong (ZG, 20 SNPs), Heizang (HZ, 60 SNPs), Gongga (GG, 60 SNPs), and Tao sheep (TS, 30 SNPs), can also be distinguished from other Tibetan sheep populations with only a few SNP loci (20–60), and the distinguishing effect reached 100%. Overall, we successfully obtained a Yunnan region-specific (60 SNPs) genetic marker set and 4 breed-specific SNP genetic marker sets (20–60 SNPs) for the first time for the identification of Tibetan sheep breeds at the molecular level. These made up for the lack of genetic marker sets for the identification of Tibetan sheep breeds, and provided a genomic basis for the scientific classification and accurate identification of livestock and poultry genetic resources on the Qinghai–Tibet Plateau.

Coseismic and early postseismic deformation of the 2020 Nima Mw 6.4 earthquake, central Tibet, from InSAR and GNSS observations

The 2020 Mw6.4 Nima earthquake is one of the largest normal-faulting earthquakes recently occurring north of the Banggong suture zone in remote central Tibet, where geologic investigation of active faults is extremely limited. We analyze jointly InSAR and GNSS observations over 9 months after the Nima earthquake and calculate the coseismic and postseismic displacement. The optimal coseismic slip model suggests this event is the result of moderate-angle down-dip slip on a complex reversed “S-shape” three-segmented structure at fault junctions of the West Yibu-Chaka fault, the Heishi fault, and an unmapped blind fault, with a small component of left-lateral slip. The superposition of seismic waves from faults with different strikes and dips accounted for a large non-double-couple component in the long-period point-source solutions. The geodetic moment released by the mainshock is 6.4 × 1018 N⋅m, equivalent to Mw 6.42. Coseismic rupture concentrated at a depth of 4–15 km, with a peak slip of 1.36 m at 8.5 km depth. The cumulative afterslip moment within 9 months after the mainshock is 1 × 1018 N m, about 15.6% of that released by the mainshock coseismic slip. The afterslips contributed largely to the release of additional strain energy. In addition, shallow creep on the northern part of the blind fault, and deep uplift on the east normal fault system are promoted by stress perturbations. A significant proportion of down-dip coseismic slip spreading to more than 20 km beneath the surface, and deep up-slip afterslip have implications for the rheology of down-dip extension of the dipping faults in northern Tibet. Two obvious stress loading zones of more than 1 bar highlight seismic hazards in the region, especially in the junction between normal faults and ends of the large-size sinistral Riganpei-Co and Jiangai-Zangbu faults. It is necessary to forecast accurately by longer-term afterslip observation over timescales of years for the faults. Compared with previous studies, our results suggest a more complex subsurface fault geometry linking the normal and strike-slip faults and dynamic stress adjustment in this poorly-known region of Tibet.

Middle Miocene paleoenvironmental change and paleoelevation of the Lunpola Basin, Central Tibet

The Tibetan region underwent diachronous differential rises during the Cenozoic era. Its elevation history is critical for understanding the processes of mountain building, and for evaluating its climatic effects on atmospheric circulations. However, knowledge of paleoenvironment and paleoelevation in different geological domains of the Tibetan Plateau is still limited. Here we provide chronology of lacustrine deposits of the Upper Dingqing Formation in the Lunpola Basin in Central Tibet, which yields a middle Miocene age (15–12 Ma). Both stable isotope and palynological records indicate a climatic transition at ∼13.8 Ma marked by a change towards a cooler and drier climate after the Middle Miocene Climate Transition driven by global climatic cooling. Pollen and spore assemblages suggest that the vegetation was dominated by mixed coniferous–broadleaved forest with some grasslands. New palynological elevation reconstructions constrained by the co-existence approach yield a maximum paleo-elevation of 3100–3600 m (average 3350 m) of the Lunpola Basin, which was consistent with a maximum elevation of 3400 m based on floating-leaf plants. Our new data do not support previous views that the Lunpola Basin achieved its current elevation as early as the late Eocene or early Oligocene, but instead we suggest there has been a rise of up to 1200 m since 12 million years ago. Our results bring new light on both the paleoenvironmental reconstructions and the paleo-elevation estimates of the Lunpola Basin, Central Tibet.

The oldest fossil record of Bauhinia s.s. (Fabaceae) from the Tibetan Plateau sheds light on its evolutionary and biogeographic implications

Bauhinia s.s. is a large genus in the family Fabaceae, but its evolutionary and biogeographical history is still unclear due to the scarcity of fossil records compared to the highly diverse modern species in pantropic regions. Here, we report the earliest fossil record of Bauhinia s.s., namely Bauhinia tibetensis Y. Gao et T. Su sp. nov., based on leaves from the latest Paleocene of the southern Tibetan region. Combined with palaeoecological niche simulations and ancestral state reconstruction, the new fossils suggested a Paleocene origin of Bauhinia s.s. in the Afrotropical realm that subsequently dispersed to the Neotropical and Indomalayan realms. Bauhinia tibetensis belongs to the Asian clade of Bauhinia s.s. that reached the southern Tibetan region from the Afrotropical realm via the Kohistan-Ladakh Island Arc in the early Paleocene. This clade spread to south-eastern China during the Oligocene and entered northern India during the Neogene or earlier. The discovery of the oldest Bauhinia s.s. from what is now the southern Tibetan Plateau updates our understanding of the biogeographical history of this genus and demonstrates that the Kohistan-Ladakh Island Arc is an ancient corridor for floristic interchange between Africa and India.

Regional variation in growth status: A cross-sectional survey among Tibetan adolescents living at three different high altitudes in Tibet, China.

To explore the regional and age variation in growth status and age-by-site interaction effect on the growth status among Chinese Tibetan adolescents at different altitudes in Tibet, China. The research was conducted in three regions of Tibet, China: Nyingchi (average altitude 3100 m), Lhasa (average altitude 3650 m), and Nagqu (average altitude 4500 m). A total of 3817 Chinese Tibetan adolescents aged 12-18 years were tested for height, weight, chest circumference, and waist circumference. One-way ANOVA was used to compare the growth status of Chinese Tibetan adolescents. Two-way ANOVA was used to explore the age-by-site interaction effect on the growth status of Chinese Tibetan adolescents. The height, weight, and chest circumference of Chinese Tibetan adolescents in Nagqu are the lowest among the three cities. Age and site have an interaction effect influence on the growth status of Chinese Tibetan adolescents (p < .01). The growth indicators (height, weight, chest circumference, WC) of Chinese Tibetan adolescents differed with altitudes. Policies to improve the growth status of Chinese Tibetan adolescents in Nagqu are urgently needed.

Quantitative Assessment of Spatial Pattern of Geodiversity in the Tibetan Plateau

Geodiversity is considered a new tool to exploit the resources of regional and local geotourism. Hitherto, few assessments of geodiversity have been conceived for huge geographic units. The spatial pattern of geodiversity in the Tibetan Plateau (TP) is the purpose of this study. A total of 96 abiotic units in six geo-groups of hydrology, pedology, landform, elevation, geology, and geosites were quantified and normalized to assess the geodiversity index. Geosites that represent interdisciplinary and specific abiotic elements are included as an independent component in the parameters of geodiversity assessment. The TP was divided into 1145 areas by fishnet, for counting of abiotic units, geodiversity calculation, and visualization of findings. The results indicated that the Pamir Plateau, Mt. Kunlun, the Delingha area, Mt. Qilian, the Xining area, Langmusi Town, Mt. Siguniang, Mt. Hengduan, the Nyainqentanglha Range, and the Lhasa area are the zones with very high geodiversity. The low geodiversity areas are mainly concentrated in the Qaidam Basin, the Qingnan Plateau, and the South Tibet region. In the TP, international tourist destinations such as UNESCO World Natural Heritage Sites and Global Geoparks, are developed in areas of high geodiversity. The spatial pattern of geodiversity could be indicative of geotourism potential, and be used to guide the development planning of geotourism in the TP. The quantitative assessment of geodiversity also provides a new parameter for geoconservation in China.

The polymorphic analysis of cox1 and cob genes of Echinococcus granulosus in the Ngari region of Tibet in China

Cystic echinococcosis (CE) is an important zoonotic parasitic disease caused by Echinococcus granulosus (E. granulosus). CE seriously threatens human health and the development of animal husbandry. The Ngari region is one of the world's highest endemic regions for CE, while genetic polymorphisms of E. granulosus were unclear. Paraffin slices of liver Cyst were collected from seventy-nine surgical patients with echinococcosis in the Ngari region. DNA was extracted from samples. The cox1 and cob genes of mitochondrial DNA of E. granulosus were simultaneously amplified and sequenced. The sequencing results were compared with the standard sequence (KU925397.1and HF947574.1). Phylogenetic trees and the haplotype network of cob and cox1 genes were constructed and analyzed genotypes of E. granulosus isolated from humans in the Ngari Region of Tibet. Out of 79 hydatid cyst samples collected from surgery patients, 60 isolates were identified as G1/ G3, and two isolates were identified as G6/ G7. Analysis of the cob/ cox1 genes revealed 9/7 mutations resulting in 8/6 haplotypes, respectively. The cob and cox1 neutrality indices computed by Tajima's D and Fu's Fs tests showed high negative values in Echinococcus granulosus sensu stricto (E. granulosus s. s.). The result suggested that E. granulosus in the Ngari region experienced population expansion or a negative selection. We found that G1/ G3 was still the main genotype, and G6/ G7 was found occasionally in humans of the Ngari region. Therefore, we recommend future surveys and control efforts to investigate G1/ G3 and G6/ G7 transmission in the Ngari region.

Field Study on Indoor Thermal Environments of Monastic Houses and Thermal Comfort of Monks.

Monastic houses are an essential part of the Tibetan monastic system in China. In this study, the monastic houses of Labrang in the Tibetan region of Gannan were used as the research objects. Physical parameters such as indoor temperature, humidity, and radiation temperature of the monastic houses were measured. The measured results were compared with the standard values, while the air temperature was linearly fitted using TSV, PMV, and aPMV. The results show that the temperature inside and outside the monastic houses fluctuates considerably; the theoretical thermal neutral temperature of the tested monks in winter is 22.46 °C, which is higher than the measured thermal neutral temperature in winter of 16.43 °C. When analyzing the results, it was found that the local climate, dress code, and the monks' specific habits all impact the perception of thermal comfort, which creates a discrepancy between the accurate results and the standard values. The above findings provide a more comprehensive reference for the thermal comfort requirements of the monks in cold areas, which can be used as a guide for the improvement and evaluation of the monastic houses in cold areas.

Study on Seismic Dynamic Response of Deep-Buried Tunnel Based on Tectonic Stress

The southeast region of Tibet in China is prone to earthquakes at high seismic levels. Since the construction of tunnels in this region faces a seismic hazard, it is necessary to explore the seismic responses of related construction areas there. In this study, a high-precision finite model of a mountain in a construction area was established based on a deep-buried tunnel in Southeast Tibet. Core specimens were obtained through on-site drilling, with the initial tectonic stress in the tunnel area measured by using the hydraulic fracturing method. Dynamic mechanical parameters of the rocks were acquired through in-situ testing. Moreover, indoor tests were conducted to obtain the physical and mechanical properties of the rocks. The tectonic stress, identified through multiple linear regression inversions, was used as the initial condition for dynamic calculation. The dynamic responses of the tunnel-engineering area under seismic action were calculated, followed by an analysis of the dynamic response characteristics. In addition to dramatic fluctuations in mountain topography, complex dynamic response characteristics of the mountain structure in earthquake environments were also revealed. Although the displacement time-history curve of each observation point displayed a consistent fluctuating pattern, the dynamic displacement extremes in different areas of the mountain varied significantly when the time arrived for their appearance. A maximum dynamic displacement of 0.53 m was observed at the observation point with the highest elevation (5,265.8 m). The acceleration amplification effect inside the mountain body was obvious, with the acceleration increasing as the elevation rose. The time for the occurrence of PGA (acceleration extreme) of each observation point in different directions differed substantially. The extreme value of dynamic stress along the tunnel axis conformed to the distribution pattern of the initial tectonic stress. Compared to the initial tectonic stress, the dynamic stress increased significantly at all observation points along the tunnel axis, with the dynamic stress increasing at a larger rate in the areas at a greater buried depth. Horizontal dynamic stress Sx at the maximum buried depth and Sy increased to 13.86 MPa and 10.32 MPa, respectively, and vertical dynamic stress Sz increased to 4.30 MPa. Variations in horizontal stress became more apparent as the elevation rose, in contrast to weakened variations in vertical stress as the elevation dropped. This study aims to explore the dynamic responses of mountains and the variation law of tectonic stress in deep-buried tunnels in earthquake environments in Tibet through qualitative analysis. The results revealed drastic changes in acceleration, dynamic displacement, and ground stress in the tunnel-engineering area. It is hoped that the contents of the study will contribute to the prevention and control of seismic geological hazards in the tunnel-engineering region and render technical support for the design and construction of similar projects in this region.

A demonstration concentrating solar power plant in China: Carbon neutrality, energy renewability and policy perspectives

Concentrating solar power (CSP) is considered as a promising renewable electricity source due to its superiority in providing dispatchable and base-load electricity. This study performs a systems process analysis to quantify the carbon emissions and nonrenewable energy costs induced by a state-of-art demonstration CSP plant located in the Tibetan plateau. Estimated to induce 111.2 g CO2 eq/kWh carbon emissions and 1.42 MJ/kWh non-renewable energy consumption, the CSP plant is considered to have extremely high carbon neutrality (88.8%) and energy renewability (86.4%). The prominent performance of carbon emissions reduction and energy conservation induced by the CSP plant shed light on its superiority of reliable power supply and environmental benefits. The plant is expected to cumulatively fulfill 3.4 million tons of carbon emissions reduction over its life cycle. In contrast to coal-based power and other renewable energy technologies, CSP technology is shown to be a promising solution to the low-carbon energy transition. Besides, a scenario analysis indicates that the incremental employment of CSP technologies will play a critical role in coping with climate change and energy security in China. Moreover, multiple policies to facilitate the development of the CSP system in China are elaborated, such as the promotion of integrated solar combined-cycle systems. The empirical finding draws a holistic picture of the carbon neutrality and energy sustainability performance of CSP technologies, and the systematic analysis in this study provides comprehensive policy perspectives for energy policy in the Tibetan region as well as in China in the context of global climate change.

Precipitation consistently promotes, but temperature inversely drives, biomass production in temperate vs. alpine grasslands

Comparisons of vegetation production between temperate and alpine grasslands are not well studied, and the understanding of the underlying mechanisms is still incomplete. To address this issue, we selected the Inner Mongolia and Tibet regions to conduct large-transect surveys for temperate grassland (TG) and alpine grassland (AG), respectively, in China, to reveal the universal and differential mechanisms of above- and belowground biomass production (GB, AGB and BGB) and precipitation use efficiencies (PUE) in the two grasslands. The relative importance of climatic factors on biomass and PUE is greater than that of soil and biological factors. Elevated mean annual precipitation (MAP) consistently increased GB in both TG and AG. Increased mean annual temperature (MAT) reduced GB by weakening the soil nutrient status in TG, whereas it increased GB by improving the soil nutrient status in AG. MAP promoted more AGB than BGB in TG, whereas MAT affected BGB more than AGB in AG. When the multicomponent heterogeneity of other factors in grasslands was eliminated, the effect of MAP on GB remained significant for both TG and AG. After removing the effect of multifactorial heterogeneity, however, the significant effect of MAP on PUE of the two grasslands was largely enhanced. From these results, we can conclude that climatic factors do not always exert identical effects on different grasslands. In particular, highlighting the divergent mechanisms of biomass production and precipitation use efficiency between temperate and alpine grasslands can improve the understanding of the carbon sink and hydraulic sensitivity of various grasslands.

Impact of Farmland Change on Vegetation NPP in the One River and Two Streams Region of Tibet

Studies on the impacts of a particular land use type change are relatively rare, especially in the Tibetan Plateau region (TP). This study focused on the impacts of farmland use change on grain supply and ecosystem stability in the Yarlung Zangbo river and its two tributaries (also known as One River and Two Streams, ORTS), using net primary productivity (NPP), known as the total amount of organic matter left after removal of carbon absorbed from the atmosphere by vegetation through photosynthesis, as a common proxy for farmland productivity and ecosystem stability. The trend analysis method was applied to measure the inter-annual change of NPP, and an ecological impact index was constructed to quantify the impact of farmland use change on the NPP change in the ORTS region. The results showed that: (1) The total area of farmland decreased by 6.09% from 2000 to 2018. Built-up land occupation and ecological restoration were the main reasons for the decrease of farmland area, while there was also new reclaimed farmland, transferred from ecological land. (2) The NPP in the ORTS region was roughly on an increasing trend, while the trends of NPP in different farmland change areas were not the same. Specifically, the NPP of ecological restoration, newly reclaimed farmland, and unchanged farmland areas all showed a significant increasing trend, while the NPP in the area of farmland occupied by built-up land showed a significant decreasing trend. (3) The impact of farmland changes from 2000 to 2018 contributed 1.22% to the increase of NPP in the ORTS region. This study not only provides a research paradigm in quantifying the production and ecological impacts of a particular land use type change that can be applied in related studies in other regions, but at the same time, the results of the empirical analysis in the ORTS region can also provide suggestions for the rational use and conservation of farmland and the stability and sustainable development of ecosystems for the region and even the TP.

Plutonic-subvolcanic connection of the Himalayan leucogranites: Insights from the Eocene Lhunze complex, southern Tibet

The Lhunze region of southeast Tibet uniquely juxtaposes Cenozoic granitic plutons with subvolcanic rocks in the Tethyan Himalayan Sequence. In this study, the potential petrogenetic connection between two-mica granite and subvolcanic rhyolite porphyry from the Lhunze area is investigated using petrology, geochronology, and geochemistry. Monazite Th Pb ages imply the two-mica granite crystallized during the mid-Eocene at c. 43.5–43.1 Ma, consistent with previous zircon U Pb isotope data. Monazite in the porphyry also records Th Pb ages of c. 44.5–42.9 Ma , suggesting contemporaneous emplacement with the two-mica granite. Porphyritic structure, feldspar aggregates and comb alignment demonstrate that the two-mica granite resulted from transient melt flow associated with melt extraction. Some plagioclase phenocrysts from the porphyry have consistent An contents with the two-mica granite, indicating that both the two-mica granite and the porphyry probably originated from a similar melt. However, the porphyry has a higher SiO 2 concentration (72.2–75.9 wt%) than the two-mica granite (69.0–73.0 wt%). In addition, the porphyry is characterized by lower TiO 2 , MgO, CaO, Ba, Sr, and Zr contents as well as Zr/Hf, Sr/Y, Nb/Ta ratios than the two-mica granite. Moreover, strontium and REE contents of monazite in both the two-mica granite and porphyry also imply that crystal fractionation dominated melt evolution. Whole-rock Sr Nd and in situ monazite Nd isotope compositions indicate that the porphyry is slightly more radiogenic than the two-mica granite, implying that the porphyry likely assimilated more ancient country rocks during its evolution. We interpret the two-mica granite and porphyry as comagmatic intrusives linked by fractional crystallization of a cognate magma mush, in which the crystals accumulated to form the two-mica granite, and the complementary high silicic melt segregated to form the porphyry. Plagioclase accumulation is responsible for the generation of the high Sr /Y adakitic geochemical feather within two-mica granite. The scenario of complementary melt extraction and crystal fractionation might also have been an important process in forming the Himalayan leucogranites. Regionally, Neo-Tethyan slab breakoff during the Eocene could have increased mantle heat flow and triggered the generation and extraction of large volumes of silicic melt. • Two-mica granite and subvolcanic rhyolite porphyry have a coeval crystallization age at 44–43 Ma . • Two-mica granite represents cumulate and the porphyry as its complementary highly fractionated melt. • Magma differentiation via melt extraction from crystal mush is an effective mechanism to produce Himalayan leucogranites.

Difference in soil water holding capacity and the influencing factors under different land use types in the alpine region of Tibet, China

To investigate the variation of soil water holding capacity under different land use types can provide scientific basis for evaluating the change characteristics and regulation mechanism of water conservation capacity in alpine ecosystems. We collected soil samples at different depth intervals (0-10, 10-20 and 20-30 cm) under three land use types (farmland, forest, and grassland) in Tibet alpine region to measure the maximum water holding capacity, capillary water holding capacity, field capacity, and basic soil physicochemical properties. The associated environmental factors (mean annual precipitation, normalized difference vegetation index, altitude, slope gradient and surface roughness) were extracted to analyze the change characteristics and influencing factors of soil water holding capacity under different land use types. The results showed that soil water holding capacity (the maximum water holding capacity, capillary water holding capacity, and field capacity) of farmland, forest, and grassland all decreased with increasing soil depth. The mean values of the maximum water holding capacity, capillary water holding capacity, and field capacity in the 0-30 cm soil layer of grassland were 379.79, 329.57 and 194.39 g·kg-1, respectively, which were significantly higher than that of farmland (301.15, 259.67, and 154.91 g·kg-1) and forest (293.09, 251.49, and 117.01 g·kg-1). Results of the redundancy analysis showed that soil properties significantly influenced soil water holding capacity, with explanation rate of 44.6%, 42.7%, 37.6% and 35.8% for total porosity, soil organic matter, capillary porosity and soil bulk density, respectively. Results of the principal component analysis showed that mean annual precipitation, normalized difference vegetation index, altitude, slope gradient, and surface roughness were the main environmental factors affecting the spatial variation of soil water holding capacity, with a cumulative contribution of 72.4%. The grassland in the alpine region of Tibet had the highest water holding capacity and could effectively prevent soil erosion. Therefore, the implementation of returning farmland to grassland and the enclosure management of degraded grassland would be conducive to improve soil water conservation capacity in the alpine regions.