Trophic niche and adaptation in highland lizards: sex has greater influences than species matching

The plateau environments are typically arid, cool, and high altitude, posing formidable challenges to wildlife survival due to resource scarcity and harsh conditions. Unraveling ecological adaptability in severe conditions requires a deeper understanding of the niche characteristics of plateau species. Trophic niche, which is a comprehensive indicator describing the energy acquisition strategy of animals, remains relatively understudied in plateau species. Here, by combining stable isotopes and morphological data, we quantified the trophic niches of two allopatric lizard species (Phrynocephalus vlangalii and P. erythrurus) that live in the hinterland of the Qinghai-Tibetan Plateau, and explored how their trophic niches correlate with morphological and environmental factors. While both trophic niche and morphological traits were similar between species, noteworthy distinctions were observed between male and female Phrynocephalus lizards. The morphological traits associated with predation (i.e. limb length and head size) and reproduction (i.e. abdomen length), annual mean temperature, and sex played influential roles in shifting trophic niches. These results imply that sexual dimorphism may facilitate inter-sex divergence in resource utilization, leading to trophic niche variations in the highland lizards. Furthermore, extreme environmental stress can constrain interspecific divergence in morphological and trophic traits. Our findings illustrate the dynamic variations of trophic niches in highland lizards, contributing to a more comprehensive understanding of the adaptation strategies employed by lizard species in plateau environments.

Soil phosphorus availability mediates the effects of nitrogen addition on community- and species-level phosphorus-acquisition strategies in alpine grasslands

Plants modulate their phosphorus (P) acquisition strategies (i.e., change in root morphology, exudate composition, and mycorrhizal symbiosis) to adapt to varying soil P availability. However, how community- and species-level P-acquisition strategies change in response to nitrogen (N) supply under different P levels remains unclear. To address this research gap, we conducted an 8-year fully factorial field experiment in an alpine grassland on the Qinghai-Tibet Plateau (QTP) combined with a 12-week glasshouse experiment with four treatments (N addition, P addition, combined N and P addition, and control). In the field experiment (community-level), when P availability was low, N addition increased the release of carboxylate from roots and led to a higher percentage of colonisation by arbuscular mycorrhizal fungi (AMF), along with decreased root length, specific root length (SRL), and total root length colonised by AMF. When P availability was higher, N addition resulted in an increase in the plant's demand for P, accompanied by an increase in root diameter and phosphatase activity. In the glasshouse experiment (species-level), the P-acquisition strategies of grasses and sedge in response to N addition alone mirrored those observed in the field, exhibiting a reduction in root length, SRL, and total root length colonised, but an increased percentage of AMF colonisation. Forbs responded to N addition alone with increased investment in all P-acquisition strategies, especially increased root biomass and length. P-acquisition strategies showed consistent changes among all species in response to combined N and P addition. Our results suggest that increased carboxylate release and AMF colonisation rate are common P-acquisition strategies of plants in alpine grasslands under N-induced P limitation. The main difference in P-acquisition strategies between forbs and grasses/sedges in response to N addition under low-P conditions was an increase in root biomass and length.

Taxonomic Reinstatement of the Endemic Chinese Species Iris thoroldii (Iridaceae) from I. potaninii and Reassessment of I. zhaoana

Iris thoroldii is a perennial herbaceous plant with yellow, blue, or purple flowers. The species is native to the Tibetan Plateau and adjacent areas. In the literature and databases, I. thoroldii has long been treated in synonymy with I. potaninii. Currently, yellow-flowered plants of I. thoroldii are considered I. potanii, and blue-flowered plants are considered I. zhaoana, a replacement name for I. potaninii var. ionantha. This study aimed to clarify the taxonomic identity of I. thoroldii. A critical examination of original material, herbarium specimens, images of living plants, and the literature has shown I. thoroldii to be different from I. potaninii in some previously neglected macromorphological traits and to be conspecific with I. zhaoana. Thus, I. thoroldii is removed here from the synonymy of I. potaninii and accepted as a distinct species. This is endemic to China (central Gansu, Qinghai, and northwestern Sichuan provinces, and also Xinjiang Uygur and Tibet autonomous regions) and reaches the highest elevations compared with all other species in the genus Iris s.l. A revised taxonomy of I. thoroldii is provided, and two color forms, often co-occurring, are accepted: the autonymic yellow-flowered form (including a new synonym I. tigridia var. flavescens for which a lectotype was designated) and a form with blue or purple colors is proposed here, I. thoroldii f. ionantha. In addition, images of type specimens and detailed photographs of living plants for easy identification, along with the list of specimens of I. thoroldii that were examined, and also, comments on its distribution and habitats are provided.

Blood Service in a Region of China's Qinghai-Tibetan Plateau

Objectives: The purpose of this paper is to describe blood services in the Aba Tibetan and Qiang Regions, (hereinafter referred to as Aba Prefecture), a region of China's Qinghai-Tibetan Plateau, the third largest area of Tibet and the main inhabited area of the Qiang people. Design: We present a comprehensive investigation into blood donations, donors, screening and supply in the 13 counties of Aba Prefecture based on data from 2013 to 2018. Geography and population were also used to analyze the differences in blood services among different regions. Participants: The number of blood donors totaled 19,047. Results: Over the past 6 years, blood donations have increased by 29 and clinical blood usage by 45%. The blood donation rate was 3.4‱ and per capita blood use was 1.04 mL, both of which were significantly lower than the national average, and blood donation decreased with altitude. It should be noted that the donation rate of the Tibetan and Qiang peoples is much lower than that of the Han population. Moreover, the rejection rate of blood in laboratory testing was found to be higher than the national average, especially in counties located at higher altitudes. Conclusions: Blood donations and usage increased every year in Aba Prefecture, but blood shortage is still an important issue. In addition, the prevalence of transfusion-transmitted diseases is relatively high, which may be linked to lower-education and unfavorable geographical and medical conditions.

Spatial-temporal evolution of production-living-ecological space and layout optimization strategy in eco-sensitive areas: a case study of typical area on the Qinghai-Tibetan Plateau, China

To achieve sustainable development goals and to solve environmental problems, land resources in eco-sensitive areas should be used and optimized. Qinghai, which is an important eco-sensitive area in China, represents a typical ecological vulnerable region on the Qinghai-Tibetan Plateau. Using land use/cover data for 2000, 2010 and 2020, this study applied a series of quantitative methods to analyze the spatial pattern and structure of the production-living-ecological space (PLES) in Qinghai. The results indicated that the spatial pattern of the PLES in Qinghai was stable over time, but the spatial distribution was very different. The structure of the PLES in Qinghai was stable, and the proportion of each space from high to low was ecological (81.01%), production (18.13%) and living (0.86%). We found that the proportion of ecological space in both the Qilian Mountains and the Three River Headwaters Region was lower than the rest of the study area, except for the Yellow River-Huangshui River Valley. Our study objectively and credibly presented the characteristics of the PLES in an important eco-sensitive area in China. This study further formulated targeted policy suggestions to provide a basis for regional sustainable development, ecological environment protection, and land and space optimization in Qinghai.

Impacts of human pressure and climate on biodiversity-multifunctionality relationships on the Qinghai-Tibetan Plateau

Many studies have investigated the effects of environmental context on biodiversity or multifunctionality in alpine regions, but it is uncertain how human pressure and climate may affect their relationships. Here, we combined the comparative map profile method with multivariate datasets to assess the spatial pattern of ecosystem multifunctionality and further identify the effects of human pressure and climate on the spatial distribution of biodiversity-multifunctionality relationships in alpine ecosystems of the Qinghai-Tibetan Plateau (QTP). Our results indicate that at least 93% of the areas in the study region show a positive correlation between biodiversity and ecosystem multifunctionality across the QTP. Biodiversity-multifunctionality relationships with increasing human pressure show a decreasing trend in the forest, alpine meadow, and alpine steppe ecosystems, while an opposite pattern was found in the alpine desert steppe ecosystem. More importantly, aridity significantly strengthened the synergistic relationship between biodiversity and ecosystem multifunctionality in forest and alpine meadow ecosystems. Taken together, our results provide insights into the importance of protecting and maintaining biodiversity and ecosystem multifunctionality in response to climate change and human pressure in the alpine region.

Gradual genome size evolution and polyploidy in Allium from the Qinghai-Tibetan Plateau

BACKGROUND AND AIMS

Genome size is an important plant trait, with substantial interspecies variation. The mechanisms and selective pressures underlying genome size evolution are important topics in evolutionary biology. There is considerable diversity in Allium from the Qinghai-Tibetan Plateau, where genome size variation and related evolutionary mechanisms are poorly understood.

METHODS

We reconstructed the Allium phylogeny using DNA sequences from 71 species. We also estimated genome sizes of 62 species, and determined chromosome numbers in 65 species. We examined the phylogenetic signal associated with genome size variation, and tested how well the data fit different evolutionary models. Correlations between genome size variations and seed mass, altitude and 19 bioclimatic factors were determined.

KEY RESULTS

Allium genome sizes differed substantially between species and within diploids, triploids, tetraploids, hexaploids and octaploids. Size per monoploid genome (1Cx) tended to decrease with increasing ploidy levels. Allium polyploids tended to grow at a higher altitude than diploids. The phylogenetic tree was divided into three evolutionary branches. The genomes in Clade I were mostly close to the ancestral genome (18.781 pg) while those in Clades II and III tended to expand and contract, respectively. A weak phylogenetic signal was detected for Allium genome size. Furthermore, significant positive correlations were detected between genome size and seed mass, as well as between genome size and altitude. However, genome size was not correlated with 19 bioclimatic variables.

CONCLUSIONS

Allium genome size shows gradual evolution, followed by subsequent adaptive radiation. The three well-supported Allium clades are consistent with previous studies. The evolutionary patterns in different Allium clades revealed genome contraction, expansion and relative stasis. The Allium species in Clade II may follow adaptive radiation. The genome contraction in Clade III may be due to DNA loss after polyploidization. Allium genome size might be influenced by selective pressure due to the conditions on the Qinghai-Tibetan Plateau (low temperature, high UV irradiation and abundant phosphate in the soil).

Plant-Soil Mediated Effects of Long-Term Warming on Soil Nematodes of Alpine Meadows on the Qinghai-Tibetan Plateau

Global warming is one of the most pressing environmental issues today. Our study aimed to investigate how warming affected plant and soil nematode communities in alpine meadows on the Qinghai−Tibetan Plateau over the past seven years. An artificial warming experiment with different gradients was conducted from 2011 to 2018, including temperature increases of 0 °C (CK), 0.53 °C (A), 1.15 °C (B), 2.07 °C (C), and 2.17 °C (D), respectively. Cyperaceae plants were shown to be eliminated by increasing temperature, and plant community composition tended to cluster differently under different warming gradients. The number of nematodes decreased with the increase in soil depth, and the majority of them were observed in the topsoil layer. The individual densities of soil nematodes were 197 ind.·100 g−1 dry soil at 10−20 cm and 188 ind.·100 g−1 dry soil at 20−30 cm in the A treatment, which was significantly higher than the CK (53 and 67 ind.·100 g−1 dry soil) (p < 0.05). The lowest relative abundance of bacterivore nematodes (Ba) was 31.31% in treatment A and reached the highest of 47.14% under the warming gradient of D (p < 0.05). The abundance of plant parasitic nematodes (Pp) was significantly reduced to 26.03% by excessive warming (2.17 °C increase) in comparison to CK (41.65%). The soil nematode community had the highest diversity with a 0.53 °C increase in soil temperature; 1.15 °C warming gradients were lower, and nematode communities tended to be simplified (p < 0.05). All nematode channel ratio (NCR) values were above 0.5, indicating that warming did not change the decomposition pathway of soil organic matter dominated by the bacterial channels. The Wasilewska Index (WI) in the D treatment increased significantly compared to other treatments (p < 0.05), indicating that the mineralized pathway of the food web was primarily involved with Ba and fungivores nematodes (Fu), which is conducive to the growth of micro-biophagous nematodes. The plant parasite index (PPI) decreased significantly in the D treatment compared with other treatments (p < 0.05), indicating that a high warming gradient caused a reduction in the maturity of Pp nematodes. The maturity index (MI) increased in the D treatment compared with A, B, and C treatments, indicating that overheating affected the nematode community in the later stage of succession and caused the soil to be less disturbed. A partial least squares path model (PLSPM) showed that warming indirectly affects Fu and Pp diversity by directly impacting the plant community as well as indirectly affecting Ba by directly affecting soil properties. In conclusion, plant diversity and community composition profoundly affect the soil nematode communities, thus reflecting the dynamic processes and evolution of soil ecosystems.

Serological Analysis of IgG and IgM Antibodies against Anaplasma spp. in Various Animal Species of the Qinghai-Tibetan Plateau

Anaplasma genus infects the blood cells of humans and animals by biting, causing zoonotic anaplasmosis. However, limited data are available on carrier animals for Anaplasma spp. antibodies in the Qinghai−Tibetan Plateau Area. Therefore, a serological indirect ELISA diagnostic method based on the major surface protein 5 (MSP5), derived from Anaplasma phagocytophilum, was developed in this study to analyze both IgG and IgM antibodies of Anaplasma spp. in a total of 3952 animals from the Qinghai−Tibetan Plateau, including yaks (Bos grunniens), cows (Bos taurus), cattle (Bos taurus domesticus), Tibetan sheep (Ovis aries), horses (Equus ferus caballus), pigs (Sus domesticus), chickens (Gallus gallus domesticus), donkeys (Equus asinus), stray dogs (Canis sp.), and stray cats (Felis sp.). The results showed that recombinant MSP5 protein was expressed and was successfully used to establish the indirect ELISA methods. The overall positivity for Anaplasma IgG and IgM antibodies was 14.6% (578/3952) and 7.9% (312/3952), respectively, and a total of 123 animals (3.1%) were both IgG- and IgM-positive. Moreover, the most prevalent Anaplasma IgG positivity was exhibited by donkeys (82.5%), followed by stray dogs, Tibetan sheep, pigs, chickens, horses, yaks, cows, cattle, and stray cats. The analysis for IgM antibody positivity revealed that IgM positivity was the most prevalent in the stray dogs (30.1%), followed by horses, yaks, Tibetan sheep, cows, stray cats, and cattle. Moreover, the results revealed significant differences (p < 0.05) at different altitudes in Anaplasma-specific IgG in the yaks, Tibetan sheep, and horses, and in IgM in the yaks and Tibetan sheep. In conclusion, this study is the first to demonstrate that yaks, cows, cattle, Tibetan sheep, horses, donkeys, stray dogs, stray cats, pigs, and chickens living in the Qinghai−Tibet Plateau are carrier animals for Anaplasma spp. IgG or IgM antibodies. The current findings provide valuable current data on the seroepidemiology of anaplasmosis in China and for plateau areas of the world.

Temperature sensitivity of soil enzyme kinetics under N and P fertilization in an alpine grassland, China

Soil nutrient cycling can be best studied by supplementing the soil with N and P fertilizers. Soil enzyme kinetic parameters (Vmax and Km) can be used to reflect the maximum reaction rates and affinities of soil enzymes. However, how N and P fertilizers affect the temperature sensitivity of soil enzyme kinetics is poorly understood. Therefore, our study investigated the response of soil enzyme kinetic temperature sensitivity relevant to C, N, and P cycles based on a 9-year fertilization (N and P) experiment performed in an alpine grassland on the Qinghai-Tibetan Plateau in China. Our results showed the following: N and P addition positively affected the Km of β-glucosidase (BG); P and NP interaction significantly increased the Km of phosphatase (AP), indicating that N and P addition significantly negatively affected the substrate affinity of soil enzymes. The temperature sensitivity of Michaelis-Menten kinetics was different for different enzymes. N and P fertilization decreased the temperature sensitivity of Km of BG but increased the temperature sensitivity of the Km of N-acetyl-glucosaminidase (NAG) and AP. In our study, P and NP fertilization increased the temperature sensitivity and activation energy of the Vmax of BG, indicating that P elements promoted the secretion of more extracellular enzymes by soil microbes to cope with temperature changes. The enzymes involved in the soil N and P cycle responded to the exogenous N and P through increases and decreases in the temperature sensitivity of the Km and Vmax, respectively. This study is crucial for investigating the impact of nutrient input on soil ecosystem functions under future climate warming conditions.

Vegetation History and Survival Patterns of the Earliest Village on the Qinghai-Tibetan Plateau

The upper Yellow River valley in the northeastern Qinghai-Tibetan Plateau (QTP) is an important corridor for prehistoric migration to the hinterland plateau. However, most studies have focused on the Neolithic Age, with limited evidence for earlier periods. The Shalongka (SLK) site on the northeastern QTP spans the Epipaleolithic to Bronze Age and contains cultural deposits, so provides a good basis for unraveling the evolutionary history of the human-land relationship. In this study, we sampled the 420-cm-thick section T1406E at the SLK site and undertook lithologic stratigraphic description and analysis of grain size, redness, magnetic susceptibility, geochemical elements, pollen and charcoal. Dating control was provided by accelerated mass spectrometry 14C and optically stimulated luminescence methods. Results show that SLK site was affected by the local fluvial sedimentary environment. The absolute dating results of the SLK site have revealed that humans occupied the site during the Epipaleolithic (8.5-7.3 cal ka BP), Yangshao culture (5.9-5.1 ka) and Qijia Culture (4.1-3.9 cal ka BP). Pollen analysis showed that the humans lived in a landscape that was predominated by forest-steppe. Consolidating with multidisciplinary evidence, we learned that Epipaleolithic sites were occupied by microlithic hunter-gatherers and comprised by relatively fixed seasonal central campsites, and their mobility was significantly decreased from the early to late period. Subsequently, farmers of the Yangshao culture migrated from the low elevation (Chinese Loess Plateau) to the upper Yellow River valleys on the QTP and founded the earliest settlement villages (~5.9 ka) on the QTP. People of the Qijia culture adopted diversified survival strategies under the settled lifestyle. In all, we infered that SLK site may play an important role in the communication and integration between different people and cultures.

The Potential Roles of Unique Leaf Structure for the Adaptation of Rheum tanguticum Maxim. ex Balf. in Qinghai-Tibetan Plateau

Leaves are essential plant organs with numerous variations in shape and size. The leaf size is generally smaller in plants that thrive in areas of higher elevation and lower annual mean temperature. The Qinghai-Tibetan Plateau is situated at an altitude of >4000 m with relatively low annual average temperatures. Most plant species found on the Qinghai-Tibetan Plateau have small leaves, with Rheum tanguticum Maxim. ex Balf. being an exception. Here, we show that the large leaves of R. tanguticum with a unique three-dimensional (3D) shape are potentially an ideal solution for thermoregulation with little energy consumption. With the increase in age, the shape of R. tanguticum leaves changed from a small oval plane to a large palmatipartite 3D shape. Therefore, R. tanguticum is a highly heteroblastic species. The leaf shape change during the transition from the juvenile to the adult phase of the development in R. tanguticum is a striking example of the manifestation of plant phenotypic plasticity. The temperature variation in different parts of the leaf was a distinct character of leaves of over-5-year-old plants. The temperature of single-plane leaves under strong solar radiation could accumulate heat rapidly and resulted in temperatures much higher than the ambient temperature. However, leaves of over-5-year-old plants could lower leaf temperature by avoiding direct exposure to solar radiation and promoting local airflow to prevent serious tissue damage by sunburn. Furthermore, the net photosynthesis rate was correlated with the heterogeneity of the leaf surface temperature. Our results demonstrate that the robust 3D shape of the leaf is a strategy that R. tanguticum has developed evolutionarily to adapt to the strong solar radiation and low temperature on the Qinghai-Tibetan Plateau.

Community Composition and Structure Affect Ecosystem and Canopy Water Use Efficiency Across Three Typical Alpine Ecosystems

Unique ecosystems distributed in alpine areas of the Qinghai-Tibetan Plateau play important roles in climate change mitigation, local food supply, and conservation of species diversity. To understand the water use efficiency (WUE) of this fragile and sensitive region, this study combined observed data from the eddy covariance system and the Shuttleworth-Wallace (S-W) model to measure the continuous mass exchange, including gross primary productivity (GPP), evapotranspiration (ET), and canopy transpiration (T) throughout 2 or 3 years (2016-2018) in three common alpine ecosystems (i.e., alpine steppe, alpine meadow, and alpine swamp). These ecosystems represent a water availability gradient and thus provide the opportunity to quantify environmental and biological controls on WUE at various spatiotemporal scales. We analyzed the ecosystem WUE (WUEe; defined as the ratio of GPP to ET) and canopy WUE (WUEc; defined as the ratio of GPP and canopy T). It was found that the yearly WUEe was 1.40, 1.63, and 2.16 g C kg-1 H2O, and the yearly WUEc was 8.93, 2.46, and 5.19 g C kg-1 H2O in the three typical ecosystems, respectively. The controlling factors of yearly WUE diverged between WUEe and WUEc. We found that plant functional group proportion (e.g., gramineous and Cyperaceae) highly explained the yearly WUEe variation across sites, and a good correlation was observed between community species diversity and WUEc. These findings suggest that community composition and trait change are critical in regulating WUEe and WUEc across different alpine ecosystems and that the regulation mechanisms may differ fundamentally between WUEe and WUEc.

How do Snow Partridge (Lerwa lerwa) and Tibetan Snowcock (Tetraogallus tibetanus) coexist in sympatry under high-elevation conditions on the Qinghai-Tibetan Plateau?

The Qinghai-Tibetan Plateau (QTP) has the highest elevations of all biodiversity hotspots. Difficulties involved in fieldwork at high elevations cause challenges in researching mechanisms facilitating species coexistence. Herein, we investigated Snow Partridge (Lerwa lerwa) and Tibetan Snowcock (Tetraogallus tibetanus), the only two endemic Galliformes on the QTP, to understand species coexistence patterns and determine how they live in sympatry for the first time. We assembled occurrence data, estimated habitat suitability differences and the underlying factors between two species at different scales using ecological niche models. Niche overlap tests were used to investigate whether niche differences between these species allow for their coexistence. We found that elevation was the most important factor determining habitat suitability for both species. At the meso-scale, two species have similar ecological niches with their suitable habitats lying predominantly along ridge crests. However, ridge crests were more influential for habitat suitability by L. lerwa than for that of T. tibetanus because the latter species ranges further afield than ridge crests. Thus, differences in habitat suitability between these species lead to habitat partitioning, which allows stable coexistence. At the macro-scale, temperature and precipitation were major factors influencing habitat suitability differences between these species. Tetraogallus tibetanus extended into the hinterland of the QTP and occurred at higher elevations, where colder and drier alpine conditions are commonplace. Conversely, L. lerwa occurred along the southeastern margin of the QTP with a lower snow line, an area prone to rainy and humid habitats. Niche overlap analysis showed that habitat suitability differences between these species are not driven by niche differentiation. We concluded that the coexistence of these two pheasants under high-elevation conditions could be an adaption to different alpine conditions.

Plastome sequencing reveals phylogenetic relationships among Comastoma and related taxa (Gentianaceae) from the Qinghai-Tibetan Plateau

Genus Comastoma (subt. Swertiinae, Gentianaceae) contains species, such as "Zangyinchen," that are important herbs in Tibetan medicine. The phylogenetic relationship of this within Gentianaceae and the circumscriptions of its species have long been controversial with conflicting morphological and molecular data reported. Here, we used whole chloroplast genome sequences for Comastoma species and related taxa to reconstruct their phylogeny and clarify their taxonomic relationships. The results revealed that the length of all plastome sequenced varied from 149 to 151 kb and have high similarity in structure and gene content. Phylogenomic analysis showed that Comastoma is a monophyletic group, closely related to the genus Lomatogonium. The divergence time estimation showed that Gentianaceae diverged at about 21.81 Ma, while the split of Comastoma occurred at 7.70 Ma. However, the results suggested the crown age of species formation in this genus is after 4.19 Ma. Our results suggest that QTP uplift, the alternation of Quaternary glaciation and interglaciation, and monsoon changes might have acted as drivers of speciation in Comastoma.

Nitrogen addition, rather than altered precipitation, stimulates nitrous oxide emissions in an alpine steppe

Anthropogenic-driven global change, including changes in atmospheric nitrogen (N) deposition and precipitation patterns, is dramatically altering N cycling in soil. How long-term N deposition, precipitation changes, and their interaction influence nitrous oxide (N2O) emissions remains unknown, especially in the alpine steppes of the Qinghai-Tibetan Plateau (QTP). To fill this knowledge gap, a platform of N addition (10 g m-2 year-1) and altered precipitation (±50% precipitation) experiments was established in an alpine steppe of the QTP in 2013. Long-term N addition significantly increased N2O emissions. However, neither long-term alterations in precipitation nor the co-occurrence of N addition and altered precipitation significantly affected N2O emissions. These unexpected findings indicate that N2O emissions are particularly susceptible to N deposition in the alpine steppes. Our results further indicated that both biotic and abiotic properties had significant effects on N2O emissions. N2O emissions occurred mainly due to nitrification, which was dominated by ammonia-oxidizing bacteria, rather than ammonia-oxidizing archaea. Furthermore, the alterations in belowground biomass and soil temperature induced by N addition modulated N2O emissions. Overall, this study provides pivotal insights to aid the prediction of future responses of N2O emissions to long-term N deposition and precipitation changes in alpine ecosystems. The underlying microbial pathway and key predictors of N2O emissions identified in this study may also be used for future global-scale model studies.

Ecogeographical Adaptation Revisited: Morphological Variations in the Plateau Brown Frog along an Elevation Gradient on the Qinghai-Tibetan Plateau

Simple Summary

A number of studies have explored how the body size and extremities of frogs vary in response to the changing environmental conditions across different geographical gradients, but the outcomes remain controversial. Here, we studied the morphological variations of the plateau brown frog (Rana kukunoris) along an elevation gradient (~1800–3500 m) on the eastern margin of the Qinghai–Tibetan Plateau to understand how environmental and biological factors affect them, and to assess whether these variations help to improve thermoregulation. Although we found that male and female frogs showed different variations in body size and extremities along the elevational gradient, both of them showed a significant decrease in the ratio of extremities to body size with increasing elevation. The decreasing ratio implies a gain of thermoregulatory benefits based on the ecogeographical rules. Moreover, the morphological variations were found to be strongly related to both environmental and biological factors. These results suggest that ecogeographical adaptation in frogs may be more complicated than other terrestrial vertebrate species. Most importantly, the adaptation should be viewed as a result of both environmental and biological factors, while it may also appear as an interactive change between body size and extremities.

Abstract

Several anurans have broad elevational and latitudinal distribution ranges; distinct species and populations may face various environmental and selection stresses. Due to their environmental sensitivity, adaptation is critical for the long-term persistence of anurans. Previous studies have tried to identify the ecogeographical pattern and its mechanism in anurans, suggesting different patterns, but the related explanatory mechanisms are yet to be generally supported and are suggested to be complicated. To explore the elusive mechanisms, we studied the morphological variation of the plateau brown frog (Rana kukunoris) along an elevational gradient on the eastern margin of the Qinghai–Tibetan Plateau. Using body size, extremity length, and the ratio between them (extremities/body size) as testing indicators, we examined potential ecogeographical adaptations and investigated how environmental and biological factors could shape the morphological development in R. kukunoris. We found that males and females showed different variations in body size and extremities along the elevational gradient, whereas both of them showed a decreasing extremities/body size ratio along elevation. Together with the strong correlations between environmental and biological factors and the morphometrics, we identified ecogeographical adaptation and a sexual difference in the selective pressures on the extremities and body size of the plateau brown frog. Our results imply that geographic variations in anuran morphological traits should be understood as an outcome of environmental and biological factors. Furthermore, ecogeographical adaptation in anurans can manifest as an interactive change between body size and extremities.

Dorsal Pigmentation and Its Association with Functional Variation in MC1R in a Lizard from Different Elevations on the Qinghai-Tibetan Plateau

Identification of the role of the MC1R gene has provided major insights into variation in skin pigmentation in several organisms, including humans, but the evolutionary genetics of this variation is less well established. Variation in this gene and its relationship with degree of melanism was analyzed in one of the world’s highest-elevation lizards, Phrynocephalus theobaldi from the Qinghai–Tibetan Plateau. Individuals from the low-elevation group were shown to have darker dorsal pigmentation than individuals from a high-elevation group. The existence of climatic variation across these elevations was quantified, with lower elevations exhibiting higher air pressure, temperatures, and humidity, but less wind and insolation. Analysis of the MC1R gene in 214 individuals revealed amino acid differences at five sites between intraspecific sister lineages from different elevations, with two sites showing distinct fixed residues at low elevations. Three of the four single-nucleotide polymorphisms that underpinned these amino acid differences were highly significant outliers, relative to the generalized MC1R population structuring, suggestive of selection. Transfection of cells with an MC1R allele from a lighter high-elevation population caused a 43% reduction in agonist-induced cyclic AMP accumulation, and hence lowered melanin synthesis, relative to transfection with an allele from a darker low-elevation population. The high-elevation allele led to less efficient integration of the MC1R protein into melanocyte membranes. Our study identifies variation in the degree of melanism that can be explained by four or fewer MC1R substitutions. We establish a functional link between these substitutions and melanin synthesis and demonstrate elevation-associated shifts in their frequencies.

Bacterial community changes and their responses to nitrogen addition among different alpine grassland types at the eastern edge of Qinghai-Tibetan Plateau

Soil microbes play a fundamental role in maintaining nutrient biogeochemical cycles. To understand the distribution of soil bacterial communities on grassland plateaus, high-throughput sequencing was used to compare bacterial communities in soils from swamp meadows (SM), alpine meadows (AM), alpine steppes (AS), and desert steppes (DS) at the eastern edge of the Qinghai-Tibetan Plateau (QTP) in China. We then compared response to nitrogen addition between SM and DS soils in microcosms. Bacterial α-diversity decreased from SM > AM > AS > DS. Variations in soil properties across grassland types was associated with different soil bacterial communities corresponding to bacterial species associated with nutrient cycles to those associated with degradation. Soil moisture, pH, and total phosphorus were the main drivers of these differences. Nitrogen addition decreased bacterial diversity but had inconsistent effects on soil bacterial communities in SM and DS, which may also indicate that different alpine grassland soil types have unique bacterial communities. Alpine grassland degradation significantly affects bacterial communities, and the response to nitrogen addition depends on the alpine grassland type. These results allow for better predictions of soil bacteria community-level responses to geochemical and environmental change in alpine areas.

Bacterial Community Characteristics in the Gastrointestinal Tract of Yak (Bos grunniens) Fully Grazed on Pasture of the Qinghai-Tibetan Plateau of China

Simple Summary

The Qinghai–Tibetan plateau is considered as the third Pole of the world and is characterized by low oxygen, high altitude, extreme cold weather and strong ultraviolet radiation. Yak, as the main domestic animals raised on the plateau, play various roles in local herdsmen’s lives by supplying necessities such as meat, milk and fuel. Yak are adapted to the harsh environment on the plateau; microbiota in gut equip the hosts with special abilities including adaptability, as illustrated by numerous research projects. Accordingly, the microbes in the gastrointestinal tract of yak must be characteristically profiled as a strategy to adapt to the environment. However, little is known about the microbial community in whole tract of yak; almost all of reported researches focused on rumen. Therefore, in the current study the bacterial community in the gastrointestinal tract of yak was explored using 16S rDNA amplicon sequencing technology, and the community profiling characteristic in each section was clearly elucidated.

Abstract

In the current research, samples of yak gastrointestinal tracts (GITs) were used to profile the bacterial compositional characteristics using high through-put sequencing technology of 16S RNA amplicon. A total of 6959 OTUs was obtained from 20,799,614 effective tags, among which 751 OTUs were shared by ten sections. A total of 16 known phyla were obtained in all samples—the most abundant phyla were Firmicutes (34.58%), Bacteroidetes (33.96%) and Verrucomicrobia (11.70%). At the genus level, a total of 66 genera were obtained—Rikenellaceae_RC9_gut_group (7.24%), Akkermansia (6.32%) and Ruminococcaceae_UCG-005 (6.14%) were the most abundant. Species of Observed (Sob), Shannon and Chao values of the Stomach were the greatest, followed by the large intestine, while small intestine had the lowest diversity (p < 0.05). Bacteroidete were more abundant in sections from rumen to duodenum; while Firmicutes were the most abundant in sections from jejunum. ABC transporters (7.82%), Aminoacyl-tRNA biosynthesis (4.85%) and Purine metabolism (3.77%) were the most abundant level-3 pathways in all samples. The results of associated correlation analysis indicated that rectum samples might be used as an estimator of rumen bacterial communities and fermentation. The results of this research enrich the current knowledge about the unique animals of the QTP and extend our insight into GITs microecology of various animals.

Seroprevalence and associated risk factors of Toxoplasma gondii infection in yaks (Bos grunniens) on the Qinghai-Tibetan Plateau of China

Toxoplasma gondii is an intracellular parasite that is extensively prevalent globally. Studies have indicated the presence of T. gondii infection in animals in some provinces of China, but little is known about T. gondii infection in yaks (Bos grunniens) on the Qinghai-Tibetan Plateau. In the current study, to determine the seroprevalence and associated risk factors of T. gondii, a total of 2784 serum samples were collected from 18 different sampling sites in eight counties of the Qinghai and Tibet regions of China from 2018 to 2019. Serum antibodies against T. gondii were detected in 261 yaks (9.38%) via enzyme-linked immunosorbent assay (ELISA). We found that seroprevalence differed significantly among different counties (ranging from 5.41% in Gangcha to 19.79% in Datong), by year in the Tibet Autonomous Region (from 2.34% in 2018 to 13.24% in 2019), and by age (from 5.59% in 0 < year ≤ 1 to 11.76% in year > 7) (p < 0.05). Climate, geographical conditions, and age are the main factors influencing T. gondii infection in yaks in these regions. Therefore, our study provides a data reference for public health and prevention of yak toxoplasmosis.

Comparing the Bacterial Community in the Gastrointestinal Tracts Between Growth-Retarded and Normal Yaks on the Qinghai-Tibetan Plateau

In ruminants, the bacterial community in the gastrointestinal tract (GIT) has an essential role in healthy growth. Examining the bacterial composition in the GIT between growth-retarded and normal yaks could improve our understanding of the role of microorganisms in yaks with growth retardation. In this study, eight male yaks with growth retardation were used as the growth-retarded yak (GRY) group, and another eight male growth normal yaks (GNYs) with the same breed and age were used as the GNY group. We compared the bacterial community in the rumen, duodenum, jejunum, ileum, cecum, and colon between GRY and GNY groups based on the 16S ribosomal RNA gene sequencing. Alpha-diversity revealed that the Shannon index in the duodenum and ileum of the GNY group was higher (P < 0.05) than that of the GRY group. However, the opposite trend was found in the jejunum and cecum. The principal coordinates analysis (PCoA) showed that the bacterial structure in all segments of GIT differed from each other between two groups. In the rumen, the relative abundances of Ruminococcaceae NK4A214 group, Ruminococcaceae UCG-014, and Treponema 2 were higher (P < 0.05) in the GNY group as compared with the GRY group. However, the Christensenellaceae R-7 group exhibited an opposite trend. In the jejunum, compared with the GNY group, the unclassified Chitinophagaceae was enriched significantly (P < 0.05) in the GRY group. However, the unclassified Peptostreptococcaceae, Christensenellaceae R-7 group, and Lachnospiraceae NK3A20 group were enriched (P < 0.05) in the GNY group. In the ileum, the relative abundances of the Rikenellaceae RC9 gut group and Prevotellaceae UCG-004 were higher (P < 0.05) in the GNY group than those in the GRY group. In the cecum, the GNY group showed a higher (P < 0.05) relative abundance of Prevotellaceae UCG-003 as compared with the GRY group. In the colon, the relative abundances of Treponema 2 and unclassified Lachnospiraceae were slightly higher (0.05 < P < 0.10) in the GNY group than those in the GRY group. Overall, these results improve our knowledge about the bacterial composition in the GIT of growth-retarded and normal yaks, and regulating the bacterial community may be an effective solution to promote the compensatory growth of GRYs.

Active Methanotrophs in Suboxic Alpine Swamp Soils of the Qinghai-Tibetan Plateau

Methanotrophs are the only biofilters for reducing the flux of global methane (CH4) emissions in water-logged wetlands. However, adaptation of aerobic methanotrophs to low concentrations of oxygen and nitrogen in typical swamps, such as that of the Qinghai-Tibetan Plateau, is poorly understood. In this study, we show that Methylobacter-like methanotrophs dominate methane oxidation and nitrogen fixation under suboxic conditions in alpine swamp soils. Following incubation with 13C-CH4 and 15N-N2 for 90 days under suboxic conditions with repeated flushing using an inert gas (i.e., argon), microbial carbon and nitrogen turnover was measured in swamp soils at different depths: 0-20 cm (top), 40-60 cm (intermediate), and 60-80 cm (deep). Results show detectable methane oxidation and nitrogen fixation in all three soil depths. In particular, labeled carbon was found in CO2 enrichment (13C-CO2), and soil organic carbon (13C-SOC), whereas labeled nitrogen (15N) was detected in soil organic nitrogen (SON). The highest values of labeled isotopes were found at intermediate soil depths. High-throughput amplicon sequencing and Sanger sequencing indicated the dominance of Methylobacter-like methanotrophs in swamp soils, which comprised 21.3-24.0% of the total bacterial sequences, as measured by 13C-DNA at day 90. These results demonstrate that aerobic methanotroph Methylobacter is the key player in suboxic methane oxidation and likely catalyzes nitrogen fixation in swamp wetland soils in the Qinghai-Tibetan Plateau.

Effects of Stellera chamaejasme removal on the nutrient stoichiometry of S. chamaejasme-dominated grasslands in the Qinghai-Tibetan plateau

BACKGROUND

Stoichiometric relations drive powerful constraints in several fundamental ecosystem processes. However, limited studies have been conducted on the ecological stoichiometry of plants after the change of community composition induced by Stellera chamaejasme removal in alpine grassland in the Qinghai-Tibetan Plateau.

METHODS

We investigated the effects of S. chamaejasme removal on ecological stoichiometry by estimating the C:N:P stoichiometry in species, functional group and community levels of the ecosystem. The interactions between different species, functional groups and correlation with soil nutrient, responding to S. chamaejasme removal were also analyzed.

RESULTS

For the plants that became dominant after S. chamaejasme removal (SR), N content decreased and their C:N increased. S. chamaejasme removal significantly affected the nutrient stoichiometry of different functional groups. Specifically, Gramineae in the SR sites had decreased N content and N:P, and increased C:N; however, forbs had increased N content, C:P and N:P and decreased P content and C:N. At the community level, N content was lower and C:N higher in SR communities compared to CK. The N content of the plant community was positively correlated with soil total N content. S. chamaejasme removal could change the nutrient balance from species level, to functional group level, and to community level. Thus, supplementary measures might be cooperated with S. chamaejasme removal for the recovery of S. chamaejasme-dominated degraded grassland. These results provide insight into the role of S. chamaejasme in ecological protection and conservation, and the conclusions from this study could be used to develop effective and sustainable measures for S. chamaejasme control in the Qinghai-Tibetan Plateau.

Ethnic Differences Shape the Alpha but Not Beta Diversity of Gut Microbiota from School Children in the Absence of Environmental Differences

Although the human gut microbiome is shaped by factors such as diet, environment, and genetic background, most studies investigating the relationship between ethnicity and microbiota have compared groups living in separate geographical locations. To isolate the effects of ethnicity on microbial diversity by minimizing environmental differences, we selected 143 school children from Han, Tibetan, and Hui populations from the same town on the Qinghai–Tibetan Plateau for fecal microbiome 16S rDNA sequencing. We characterized the diversity, identified signature taxa, and performed correlation analysis between diet and community composition. Firmicutes (47.61%) and Bacteroidetes (38.05%) were dominant phyla among the three ethnic groups; seven genera showed significant differences in relative abundance. Tibetan populations had a higher relative abundance of Oscillibacter and Barnesiella, compared with Han and Hui populations. Alpha diversity analyses (observed species, ACE, and Shannon indices) showed that the Tibetan population had the highest diversity compared to the Hui and Han groups, whereas beta diversity analysis revealed no significant differences between groups. The consumption of grains, milk, eggs, and fruits were positively correlated with specific taxa. Under similar environments and diet, ethnic background significantly contributed to differences in alpha diversity but not beta diversity of gut microbiota.

Spatial Variation and Controlling Factors of H and O Isotopes in Lancang River Water, Southwest China

Climate changes and other human activities have substantially altered the hydrological cycle with respect to elevation. In this study, longitudinal patterns in the stable isotopic composition (δ²H and δ¹⁸O) of Lancang River water, originating from the Qinghai–Tibetan Plateau, are presented, and several controlling factors in the wet season are hypothesized. Lancang River water δ²H (−145.2‰ to −60.7‰) and δ¹⁸O (−18.51‰ to −8.49‰) were low but close to those of the Global Meteoric Water Line. In the upper reaches of the river, δ²H decreased longitudinally, potentially due to groundwater inputs and melting ground ice in the headwater zone and to an increasing proportion of glacier meltwater with decreasing elevation. In the middle reaches of the river, δ²H values increased slowly moving downstream, likely due to shifts in precipitation inputs, as evidenced by the isotopic composition of tributaries to the main stream. In the lower reaches of the river, the isotopic composition was relatively invariant, potentially related to the presence of large artificial reservoirs that increase the water resident time. The results reveal different hydrological patterns along an alpine river in central Asia associated with both natural and anthropogenic processes. Understanding the degree and type of human interference with the water cycle in this region could improve water management and water security.

Exploring the community phylogenetic structure along the slope aspect of subalpine meadows in the eastern Qinghai-Tibetan Plateau, China

Exploring the community assembly has been important for explaining the maintenance mechanisms of biodiversity and species coexistence, in that it is a central issue in community ecology. Here, we examined patterns of the community phylogenetic structure of the subalpine meadow plant community along the slope gradient in the Qinghai-Tibetan Plateau of China. We surveyed all species and constructed the phylogenetic tree of the plant community based on data from the Angiosperm Phylogeny Group III. We selected the net relative index (NRI) and evaluated the community phylogenetic structure along the five slope plants communities. We found that the phylogenetic structure varied from phylogenetic clustering to phylogenetic overdispersion with the slope aspect from north to south. In the north slope, the community phylogenetically cluster indicated that the limiting similarity played a leading role in the community assembly and the maintenance of biodiversity. Community phylogenetic overdispersion in the east, southeast, and south slopes indicated that habitat filtration was the driving force for community assembly. The NRI index of the northeast slope was close to zero, implying random dispersion. But it may be driven by the neutral process or limiting similarity, in that the community assembly process was the result of a combination of several ecological factors and thus required further study.

Mountains as Evolutionary Arenas: Patterns, Emerging Approaches, Paradigm Shifts, and Their Implications for Plant Phylogeographic Research in the Tibeto-Himalayan Region

Recently, the "mountain-geobiodiversity hypothesis" (MGH) was proposed as a key concept for explaining the high levels of biodiversity found in mountain systems of the Tibeto-Himalayan region (THR), which comprises the Qinghai-Tibetan Plateau, the Himalayas, and the biodiversity hotspot known as the "Mountains of Southwest China" (Hengduan Mountains region). In addition to the MGH, which covers the entire life span of a mountain system, a complementary concept, the so-called "flickering connectivity system" (FCS), was recently proposed for the period of the Quaternary. The FCS focuses on connectivity dynamics in alpine ecosystems caused by the drastic climatic changes during the past ca. 2.6 million years, emphasizing that range fragmentation and allopatric speciation are not the sole factors for accelerated evolution of species richness and endemism in mountains. I here provide a review of the current state of knowledge concerning geological uplift, Quaternary glaciation, and the main phylogeographic patterns ("contraction/recolonization," "platform refugia/local expansion," and "microrefugia") of seed plant species in the THR. In addition, I make specific suggestions as to which factors future avenues of phylogeographic research should take into account based on the fundamentals presented by the MGH and FCS, and associated complementary paradigm shifts.

Soil organic carbon and total nitrogen stocks in alpine ecosystems of Altun Mountain National Nature Reserve in dry China

The Altun Mountain National Nature Reserve (AMNNR), characterized by complex topography, is located on the northern edge of the Qinghai-Tibetan Plateau. The stocks of soil organic carbon (SOC) and total nitrogen (TN) are critically important for carbon and nitrogen sequestration in dry alpine ecosystems of the AMNNR, which is a "natural laboratory" for assessing the carbon and nitrogen storage without human disturbance. We explored the stocks of SOC and TN in soils of different dry alpine ecosystems by sampling 23 sites across the AMNNR during 2013. The results showed that the SOC and TN stocks of AMNNR varied significantly with ecosystem types. The SOC stocks of 0-15 cm were highest in the alpine wet meadow (7.96 kg/m²), followed by alpine steppe (2.63 kg/m²). The stocks of SOC and TN in 0-5 and 5-10 cm soils of alpine wet meadow were significantly (P < 0.05) higher than those in the soils of other dry alpine ecosystems. In the whole AMNNR, total storage of SOC and TN were approximately 80.97 and 4.48 Tg, 34.25% of SOC and 24.01% of TN were stored in the alpine steppe, 21.51% of SOC and 26.01% of TN were stored in the alpine scrub, the largest ecosystem in the AMNNR. Our findings suggested it is important to protect the soil and vegetation of the dry alpine ecosystems, particularly the alpine wet meadow and alpine scrub to promote the carbon storage.

Increasing grassland degradation stimulates the non-growing season CO2 emissions from an alpine meadow on the Qinghai-Tibetan Plateau

The alpine meadow ecosystem is one of the major vegetation biomes on the Qinghai-Tibetan Plateau, which hold substantial quantities of soil organic carbon. Pronounced grassland degradations (induced by overgrazing/climate change and further exacerbated by the subterranean rodent activities) that have widely occurred in this ecosystem may significantly alter the non-growing season carbon turnover processes such as carbon dioxide (CO₂) efflux, but little is known about how the non-growing season CO₂ emissions respond to the degradation (particularly the exacerbated degradations by plateau zokor), as most previous studies have focused primarily on the growing season. In this study, the effects of four degradation levels (i.e., the healthy meadow (HM), degraded patches (DP), 2-year-old zokor mounds (ZM2), and current-year zokor mounds (ZM1)) on CO₂ emissions and corresponding environmental and agronomic variables were investigated over the two non-growing seasons under contrasting climatic conditions (a normal season in 2013-2014 and a "warm and humid" season in 2014-2015). The temporal variation in the non-growing season CO₂ emissions was mainly regulated by soil temperature, while increasing degradation levels reduced the temperature sensitivity of CO₂ emissions due to a reduction in soil water content. The cumulative CO₂ emissions across the non-growing season were 587-1283 kg C ha^-1 for all degradation levels, which varied significantly (p < 0.05) interannually. The degradation of alpine meadows significantly (p < 0.05) reduced the vegetation cover and aboveground net primary productivity as well as the belowground biomass, which are typically thought to decrease soil CO₂ emissions. However, the non-growing season CO₂ emissions for the degraded meadow, weighted by the areal extent of the DP, ZM2, and ZM1, were estimated to be 641-1280 kg C ha^-1, which was significantly higher (p < 0.05) as compared with the HM in the warm and humid season of 2014-2015 but not in the normal season of 2013-2014. Additionally, grassland degradation substantially increased the productivity-scaled non-growing season CO₂ emissions, which showed an exponential trend with increasing degradation levels. These results suggest that there is a strong connection between grassland degradation and soil carbon loss, e.g., in the form of CO₂ release, pointing to the urgent need to manage degraded grassland restoration that contributes to climate change mitigation.

Heavy metal enrichment in roadside soils in the eastern Tibetan Plateau

The effects of human activities on heavy metal pollution in soil have been less investigated on the Tibetan Plateau. The present study was designed to assess the effects of highway traffic on Cu, Zn, Pb, and Cd enrichments in the 0-60-cm soil profile in the eastern Tibetan Plateau. Soils were sampled at four transects (with an altitude range of 2643-2911 m) across the G212 highway and five transects (3163-3563 m) across the G213 highway. Background concentrations of Cu, Zn, Pb, and Cd to the 60-cm soil depth (measured at each transect 400 m away from highways) varied greatly among transects and between highways. However, this spatial variation in the heavy metal concentrations was not related to the altitude of the investigated areas. On each the left and right sides of G212 or G213, Cu, Zn, and Pb concentrations to the 60-cm depth, at 5, 10, 20, and 50 m away from the highway, were all generally greater than the respective metal background concentrations. Cd concentrations to the 20 cm on G212 or 60-cm soil depth on G213 increased prominently within a distance of 20 m away from the highways, compared to background values in different depths. From the curb to 400 m away from highways, concentrations of Cu, Zn, Pb, and Cd were generally higher in the upper than in the lower soil layers. This may suggest that other factors such as atmospheric deposition were also contributable to the accumulation of heavy metals in soil. The contamination factor (C _f ) calculation showed that roadside soils to the 60-cm depth, within a distance of 50 m from the curbs of both G212 and G213, were moderately (1 ≤ C _f  < 3) contaminated with Cu, Zn, and Pb. The contamination from Cd mainly occurred (1 ≤ C _f  < 8) in the top 20 cm soil with a closer distance from the highways. Our results indicated that traffic effects in enriching heavy metals reached 60-cm depth in roadside soils on the eastern Tibetan Plateau. For assessment of heavy metal pollutions in soil in mountainous areas, it is necessary to in situ identify the background values.

Different responses of ecosystem carbon exchange to warming in three types of alpine grassland on the central Qinghai-Tibetan Plateau

Climate is a driver of terrestrial ecosystem carbon exchange, which is an important product of ecosystem function. The Qinghai-Tibetan Plateau has recently been subjected to a marked increase in temperature as a consequence of global warming. To explore the effects of warming on carbon exchange in grassland ecosystems, we conducted a whole-year warming experiment between 2012 and 2014 using open-top chambers placed in an alpine meadow, an alpine steppe, and a cultivated grassland on the central Qinghai-Tibetan Plateau. We measured the gross primary productivity, net ecosystem CO 2 exchange (NEE), ecosystem respiration, and soil respiration using a chamber-based method during the growing season. The results show that after 3 years of warming, there was significant stimulation of carbon assimilation and emission in the alpine meadow, but both these processes declined in the alpine steppe and the cultivated grassland. Under warming conditions, the soil water content was more important in stimulating ecosystem carbon exchange in the meadow and cultivated grassland than was soil temperature. In the steppe, the soil temperature was negatively correlated with ecosystem carbon exchange. We found that the ambient soil water content was significantly correlated with the magnitude of warming-induced change in NEE. Under high soil moisture condition, warming has a significant positive effect on NEE, while it has a negative effect under low soil moisture condition. Our results highlight that the NEE in steppe and cultivated grassland have negative responses to warming; after reclamation, the natural meadow would subject to loose more C in warmer condition. Therefore, under future warmer condition, the overextension of cultivated grassland should be avoided and scientific planning of cultivated grassland should be achieved.

Carbon isotopic signature reveals the geographical trend in methane consumption and production pathways in alpine ecosystems over the Qinghai-Tibetan Plateau

On the Qinghai-Tibetan Plateau, isotopic signatures in soil-atmosphere CH₄ fluxes were investigated in nine grasslands and three wetlands. In the grasslands, the fractionation factor for soil CH₄ uptake, α_soil, was much smaller than the usually reported value of 0.9975-1.0095. Stepwise multiple variation analysis indicates that α_soil is higher for higher soil water contents but is lower for higher C/N ratios of soil surface biomass. In the three wetlands, the soil-emitted δ¹³C-CH₄ was similar (-55.3 ± 5.5 ‰ and -53.0 ± 5.5 ‰) in two bogs separated by >1000 km but was lower (-63.4 ± 6.3 ‰) in a marsh. Environmental factors related to intrasite variations in soil-emitted δ¹³C-CH₄ include the soil C/N ratio, oxidation-reduction potential, soil C concentration and soil water contents. Geographical isotopic surveys revealed environmental constraints on the CH₄ consumption pathways in grasslands and the biome type-specific consistency in CH₄ production pathways in wetlands.

Changes of hemoglobin expression in response to hypoxia in a Tibetan schizothoracine fish, Schizopygopsis pylzovi

Fishes endemic to the Qinghai-Tibetan Plateau are comparatively well adapted to aquatic environments with low oxygen partial pressures (hypoxia). Here, we cloned the complete cDNA of hemoglobin (Hb) α and β from the Tibetan schizothoracine fish Schizopygopsis pylzovi, and then investigated changes in Hb mRNA and protein levels in spleen, liver and kidney in response to hypoxia. We applied severe hypoxia (4 h at PO₂ = 0.6 kPa) and moderate hypoxia (72 h at PO₂ = 6.0 kPa) to adult S. pylzovi. Changes of Hb expression under hypoxia, together with the investigations of spleen somatic index, kidney somatic index and Hb concentration in circulation, suggest that the kidney may not only serve as the erythropoietic organ, but also act as the major blood reservoir in S. pylzovi. From this perspective, the transcriptional activity of Hb in S. pylzovi, as reflected in the kidney, was turned down quickly after the onset of severe hypoxia, while under moderate hypoxia the transcriptional activity of Hb showed upregulation for a short time, but then the transcriptional machinery was turned down slowly on prolonged exposure. Notably, the changes in Hb protein levels in spleen, liver and kidney in response to severe and moderate hypoxia were not in line with the changes in mRNA levels, which are related with the blood reservoir in the kidney. Tibetan schizothoracine fish, at least S. pylzovi, show a particular response of the transcription regulation of Hb to moderate hypoxia, which is different from that of other fish species.

More than a century of Grain for Green Program is expected to restore soil carbon stock on alpine grassland revealed by field (13)C pulse labeling

Anthropogenic changes in land use/cover have altered the vegetation, soil, and carbon (C) cycling on the Qinghai-Tibetan Plateau (QTP) over the last ~50years. As a result, the Grain for Green Program (GfGP) has been widely implemented over the last 10years to mitigate the impacts of cultivation. To quantify the effects of the GfGP on C partitioning and turnover rates at the ecosystem scale, an in situ (13)C pulse labeling experiment was conducted on natural and GfGP grasslands in an agro-pastoral ecotone in the Lake Qinghai region on the QTP. We found that there were significant differences in the C stocks of all the considered pools in both the natural and GfGP grasslands, with higher CO2 uptake rates in the GfGP grassland than that in the natural grassland. Partitioning of photoassimilate (% of recovered (13)C) in C pools of both grasslands was similar 25days after labeling, except in the roots of the 0-15 and 5-15cm soil layer. Soil organic C (SOC) sequestration rate in the GfGP grassland was 11.59±1.89gCm(-2)yr(-1) significantly greater than that in the natural grassland. The results confirmed that the GfGP is an efficient approach for grassland restoration and C sequestration. However, it will take more than a century (119.19±20.26yr) to restore the SOC stock from the current cropland baseline level to the approximate level of natural grassland. We suggest that additional measures are needed in the selection of suitable plant species for vegetation restoration, and in reasonable grazing management.

Warming decreased and grazing increased plant uptake of amino acids in an alpine meadow

Organic nitrogen (N) uptake by plants has been recognized as a significant component of terrestrial N cycle. Several studies indicated that plants have the ability to switch their preference between inorganic and organic forms of N in diverse environments; however, research on plant community response in organic nitrogen uptake to warming and grazing is scarce. Here, we demonstrated that organic N uptake by an alpine plant community decreased under warming with ¹³C–¹⁵N‐enriched glycine addition method. After 6 years of treatment, warming decreased plant organic N uptake by 37% as compared to control treatment. Under the condition of grazing, warming reduced plant organic N uptake by 44%. Grazing alone significantly increased organic N absorption by 15%, whereas under warming condition grazing did not affect organic N uptake by the Kobresia humilis community on Tibetan Plateau. Besides, soil NO₃–N content explained more than 70% of the variability observed in glycine uptake, and C:N ratio in soil dissolved organic matter remarkably increased under warming treatment. These results suggested warming promoted soil microbial activity and dissolved organic N mineralization. Grazing stimulated organic N uptake by plants, which counteracted the effect of warming.

Phylogeny and historical biogeography of Isodon (Lamiaceae): rapid radiation in south-west China and Miocene overland dispersal into Africa

Rapid organismal radiations occurring on the Qinghai-Tibetan Plateau (QTP) and the mechanisms underlying Asia-Africa intercontinental disjunctions have both attracted much attention from evolutionary biologists. Here we use the genus Isodon (Lamiaceae), a primarily East Asian lineage with disjunct species in central and southern Africa, as a case study to shed light upon these processes. The molecular phylogeny and biogeographic history of Isodon were reconstructed using sequences of three plastid markers, the nuclear ribosomal internal transcribed spacer (nrITS), and a low-copy nuclear gene (LEAFY intron II). The evolution of chromosome numbers in this genus was also investigated using probabilistic models. Our results support a monophyletic Isodon that includes the two disjunct African species, both of which likely formed through allopolyploidy. An overland migration from Asia to Africa through Arabia during the early Miocene is proposed as the most likely explanation for the present disjunct distribution of Isodon. The opening of the Red Sea in the middle Miocene may appear to have had a major role in disrupting floristic exchange between Asia and Africa. In addition, a rapid radiation of Isodon was suggested to occur in the late Miocene. It corresponds with one of the major uplifts of the QTP and subsequent aridification events. Our results support the hypothesis that geological and climatic events play important roles in driving biological diversification of organisms distributed in the QTP area.

A comparison of methane emission measurements using Eddy Covariance and manual and automated chamber-based techniques in Tibetan Plateau alpine wetland

Comparing of different CH4 flux measurement techniques allows for the independent evaluation of the performance and reliability of those techniques. We compared three approaches, the traditional discrete Manual Static Chamber (MSC), Continuous Automated Chamber (CAC) and Eddy Covariance (EC) methods of measuring the CH4 fluxes in an alpine wetland. We found a good agreement among the three methods in the seasonal CH4 flux patterns, but the diurnal patterns from both the CAC and EC methods differed. While the diurnal CH4 flux variation from the CAC method was positively correlated with the soil temperature, the diurnal variation from the EC method was closely correlated with the solar radiation and net CO2 fluxes during the daytime but was correlated with the soil temperature at nighttime. The MSC method showed 25.3% and 7.6% greater CH4 fluxes than the CAC and EC methods when measured between 09:00 h and 12:00 h, respectively.