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Grassland is the largest ecosystem on the Qinghai–Tibetan Plateau (QTP) and provides multiple ecosystem functions and services. Understanding the endowment of the QTP grassland and how to revitalize it have profound implications for the sustainable use and efficient conservation of these unique and globally valuable ecosystems. In this paper, we highlight the importance of the QTP grassland in regional and global settings, stress the values of the QTP grassland in ecological and socioeconomic dimensions, and emphasize the actions needed to restore degraded grassland in the QTP region. The QTP is the largest single area of alpine grassland in the world and an important gene pool of alpine biological resources. The QTP grassland covers two critical ecoregions for conserving the best and most representative habitats for alpine biodiversity on the planet. The QTP grassland is also regarded as one of the best carriers and objects of socio‐ecological systems in the world. To promote the resilience and sustainability of the QTP grassland through adaptation, different parties need to work together to find feasible options to resist shock, stresses, and disturbance and to maintain the fundamental functions and basic structures of the QTP grassland. [ABSTRACT FROM AUTHOR]

Background: N (nitrogen) and P (phosphorus) play important roles in plant growth and fitness, and both are the most important limiting factors that affect grassland structure and function. However, we still know little about plant physiological responses to N and P enrichment in alpine grassland of the Qinghai-Tibetan Plateau. In our experiment, five dominant common herbaceous species were selected and their photosynthetic parameters, leaf N content, and aboveground biomass were measured. Results: We found that species-specific responses to N and P enrichment were obvious at individual level. N addition (72 kg Nha−1 yr−1), P addition (36 kg Pha−1 yr−1) and NP addition (72 kg Nha−1 yr−1and 36 kg P ha−1 yr−1, simultaneously) significantly promoted net photosynthetic rate of Leymus secalinus. Differential responses also existed in the same functional groups. Responses of forb species to the nutrients addition varied, Aconitum carmichaeli was more sensitive to nutrients addition including N addition (72 kg Nha−1 yr−1), P addition (36 kg Pha−1 yr−1) and NP addition (72 kg Nha−1 yr−1and 36 kg P ha−1 yr−1). Responses of plant community photosynthetic traits were not so sensitive as those of plant individuals under N and P enrichment. Conclusions: Our findings highlighted that photosynthetic responses of alpine plants to N and P enrichment were species-specific. Grass species Leymus secalinus had a higher competitive advantage compared with other species under nutrient enrichment. Additionally, soil pH variation and nutrients imbalance induced by N and P enrichment is the main cause that affect photosynthetic traits of plant in alpine steppe of the Qinghai-Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Global grassland degradation has prompted professionals and practitioners to critically consider about the future of grassland resources. Restoration actions related to payment for ecosystem services (PES) have been proposed as a possible approach to balancing grassland sustainable development and ecosystem service supply. Since 2005, approximately one billion U.S. dollars have been invested in the Three-River Headwater Region (TRHR) of China to restore 5.69 × 106 ha of degraded grasslands via grassland cultivation and fencing. Unfortunately, few literature has drawn valid and generalizable conclusions regarding the economic performance of these PES programs. Therefore, field data from multiple sites were collected to evaluate the economic returns of restoration actions, returns on investments (ROI), and trade-offs among ecosystem services of cultivated and fenced grasslands over different restoration years in the TRHR. The results revealed that PES-related restoration efforts in the TRHR had yielded a net profit of $14.34 billion, with $13.20 billion from the alpine meadow, $0.74 billion from the alpine steppe and $0.40 billion from the temperate steppe. These substantial economic can be attributed to the combined effects of the surge in specific ecosystem services and the synergistic improvement of all ecosystem services. The ROI of supporting service accounted for the largest proportion of ROI in total ecosystem services and exhibited drastic fluctuations with restoration years, whereas the ROI of other services either increased gradually or remained stable across different restoration periods. The trade-offs in ecosystem services varied greatly with grassland type. We observed an increasing synchronization of ecosystem services over time in the fenced alpine steppe, cultivated alpine meadow, and cultivated temperate steppe; whereas a similar trend was not detected in other grasslands. Our research underscores the importance of incorporating herders' willingness, assessing restoration performance of grasslands and adopting more targeted and adaptive restoration actions in subsequent PES programs. • PES helped balance sustainable development and ecosystem conservation. • Multiple site data was collected to explore ecological returns of restoration actions. • Restoration actions with PES programs had yielded a net profit of $14.34 billion. • Gains were owed to surge of specific ecosystem services and synergy of all services. • Herders' willingness and more targeted actions should be considered in next steps. [ABSTRACT FROM AUTHOR]

• N deposition effects on soil C:N:P stoichiometry of ungrazed and grazed grassland varied. • Livestock grazing may weaken N deposition effects on soil C:N:P stoichiometry. • Climate variability and other environmental factors can also mediate N deposition effects. Increased nitrogen (N) deposition is expected to impact the grassland ecosystem by changing soil C:N:P stoichiometry. However, N deposition effects on soil C:N:P stoichiometry is still in debate. In addition, we still know less about how N deposition affects soil C:N:P stoichiometry in grazed grassland as most studies focus on natural grassland. Hence, it is necessary to examine N deposition effects on both ungrazed and grazed grassland and clarify the disparity. We conducted a simulated N deposition experiment in ungrazed and grazed grassland of two grassland types including alpine meadow (AM) and alpine steppe (AS) to test such effects. Results showed that N deposition effects on ungrazed and grazed grassland varied. Soil C, soil N, soil P, soil C:N, soil N:P and soil C:P were significantly affected by N deposition in ungrazed grassland while only soil N, soil P, soil C:N, soil N:P were significantly affected by N deposition in grazed grassland. Soil C and soil N:P were not sensitive to N deposition in grazed grassland. N deposition negatively affects soil P in ungrazed grassland yet positively affected soil P in grazed grassland. N deposition effects accounted for 30% in ungrazed grassland, while significantly decreased to 12% when grazing effects were considered suggesting that livestock grazing might weaken N deposition effects on soil C:N:P stoichiometry. In addition, other climate and environmental factors such as MAT, MAP, and grassland type can also mediate N deposition effects on soil C:N:P stoichiometry in both ungrazed and grazed grasslands. On the whole, our findings suggested that there existed a disparity of N deposition effects on soil C:N:P stoichiometry between ungrazed and grazed grassland, and livestock grazing may weaken N deposition effects on soil C:N:P stoichiometry in alpine grassland of the Qinghai-Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Data from long-term monitoring, remote sensing, and controlled experiments indicate that climate change is altering and reshaping patterns of vegetation growth, and these changes will have cascading effects on the structure and functioning of alpine ecosystems (Li et al. [14]; Ma et al. [18]; Liu et al. [17]; Wang et al. [25]). Tian et al. ([24]) showed that plant diversity and soil carbon sequestration were differently affected by warm- and cold-season grazing, highlighting the importance of considering the grazing strategies in maintaining ecosystem sustainability. Similarly, Zhao et al. ([36]) found that ecosystem respiration was lower in the bare soil caused by burrowing activities of pika than in vegetated soil. References 1 Bai Y, Ma L, Degen AA, Rafiq MK, Kuzyakov Y, Zhao J, Zhang R, Zhang T, Wang W, Li X, Long R, Shang Z (2020) Long-term active restoration of extremely degraded alpine grassland accelerated turnover and increased stability of soil carbon. [Extracted from the article]

One of the important mechanisms for the stabilization of soil organic carbon (SOC) is its spatial inaccessibility for microbial biodegradation within soil aggregates. However, little has been documented regarding soil aggregate stability with grassland degradation in the alpine region of the Qinghai‐Tibetan Plateau (QTP). In this study, we used physical and density fractions to elucidate the mechanisms of differences in SOC in non‐degraded and degraded grasslands of two grassland biomes, alpine meadow and alpine steppe in the QTP. There were considerable differences between non‐degraded and degraded grasslands for the soil physical and chemical properties, aggregate distribution and aggregate‐SOC content. The non‐degraded alpine meadow (AMND) had the largest value among all the alpine grasslands for the SOC content of the microaggregate fraction, with values of 31.83 g kg−1. The degraded grasslands showed significantly larger SOC content of macroaggregates than non‐degraded grasslands. The degraded alpine steppe (ASD) had the largest SOC content, with the value of 25.51 g kg−1. The aggregate distribution of the macroaggregate, microaggregate and free silt+clay fractions was consistent with the variation in SOC content of these three aggregate fractions. The fine intra‐aggregate particulate organic matter (fiPOM) content was significantly less in degraded grasslands, indicating that grassland degradation might have disrupted the fiPOM‐C. The increase in CO2 emissions was related to the destruction of soil aggregates in the alpine grasslands of the QTP. Highlights: Effects of alpine grassland degradation on aggregate‐associated SOC were investigated.Used soil aggregate fractions to evaluate the variation of aggregate‐associated SOC.Grassland degradation promoted the destruction of soil aggregates in the alpine grasslands of the QTP.Destruction of soil aggregates promoted CO2 emissions in the degraded alpine grasslands of the QTP. [ABSTRACT FROM AUTHOR]

Qinghai-Tibetan Plateau (QTP), >4000 m known as the "third pole of the earth" and is highly sensitive to nitrogen (N) deposition, understanding the effects of N deposition on multifaceted plant diversity (taxonomy diversity, functional diversity and phylogenetic diversity) in the alpine grasslands of Qinghai-Tibet Plateau are vital for the conservation of alpine plant diversity and the sustainability of alpine grasslands ecosystem services. We added N of different gradients to test the effects of soil acidification, soil eutrophication, and phosphorus limitation independently, and interactively on the multifaceted plant richness and evenness in both an alpine meadow and an alpine steppe of the QTP. We found that all the p -value of taxonomy diversity, functional diversity and phylogenetic diversity were >0.05 and values of R2 of fixed factors by nitrogen addition gradients was low (<0.10). In contrast to the alpine steppe, diversity of alpine meadow is more sensitive to soil factors than alpine steppe. Soil acidification caused by nitrogen deposition changed taxonomic evenness (p < 0.05), while eutrophication associated with nitrogen deposition altered taxonomic richness and phylogenetic evenness (p < 0.05) in the alpine meadow and functional richness (p < 0.05) in the alpine steppe. These findings suggest that the effects of N deposition on the multifaceted plant diversity (taxonomic, functional and phylogenetic diversity) varied with N deposition gradients and ecosystem types. Rational adaptation and mitigation techniques should be considered for different types of alpine grasslands on the QTP according to their different responses to the nitrogen deposition gradients in the future. Unlabelled Image • Nitrogen addition showed insignificant effects on most of the diversity. • Diversity of alpine meadow is more sensitive to soil factors than alpine steppe. • pH caused by nitrogen deposition changed taxonomic evenness in alpine meadow. • Eutrophication by nitrogen deposition altered functional richness in alpine steppe. • Eutrophication altered taxonomic richness and phylogenetic evenness in alpine meadow. [ABSTRACT FROM AUTHOR]

• Endangered plants in Sanjiangyuan mainly locate in the east and the south. • Distribution of endangered plants will expand to the west and north in the future. • Habitats in the northeast are at the highest ecosystem risk. • Most of the highest risk areas are not strictly protected. Sanjiangyuan, called the "Water tower of Asia", is critically important in the ecological services of water provision and regulation and in biodiversity conservation. To strengthen protection in this eco-region, The Chinese government established the Sanjiangyuan National Nature Reserve (SNNR) in 2001 and Sanjiangyuan National Park (SNP) in 2014. To assess the effectiveness of these two conservation practices, on the endangered plant species, we used an integrated method to identify the priority areas of the endangered plant species in the Sanjiangyuan Area which showed if some areas need more conservation efforts. After identifying the potential habitats of high-valued species in Sanjiangyuan with MaxENT, a model that combined the hotspots of endangered plant species richness (H), vegetation condition (V), soil condition (S), human disturbance (D) and climate change impact (C) was used to calculate ecosystem risk (ER) associated with each habitat. Projections of climate modeling show that the distribution of endangered plants in Sangjiangyuan will expand to the west and north with the warmer and wetter climate in the future. In both current and future scenarios, the habitats in the northeast of the SNNR are at the highest ecosystem risk and need to be protected strictly. However, most of the high ecosystem risk/conservation priority regions we identified - either current or predicted future status (in 2070 under RCP 2.6) were not protected by SNNR or SNP. Identified conservation gaps call for the well-targeted planning and delineated scientific interventions for protecting the key habitats of these endangered plant species. Conservation priority should be given to eastern Xinghai County and northeastern Tongde County in the east of SNNR, where the habitats are at high ecosystem risk and have high conservation priority. [ABSTRACT FROM AUTHOR]

• Grazing enhances plants photosynthetic capacity directly and indirectly. • Grazing increases soil N content and promotes plant N uptake. • Grazing affects plant photosynthesis mainly through the effects on soil N. The eco-physiological processes associated with the influences of grazing on plant traits and soil properties of alpine grasslands has remained poorly understood. To determine the effects of grazing on photosynthesis of alpine grassland plants, we measured nutrient level in plant and soil, as well as photosynthetic parameters of common herbage species in the grazed and fenced plots of an alpine meadow and an alpine steppe on Qinghai-Tibetan plateau. The results showed that grazing significantly enhanced most herbages' carbon(C) and nitrogen (N) content, net photosynthetic rate (A), stomatal conductance (gs), intercellular CO 2 concentration (Ci), transpiration rate (Tr), water use efficiency (WUE) and light use efficiency (LUE), as well as soil C and N content. Through the SEM modeling, we found both direct and indirect paths that grazing enhanced plants photosynthetic capacity. Grazing can directly enhance soil N content and thus promote plant N uptake, further increase plant gs , WUE and LUE , finally promote the A of plants. Additionally, grazing can also directly enhanced plant photosynthetic capacity through promoting the plant gs. Soil N and plant gs are the two key factors that determine the improvement of photosynthetic capacity under grazing. Sustainable moderate grazing management is expected to promote the photosynthetic potentials of alpine plants mainly through the improvement of soil N. [ABSTRACT FROM AUTHOR]

The spectral characterization of flow-field parameters provides a new perspective for understanding the spatiotemporal evolution of unsteady supersonic exhaust plumes and for extracting typical structures. In this study, a large-eddy simulation is performed to calculate the three-dimensional unsteady supersonic plume flow field of rocket engines, and a spectral proper orthogonal decomposition (SPOD) method with a spatiotemporal separation is established. This approach is used to extract the coherent structural features of the unsteady exhaust plume flow field and analyze the mode space structure at different frequencies. The three-dimensional reconstruction and denoising of the exhaust plume flow-field parameters can be achieved via the frequency- and time-domain reconstructions of the SPOD algorithm and oblique projection method, respectively. The ground rocket exhaust plume of ballistic evaluation motor-II is analyzed. The results indicate that the SPOD method can effectively extract the single-frequency mode structure of the reactive supersonic flow field, and that low-order behavior appears in the m = 0 and m = 1 azimuth modes. The potential core exhibits a high-frequency wave-packet structure that is affected by shock waves and shear layers. Time-domain reconstruction based on the oblique projection method facilitates the capture of the dynamic characteristics of the flow field. For the first-order SPOD mode, the frequency- and time-domain reconstruction errors are 3.3% and 1.5%, respectively. The frequency-domain reconstruction method exhibits a 4% improvement in denoising ability compared to low-pass filters. This study provides a novel method for the spectral characterization and spatiotemporal feature extraction of supersonic exhaust plume flow fields. [ABSTRACT FROM AUTHOR]

• Soil total nitrogen and biodiversity were improved by restoration intervention. • The relationships of above- and belowground ecosystem services changed over time. • Economic profit of ecological restoration was insignificantly changed over time. A great number of ecological conservation and restoration projects have been implemented to prevent the deterioration of alpine grasslands on the Qinghai-Tibetan Plateau. However, few researches have documented the effects of ecological projects on the improvement of ecosystem services of alpine grasslands based on field investigations. In this study, 24 plots of alpine meadow along different succession times were investigated to estimate the impacts of ecological restoration on four key ecosystem services (i.e., soil organic carbon sequestration (SOCS), soil total nitrogen sequestration (STNS), biodiversity, and aboveground biomass) in the Glog Tibetan Autonomous Prefecture of Qinghai Province, China. The results showed that STNS and biodiversity of degraded alpine meadows were significantly improved through restoration actions, while SOCS and aboveground biomass didn't change. The relationships of above- and belowground ecosystem services changed over restoration time. Trade-offs between aboveground biomass and biodiversity, between aboveground biomass and SOCS at stage Ⅲ were significantly improved, in contrast to those at stage Ⅰ. Trade-off between STNS and biodiversity at stage Ⅱ was significantly increased, in contrast to those at stage Ⅰ. Economic profit of ecological restoration was insignificantly changed along restoration time. Our results suggested that human-induced restoration was a feasible approach to improve the ecological and economical values of "Black Beach" on the Qinghai-Tibetan Plateau, and further restoration actions and long-term research are required to enhance the ecosystem services of revegetated degraded meadow. [ABSTRACT FROM AUTHOR]

• Alpine plant and soil quality was improved by grassland cultivation. • Non-linear trajectory of plant and soil restoration existed in cultivated grassland. • Asynchrony existed between soil and plant quality along the recovery years. • Restoration of severely degraded alpine meadow took minimally 16–18 years. Resilience is crucial to promote the ecosystem sustainability and maintain ecosystem functions and services. Clarifying the variation regularity of the resilience can provide a theory foundation for the restoration and management of degraded ecosystems. Grassland cultivation has been largely used to restore extensively distributed "Black Beach", the severely degraded alpine meadow on the Qinghai-Tibetan Plateau (QTP). However, few researchers have documented the resilience of the revegetated grasslands along the succession gradients. In this study, we surveyed the revegetated grasslands on the QTP at different restoration times: 4-year, 6-year, 9-year, 12-year, 13-year, 14-year, 16-year, 18-year by using chronosequence approach to identify the resilience of the revegetated grasslands from the perspectives of plant and soil quality. We treated "Black Beach" as the baseline for restoration, and non-degraded healthy alpine meadow as the target for the restoration. We used the MDS method to identify the appropriate indicators and created an integrated assessment system that quantified the resilience of plant, soil, plant-soil system of the revegetated grasslands at different recovery years. The results showed that the non-linear resilience of revegetated grasslands were identified for the plant, soil and plant-soil systems along the temporal gradients. The plant resilience of the revegetated grasslands peaked at the 12th recovery year. The soil of the revegetated grasslands was superior to severely degraded grasslands after 13 years of revegetation. Asynchrony existed between the resilience of soil and that of the plant along the temporal gradients. The plant-soil system resilience of the revegetated grasslands peaked at the 16th recovery year. From the perspectives of plant, soil, plant-soil system, the recovery time of severely degraded grassland should be at least 16–18 years to reach a relative stable state. Revegetated grassland can be used as an effective restoration approach to improve the quality and resilience of plant and soil in the severely degraded alpine meadow on the QTP. [ABSTRACT FROM AUTHOR]

Abstract Nitrogen deposition is notable in China, even in the high altitude region of Qinghai-Tibet Plateau (QTP). To identify the effects of nitrogen deposition on soil nutrient and ecological stoichiometry of the QTP's alpine grasslands, we treated three major types of grasslands (alpine meadow, alpine steppe, and cultivated grassland) with 6 different nitrogen addition levels: 0, 8, 24, 40, 56, 72 kg N ha−1 yr−1 through the years of 2015 to 2016. We sampled the soils at two depths, 0–10 and 10–20 cm in the peak-growing season (July) of each year. Results showed that: (i) soil total carbon and phosphorus are relatively stable under nitrogen deposition. (ii) Soil total nitrogen increases under low nitrogen addition rates while decreases under higher rates, and soil available nitrogen increases under nitrogen deposition in surface soil while decreasing in deeper soil. (iii) C:N, C:P, N:P had no significant difference between different nitrogen addition levels while there were significant differences between the two years under nitrogen addition. We speculate that nitrogen addition could alter soil nutrient conditions but there were certain limit of soil nutrient under N deposition. Highlights • Soil total C and P are stable under N deposition. • Total N increase under low N addition rate while decrease under higher rate. • Available N increase under N deposition in surface soil while decrease in deep soil • Stoichiometry had no significant difference between N addition levels. [ABSTRACT FROM AUTHOR]

Highlights • Biodiversity-productivity relationship in the grasslands of QTP varied along the spatial scales. • Species richness positively related to above- and below-ground biomass at landscape scale. • Shannon–Wiener index positively related to above- and below-ground biomass at landscape scale. • Pielou evenness index negatively related to above- and below-ground biomass at landscape scale. • Plant biomass partitioning between root and shoot was independent of plant diversity at all scales. Abstract There is no consensus about the relationship between plant species diversity and productivity in grasslands. Lack of consensus might be caused by different diversity metrics used and different spatial scales examined. In particular, the impacts of different biodiversity indices on the plant diversity–plant productivity relationship of alpine grasslands at different spatial scales of the Qinghai–Tibetan Plateau (QTP) require investigation. We investigated the relations of multi-dimensional diversity indices (species richness, Shannon–Wiener diversity, and Pielou evenness) with aboveground and belowground plant biomass in the alpine grasslands of the QTP by linear mixed model (LMM). We assessed the plant diversity and biomass of alpine meadow, alpine steppe, and alpine desert steppe from 5 sites across the vast landscape of the QTP by using 6 randomly placed plots in each site and 27 replicated quadrats in each plot. The species richness of the studied alpine grasslands ranged from 2 to 35, aboveground plant dry biomass ranged from 17 to 838 g m−2, and belowground plant dry biomass ranged from 398 to 3945 g m−2. The species richness and Shannon–Wiener indices were positively correlated with aboveground plant biomass and belowground plant biomass at the landscape scale, whereas the Pielou evenness index was negatively correlated with aboveground plant biomass and belowground plant biomass at the landscape scale. Less than 20% sites showed significant relationships between plant diversity indices and plant biomass at site scale. Plant biomass partitioning between the root and shoot was not correlated with the species richness, Shannon–Wiener and Pielou evenness indices at all scales. The plant diversity–biomass relationships of the alpine grassland ecosystems in the QTP depend on both the type (or dimension) of the biodiversity index and the spatial scale of sampling. Thus, the design and implementation of plant diversity conservation should consider different dimensions of plant diversity. It is not enough to increase species richness only in the process of grassland restoration and conservation, but also to reduce species evenness so as to promote productivity more fully, for example, in planting artificial grassland. [ABSTRACT FROM AUTHOR]

Questions: The impact of grazing on the phenology of alpine plants has not been deeply explored. In particular, how the phenology of all species in the alpine plant community is affected by grazing has seldom been monitored. Study Site: Qinghai‐Tibetan Plateau of China. Methods: A linear mixed model was used to explore the effect of grazing regimes (continuous grazing, grazing exclusion and rotational grazing), species, and individuals of species on phenological stages at the community level. One‐way ANOVA was used to examine the difference in phenological stage across different species under the same grazing regime and timing of the phenological stages of each species across different grazing regimes. Pearson correlation analysis was used to explore linkages between plant phenology and leaf traits, linkages between phenological stages, as well as their intervals across different species. Results: The green‐up and withering time of different species both exhibited various response patterns to grazing regimes. The flowering time of most species was delayed by grazing, whereas the fruiting time of most species remained stable across grazing regimes. There were significant linkages between phenological stages and leaf traits; for example fruiting time was negatively related to the ratio of leaf N content (LNC) to leaf P content (LPC) under all grazing regimes. The phenological stages themselves, and their intervals, showed close relations; for example fruiting time was positively related to withering time, and negatively related to its interval. The divergence was higher during the flowering time than during other phenological stages. The divergence of all phenological stages was highest under grazing exclusion. Conclusions: The shifts in flowering time were advantageous for these plants to adapt to grazing, as flowering time can regulate interspecific temporal patterns and maintain the stability of subsequent phenological stages. Among grazing regimes, grazing exclusion led to greatest divergence of phenological stages across species, which possibly creates potential reproductive gaps. In the alpine meadows of the Qinghai‐Tibetan Plateau, the flowering time of most species was delayed by grazing, but the fruiting time of most species remained stable. Fruiting time was negatively related to the ratio of leaf N content to leaf P content. Grazing exclusion led to the greatest divergence of phenological stages across species, which possibly creates potential reproductive gaps. [ABSTRACT FROM AUTHOR]

Temperate desert is one of the globally important biomes with unique and valuable biodiversity, which might be threatened by environmental stresses and human disturbance associated with rapid development. However, few studies have documented the spatial distribution of the multifaceted plant diversity of the temperate desert and their relationships with external impacting factors. We sampled multifaceted plant species diversity including taxonomic diversity, functional diversity and phylogenetic diversity in the Alashan Desert along Beijing-Xinjiang Expressway (G6) in Northern China to identify the key factors and process which regulate the multifaceted plant diversity of the temperate desert. We found that the dynamics of species richness, functional richness, and phylogenetic richness along the elevational gradient corresponded to the unimodal model. Species phylogenetic development shifted from aggregation to divergence, while species functional traits were the opposite along the elevational gradient. The sites at an elevation around 1200–1400 m were the key habitats for the occurrence of high plant diversity including species richness, functional richness and phylogenetic richness. There were no significant differences ( p  > 0.05) in plant diversity at different distances from the road (500 m, 1000 m and 1500 m) and human disturbances (the distance from the nearest human settlements). Temperature, temperature variability, precipitation, precipitation variability, soil physical and chemistry properties showed no significant effects on plant diversity. It was concluded that evolutionary history and functional traits, not environmental or anthropogenic factors were the key determinants of the pattern of multifaceted plant diversity. [ABSTRACT FROM AUTHOR]

The wild yak (Bos mutus) is an endemic and flagship species on the Qinghai-Tibetan Plateau (QTP) of China. Because this is an aggressive and huge ungulate living in the Altun National Nature Reserve (ANNR), monitoring and surveying of wild yaks at a close distance is very difficult. An Unmanned Aerial Vehicle (UAV) offers a useful and effective tool to monitor and survey wild yaks. We used this approach in the Kumkury Desert of the ANNR, which is the highest desert in the world. The results showed that the proportion of (1) adult bulls, (2) young bulls and adult cows, and (3) calves was 1:10:5. The slopes traversed (0°-28°) within habitats and between two major habitats was higher than those (1°-13°) between habitats and water bodies, and between water bodies and food areas (alpine wet meadow in the north). There were five movement routes from rest habitats to food areas. Moreover, vehicle tracks disrupted yak migration routes from two major habitats to food areas. In conclusion, a UAV is a new multi-purpose monitoring approach for surveying large wildlife and their habitats in remote and very sparsely populated areas, and for identifying human disturbances. Using a UAV can capture detailed data on animal movements for scientific researchers. A UAV can patrol a large area that is hard to reach and provide information quickly; it can also reduce the costs of daily patrolling to determine movements. [ABSTRACT FROM AUTHOR]

Fencing and grass plantation are two key interventions to preserve the degraded grassland on the Qinghai-Tibetan Plateau (QTP). Climate warming and N deposition have substantially affected the alpine grassland ecosystems. However, molecular composition of soil organic carbon (SOC), the indicator of degradation of SOC, and its responses to climate change are still largely unclear. In this study, we conducted the experiments in three types of land use on the QTP: alpine meadow (AM), alpine steppe (AS), and cultivated grassland (CG) under 2 °C climatic warming, 5 levels of nitrogen deposition rates at 8, 24, 40, 56, and 72 kg N ha − 1 year − 1 , as well as a combination of climatic warming and N deposition (8 kg N ha − 1 year − 1 ). Our findings indicate that all three types of land use were dominated by O-alkyl carbon. The alkyl/O-alkyl ratio, aromaticity and hydrophobicity index of the CG were larger than those of the AM and AS, and this difference was generally stable under different treatments. Most of the SOC in the alpine grasslands was derived from fresh plants, and the carbon in the CG was more stable than that in the AM and AS. The compositions of all the alpine ecosystems were stable under short-term climatic changes, suggesting the short-term climate warming and nitrogen deposition likely did not affect the molecular composition of the SOC in the restored grasslands. [ABSTRACT FROM AUTHOR]

Increases in nitrogen (N) deposition along with climate warming can change the dynamics of carbon and nitrogen in the soil, and alter greenhouse gases (GHGs) fluxes. To examine how N deposition and warming affect GHGs (CH 4 , CO 2 and N 2 O) fluxes in alpine grasslands, we conducted experiments in an alpine meadow (AM), alpine-steppe (AS), and alpine cultivated grassland (CG) on the Qinghai-Tibetan Plateau (QTP). We simulated N deposition by treating soil with ammonium nitrate (NH 4 NO 3 ) (8 kg N ha − 1 year − 1 ), a warming treatment using an open top chamber (OTC) was carried out, and a combined treatment of warming and N deposition (8 kg N ha − 1 year − 1 ) was conducted. The GHGs were collected during early, peak, and late plant growing seasons, i.e., May, August, and October of 2015, respectively, using a static chamber. We found, in general, neither N deposition nor warming solely altered CH 4 and N 2 O fluxes in the alpine grasslands. The N deposition under warming conditions reduced CO 2 emission significantly. The reduction of CO 2 emission was most significant in the alpine steppe. The effects of climatic warming and N deposition on the GHGs varied greatly across the grassland types and the growing seasons. The cultivated grasslands were much more unstable than the native grasslands in CH 4 uptake. In can be concluded the N deposition associated with human activities may buffer the CO 2 emission in the alpine grassland ecosystems in terms of climate changes on the QTP. [ABSTRACT FROM AUTHOR]

Climate change has affected the geographic distribution of many species and numerous endemic species with narrow distribution ranges on the Qinghai-Tibetan Plateau of China, one of the biodiversity hotspots and critical eco-regions in the world. Altun Mountain National Nature Reserve is one of the most important refuges for the flagship species and threatened endemic ungulates, Tibetan antelope ( Pantholops hodgsoni), wild Tibetan donkey ( Equus kiang), and wild yak ( Bos mutus). We surveyed the distribution of these three species and their forage plants in the nature reserve between 2012 and 2013. Using the Maxent model, we projected the potential distribution of the Tibetan antelope, wild Tibetan donkey, and wild yak and their forage plants based on the four representative concentration pathways set by the IPCC Fifth Assessment Report for 2070. We generated 36 future model scenarios to assess and reduce the model uncertainties. We found that projected food availability associated with climate niche would be more realistic for ungulates distribution projections under climate change. Our results demonstrated that future climate change would greatly change the habitats of three threatened endemic ungulates and their forage plants. The ranges of climate niche projected for the Tibetan antelope, wild Tibetan donkey, and wild yak would be reduced by 44, 7, and 20%, respectively, with future climate change under representative concentration pathways 2.6 scenario. Among them, the ranges of Tibetan antelope and wild Tibetan donkey would reduce even more under warmer scenarios, but wild yak would be opposite. The projected distribution ranges of forage plants reduced with the climate change in the future. The combined effects of shifting climate niche and food resources would lead to the reduction of habitats for Tibetan antelope, wild Tibetan donkey, and wild yak by 82, 34, and 30% under representative concentration pathways 2.6. However, conditions would be worse for Tibetan antelope and wild Tibetan donkey but better for wild yak under other scenarios. We suggested that future conservation efforts should be focused on improving habitat quality (including food availability) and finding alternative habitats for the three ungulates especially Tibetan antelope and wild Tibetan donkey. [ABSTRACT FROM AUTHOR]

Alpine ecosystems are known to be sensitive to climate change and human disturbances. However, the knowledge about the changes of their underground microbial communities is inadequate. We explored the diversity and structure of soil bacterial and fungal communities using Ilumina MiSeq sequencing in native alpine grasslands (i.e. the alpine meadow, alpine steppe) and cultivated grassland of the Qinghai-Tibetan Plateau (QTP) under three-year treatments of overgrazing, warming and enhanced rainfall. Enhanced rainfall rather than warming significantly reduced soil microbial diversity in native alpine grasslands. Variable warming significantly reduced it in the cultivated grassland. Over 20% and 40% variations of microbial diversity could be explained by soil nutrients and moisture in the alpine meadow and cultivated grassland, separately. Soil microbial communities could be clustered into different groups according to different treatments in the alpine meadow and cultivated grassland. For the alpine steppe, with the lowest soil nutrients and moistures, < 10% variations of microbial diversity was explained by soil properties; and the soil microbial communities among different treatments were similar. The soil microbial community in the cultivated grassland was varied from it in native grasslands. Over 50% variations of soil microbial communities among different treatments were explained by soil nutrients and moisture in each grassland type. Our results suggest that climate change and human activities strongly affected soil microbial communities by changing soil nutrients and moistures in alpine grassland ecosystems. [ABSTRACT FROM AUTHOR]

The plateau pika ( Ochotona curzoniae ) is considered a keystone species on the Qinghai–Tibetan Plateau (QTP). Under a moderate burrow density condition, we investigated plant community and soil properties surrounding pika's burrows in comparison to the control sites (without pika's burrows) in an alpine meadow ecosystem. The results demonstrated that plant biomass, especially aboveground biomass around pika's burrow, was improved. The contents of available soil nutrients around the pika's burrow were improved as well. The highest aboveground biomass and highest contents of NH 4 -N, available phosphorus and available potassium was detected at the back of the burrow. The compositions of plant community were not changed significantly around the pika burrow, excluding at the front of the burrow. Our findings revealed that the activities of plateau pika can improve the production of alpine meadow and increase the soil fertility at individual burrow level when the burrow density was not out of control. [ABSTRACT FROM AUTHOR]

Background:The common fresh-frozen allografts that are used for anterior cruciate ligament (ACL) reconstructions behave slower during the remodeling process and produce weaker tendon-bone integrations than do autografts. Decellularization of allogenic tendons results in a clean and porous collagen scaffold with low antigenicity and high compatibility, which may be more suitable for ACL reconstructions.Hypothesis:Allograft decellularization will result in a tissue structure with suitable mechanical characteristics for ACL reconstruction, thereby promoting graft remodeling and enhancing tendon-bone healing.Study Design:Controlled laboratory study.Methods:Decellularized allograft tissues were prepared with a pH-modified decellularization process and evaluated for their biocompatibility and biomechanical character in vitro. Eighty New Zealand White rabbits were divided into 2 groups, with 40 in each group, to receive ACL reconstruction with either fresh-frozen (common) allografts or decellularized allografts on both knees. At 2, 4, 8, and 12 weeks postoperatively, the rabbits were euthanized for biomechanical testing, micro–computed tomography analysis, and histologic analysis.Results:The pH-modified decellularized allograft tissues kept excellent biocompatibility and biomechanical character during the in vitro study. Biomechanical testing indicated that the decellularized allograft had significantly higher ultimate load (P = .02) and stiffness (P = .01) levels than the common allograft at 12 weeks, and there was no significant difference between the 2 groups at any other time point. The micro-CT evaluation determined significantly higher bone mineral density (P < .01) in the decellularized allograft group than that in the common allograft group at 12 weeks, but no difference between the 2 groups was observed at any other time point. Regarding bone volume/total volume, there was no difference between the 2 groups at any time point. Fibroblast ingrowths, vascular formation, and connective tissue formation in the tendon-bone interface were better in the decellularized group within 8 weeks. New bone formation was more common in the decellularized allograft group. The collagen birefringence was restored more quickly in the decellularized allograft group than in the common allograft group at all time points.Conclusion:The use of pH-modified decellularized allografts compared with the common allografts resulted in better cellularity, vascularity, collagen matrix remolding, new bone formation around the graft, enhanced tendon-bone healing, and higher ultimate failure load and stiffness of the graft after ACL reconstruction in the rabbit model.Clinical Relevance:The pH-modified decellularized allograft may be a better graft option than the common fresh-frozen allograft for knee ligament reconstructions. [ABSTRACT FROM AUTHOR]

Background:In previous studies, unimodal, small-diameter collagen fibrils have been commonly observed as the final collagen ultrastructure of the implanted grafts used in anterior cruciate ligament (ACL) reconstruction. However, the native ACL and hamstring tendon show bimodal collagen fibril distribution, consisting of both large- and small-diameter collagen fibrils.Hypothesis:Bimodal collagen fibril distribution of the graft is a common phenomenon after ACL reconstruction with hamstring tendon grafts and is time dependent.Study Design:Controlled laboratory study.Methods:A total of 52 patients who underwent double-bundle ACL reconstruction using autogenous hamstring tendons and who also underwent second-look arthroscopic surgery were enrolled. The patients were divided into 2 groups according to the time interval between the 2 operations: the midterm group (27 patients), with a 13- to 30-month time interval between operations, and the long-term group (25 patients) with a 31- to 62-month interval. During the second-look arthroscopic procedures, ACL graft biopsies were performed. Normal ACL tissues were harvested from 9 patients who underwent total knee replacement, and biopsy specimens of the to-be-grafted semitendinosus tendon tissues were also harvested from another 9 patients who underwent ACL reconstruction with hamstring tendons, which were designated as normal controls. Graft vascularity, cellularity, metaplasia, cellular metabolism, and collagen fibril distribution were analyzed.Results:Large-diameter (>100 nm) collagen fibrils were detected in 81.5% of the specimens in the midterm group and in 68.0% of the specimens in the long-term group. A typical bimodal distribution mode was observed in 62.6% of the specimens in the midterm group and in 52.0% of the specimens in the long-term group. There was no significant difference between groups with respect to the presence of large-diameter collagen fibrils, bimodal distribution, graft vascularity, cellularity, metaplasia, or cellular metabolic status.Conclusion:Graft ultrastructural maturation, characterized by large-diameter collagen fibrils and a bimodal collagen fibril distribution, is a common phenomenon and is not time dependent in the midterm to long term.Clinical Relevance:After hamstring tendon ACL reconstruction, the implanted grafts can transform into ACL-like tissue with a similar ultrastructure and metabolism, implying their usefulness as grafts. [ABSTRACT FROM AUTHOR]

[Display omitted] • The excited states of the LiAu molecule are investigated for the first time. • The spin orbit coupling effect is considered in the calculation. • Transition property of LiAg and LiAu molecules are explored. • A cooling scheme of LiAu molecule is proposed. The electronic structure and the possibility of laser cooling of LiAg and LiAu are investigated using ab initio method. The potential energy curves of Λ - S and Ω states for LiAg and LiAu molecules are calculated in our work. The spectroscopic parameters of electronic state are evaluated and the values are in good agreement with available theoretical and experimental data. We also predicated the transition property of LiAg and LiAu molecules, which include transition dipole moments, Franck – Condon factors and radiative lifetimes. The calculated results show that the b3Π 1 − Χ1Σ+ 0+ transition possess highly diagonal Franck -Condon factors (f 00 = 0.8918) and enough short radiative lifetime (3.0 × 10−6 s), which could meet the criterias of laser cooling molecule. A cycling system for laser cooling LiAu molecule is proposed by three lasers at wavelengths around 338 and 344 nm with 2500 cycles for photon. [ABSTRACT FROM AUTHOR]

Massive grasslands on the Qinghai-Tibetan Plateau(QTP) provide vital ecosystems services, which have been decreased by land degradation associated with global change. Effective efforts and actions of restoration and management are required to promote the sustainable development of these grassland ecosystems with global importance. This special issue collected numerous papers to address share the innovative theoretical foundations and practical approaches for restoring and protecting QTP's grassland ecosystems in the era of global change. The findings from the collected papers of this special issue stated that the ecosystems services of the QTP's grasslands are declining due to weakened interfaces among soil, plant and grazing animals in the QTP's grassland ecosystems by climate and land use changes. Applicable actions such as climate change mitigation and adaptation, close-to-nature restoration, rotational grazing regime with moderate grazing intensity should be taken to enhance the ecosystem services through rebuilding rational soil-plant-animal interfaces. • Both climate change and human activities led to grassland degradation. • Grassland degradation have weakened the ecosystem services. • Restoration and rational grazing can enhance sustainability of grasslands. [ABSTRACT FROM AUTHOR]

• P addition increased N retention mainly by promoting plant N uptake. • N addition without P showed neutral effects of N retention. • N addition showed positive effects on gaseous losses of N. • N loss through NH 3 and N 2 O emissions was quite low. Nitrogen (N) and phosphorus (P) are common limiting nutrients affecting plant growth in alpine ecosystems. Anthropogenic activities significantly increase N input in ecosystems, thereby increasing P limitation when in excess. The increase of N input and P limitation may affect N retention, which is a critical ecosystem function. To understand how ecosystem N retention and N loss respond to N and P addition, this study investigated the effects of N and P addition on NH 3 volatilization, N 2 O emissions, and N pools of plants and soil in two alpine grasslands (alpine meadow and alpine steppe). The results showed that P addition (with or without N) increased N retention, mainly by promoting plant N uptake, underlining the importance of P availability in N retention in the QTP alpine grassland ecosystems while increasing N deposition. N addition without P showed neutral effects of N retention of plant, soil and microbes, and N addition (with or without P) showed positive effects on gaseous losses of N. N loss through NH 3 volatilization and N 2 O emissions was quite low (less than 1%), suggesting that N gaseous loss was not a significant pathway of N loss from the alpine grassland ecosystems. These results were meaningful for estimating the impacts of N retention and N loss under future N deposition scenarios in alpine grassland ecosystems in the QTP. [ABSTRACT FROM AUTHOR]

• Restoration actions improved community species richness, target species richness and target species aboveground biomass, not community biomass. • Community species richness was impacted by the restoration strategies. • Community biomass was impacted by the mean annual precipitation and temperature. • Recovery performance of target species was impacted by all the influencing factors. Ecological conservation and restoration projects in Three-river Headwater Region (TRHR) have been implemented to respond to the serious degradation of alpine meadow ecosystem. Compared with the substantial amount of studies on the recovery of plant communities, soil quality and ecosystem services, few studies have focused on the restoration performance of target species. Therefore, we conducted this study to analyze the dynamics and underlying mechanisms of species richness and aboveground biomass of plant communities and target species. The results showed that restoration actions (grassland cultivation and fencing) did not significantly improve the community aboveground biomass of the degraded alpine meadows, while the actions did significantly promote community species richness, target species richness and target species aboveground biomass. Community species richness (20%-45%) was significantly impacted by the restoration strategies, and community aboveground biomass (31%-53%) was impacted by the mean annual precipitation and mean annual temperature. The species richness (57%) and aboveground biomass (63%) of the target species were directly and indirectly impacted by restoration actions, climatic factors, biotic factors and soil factors. The implications of this study stress that target species should be highlighted in assessing the restoration success of degraded alpine meadows. Integrating climatic factors, target species and other biotic and abiotic indicators could help us better understand and evaluate restoration actions for degraded alpine meadows in the TRHR or other similar regions worldwide. [ABSTRACT FROM AUTHOR]

Highlights: [•] We studied the variation of fish assemblages before and after damming. [•] The unique and pristine native fish assemblages were greatly impacted by damming. [•] Modified F-IBI showed the change of biological integrity associated with damming. [•] The biotic homogenization of fish assemblages increased dramatically after damming. [•] Dam can lead to fish diversity loss, native fish fragmentation and extirpation. [ABSTRACT FROM AUTHOR]

Highlights: [•] The phytoplankton assemblages were investigated before and after cascading dams. [•] The phytoplankton assemblages were sensitive in the aquatic ecosystem. [•] The P-IBI showed the biological integrity associated with cascading dams. [•] The habitat and longitudinal connectivity of river were destroyed by cascading dams. [•] Cascading dams can induce accumulation effect on the aquatic ecosystem. [ABSTRACT FROM AUTHOR]

Quantifying the carbon storage of grasslands under different management strategies can help us understand how this ecosystem responds to different land management practices. To assess the C cycle and the importance of soil microbial biomass carbon, we measured the levels of soil organic carbon, biomass carbon (above- and underground) and soil microbial biomass carbon in areas with different grazing intensities and different management strategy (fenced and unfenced) in the Qinghai-Tibetan Plateau. We also calculated the ratio of soil microbial biomass carbon to soil organic carbon as an indicator of the soil organic matter availability and quality. Results showed that degradation had significant effects on the soil organic carbon, biomass carbon and microbial biomass carbon (P < 0.05). However, fencing only had a significant effect on the non-degraded and moderately degraded grasslands (P < 0.05). We also found that the level of soil microbial biomass carbon was positively correlated with the biomass carbon and soil organic carbon. From our research, we concluded that the level of soil microbial biomass carbon was crucial to the C cycle in the alpine grasslands and that fencing may be an important management strategy for restoring lightly or moderately degraded grassland in the Qinghai-Tibetan Plateau. [Copyright &y& Elsevier]

The Qinghai-Tibet Plateau (QTP) is experiencing increasing nitrogen (N) deposition, which may have great impacts on the physical, chemical, and biological factors that determine the stabilization of soil organic carbon (SOC). However, few studies have been conducted to quantify the relative contributions of these factors to SOC stabilization at various N addition levels in alpine habitats. We established a N manipulation experiment from 2015 to 2016 in an alpine meadow on the QTP to examine the impacts of N addition gradients on SOC stabilization under different scenarios of N deposition including 8, 24, 40, 56, and 72 kg N ha−1 yr−1. Using solid-state 13C NMR spectroscopy, we assessed the changes in the chemical composition of SOC. We measured soil aggregate size fractions, iron ions, soil microbes, and soil chemicals to investigate their contributions to SOC stabilization. We found that there were response thresholds of SOC to N addition in this alpine meadow on the QTP. The critical level of N addition for the change of SOC was close to 16 kg N ha−1 yr−1 plus the natural atmospheric N deposition (approximately 8 kg N ha−1 yr−1). N addition affected SOC stabilization in this alpine meadow mainly by affecting soil aggregates and soil microbes. These results of this study suggest that an exogenous N input lower than the critical load is beneficial for C sequestration in this alpine meadow on the QTP. This is potentially important for understanding the influences of atmospheric N deposition on soil properties, with subsequent effects on SOC stabilization on the alpine meadow of QTP and similar fragile ecosystems worldwide. • There were response thresholds of SOC to N input in alpine meadows. • The critical load of N input was close to 16 kg N ha−1 yr−1 for SOC change. • N input affected SOC stability mainly by affecting soil aggregates and microbes. [ABSTRACT FROM AUTHOR]

Aims: To determine the effect of grassland degradation on the soil carbon pool in alpine grassland. Methods: In this study, we calculated the carbon pool in the above-and below-ground biomass, the soil microbial biomass carbon pool, the total organic carbon pool and the soil total carbon. Results: Grassland degradation has resulted in decreases in biomass and carbon content and has changed the ratio of roots to shoots. However, there was less influence of degradation on dead root biomass. There was most likely a lag effect of changes in dead root biomass following grassland degradation. In the alpine grassland ecosystem, the carbon pool in soil accounts for more than 92 % of the total carbon both in vegetation and soil. The carbon in alpine grassland is stored primarily in the form of total organic carbon below-ground. As organic carbon decreases, the ratio of the microbial biomass carbon pool to the total organic carbon pool increases and then declines with increasing degradation level. Along the grassland degradation gradient, the total vegetation biomass (above-and below-ground) and the soil carbon pool (microbial biomass C, total organic C and total C) all decreased. [ABSTRACT FROM AUTHOR]

The deterioration of alpine grassland has great impact on ecosystem services in the alpine region of Qinghai-Tibetan Plateau. However, the effect of grassland degradation on ecosystem services and the consequence of grassland deterioration on economic loss still remains a mystery. So, in this study, we assessed four types of ecosystem services following the Millennium Ecosystem Assessment classification, along a degradation gradient. Five sites of alpine grassland at different levels of degradation were investigated in Guoluo Prefecture of Qinghai Province, China. The species composition, aboveground biomass, soil total organic carbon (TOC), and soil total nitrogen (TN) were tested to evaluate major ecological services of the alpine grassland. We estimated the value of primary production, carbon storage, nitrogen recycling, and plant diversity. The results show the ecosystem services of alpine grassland varied along the degradation gradient. The ecosystem services of degraded grassland (moderate, heavy and severe) were all significantly lower than non-degraded grassland. Interestingly, the lightly degraded grassland provided more economic benefit from carbon maintenance and nutrient sequestration compared to non-degraded. Due to the destruction of the alpine grassland, the economic loss associated with decrease of biomass in 2008 was $198/ha. Until 2008, the economic loss caused by carbon emissions and nitrogen loss on severely degraded grassland was up to $8 033/ha and $13 315/ha, respectively. Urgent actions are required to maintain or promote the ecosystem services of alpine grassland in the Qinghai-Tibetan Plateau. [ABSTRACT FROM AUTHOR]

A field replacement experiment was used to study the interspecific interaction among three perennial grasses ( Elymus nutans, Festuca sinensis and Festuca ovina) that are distributed widely on the east Qinghai-Tibetan plateau. The experiment consisted of four different species mixtures at four seeding densities and two fertilizer levels. Above-ground biomass, relative yield and complementary effect were determined from harvested shoot dry weights. The results showed that above-ground biomass was greater in all species mixtures than in monocultures. The difference between the observed and expected relative yield was greater than zero in all mixtures for E. nutans and was greater than zero in the F. sinensis/F. ovina mixture, but was below zero in all other mixtures for F. sinensis, and was below zero in all mixtures for F. ovina. The complementary effect was more negative across all seeding densities except at a seeding density of 400 seeds/m2, and was negative across all mixtures except the F. sinensis/F. ovina mixture. In addition, fertilization had an insignificant impact on the relative yield, but a significant impact on the complementary effect. Fertilization enhanced negative interspecific interaction among the species. [ABSTRACT FROM AUTHOR]

Ten case studies from seven major pastoral regions across six continents were studied in this paper by conceptualizing three factors (agro-ecosystem resilience, livelihood options, and institution capacity) as the axes of a three-dimensional vulnerability framework. This analysis highlights the vulnerability of agriculture-based livelihood systems to global changes and helps identify what institutions have the potential to mobilize effective relief in different pastoral regions. In terms of results, this vulnerability assessment shows that the vulnerability of pastoralism was very different in all the cases across the globe. As such, a further analysis, based on the pressure-state-response (PSR) model was undertaken to enhance our understanding of the ways that global changes put pressures on pastoral livelihoods worldwide. From this we conclude that climate change and climate variability are driving fragile pastoral ecosystems into more vulnerable conditions. Socioeconomic factors, such as changes in land tenure, agriculture, sedentarization, and institutions are fracturing large-scale pastoral ecosystems into spatially isolated systems. The implications of this analysis are that professionals, practitioners, and policy makers should jointly develop a coupled human and natural systems approach that focuses on enhancing the resilience of pastoral communities and their practices. This requires institutional developments to support asset building and good governance to enhance adaptive capability. In addition, pastoralists' adaptation strategies to global change need to be supported by public awareness and improved by institutional decisions at different scales and dimensions. [ABSTRACT FROM AUTHOR]

The relative competitive abilities of Elymus nutans, Festuca sinensis and Festuca ovina were studied in the east Qinghai-Tibetan plateau. Emergence percentage, numbers of plants established, establishment rate and the relative competitive intensity (RCI) based on harvested shoot biomass were measured for the three species as monocultures and in all possible combinations of mixtures in four randomised complete blocks. In the seedling stage, ANOVA showed that emergence percentage was density independent and was greatest for E. nutans, somewhat lower for F. sinensis, and least for F. ovina. The multiple comparisons (Tukey HSD) showed that the emergence percentage was significantly different among the three species. In the adult stage, the result of correlation analysis showed that the establishment rate of a species was density dependent. The multiple comparisons show that the established numbers and establishment rate were significantly different among the three species. At the same time, the competitive ability between E. nutans and F. sinensis and between E. nutans and F. ovina was significantly different, and between F. sinensis and F. ovina was not significantly different based on the RCI. The relative competitive ability of a species depended on density. For low densities, E. nutans was most competitive, followed by F. ovina and lastly by F. sinensis. In higher densities, the competitive order was reversed. E. nutans was most competitive, followed by F. sinensis and, lastly by F. ovina. A three-way ANOVA on RCI showed that clipping and fertilisation changed the competition intensity among the three species but did not change the relative competitive order in mixtures. [ABSTRACT FROM AUTHOR]

Abstract: Rangelands represent one of the most important natural resources in mountainous regions of northern Nepal. However, a poor understanding of the social dimensions of rangeland use has limited their proper management and sustainable development, which represent major challenges for Nepal''s resource managers. Institutional development is thought to be a viable solution to this problem and may ultimately lead to improved rangeland management in Nepal. Based on this hypothesis, a study was conduced in the Rasuwa district of northern Nepal to examine the effectiveness of institutional development at the local and national levels in mitigating the problems facing sustainable rangeland management by using an institutional analysis and development (IAD) framework. The information and data were mainly collected from different stakeholders, farmers, professionals and practitioners using a toolkit of participatory rural appraisal (PRA), workshops and literature review. It can be concluded from this case study that a number of institutional development efforts are needed to promote sustainable rangeland management in this region. First, local herders represent a repository of rich indigenous knowledge essential to sustaining sound rangeland management practices; hence, indigenous practices need to be integrated into modern technologies. Second, public services and technical support are currently unavailable or inaccessible to local herders; hence, research, development and extension interventions need to be initiated for marginalized pastoral communities. Third, rangeland institutions are incomplete and ill-organized, so institutional development of various organizations is necessary for promoting sustainable rangeland management. Fourth, the policies and governance necessary for promoting rangeland management are not well-designed; hence, governance reform and policy development need to be formulated through internal and external agencies and organizations. [Copyright &y& Elsevier]

• Responses of different functional groups to overgrazing and overgrazing with N deposition varied. • Overgrazing and overgrazing with N deposition provided a favorable living environment for forbs. • Overgrazing with N deposition obviously promoted forbs dominance both directly and indirectly. Alpine grasslands are sensitive to grazing and atmospheric nitrogen (N) deposition. Despite increases in N deposition, few field studies have assessed the effects of grazing in conjunction with increased N deposition on alpine grassland vegetation. In this two-year field study, we examined the effects of overgrazing and overgrazing plus N deposition on eco-physiological processes of alpine grassland plants at the functional group level. We found that both overgrazing and overgrazing plus N deposition altered species composition and the dominance of three plant functional groups (grasses, sedges, and forbs) in an alpine meadow and alpine steppe. In the overgrazing and overgrazing plus N deposition treatments, forbs dominated the plant community. Grass and sedge dominance decreased substantially, relative to a ungrazed treatment. The underlying eco-physiological processes that led to the forb-dominated plant community differed between the overgrazing and overgrazing plus N deposition treatments. Overgrazing plus N deposition increased forb dominance both directly by selective herbivory and indirectly by enhancing forb photosynthetic rates. Our results suggest that overgrazing concomitant with increases in N deposition will likely shift the plant community composition of alpine grasslands on the Qinghai-Tibetan Plateau from grass/sedge communities to forb-dominated communities in the future. [ABSTRACT FROM AUTHOR]

• In restoring grassland bacterial biodiversity decreased, while fungi did not change. • Functional groups of microbial were more similar to healthy grassland. • Microbes become stronger and more connected as succession progressed. Numerous restoration measures have been implemented to rebuild degraded alpine grasslands on the Qinghai-Tibetan Plateau, one of the most fragile regions in the world. Understanding the responses of soil microbes to restoration activities is critical to predict restoration direction and trajectories, as soil microbes play a key role in ecosystem functioning and nutrients cycling. In this study, we identified the effects of revegetation on soil microbial community composition and diversity, and the interaction between bacterial and fungal taxa in different successional stages (early stage, middle stage, late stage) by using a severely degraded grassland as the baseline, and healthy grassland as the target. Our results show that the composition of bacteria at phylum level and fungi at class level were significantly changed between successional stages. The diversity of bacteria at OTU level was significantly decreased, while the diversity of fungal OTUs were not significantly changed with successional stages. Plant and soil properties explained 53.15% variation of bacterial structure and 46.16% variation of fungal structure. Plant community, soil organic carbon, total nitrogen, and soil pH mainly influence microbial community during recovery process. Bacterial and fungal groups would become more similar to that of the healthy grassland along successional stages, because of the shift in soil resources and plant community. Total links and negative links of bacteria-fungi interaction networks increased along successional stages of revegetated grasslands. Keystone species in each network also changed with successional stages. These findings verified that revegetation could be effective to restore the microbial community of severely degraded grassland on the Qinghai-Tibetan Plateau. [ABSTRACT FROM AUTHOR]

• Benefit for single objective varies under different management practices. • Trade-off among multiple objectives varies under different management practices. • The overall benefit does not change due to the existence of trade-off. Developing sustainable management practices for alpine grassland on the Qinghai-Tibetan Plateau is a key challenge related to the protection of regional ecological environments, the provision of husbandry production and the improvement of pastoralist welfare. This challenge requires researchers and policymakers to seek options that optimize benefits among multiple objectives in ecological, productivity and livelihood dimensions. In this study, we developed a novel tool to value the overall benefits and trade-offs of ecological protection, livestock production and pastoral welfare from four types of grassland management practices mainly used on the Qinghai-Tibetan Plateau: individual grassland management (IGM), joint household grassland management (JHGM), shareholding cooperative grassland management (SCGM) and communal grassland management (CGM). The results showed that JHGM led to the highest ecological benefits, while CGM led to the highest benefits for livestock production and livelihood welfare. SCGM resulted in the lowest level of trade-offs as well as relatively high total benefits among multiple objectives in the ecological, productivity and livelihood dimensions. The results of this study provided empirical evidence that the effect of trade-offs among multiple objectives varied with different grassland management practices. We argue that grassland management practices may be biased if a single objective (i.e., ecological protection, livestock production provision or pastoral welfare improvement) is stressed due to the high level of trade-offs among them. The SCGM showed great potential to balance multiple objectives if properly designed. [ABSTRACT FROM AUTHOR]

• Grassland cultivation and fencing promoted EMF of the degraded alpine steppe. • Plant community composition was more correlated with EMF than soil community composition. • Biotic and abiotic factors together could explain more EMF than biotic factors alone. Alpine steppe is one of the most important grassland ecosystems on Qinghai-Tibetan Plateau (QTP), which has been greatly degraded in past decades. However, few studies have paid attention to the ecosystem multifunctionality (EMF) of restored degraded alpine steppes. Four treatments of alpine steppes (degraded alpine steppes, cultivated alpine steppes, fenced alpine steppes and intact alpine steppes) were investigated to explore the effect of treatment, biotic (above- and belowground community composition) and abiotic factors (pH and soil moisture) on restoring nine ecosystem functions (above- and belowground plant biomass, plant nitrogen content, soil organic carbon, soil nitrogen, soil phosphorus, soil microbial biomass carbon, microbial biomass nitrogen and microbial biomass phosphorus) and EMF of alpine steppe ecosystem in Madoi County of Qinghai Province, China. Our results showed that both grassland cultivation and fencing significantly promoted EMF of the degraded alpine steppes. Aboveground plant community composition was more significantly correlated with EMF of the alpine steppes than belowground soil community composition in the process of ecological restoration. Combining abiotic factors with biotic factors could improve the ability to explain EMF than biotic factors alone. Overall, aboveground community composition and soil moisture played determining roles in restoring EMF of alpine steppes. [ABSTRACT FROM AUTHOR]

Increased nitrogen (N) deposition can affect ecosystem processes and thus influence plant eco-physiological processes in grasslands. However, how N deposition affects eco-physiological processes of leguminous and non-leguminous forbs in alpine grasslands is understudied. A long-term field experiment using a range of simulated N deposition rates (0, 8, 24, 40, 56, and 72 kg N ha−1 year−1) was established to examine the effects of N deposition on various eco-physiological parameters in leguminous and non-leguminous forbs in an alpine meadow of the Qinghai-Tibetan Plateau. We found that the responses of leguminous and non-leguminous forbs to simulated N deposition varied. Net photosynthetic rate of leguminous and non-leguminous forbs exhibited different response patterns, but chronic increases in simulated N deposition rates may lead to negative effects in both functional groups. Neither functional group responded differently in aboveground biomass under the highest N addition level (72 kg N ha−1 year−1) compared to the control. Differences in aboveground biomass of leguminous forbs were observed at intermediate N levels. Short-term simulated N deposition significantly promoted N uptake of both functional groups. In leguminous forbs, simulated N deposition affected net photosynthetic rates (P N) and aboveground biomass (AGB) mainly via stomatal conductance (g s), water use efficiency (WUE), and plant N uptake. In non-leguminous forbs, simulated N deposition affected P N and AGB mainly through WUE and plant N uptake. Our findings suggest that leguminous and non-leguminous forbs have differential response mechanisms to N deposition, and compared with non-leguminous forbs, leguminous forbs are more sensitive to continuing increased N deposition. The obvious decline trend in photosynthetic capacity in leguminous forbs is likely to exacerbate the already divergent ecological processes between leguminous and non-leguminous forbs. More importantly, these changes are likely to alter the future composition, function, and stability of alpine meadow ecosystems. Unlabelled Image • Leguminous and non-leguminous forbs have differential response mechanism to N deposition. • Leguminous forbs are more sensitive to N deposition compared with non-leguminous forbs. • Leguminous productivity is susceptible to chronic elevating N deposition. [ABSTRACT FROM AUTHOR]