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The species number of bryophytes is the second highest among land plants. Alpine grasslands on the Qinghai–Tibet Plateau (QTP) are the largest among global alpine biomes. However, bryophyte flora in alpine grasslands on the QTP remains poorly explored relative to its large geographic extent. A total of 347 plots were surveyed across the QTP, and 149 bryophyte taxa in 24 families and 49 genera were recorded in alpine grasslands. The largest family was Pottiaceae, followed by Bryaceae and Brachytheciaceae. The most species-rich genus was Bryum, followed by Didymodon and Brachythecium. The dominant species were Didymodon tectorus, Didymodon fallax, Bryum caespiticium, Didymodon constrictus, and Didymodon ditrichoides. The Jaccard similarity indexes of bryophyte compositions between alpine meadow and alpine steppe at the family, genus, and species levels were 0.375, 0.367, and 0.282, respectively. Turf was the most common life-form (75.2%), followed by weft (16.1%) and cushion (5.4%). Endemic species to China accounted for 8.05% of the total taxa. Bryophyte diversity in alpine grasslands on the QTP is exceptional and irreplaceable. The changes in species composition and life-forms between different grassland types reflect the adaptations of bryophytes to harsh environments. [ABSTRACT FROM AUTHOR]

Nitrogen is the crucially sustainable element for most ecosystem including grassland. Fenced alpine meadow grassland (FG), lightly, moderately and heavily degraded (LD, MD and HD) alpine meadow in spring, summer and winter were studied to clear the effects of alpine meadow degradation on soil total nitrogen (TN), available nitrogen (AN), ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3–-N), inorganic nitrogen (IN) content and the ratio of inorganic nitrogen to available nitrogen (IN/AN), and to find practical management strategies on the background of alpine meadow degradation and ecological environment restoration in the Eastern Qilian Mountains area, northwest China. The results showed that soil total nitrogen contents of the alpine meadow types were at a low level, ranged from 1.60 g·kg−1 to 5.15 g·kg−1, but soil available nitrogen contents was at a high level, ranged from 373.2 mg·kg−1 to 650.8 mg·kg−1in the study area. Alpine meadow degradation can seasonally change soil nitrogen status. Degraded alpine meadow had more inorganic nitrogen than fenced meadow in surface soil. Degradation only changed soil NO3−-N profile distribution in winter and had no significant effect on profile distribution of TN, AN, NH4+-N and IN. There were significant interactions of alpine meadow types, seasons and soil depth on soil available nitrogen, NH4+-N, NO3–-N and inorganic nitrogen content. Although soil available nitrogen increased under degradation, nitrogen input is needed in the restoration of heavily degraded alpine meadow during the summer growing season to improve vegetation coverage because of the low soil inorganic nitrogen and IN/AN ratio in summer growing season in 10–20 cm and 20–30 cm depth. [ABSTRACT FROM AUTHOR]

Question: Patchiness of herbaceous species is a common feature of degraded alpine grasslands on the Qinghai–Tibet Plateau; however, the impact of this phenomenon on vegetation, soil seed bank (SSB), and soil carbon (C) and nitrogen (N) is largely unknown. We asked how different herbaceous patches affect above‐ground vegetation, the SSB and soil organic C (SOC) and total N (TN) contents in alpine meadows. Location: An alpine meadow on the Qinghai–Tibetan Plateau, China. Methods: We used field and greenhouse experiments to evaluate above‐ground vegetation parameters, the SSB composition, and SOC and TN contents of four commonly distributed herbaceous patches (Leymus secalinus, Kobresia humilis, Leontopodium nanum and Pedicularis kansuensis) and non‐patch vegetation (control). Results: There were significant differences in the species composition of above‐ground vegetation, with the plant species richness, Shannon–Wiener index, Simpson index, and Pielou evenness index reduced in the four patches compared to the control. In addition, patches had increased above‐ground biomass (AGB) and a lower below‐ground biomass to above‐ground biomass ratio (BGB:AGB); while the species diversity indices did not change considerably among the patches. The species composition of the SSB in the four patches differed from that in the control and the seed density increased markedly, but the species richness and diversity of the SSB remained unaltered. Moreover, the contents of SOC, total C, TN, microbial biomass C, and microbial biomass N in the four patches were markedly lower than in the control. Conclusions: These findings suggest that patchiness of herbaceous species can alter the flora composition of alpine meadows and reduce plant species diversity, as well as the SOC and TN contents, which will adversely impact grassland biodiversity conservation and soil C sequestration, and then may intensify the degradation of alpine meadows on the Qinghai–Tibet Plateau. [ABSTRACT FROM AUTHOR]

The relationship between biodiversity and ecosystem multifunctionality (EMF) is critical to understanding the dynamics of ecosystem services. Several studies have investigated alterations in multiple ecosystem functions under grassland degradation and its relationship with taxonomic diversity. However, how multidimensional biodiversity (taxonomic, functional, and phylogenetic diversity) and abiotic factors mediate EMF in degraded alpine meadows has yet to be well been explored. In this study, alpine meadows with different degrees of degradation were investigated in Maqu County, Gansu Province, China. The average and multi‐threshold methods were used to quantify EMF, while structural equation modeling (SEM) was used for statistical analysis. The results show that: (1) Degradation of alpine meadows has altered the species composition and diversity of plant communities. (2) Taxonomic, functional, and phylogenetic diversity were all significantly and positively correlated with EMF, and species richness, functional richness and Faith's PD effectively drive EMF within thresholds of 22%–75%, 20%–86% and 42%–72%, with maximum effects of 0.29, 0.33 and 0.12, respectively. (3) Degradation of alpine meadows directly and significantly reduced EMF, and mediated indirectly through plant diversity and soil abiotic factors. The multifunctionality index for different degrees of degradation showed non‐degraded (60.89) > light degraded (37.84) > moderate degraded (−14.17) > heavy degraded (−48.55). The results of this study reveal the relative importance of multidimensional plant diversity in predicting EMF of degraded alpine meadows, and potential mechanisms by which plant diversity and abiotic factors mediate the effects of alpine meadow degradation on EMF. [ABSTRACT FROM AUTHOR]

Over recent decades, there has been a severe nitrogen-deposition in alpine meadows which often leads to phosphorus limitation of plant productivity. In these high-altitude localities, Cyperaceae have an increasing biomass while other functional groups decrease. Meanwhile, Cyperaceae are known to have the ability of producing dauciform roots, which are formed under phosphorus limitation, but in China, are only described in these high-altitude places. So, is the superiority of Cyperaceae and the formation of dauciform roots in high-altitude localities related to the accumulation of nitrogen? And is there a link between them? A Carex filispica dominated community in Baima Snow Mountain was selected and quantitative fertilization with four levels of nitrogen and three levels of phosphorus was performed. After 2 weeks, Carex filispica individuals with and without dauciform roots were separated and analyzed for their regular root properties, dauciform root properties, biomass and chemical traits of above- and belowground parts. The total cover of the community declined under phosphorus limitation with increasing nitrogen supply, while the relative cover difference of Carex filispica increased with increasing nitrogen supply and decreased with increasing phosphorus supply. Dauciform roots had a more significant response to nitrogen supply than to phosphorus supply and they were formed the most at a low supply of nitrogen. The biomass and root properties of individuals with dauciform roots were enhanced by nitrogen supply and inhibited by phosphorus supply, while those of individuals without dauciform roots were often enhanced by phosphorus supply. Individuals with and without dauciform roots showed two different mechanisms, and were limited by significantly different factors, which can explain the opposite performance of Cyperaceae after nitrogen and phosphorus supply in previous studies. [ABSTRACT FROM AUTHOR]

Light use efficiency (LUE) is a crucial indicator used to reflect the ability of terrestrial ecosystems to transform light energy. Understanding the long-term trends in LUE and its influencing factors are essential for determining the future carbon sink and carbon sequestration potential of terrestrial ecosystems. However, the long-term interannual variability of LUE in grasslands in northern China at the ecosystem scale is poorly understood due to the limitations of the year length and the coverage of the site data. In this study, we assessed the long-term LUE trends in the grasslands of northern China from 1982 to 2018 and then revealed the relationships between interannual variability in LUE and climate factors. Our study showed a substantial rising trend for LUE from 1982 to 2018 in the grasslands of northern China (3.42 × 10−3 g C/MJ/yr). Regarding the different grassland types, alpine meadow had the highest growth rate (4.85 × 10−3 g C/MJ/yr), while temperate steppe had the lowest growth rate (1.58 × 10−3 g C/MJ/yr). The climate factors driving LUE dynamics were spatially heterogeneous in grasslands. Increasing precipitation accelerated the interannual growth rate of LUE in temperate steppe, and increasing temperature accelerated the interannual growth rate of LUE in other types. In addition, the temporal dynamic of LUE showed different trends in relation to time scales, and the growth trend slowed down after 1998. Our results should be considered in developing future grassland management measures and predicting carbon cycle–climate interactions. [ABSTRACT FROM AUTHOR]

Overgrazing leads to grassland degradation and productivity decline. Rest‐grazing during the regreen‐up period can quickly restore grassland and fertilization is a common restoration strategy. However, the effects of rest‐grazing time and fertilization on soil microorganisms are unclear in the alpine grasslands. Therefore, the experiment of rest‐grazing time and fertilization was carried out to explore the response of soil microorganisms to rest‐grazing time and fertilization measures. A field control experiment with rest‐grazing time and fertilization as factors have been conducted from the time when grass returned to green till the livestock moved to the summer pasture in Dawu Town of Maqin County of China. The primary treatment we established was the five rest‐grazing time, including rest‐grazing time of 20 days, 30 days, 40 days, 50 days, and traditional grazing was used as a check group. At the same time, the secondary treatment was nitrogen addition of 300 kg·hm−2 in each primary treatment. The results showed that the total phospholipid fatty acid (total PLFA), actinomyces (Act), and arbuscular mycorrhizal fungi (AMF) showed an ever‐increasing biomass with the increase of rest‐grazing time and the highest was at 50 days of rest‐grazing, and they were all significantly higher than CK. In addition, soil microbial biomass carbon‐nitrogen ratio (MBC/MBN) had great influence on the change of microbial community. Applying nitrogen fertilizer can increase the maximum value of biomass of all PLFA groups and the biomass of all PLFA groups changed in an "inverted V" shape with the increase of rest‐grazing time. Besides, instead of MBC/MBN, NO3−‐N was positively correlated with the biomass of all PLFA groups, which actively regulated the trend of microbial functions. The longer rest‐grazing time is more conducive to the biomass of all PLFA groups. However, applying nitrogen fertilizer could break this pattern, namely, the 30 days rest‐grazing would be beneficial to the biomass of all PLFA groups. These findings provide key information that rest‐grazing during the regreen‐up period is benefiscial to the all PLFA groups and fertilization could change the response of microorganisms to rest‐grazing, which provide reference measures for the restoration of degraded alpine meadows. [ABSTRACT FROM AUTHOR]

In the natural habitats of China, dauciform roots were only described in degraded alpine meadows. It was found that the presence of dauciform roots of Carex filispica was related to the advantage of multiple functional traits after trampling, reflecting short‐term resistance. However, the long‐term response of dauciform roots to trampling and the recovery of C. filispica with and without dauciform roots to trampling require further studies. In this study, different intensities of trampling (0, 50, 200 and 500 passages) were performed in an alpine meadow. One year later, individuals with and without dauciform roots were separated and their functional traits related to the economic spectrum of leaves and roots were measured as a reflection of recovery from trampling. The results showed that: (1) 1 year after trampling, the number of dauciform roots showed an increase with trampling intensity; (2) 1 year later, there was no significant difference in the response of economic spectrum traits among trampling intensities, or between plants with and without dauciform roots; (3) the number of dauciform roots was positively correlated with the leaf area of both individuals with and without dauciform roots, as well as with the biomass of those without dauciform roots; and (4) plants with more resource‐conservative roots showed an advantage after trampling recovery: specifically, plants with dauciform roots showed such an advantage in the control group, which was lost with a leaning towards resource‐acquisitive roots and an increased density of dauciform roots once trampled. In contrast, plants without dauciform roots showed a significant advantage of conservative roots only after trampling. In conclusion, the presence of dauciform roots is related to the plants' position on the root economic spectrum, thereby influencing the recovery of C. filispica from trampling. Carex filispica showed strong recovery from trampling after 1 year, which makes it an adequate choice for ecological restoration in alpine meadows. Dauciform roots showed a positive correlation with the aboveground growth of both plants with and without them, however, it requires a lab‐controlled study to confirm whether there is indeed a positive effect on the growth of neighbouring plants. [ABSTRACT FROM AUTHOR]

Over recent decades, there has been a severe nitrogen-deposition in alpine meadows which often leads to phosphorus limitation of plant productivity. In these high-altitude localities, Cyperaceae have an increasing biomass while other functional groups decrease. Meanwhile, Cyperaceae are known to have the ability of producing dauciform roots, which are formed under phosphorus limitation, but in China, are only described in these high-altitude places. So, is the superiority of Cyperaceae and the formation of dauciform roots in high-altitude localities related to the accumulation of nitrogen? And is there a link between them? A Carex filispica dominated community in Baima Snow Mountain was selected and quantitative fertilization with four levels of nitrogen and three levels of phosphorus was performed. After 2 weeks, Carex filispica individuals with and without dauciform roots were separated and analyzed for their regular root properties, dauciform root properties, biomass and chemical traits of above- and belowground parts. The total cover of the community declined under phosphorus limitation with increasing nitrogen supply, while the relative cover difference of Carex filispica increased with increasing nitrogen supply and decreased with increasing phosphorus supply. Dauciform roots had a more significant response to nitrogen supply than to phosphorus supply and they were formed the most at a low supply of nitrogen. The biomass and root properties of individuals with dauciform roots were enhanced by nitrogen supply and inhibited by phosphorus supply, while those of individuals without dauciform roots were often enhanced by phosphorus supply. Individuals with and without dauciform roots showed two different mechanisms, and were limited by significantly different factors, which can explain the opposite performance of Cyperaceae after nitrogen and phosphorus supply in previous studies. [ABSTRACT FROM AUTHOR]

In China, dauciform roots were hardly studied and only reported in alpine meadows, where sedges showed a different tendency from other functional groups such as grasses and forbs with degradation. In addition, Carex species were proved to have shifting scaling relationships among LES (leaf economics spectrum) traits under disturbance. So, are these unique performances of sedges related to the presence of dauciform roots, and if so, how? An alpine meadow dominated by Carex filispica in Baima Snow Mountain was selected, and quantitative trampling was performed (0, 50, 200, and 500 passes). The cover and dauciform root properties of Carex filispica were measured, as well as the morphological, chemical traits and biomass of leaves and roots, their correlations and the differences between individuals with and without dauciform roots were analyzed. After the trampling, individuals with dauciform roots showed multiple resource‐acquisitive traits: Larger, thicker leaves, more aboveground biomass, higher efficiency of nutrient utilization, and slenderer roots. Additionally, they had a tighter correlation among belowground biomass, morphological and chemical traits, as well as dauciform root properties and morphology of leaves, suggesting that their traits were more related than those without dauciform roots. The presence of dauciform roots in Carex filispica was related to advantages in multiple traits after trampling, which is consistent with and might be responsible for the unique performances of sedges. [ABSTRACT FROM AUTHOR]

Background and aims: This study explores trends in soil fungal patterns, potential functions and their responses to carbon and nitrogen applications over alpine grassland succession in the Qilian Mountain area of China. Methods: The soil fungal community was characterized via Illumina sequencing of ITS genes. The FUNGuild database was used to predict functional groups in alpine grassland succession from swamp meadow to alpine meadow and steppe meadow. The levels of soil carbon and nitrogen, vegetation carbon and nitrogen, and soil enzyme activity were also assessed. Results: Soil fungal operational taxonomic units increased from swamp meadow to alpine meadow stage and then reached a relatively stable state in steppe meadow successional stage. This result is consistent with the changing trend of sobs and Chao1 index. Moreover, the soil fungal community differed significantly between different succession stages. During succession, while most phyla of soil fungi followed linear decreasing trends, Ascomycota was the dominant fungal phylum. Its abundance increased significantly, from 60.00% in swamp meadow to 72.26% in steppe meadow. The relative abundances of Pathotroph and Saprotroph fungal functions increased with successional stages, while Symbiotroph did not change significantly. Soil ammonium nitrogen and organic carbon levels dominated the effect on the soil fungal microbial community and functional groups. Conclusion: These findings indicate that the fungal community shifted dramatically in the first stage(swamp to alpine meadow) of succession but then reached a relatively stable state in the second(alpine to steppe meadow) successional stage. The soil fungal function group did not follow the same successional trajectory. Soil ammonium nitrogen and soil organic carbon levels imposed the strongest influence on the fungal community and its function, respectively. [ABSTRACT FROM AUTHOR]

Gynaephora alpherakii (G. alpherakii) is one of the dominant pests in the alpine meadow; its outbreak has substantial impacts on grass vegetation production and carrying capacity. The increasing frequency of G. alpherakii outbreaks will take place with global warming and human activities. Therefore, it is crucial to identify inhabitable areas to apply prevention measures efficiently and facilitate sustainable grassland management. In this study, field measurements of G. alpherakii (from 2010 to 2021) were used to explore the relationships between its density and environmental factors in the National Park of Qilian Mountain, China. Then, the inhabitability area was mapped. The results showed that (1) eight of the twenty-five factors studied (average and maximum value of solar radiation; minimum, standard deviation, and average value of normalized difference vegetation index (NDVI); maximum precipitation; and digital elevation model) had a greater influence on G. alpherakii density. (2) Among all of the estimation models, models based on the average of solar radiation, the minimum of NDVI, and the maximum precipitation were better than other factors, with a higher determination coefficient (R2) of 0.53–0.66 and a lower root mean square error (RMSE) of 40.54–47.32 head/m2. Models based on rest factors had a lower accuracy, with R2 within 0.38–0.49 and an RMSE of 50.91–58.68 head/m2. (3) The inhabitable area which was most suited for G. alpherakii growth, development, and frequent outbreaks was located in the northeast of the research area (24.72%), with inhabitability decreasing from southeast to northwest. This method is helpful for clarifying the distribution regions and occurrence dynamics of the G. alpherakii in the alpine meadow. The spatial distribution of G. alpherakii in the National Park of Qilian Mountain can also be clearly defined by using this method, which can provide data support for its prevention and control. [ABSTRACT FROM AUTHOR]

The Three Rivers Source Region (TRSR) is a natural habitat for rare animals and a genetic treasure trove of plateau organisms. It is an important eco-safety barrier in China and even Asia, and a priority of China's to promote ecological advancement. Precisely assessing the dynamics and mechanisms of alpine grassland ecosystem carbon budgets is beneficial for quantifying the response to climate change on a regional scale. The spatial distribution and dynamic changes in carbon fluxes in the TRSR from 1985 to 2018 were analyzed by the Theil–Sen + Mann–Kendall and ensemble empirical mode decomposition (EEMD) methods, and multiple linear regression was used to quantify the contribution of meteorological elements to the carbon flux trends. The results indicated that (1) the alpine grassland ecosystem was a weak carbon sink. The multiyear mean gross primary production (GPP) and net ecosystem production (NEP) in the TRSR were 147.86 and 11.27 g C/m2/yr, respectively. The distribution of carbon fluxes progressively decreased from east to west. (2) The carbon fluxes of the alpine grassland ecosystem were dominated by a monotonically increasing trend, with increasing rates of GPP and NEP of 1.31 and 0.40 g C/m2/yr, respectively. A total of 48.60% of the alpine grassland showed a significant increase in NEP, whereas only 0.21% showed a significant decrease during the research term. (3) The alpine meadow sequestered carbon better than the alpine steppe did and accounted for more than 60% of the regional carbon sink. (4) In a correlation analysis between NEP and temperature, precipitation and solar radiation, the positive correlation accounted for 89.67%, 90.51%, and 21.16% of the TRSR, respectively. Rising temperatures and increased precipitation were the main drivers contributing to the increase in NEP. Research on carbon budget variability and mechanisms can help guide preservation zoning initiatives in national parks. [ABSTRACT FROM AUTHOR]

Meadow soil is a vital ecosystem component and can be influenced by meadow vegetation. Evaluating soil quality in mountain meadows subjected to different levels of tourism disturbance is essential for scientific research, ecological restoration, and sustainable management. This study aimed to evaluate meadow soil quality at different tourism-disturbance levels and attempted to establish a minimum data set (MDS) with compatible indicators for soil quality assessment of subtropical mountain meadows. We analyzed fifteen soil physical, chemical, and biological indicators in control check (CK), light disturbance (LD), medium disturbance (MD), and severe disturbance (SD) meadow areas in Wugong Mountain, west of Jiangxi, China. In addition, a soil quality index (SQI) was determined using the established MDS based on the integrated soil quality index. Average soil permeability, soil pH, available nitrogen (AN), available phosphorus (AP), and number of fungal OTUs were finally introduced into the MDS to evaluate meadow soil quality at different tourism-disturbance levels. The study found that the soil of the Wugong Mountain meadow was acidic, the bulk density was loose, and the nutrient content was rich. Additionally, SQI decreased with increase in tourism-disturbance level. The mean SQI values of the Wugong Mountain meadow areas were: CK, 0.612; LD, 0.493; MD, 0.448; and SD, 0.416. Our results demonstrate that the SQI based on the MDS method could be a valuable tool with which to indicate the soil quality of mountain meadow areas, and the SQI can be regarded as a primary indicator of ecological restoration and sustainable management. [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]

During the Second Tibetan Plateau Scientific Expedition and Research Program, we discovered that white terricolous lichenized fungal species of Buellia De Not. were widely distributed across the Tibetan Plateau. After examining their morphology, chemistry and phylogeny, we describe Buellia alpina Xin Y. Wang & Li S. Wang, sp. nov. as new to science. It is present in alpine meadows, and is characterized by its effigurate thallus, distinct linear marginal lobes, cover of thick white pruina and four-spored asci. This is also the first report of Buellia elegans Poelt and Buellia epigaea (Pers.) Tuck from China. The Buellia epigaea-group has previously been characterized by white and often effigurate thalli that occur mainly on soil. However, our results show that species in this group actually belong to two distinct clades. This conclusion is based on analyses of the nulTS region and the combined regions dataset (nuITS-nuLSU-mtSSU-β-tubulin). We discuss differences in morphology, anatomy, chemistry and ecology among the putative Buellia epigaea-group. Detailed descriptions and figures for the three species from China and a key for species of Buellia epigaea-group are provided. [ABSTRACT FROM AUTHOR]

The Qinghai-Tibet Plateau (QTP) is the largest mid-to low latitude and high-altitude permafrost. Open-pit coal mining and other activities have caused serious damage to the alpine ecological environment and have accelerated the degradation of permafrost on the QTP. In this study, the influence of open-pit coal mining on the time series ground surface deformation of the permafrost in the Muli region of the QTP was analyzed from 19 January 2018 to 22 December 2020 based on Landsat, Gaofen, and Sentinel remote sensing data. The primary methods include human-computer interactive visual interpretation and the small baseline subsets interferometric synthetic aperture radar (SBAS-InSAR) method. The results showed that the spatial distribution of displacement velocity exhibits a considerably different pattern in the Muli region. Alpine meadow is the main land use/land cover (LULC) in the Muli region, and the surface displacement was mainly subsidence. The surface subsidence trend in alpine marsh meadows was obvious, with a subsidence displacement velocity of 10–30 mm/a. Under the influence of changes in temperature, the permafrost surface displacement was characteristics of regular thaw subsidence and freeze uplift. Surface deformation of the mining area is relatively severe, with maximum uplift displacement velocity of 74.31 mm/a and maximum subsidence displacement velocity of 167.51 mm/a. Open-pit coal mining had resulted in the destruction of 48.73 km2 of natural landscape in the Muli region. Mining development in the Muli region had increased the soil moisture of the alpine marsh meadow around the mining area, resulting in considerable cumulative displacement near the mining area and the acceleration of permafrost degradation. [ABSTRACT FROM AUTHOR]

Studying grassland vegetation growing seasons' spatial patterns and their environmental controls are crucial to promoting vegetation ecological restoration, formulating effective disaster prevention and reduction measures and building a stable ecological barrier. However, multi-grassland phenological factors are different, and this has not been well studied before. In this paper, the spatiotemporal patterns of the start of the growing season (SOS) and the end of growing season (EOS) in the grassland were investigated using the Normalized Difference Vegetation Index (NDVI) on the Qinghai–Tibetan Plateau (QTP) from 2000 to 2019. At the same time, we analyzed the environmental factors (including extreme, mean climate, drought, solar radiation, etc.) regulating grassland phenology under the ongoing conditions of climate change. The results show that the SOS appeared first in mountain meadow, shrub tussock, temperature steppe and desert, and then in alpine steppe and alpine meadow, showing a significant advancing tendency in all types. The EOS occurred first in the temperature steppe, alpine steppe and alpine meadow, and then in the mountain meadow, shrub-tussock and desert. Further analysis indicated that reductions in the annual lowest value of daily min temperature (TNN), annual highest value of daily min temperature (TNX) and temperature vegetation dryness index (TVDI), and increases in annual maximum consecutive 5‐day precipitation (RX5day) advanced the grassland spring phenology, whereas the increase in solar radiation (SR) delayed the grassland spring phenology. We also found that the decrease in TVDI and TNN and the increase in yearly mean value of temperature (MAT_MEAN), yearly mean value of daily maximum temperature (MAT_MAX) and yearly mean value of daily minimum temperature (MAT_MIN) advanced the autumn phenology. The EOS and its change rate advanced and increased with increasing altitude, respectively. [ABSTRACT FROM AUTHOR]

Prediction of carbon (C) sequestration in terrestrial ecosystems under climate change depends on C‐nitrogen (N) interactions. While many newly developed C‐N coupling models predict lower C storage than their C‐only counterpart models, it has not been carefully examined whether or not such model predictions would be supported by real‐world observations. This study is to retrieve knowledge on N cycle from one field warming experiment in an alpine meadow of China so that we can better predict land C sequestration. We estimated two sets of parameters with one C‐only model and one C‐N coupling model, respectively, with the data assimilation technique. Our results showed that estimated process rates (e.g., senescence and decomposition rates) of organic C from almost all pools except standing litter and leaf are higher with the C‐N coupling model than those with the C‐only model. The allocation coefficient of C to root estimated with the C‐only model was 68.0% and 56.6% smaller than that with the C‐N coupling model under the ambient and warming treatments, respectively. Both the C‐only and C‐N coupling models simulate similar C pool sizes as observed at either the ambient or warming treatment with their respective parameter estimates. Meanwhile, the warming treatment increased the slow soil organic matter (SOM) pool due to decrease in estimated decomposition rate of the slow SOM via parameter fitting and increase in the C input from surface litter. In general, our results suggest that reparameterization is required when we add N processes to a C cycle model to realistically predict the ecosystem dynamics in response to future changes in N availability. Plain Language Summary: Models with nitrogen (N) module usually predict lower carbon (C) storage than their C‐only counterpart models, but the C storage in the real‐world ecosystems won't change according to whether or not a model considers N processes. We estimated two sets of parameters with one C‐only model and one C‐N coupling model, respectively, from a field warming experiment in an alpine meadow of China with the data assimilation technique. The technique integrates observations with model via parameter estimation. We found that a model structure change from the C‐only to C‐N coupling influences model parameterization but doesn't influence the simulations. However, warming increased soil C storage due to the larger C input and the smaller decomposition rate than the control. We suggest when we add N processes to a C cycle model, the new models should be re‐parameterized, ideally with data assimilation, to better predict the ecosystem C dynamics under chaing N availability. Key Points: Model structure changes from carbon only to carbon‐nitrogen coupling often result in lowered ecosystem carbon storage and lowered carbon sequestration, which may not reflect the reality in the real‐world ecosystemsOur study with data assimilation suggested that parameter values change with model structures whereas simulated ecosystem carbon dynamics are similar under either ambient and warning conditionsNitrogen (with other elements as well) regulates carbon cycle processes mainly through its influences on parameters in this study [ABSTRACT FROM AUTHOR]

A field experiment quantifies the impacts of two external disturbances (mowing‐simulated grazing and number of pika) on aboveground biomass (AGB) in the Yellow River Source Zone from 2018 to 2020. AGB was estimated from drone images for 27 plots subject to three levels of each disturbance (none, moderate, and severe). The three mowing severities bear a close relationship with AGB and its annual change. The effects of pika disturbance on AGB change were overwhelmed by the significantly different AGB at different mowing severities (−.471 < r < −.368), but can still be identified by inspecting each mowing intensity (−.884 < r < −.626). The impact of severe mowing on AGB loss was more profound than that of severe pika disturbance in heavily disturbed plots, and the joint effects of both severe disturbances had the most impacts on AGB loss. However, pika disturbance made little difference to AGB change in the moderate and non‐mowed plots. Mowing intensity weakens the relationship between pika population and AGB change, but pika disturbance hardly affects the relationship between mowing severity and AGB change. The effects of both disturbances on AGB were further complexified by the change in monthly mean temperature. Results indicate that reducing mowing intensity is more effective than controlling pika population in efforts to achieve sustainable grazing of heavily disturbed grassland. [ABSTRACT FROM AUTHOR]

The Qinghai–Tibet Plateau (QTP) has an important function in ensuring the water ecological security of China, even Asia, and the soil water storage of alpine grassland is an important part of the ecosystem water. Grassland degradation directly affects the soil water storage capacity. However, the impact of degradation on specific soil storage capacity, especially alpine shrubs, is rarely studied. Here, we chose two plots of alpine non-degraded shrub and degraded shrub, using the automatic soil moisture monitoring system to study the change process of soil moisture storage, and then adopted the boosted regression tree (BRT) model to quantitatively evaluate the relative influence of environmental variables on soil water storage. Our results show: (1) The soil water storage in the growing season (May–September) is higher than that in the non-growing season (January–April and October–December), and the soil water storage reaches its highest in mid-July. (2) During the growing season, the 100 cm soil temperature was the most important factor affecting the seasonal variation in soil water storage, accounting for 51% of the total variation. During the non-growing season, the 40 cm soil temperature was the most important factor affecting the variation in soil water storage, accounting for 80% of the total variation. (3) The soil water storage of non-degraded Potentilla fruticosa shrub meadow increased by 6–25%, compared with degraded grassland shrub meadow during growing-season. (4) Various meteorological factors have a weak impact on soil water storage. [ABSTRACT FROM AUTHOR]

The assessment of ecosystem services provides an intuitive source of information on the benefits humans derive from ecosystems. The equivalent factor method was applied to calculate the ecosystem service value (ESV) in combination with net primary productivity (NPP) calculated by the process-based Carnegie–Ames–Stanford approach (CASA) model. This study evaluated grassland ESV and its spatial evolution characteristics in China from 2001 to 2020 and revealed the impact of climate factors. For 2001–2020, the annual grassland ESV ranged from 1.17 × 1012 to 1.51 × 1012 yuan (renminbi, China yuan—the same below; $0.15 × 1012–$0.20 × 1012, US dollar), with an average of 1.37 × 1012 yuan ($0.18 × 1012). The spatial pattern of ESV per unit area of grassland was notably characterized by an increase from northwest to southeast. However, the value of grassland ecosystem services was relatively large (exceeding 10 × 106 yuan; $1.30 × 106) in northern and western provinces and was the lowest (less than 0.2 × 106 yuan; $0.03 × 106) in eastern and southern provinces. In the last 20 years, grassland ESV has increased in most areas of China and has decreased only in some western and northern areas. Compared with the first 10 years, the average ESV of grassland in most areas increased in the last 10 years, usually by less than 20%. However, it decreased in the western and northern parts of China, mainly concentrated in the alpine meadow and alpine grassland of the Qinghai–Tibet Plateau and the grassland around the Yili region of Xinjiang. Precipitation was the main regulating factor of grassland ESV and had a positive impact in 79% grassland areas, especially in northern China. Evapotranspiration and sunshine hours exhibited a marginal impact on ESV, but temperature and relative humidity had no significant effect. Overall, this study contributes to exploring the spatiotemporal patterns of grassland ecosystem service value and the impact of climate factors in China, thereby providing reliable guidance for grassland ecosystem management. [ABSTRACT FROM AUTHOR]

• Soil erosion rate was 3 times greater on the south-facing hillslope as compared to the north-facing hillslope. • Soil water content was the dominant factor causing the difference in erosion rates under a water-limited condition. • Greater soil erosion rates resulted in elevational distributions of soil physicochemical properties on the south-facing hillslope. Soil erosion causes serious grassland degradation in the Three-River Headwater Region (TRHR) of the Qinghai-Tibet Plateau. Identifying source areas of erosion is important, including understanding the influences of hillslope aspect on soil erosion. However, the effect of hillslope aspect on soil erosion is a much-debated process, wherein contrasting results were previously reported. We hypothesized that aspect-induced differences in environmental variables will be related to differences in erosion magnitude and spatial pattern, and that these differences will impact soil physiochemical characteristics as well. To test this hypothesis, soil samples were collected at conjoined south- and north-facing hillslopes along elevational profiles in a small watershed in Yushu County, with measurements of soil water content (SWC), soil organic carbon (SOC), soil organic matter (SOM), soil particle size distribution, soil total nitrogen (STN) and phosphorus (STP). Soil erosion rate was estimated using 137Cs technology. The results showed that soil erosion rates of the two hillslopes ranged from 0.073 to 10.83 t ha-1 yr-1, and were 3 times greater on the south-facing hillslope. Soil water content ranged from 7.6% to 76.8% on the two hillslopes with lower values on the south-facing hillslope due to the greater solar radiation. By Spearman correlation analysis and path analysis, we concluded that lower soil water content on the south-facing hillslope restricts vegetation growth, and hence resulting in greater soil erosion under the case where vegetation growth is dominantly controlled by water availability. Greater soil erosion on the south-facing hillslope caused greater surficial accumulation of coarser materials and greater loss of soil nutrients, which are expected to complicate the hydrological erosion process. Moreover, the downslope increased soil erosion rate should be fully considered in conservation practices. These results will improve our understanding of the interaction and feedback mechanisms between soil characteristics, vegetation function, and soil erosion in the TRHR. [ABSTRACT FROM AUTHOR]

• Patchiness caused significant reduction of SOC and TN stocks. • Reduced vegetation input and increased erosion output accounted for SOC and TN loss. • Grasslands with high patchiness had a great potential for C and N sequestration. Patchiness acts as an indicator of terrestrial ecosystem degradation and can lead to considerable loss of soil organic carbon and total nitrogen. However, quantitative assessments of the effects of patchiness on soil organic carbon and total nitrogen stocks and their associated mechanisms remain limited. This study aimed to explore the influence mechanisms of patchiness on soil organic carbon and total nitrogen stocks and to project the quantitative contribution of the further expansion of patchiness and vegetation recovery. Soil properties, soil organic carbon and total nitrogen stocks were investigated using a combination of field sampling and aerial photography in four grassland types, alpine meadow, alpine steppe, temperate grassland, and desert grassland, at 47 sites in northwestern China. Soil organic carbon and total nitrogen densities in the bare patches were 34–54 % and 23–41 % lower, respectively, compared to the original vegetation. At the plot-scale, current soil organic carbon and total nitrogen stocks ranged from 30.85 to 77.80 T/ha and 3.26 to 10.19 T/ha, respectively, across grassland types; with a 10–27 % and 7–24 % potential loss of soil organic carbon and total nitrogen stocks, respectively, from the further expansion of patchiness but a 10–50 % and 9–37 % potential increase in soil organic carbon and total nitrogen stocks, respectively, from vegetation recovery. Soil organic carbon and total nitrogen stocks were positively correlated with vegetation biomass, soil clay content, and precipitation (p < 0.001), whereas they were negatively correlated with patchiness (p < 0.001). In summary, patchiness reduced soil organic carbon and total nitrogen stocks by decreasing vegetation inputs and increasing erosion outputs, while vegetation recovery showed potential for increasing carbon and nitrogen stocks. Our results highlight that maintaining intact vegetation cover is critical for preserving terrestrial ecosystem carbon and nitrogen storage. [ABSTRACT FROM AUTHOR]

• Mineral-associated organic carbon and hot-water extractable carbon of the alpine meadow varied strongly across parent materials. • Soil geochemistry dominated the variation of SOC fractions in the alpine meadow. • Root functional traits exerted stronger control on SOC fractions in deeper soil. Alpine meadow occupies ～46.7 % of the grassland area and stores more than 60 % of the soil organic carbon (SOC) in the Qinghai-Tibet Plateau, with 3.19 Pg C in the top 30 cm. Parent material can highly influence SOC stocks via various mineral components with divergent adsorption abilities. However, previous studies mainly concentrated on the relation between SOC and parent material in temperate and tropical forest ecosystems, evidences from different environments are needed to gain a holistic understanding. In this study, we explored how the functional distinct SOC fractions (the particulate (POC), mineral-associated (MAOC), and hot-water extractable carbon (HWEOC)) vary among four types of parent materials (monzonitic granite (MG), slate (SL), muscovite schist (SH), and diorite (DI)) by measurements from 16 sites on the Qinghai-Tibet Plateau. We also assessed the plant and geochemical factors in controlling the divergent SOC fractions. We found that MAOC and HWEOC vary strongly, while POC remain stable among parent materials due to sufficient plant input and slow decompositions rate. Moreover, our results revealed that geochemical factors exert dominant controls on each SOC fraction, with soil pH and texture showing a significant influence. Soils developed from the SL displayed the highest MAOC and HWEOC compared with that formed on the other three parent materials due to finer soil texture as well as relative high multivalent Ca and Mg. Furthermore, root traits increased its control on SOC fractions in relatively deeper soil depth (10–30 cm). Taken together, these results provided evidence of the key role of parent material in controlling the divergent SOC fractions in the less weathered alpine regions, emphasizing that parent material and soil geochemistry should be adequately considered in the biogeochemical and Earth system models. [ABSTRACT FROM AUTHOR]

[Display omitted] • Divergent succession changed community structure with decreased Sedge and Leguminous. • Soil water holding capacity, carbon stocks functions decreased with divergent succession. • Succession to shrubs and forbs both decreased ecosystem multifunctionality of alpine meadow. Global climate change and overgrazing pressure both affects the community succession, and multifunctionality of grassland ecosystems. Alpine meadows cover 1/3 of the Qinghai-Tibetan Plateau of China's climate sensitive area and major pastures, which is the main grassland ecosystem. However, the responses of ecosystem multifunctionality during climate change and overgrazing induced divergent community succession to shrubs- and forbs-dominated community remains poorly understood in alpine meadow ecosystem. Here, we examined five ecological functions, including above- and below-ground productivity, soil water holding capacity, soil organic carbon stocks and soil erosion resistance capacity of the native Kobresia -dominated alpine meadow ecosystem during the divergent succession to shrubs- and forbs-dominated meadow located on the Qinghai-Tibetan Plateau, and identified the key factors contributing to the changes of ecosystem multifunctionality during the divergent succession. Results showed that the divergent succession to shrubs- and forbs-dominated meadow both significantly reduced community species diversity and richness, changed community structure, especially the decreasing of the Sedges and Leguminous functional groups. Meanwhile, the ecological functions including below-ground productivity, soil water holding capacity, and soil organic carbon stocks are greatly decreased along shrubs and forbs encroachment in hillside alpine meadows. Taken together, our results demonstrate that climate warming and overgrazing induced divergent successions to the shrubs-encroached and the forbs-encroached communities both decreased the ecosystem multifunctionality of hillside alpine meadows. The ecosystem multifunctionality of hillside alpine meadow ecosystem might therefore be decreased continuously under ongoing and future climate warming and overgrazing by herbivores. [ABSTRACT FROM AUTHOR]

Plant biomass reveals the productivity and stability of a biotic community and is extremely sensitive to climate warming in permafrost regions, such as the Qinghai-Tibetan Plateau (QTP) in China. However, the response of the plant biomass of different functional groups to rising temperatures in such alpine zones remains unclear. Here, infrared radiators were used to simulate year-round warming on the QTP from 2011 to 2018. During the 8-year warming experiment, air temperature increased by 0.16 °C, while humidity tended to increase by 0.27 % at 20 cm above the ground. However, the rate of the increase in air temperature declined with an increasing number of years. Soil temperature and moisture increased by 1.28 °C and 3.61 %, respectively, on average from 0 to 100 cm below the ground, and the increment of soil moisture tended to rise with increasing depth. At the depths from 0 cm to 20 cm below the ground, soil organic carbon and total phosphorus tended to decrease by 0.79 g/kg and 0.04 g/kg, respectively, while soil total nitrogen tended to increase by 0.04 g/kg. Plant biomass had non-significant responses to warming, but the variation among different plant functional groups was greatest for forbs with the increment being 12.50, 147.97, and 160.47 g/m2 for plants aboveground, belowground, and total biomass, respectively. The ratios of plant total biomass tended to decrease by 2.29 %, increase by 0.60 %, and increase by 1.70 % for grasses, sedges, and forbs, respectively, so warming greatly decreased the proportion of grasses and increased the proportion of forbs in community. Warming weakened the positive correlation of grass biomass with soil temperature and enhanced the negative correlation of grass biomass with soil N and P content, along with weakening the positive correlation of sedge biomass with soil moisture and N content, while enhancing the negative correlation between sedge biomass and soil temperature. Meanwhile, forb biomass was greatly increased by soil temperature in the effects of warming. In conclusion, the 8-year warming produced negative effects on grasses and sedges by increasing soil temperature and N content and thus promoted the growth of forbs, which might induce a shift toward forbs in this community. [Display omitted] • Infrared radiators were used to simulate a year-round warming experiment on a frozen area over 8 years. • The melt of frozen soil caused an increment of soil moisture in deep layers under the 8-year warming. • The increment of soil moisture induced downward transport of soil nutrients and root biomass to deep layers. • The transport of soil nutrients and root biomass altered plant composition among different functional groups. • Eight-year warming might induce shift toward forbs by increasing soil temperature and nitrogen content. [ABSTRACT FROM AUTHOR]

Grassland is an important vegetation type in Xinjiang of western China, particularly on the coordinated development of ecological protection and animal husbandry. It is of great significance to rapidly and accurately evaluate the productivity of regional grasslands, thereby revealing the carrying capacity of herbivores in the warm season of high-altitude grasslands, especially for the balanced management of regional grasslands and herbivorous livestock. However, there are only a few reports on the temporal and spatial changes of grassland Aboveground Biomass (AGB) in high-altitude regions using long-term series. It is necessary to effectively evaluate the carrying capacity considering some limiting factors. Taking the Hejing County of Xinjiang as the research area, this study aims to explore the spatiotemporal dynamics and carrying capacity of the grassland AGB using MODIS 17A3H/NPP (Net Primary Productivity, NPP) data products. An estimation model was also proposed to improve the traditional field sampling, in terms of data availability, multi-year monitoring continuity, and regional coverage. The natural and management factors were considered to further modify the model, according to the grassland type, landform, and township. The results showed that: 1) The Aboveground Net Primary Productivity (ANPP) of grassland presented a Root Mean Square Error (RMSE) value of 3.23-11.89 g/m2, indicating a higher accuracy. 2) The AGB average value was 1 252.34 kg/ hm2 during the study period (2000—2018), indicating a fluctuating upward trend. Specifically, the linear growth rate was 7.78 kg/(hm2·a) (P<0.01), and the overall AGB of grassland was a slight upward trend, where the proportion of grassland with the AGB growth reached 74.90%. The degradation was distributed mostly in the areas with a slope of more than 30%. 3) The annual average aboveground hay was 150 100 t. Among them, the alpine grassland and meadow over 2 500 m produced the largest hay, accounting for 24.20% and 57.46%, respectively. The available hay was reduced to 86 200 t after revision. 4) The average theoretical carrying capacity of grassland in the study area was 242 600 to 319 400 heads. The theoretical carrying capacity of standard sheep without considering natural and management factors was 319 400 heads, the underload of grassland is 2.99%; after revised the carrying capacity was 242 600 heads, and the grass was overloaded by 27.82%, it further illustrated that there was a certain overload risk in the development of grassland animal husbandry in the study area. The research results could provide references for the formulation of regional land management and animal husbandry planning policies, and played a positive role in promoting the sustainable economic development of regional natural resources. The average theoretical carrying capacity of grassland was 242 600 to 319 400 heads. The theoretical carrying capacity of standard sheep was 319 400 heads without considering the natural and management factors, where the underload of grassland was 2.99%. After that, the carrying capacity was 242 600 heads, and the grass was overloaded by 27.82%. Consequently, there was a certain overload risk in the development of grassland and animal husbandry in the study area. The findings can provide a strong reference for the decision-making on the land and animal husbandry, thereby promoting the sustainable development of regional natural resources. [ABSTRACT FROM AUTHOR]

Plant phenology under changing climate is a critical factor controlling terrestrial vegetation productivity. However, large uncertainties exist due to different data sources and phenological parameter extraction methods. In this study, we took advantage of a suite of long-term field observational data in northern grassland of China to investigate the drivers of phenological shifts and their effect on the maximum aboveground net primary productivity (ANPPmax) across four representative grassland types during 1984–2017. Results showed that drivers of phenological events (i.e., start (SOS), end (EOS), and length (GSL) of the growing season) with warming influence dramatically differed among grassland types, indicating that the synergistic effect of temperature and precipitation should be highlighted. For temperate desert steppe and alpine meadow, GSL of dominant species was both significantly lengthened with temperature rising with averaged 0.94 days year−1 (P < 0.001) and 1.15 days year−1 (P < 0.001), respectively, while for typical temperate grassland, GSL was considerably shortened by an average of 0.58 days year−1 (P < 0.01) as a result of water deficit caused by sharp warming and precipitation decreasing in summer and autumn. For most grassland types in our study, both SOS and GSL were significantly correlated with ANPPmax under different precipitation gradients with SOS advanced and GSL extended leading to higher ANPPmax. Only the typical temperate grassland presents a relatively poor correlation between phenological events and productivity. Furthermore, compared with GSL, ANPPmax was more sensitive to the advancement of SOS for every 1-day phenological change. However, the effect of EOS on ANPPmax across the four grassland types was much weaker and unstable. There were spatial response differences between ANPPmax and phenological transition events, with the temperate meadow grassland tending to be more sensitive compared with three other grassland types. [ABSTRACT FROM AUTHOR]

Plant phenological events are sensitive indicators of climate change, and their change could markedly affect the structure and function of ecosystems. Previous studies have revealed the spatiotemporal variations in the phenological events of woody plants. However, limited studies have focused on the phenophases of herbaceous plants. In this study, by using a meta-analysis method, we extracted information about the phenological changes in herbaceous plants in China's grasslands from existing studies (including the period, station, species, phenophases, phenological trends, and climatic determinants) and analyzed the patterns manifested in the dataset. The results showed that the spring phenophases (e.g., first leaf date and first flowering date) of the herbaceous plants mainly advanced over the past 30 years, but a large difference existed across grassland types. The spring phenophases of forages (species from the Cyperaceae, Gramineae, and Leguminosae families) became earlier in the desert steppe and alpine steppe but showed no apparent trends in the alpine meadow and even became later in the meadow steppe and typical steppe. In most cases, the increase in spring temperatures and precipitation promoted the greening up of herbaceous plants, while sunshine duration was positively correlated with the green-up date of herbaceous plants. For the autumn phenophases, the proportions of the earlier and later trends were very close, but the trends varied among the grassland types. The leaf coloring dates of the forages were delayed in the meadow steppe and alpine steppe but showed no distinct pattern in the typical steppe or alpine meadow and even became earlier in the desert steppe. In most cases, the increase in growing season temperature led to an earlier leaf coloring date of the herbaceous plants, but the increase in the preseason precipitation delayed the leaf coloring date. Our results suggested that the phenophases of herbaceous plants have complicated responses to multiple environmental factors, which makes predicting future phenological changes difficult. [ABSTRACT FROM AUTHOR]

A new species Tongoloa arguta (Apiaceae) is described and illustrated in this article. The new species grows in alpine bushes and meadows in south-western China. It resembles T. silaifolia, but differs from the latter by the length of the stem, ultimate segments of leaf and rays of the umbel. Phylogenetic analysis, based on nuclear ribosomal DNA internal transcribed spacer (ITS) sequences, is provided, as well as comparative morphology between related species. [ABSTRACT FROM AUTHOR]

Question: The impact of ants on the vegetation and soil seed bank of alpine meadows on the Qinghai‐Tibetan Plateau is largely unknown. We questioned how the mound‐building ant, Camponotus herculeanus, affects the above‐ground vegetation, the soil seed bank and physico‐chemical properties of the soil. Location: An alpine meadow in the northeast margin of the Qinghai‐Tibetan Plateau (37°40′ N, 102°32′ E), China. Methods: We used field and greenhouse studies to determine the above‐ground vegetation parameters and soil physico‐chemical properties, and the soil seed bank composition under the mound (UM), the herbage circle at about 10 cm width around the outside of the mound (mound edge, ME) and the area 1 m from the center of the mound (control). Results: (a) The mound edge had higher vegetation height, greater above‐ground biomass, lower vegetation coverage and lower plant richness than controls; (b) Gramineae had a higher total importance value, which was based on the height, coverage and biomass of each plant species, and composed a higher biomass proportion in the mound edge than in controls (68% vs. 38%), while most of the perennial dicotyledons were restricted to the controls; (c) dicotyledons were the main seed group in the 0–8 cm layer of soilUM (43%), soilME (51%) and soilcontrol (60%), while Gramineae had a significantly higher seed density and percentage of total seeds in the soilUM (16,507 ± 2,882.7 seeds/m3, 28.1%) than in the soilcontrol (4,200 ± 799.5 seeds/m3, 10.2%); and (d) soil in the 0–8 cm layer under the mound had lower water content and lower bulk density than soil on the mound edge and in controls. Conclusions: Mound‐building activity of Camponotus herculeanus increased the proportion of Gramineae and decreased the proportion of dicotyledons at the site of the study indicating, that mound building could enhance the transformation of a grass and sedges community to mainly a grass community in the alpine meadow. [ABSTRACT FROM AUTHOR]

Alpine permafrost regions are important sources of biogenic CH4 and methanogens play an important role in the methane-producing process. The alpine permafrost on the Qinghai–Tibetan plateau comprises about one-sixth of China's land area, and there are various types of alpine ecosystems. However, the methanogenic communities in the typical alpine ecosystems are poorly understood. In this study, the active layers and permafrost layers of the natural ecosystem of alpine grassland (DZ2-1) and alpine swamp meadow (DZ2-5) were selected to investigate the diversity and abundance of methanogenic communities. Methanobacterium (63.65%) are overwhelmingly dominant in the active layer of the alpine grassland (DZ2-1A). ZC-I cluster (26.13%), RC-I cluster (19.56%), and Methanobacterium (15.02%) are the dominant groups in the permafrost layer of the alpine grassland (DZ2-1P). Methanosaeta (32.92%), Fen cluster (29.59%), Methanosarcina (16.33%), and Methanobacterium (13.95%) are the dominant groups in the active layer of the alpine swamp meadow (DZ2-5A), whereas the Fen cluster (50.85%), ZC-I cluster (27.63%), and RC-I cluster (14.15%) are relatively abundant in the permafrost layer of the alpine swamp meadow (DZ2-5P). qPCR data showed that the abundance of methanogens was higher in the natural ecosystem of alpine swamp meadow than in alpine grassland. We found that the community characteristics of methanogens were related to environmental factors. Pearson correlation analyses indicated that the relative abundance of Methanobacterium had a significantly positive correlation with hydrogen concentration (P < 0.01), while the relative abundances of Methanosaeta and Methanosarcina were positively correlated with acetate concentration (P < 0.05). This study will help us to understand the methanogenic communities and their surrounding environments in alpine ecosystems. [ABSTRACT FROM AUTHOR]

Water Use Efficiency (WUE) refers to the ratio of water used in plant metabolism over water lost in evapotranspiration, indicating carbon-water coupling in terrestrial ecosystem and its response to global change. It is of great significance to clarify the long-term variation characteristics and influencing factors of WUE for the study of carbon and water cycles and the rational utilization of water resources. This study aims to estimate the vegetation WUE of a research site, particularly on the annual and interannual variation characteristics of WUE, and to establish the response relationship between WUE and key meteorological factors. The data used in this paper mainly include the flux and meteorological information from eight sites in China from January 2003 to December 2010. Unified quality control and interpolation methods were then used to pre-process the flux data. The daily flux and meteorological data were combined into 8-day data sets in each site. Pearson coefficient was used to analyze the correlation between vegetation WUE and Gross Primary Productivity (GPP), ET, average temperature, precipitation, and relative humidity factors. The characteristics and influencing factors of WUE were analyzed and compared in different ecosystem. The results showed that: 1)WUE fluctuated greatly in the whole year without obvious regularity in Qianyanzhou, Xishuangbanna and Dinghushan sites which locate in the tropical monsoon climate region, while WUE showed obvious seasonal variation characteristics in the other five sites, all of which increased significantly from April to July, and reached the maximum during the peak period (July to August), and then WUE decreased gradually from August to October. From November to February of the following year, WUE reached zero. 2) From 2003 to 2010, the annual WUE of alpine meadow (Damxung) was the lowest (0.18 g/kg), whereas, that of tropical rainforest (Xishuangbanna) was the highest (4.20 g/kg). The WUE increased annually in the grassland (Inner Mongolia), broad-leaved evergreen forest (Dinghu Mountain), farmland (Yucheng), alpine meadow (Damxung), and alpine meadow (Haibei), whereas, the decreasing trend occurred in the coniferous forest (Qianyanzhou), tropical rainforest (Xishuangbanna), deciduous broad-leaved and coniferous mixed forests (Changbai Mountain). 3) In the 8-day time scale, there was positively correlation between temperature and WUE in alpine meadow, farmland and grassland ecosystem, whereas there was the negatively correlation between temperature and WUE in forest ecosystem. And the negative correlation between WUE and temperature in coniferous forest ecosystem (R=-0.607, P<0.01) was higher than that in evergreen broad-leaved forest and coniferous broad-leaved mixed forest ecosystem. Compared with forest and farmland ecosystem, WUE in alpine meadow and grassland ecosystem had a higher correlation with relative humidity and precipitation; 4) In different ecosystem, the various approaches were proposed to enhance WUE of terrestrial ecosystem for the sustainable development of agriculture, forestry and animal husbandry. Soil management regulation and canopy pruning can improve water use efficiency in the case of forest ecosystem. In farmland ecosystem, water use efficiency can be elevated from irrigation mode and crop breeding. In alpine meadow and grassland ecosystem, man-made grass, rest grazing and area rotation grazing can be used to enhance grassland carbon sink, further to improve water use efficiency. The findings can provide promising potentials to alleviate water shortage against the background of global warming. [ABSTRACT FROM AUTHOR]

Background: Grassland ecosystems play an important role in the terrestrial carbon cycles through carbon emission by ecosystem respiration (Re) and carbon uptake by plant photosynthesis (GPP). Surprisingly, given Re occupies a large component of annual carbon balance, rather less attention has been paid to developing the estimates of Re compared to GPP. Results: Based on 11 flux sites over the diverse grassland ecosystems in northern China, this study examined the amounts of carbon released by Re as well as the dominant environmental controls across temperate meadow steppe, typical steppe, desert steppe and alpine meadow, respectively. Multi-year mean Re revealed relatively less CO2 emitted by the desert steppe in comparison with other grassland ecosystems. Meanwhile, C emissions of all grasslands were mainly controlled by the growing period. Correlation analysis revealed that apart from air and soil temperature, soil water content exerted a strong effect on the variability in Re, which implied the great potential to derive Re using relevant remote sensing data. Then, these field-measured Re data were up-scaled to large areas using time-series MODIS information and remote sensing-based piecewise regression models. These semi-empirical models appeared to work well with a small margin of error (R2 and RMSE ranged from 0.45 to 0.88 and from 0.21 to 0.69 g C m−2 d−1, respectively). Conclusions: Generally, the piecewise models from the growth period and dormant season performed better than model developed directly from the entire year. Moreover, the biases between annual mean Re observations and the remotely-derived products were usually within 20%. Finally, the regional Re emissions across northern China's grasslands was approximately 100.66 Tg C in 2010, about 1/3 of carbon fixed from the MODIS GPP product. Specially, the desert steppe exhibited the highest ratio, followed by the temperate meadow steppe, typical steppe and alpine meadow. Therefore, this work provides a novel framework to accurately predict the spatio-temporal patterns of Re over large areas, which can greatly reduce the uncertainties in global carbon estimates and climate projections. [ABSTRACT FROM AUTHOR]

Over the last century, anthropogenic activities have increased nitrogen (N) deposition considerably, which significantly affects ecosystem processes and has the potential to induce N saturation in the future. The continuous increase in N deposition may cause a non-linear response in soil respiration (Rs), an important component of carbon (C) cycling. However, little is known about N saturation threshold of soil respiration. In this study, we conducted coordinated experiments in four grassland types across northern China with four N addition levels to explore patterns in the Rs saturation threshold. Our results showed that an Rs saturation threshold generally exists in grassland ecosystems in response to N addition gradients. The N saturation threshold of Rs occurred at an average rate of 50 kg N ha−1 yr−1, but varied widely with grassland type; the N saturation threshold occurred at rates of 100, 50, 50, and 25 kg N ha−1 yr−1 in the alpine meadow, meadow steppe, typical steppe, and desert steppe, respectively. Autotrophic respiration (Ra) and heterotrophic respiration (Rh) responded to N addition gradients differently. Ra increased initially and became saturated at a rate of 50 kg N ha−1 yr−1 and declined thereafter. In contrast, Rh decreased monotonically after N addition. Structural equation models further confirmed that the effects of N addition gradients on Rs were primarily determined by the non-linear response of belowground biomass. Interestingly, the compiled global dataset showed that the N saturation threshold of Rs increased with precipitation and soil moisture. These findings indicate that the stimulating effect of N deposition on Rs and Ra might diminish with increasing N deposition in the future, especially in dry grassland ecosystems. [ABSTRACT FROM AUTHOR]

The alpine meadow is highly sensitive to global climate change due to its high elevation and cold environment. To understand the dynamics of ecosystem carbon cycling, CO2 fluxes were measured over the Suli alpine meadow, which is located at the upper reach of the Shule River basin at the northeastern edge of the Qinghai-Tibet Plateau (QTP), China. The measurements were taken from October 2008 to September 2012 using the eddy covariance technique. Obvious seasonal and inter-annual variations were observed in the CO2 flux. The annual net carbon exchange ranged from -195.28 g·CO2·m-2 to -118.49 g·CO2·m-2, indicating that the alpine meadow ecosystem in this area played a role as a carbon sink. The inter-annual variability in the net carbon exchange was significantly related to the length of the growing season for the alpine meadow. The results showed that the months of June, July and August were the strongest CO2 absorption periods, while April, May and October were the strongest CO2 release periods. The annual net exchanges of CO2 in the four years were -118.49 g·CO2·m-2, -130.75 g·CO2·m-2, -195.83 g·CO2·m-2 and -160.65 g·CO2·m-2, and the average value was -151.43 g·CO2·m-2. On a seasonal scale, the monthly CO2 fluxes were largely controlled by temperature. At the annual scale, there was no dominant factor that influenced the interannual variations in the CO2 flux. [ABSTRACT FROM AUTHOR]

Damage to homesteads by brown bears (Ursus arctos) has become commonplace in Asia, Europe, and the Americas. Science‐based solutions for preventing damages can contribute to the establishment of mechanisms that promote human–bear coexistence. We examined the spatial distribution patterns of house break‐ins by Tibetan brown bears (U. a. pruinosus) in Zhiduo County of the Sanjiangyuan region in China. Occurrence points of bear damage were collected from field surveys completed from 2017 to 2019. The maximum entropy (MaxEnt) model was then used to assess house break‐in risk. Circuit theory modeling was used to simulate risk diffusion paths based on the risk map generated from our MaxEnt model. The results showed that (a) the total risk area of house break‐ins caused by brown bears was 11,577.91 km2, accounting for 29.85% of Zhiduo County, with most of the risk areas were distributed in Sanjiangyuan National Park, accounting for 58.31% of the total risk area; (b) regions of alpine meadow located in Sanjiangyuan National Park with a high human population density were associated with higher risk; (c) risk diffusion paths extended southeast to northwest, connecting the inside of Sanjiangyuan National Park to its outside border; and (d) eastern Suojia, southern Zhahe, eastern Duocai, and southern Jiajiboluo had more risk diffusion paths than other areas examined, indicating higher risk for brown bear break‐ins in these areas. Risk diffusion paths will need strong conservation management to facilitate migration and gene flow of brown bears and to alleviate bear damage, and implementation of compensation schemes may be necessary in risk areas to offset financial burdens. Our analytical methods can be applied to conflict reduction efforts and wildlife conservation planning across the Qinghai–Tibet Plateau. [ABSTRACT FROM AUTHOR]

Climate change has direct impacts on wildlife and future biodiversity protection efforts. Vulnerability assessment and habitat connectivity analyses are necessary for drafting effective conservation strategies for threatened species such as the Tibetan brown bear (Ursus arctos pruinosus). We used the maximum entropy (MaxEnt) model to assess the current (1950–2000) and future (2041–2060) habitat suitability by combining bioclimatic and environmental variables, and identified potential climate refugia for Tibetan brown bears in Sanjiangyuan National Park, China. Next, we selected Circuit model to simulate potential migration paths based on current and future climatically suitable habitat. Results indicate a total area of potential suitable habitat under the current climate scenario of approximately 31,649.46 km2, of which 28,778.29 km2 would be unsuitable by the 2050s. Potentially suitable habitat under the future climate scenario was projected to cover an area of 23,738.6 km2. Climate refugia occupied 2,871.17 km2, primarily in the midwestern and northeastern regions of Yangtze River Zone, as well as the northern region of Yellow River Zone. The altitude of climate refugia ranged from 4,307 to 5,524 m, with 52.93% lying at altitudes between 4,300 and 4,600 m. Refugia were mainly distributed on bare rock, alpine steppe, and alpine meadow. Corridors linking areas of potentially suitable brown bear habitat and a substantial portion of paths with low‐resistance value were distributed in climate refugia. We recommend various actions to ameliorate the impact of climate change on brown bears, such as protecting climatically suitable habitat, establishing habitat corridors, restructuring conservation areas, and strengthening monitoring efforts. [ABSTRACT FROM AUTHOR]

In order to reveal the changes of vegetation in southern China since the Last Glacial Maximum, we have established high-resolution time scales and palynological sequences of borehole profiles by drilling cores in some weak areas of the research to restore vegetation changes over the past 20,000 years on the basis of previous work. This paper gives the vegetation zoning maps of 18, 9 and 6 ka BP respectively in southern China, and describes the distribution characteristics of plants in different zones/subzones. The results show that the vegetation zonations around 18 ka BP were significantly different from that at present. It appeared in turn with Cold-temperate coniferous forest and alpine meadow steppe zone, and Temperate mixed coniferous and broad-leaved forest zone/warm temperate deciduous broad-leaved forest zone from northwest to southeast in the west, and Temperate mixed coniferous and broad-leaved forest zone, Warm temperate deciduous broad-leaved forest zone, and Northern subtropical mixed evergreen and deciduous broad-leaved forest zone from north to south in the central and east. The vegetation distribution around 9 ka BP changed distinctively. Except that the northwest part was located in Mountain temperate mixed coniferous and broad-leaved forest zone, the vegetation in other areas occurred in turn with North subtropical mixed evergreen and deciduous broad-leaved forest subzone, Mid-subtropical typical evergreen broad-leaved forest subzone, and South sub-tropical monsoon evergreen broad-leaved forest subzone/Tropical seasonal rainforest and rainforest zone from north to south. There was little change in the appearance of vegetation zonations between 6 and 9 ka BP, but the northern edge of each vegetation belt moved a little northward, reflecting that the overall climate became warmer around 6 ka BP. The vegetation changes in southern China over the past 20,000 years were largely driven by environmental changes. Climate change was the main factor affecting the vegetation distribution. The impact of human activities became more and more remarkable in the later period. In the lower reaches of the Yangtze River and the delta region, sea level changes also influenced the vegetation distribution. [ABSTRACT FROM AUTHOR]

Based on pollen data of 274 samples from a 550-cm core at Kelashazi Peat in the southern Altai Mountains within China, we reconstructed the Holocene vegetation dynamics and climatic change. The pollen assemblages and the associated biome scores indicate that the vegetation in Kelashazi valley was dominated by alpine meadows during the early Holocene (before ~8.2 cal. kyr BP) and by taiga forests in the middle Holocene (~8.2-~5.6 cal. kyr BP) that was followed by an expansion of alpine meadows (~5.6-~3.2 cal. kyr BP). The pollen-based temperature index-indicated thermal maximum lasting from ~8.0 to ~5.6 cal. kyr BP was consistent with temperature stack for 60–30°N and the later onset warming at Kelashazi Peat was associated with the cooling influence of remnant ice sheets in the early Holocene. The pollen-based increasing moisture index curve from Kelashazi Peat is in a good agreement with the synthesized decreasing aridity index curve in low-elevation regions of the Altai Mountains and the surrounding areas during the data-overlapping period between ~12.0 and ~3.2 cal. kyr BP. The Holocene wetting trend at Kelashazi Peat might have resulted not only from the increasing trend of NAO-related winter precipitation but also from the increasing trend of AMO-modulated summer precipitation. • Holocene vegetation and climate changes was reconstructed in the southern Altai Mountains. • Thermal maximum was consistent with temperature stack for 60–30°N. • Moisture reconstruction is consistent with synthesized Holocene aridity index in low-elevation regions. • Holocene wetting trend have resulted from the increasing trends of NAO-related winter precipitation and AMO-related summer precipitation. [ABSTRACT FROM AUTHOR]

• Dominant factor for the IAVs of ET varied among the four grassland ecosystems. • Net radiation dominated the IAV of ET at the alpine marsh meadow. • Water availability mainly regulated the IAVs of ET for relatively arid sites. • Environmental responses of surface conductance varied across the grasslands. Understanding the long-term variation in evapotranspiration (ET) for the spatially distributed grasslands is crucial for the accurate prediction of ET response to climate change. In this study, we analyzed the interannual variability (IAV) of ET and its responses to environmental conditions at four grassland ecosystems across a wide range of climatic and biome conditions based on the long-term (9–11 years) eddy-covariance measurements. The four ecosystems encompassed the most prevalent grassland vegetations in China, containing a typical temperate steppe, an alpine meadow-steppe, an alpine shrubland meadow, and an alpine marsh meadow. The IAVs of annual ET at the typical temperate steppe and the alpine meadow-steppe were primarily affected by either change in precipitation (P) or relative humidity (RH). Leaf area index (LAI) was the dominant factor controlling the IAVs of annual and growing-season ET at the alpine shrubland meadow, and the IAV of LAI was significantly correlated with P variation. As to the alpine marsh meadow, net radiation turned to be the dominant factor for the IAV of annual ET, additionally with significant effects from water supply condition (P and RH) on the IAV of growing-season ET. Similar environmental responses were also found for the IAVs of mean surface conductance (g s) across the sites. Specifically, annual and growing-season mean g s significantly increased with increases in LAI at the alpine shrubland meadow, and appeared to be more sensitive to changes in water availability and VPD at the typical temperate steppe and the alpine meadow-steppe. Significant linear relationships were also observed among the IAVs of mean Priestley-Taylor coefficient (α = ET/ET eq , where ET eq is the equilibrium evaporation), decoupling coefficient (Ω), and g s on both the annual and growing-season basis in this study. Moreover, the variabilities of annual mean g s , Ω , and α further demonstrated the energy-limited conditions at the alpine marsh meadow, and the overall water-limited conditions at the other three grasslands. This study reveals the divergent environmental responses of long-term ET variations over grassland ecosystems, and contributes to the comprehensive understanding on the ET process and modeling efforts as well. [ABSTRACT FROM AUTHOR]

Microorganisms are found throughout the soil, however, our understanding of microbial diversity and the underlying assembling patterns is mostly limited to the surface horizons (0–20 cm). In this study, soil samples were collected from a total of 12 integral vertical soil profiles (from the surface layer to the parent material, up to 5 m depth) from two typical alpine habitats (wetland and meadow) in the Zoige Plateau, China. As determined from 16S rRNA sequencing, soil bacterial diversity and community composition were unique to each habitat. Similar decays in bacterial similarity over distance along soil vertical profiles were observed in both habitats, and taxonomic turnover rates were higher than phylogenetic ones. Bacterial distribution greatly depended on soil depth, with most oligotrophic taxa residing in deeper soil layers. Soil macro-nutrients were major factors regulating bacterial assembly, however, in deeper soil layers with lower nutrient effectiveness, minerals such as manganese, potassium, and sulfur were more influential. Along the whole profile, community assembly was driven mainly by deterministic processes (mostly heterogeneous selection) and to a lesser extent by stochastic processes, as shown by both a null model-based β-nearest taxon index and a normalized stochastic ratio. The habitats differed in the importance of these processes, however, with deterministic processes playing a larger role in bacterial assembly in meadows than in wetlands, and with community members in alpine meadows having narrower environmental thresholds and stronger phylogenetic signals. Additionally, bacterial communities in the subsoil exhibited a narrower niche breadth and were susceptible to deterministic processes. This trend was accompanied by the weaker phylogenetic conservation, suggesting their lower adaptation to environmental changes compared to the topsoil. Overall, our study investigated bacterial biodiversity patterns and the potential processes underlying bacterial assemblage along the vertical soil profile, and provided the first data regarding the vertical geography of soil bacterial communities in typical alpine habitats. • Vertical patterns of soil bacteria were explored in both alpine meadows and wetlands. • Bacterial assemblage exhibits similar distance-decay pattern for both habitats. • Alpine meadows have greater environmental heterogeneity than wetlands. • Stronger deterministic process thereby underpins bacterial geography in meadows. • Bacterial distribution and assembly are highly dependent on soil depth. [ABSTRACT FROM AUTHOR]

• Meadow patch coverage (MPC) regulates the magnitude of soil erosion processes. • MPC can maintain runoff and reduce sediment under different rainfall intensities. • Alpine meadow degradation can be evaluated by quantifying the decrease of MPC. • Meadow and bald patches decreased runoff coefficient in the 60% MPC. Meadow patches are caused by the fragmentation and disappearance of mattic epipedons, and can serve as evidence of degradation. This is a gradual decline in meadow patch coverage, which can result in soil and surface water loss due to increased bare soil surface. However, little is known about how the loss of mattic epipedons alters soil erosion processes in alpine regions. This study sheds light on this topic by conducting simulated rainfall experiments with different rainfall intensities to assess runoff and sediment generation. We selected representative degraded alpine meadows on the eastern Qinghai-Tibetan Plateau in China. The observed temporal variations of runoff and soil loss rates were explained by the presence of two stages of meadow patch coverage decline: an increasing and a relatively stable stage. Compared to 30% and 60% meadow patch coverage, 90% meadow patch coverage displayed an extended increasing stage with delayed entrance into the stable stage during the rainfall period. The runoff coefficients were significantly higher in 90% and 30% meadow patch coverage than in 60%. The sediment concentrations were significantly lower in 90% and 60% meadow patch coverage than in 30%. It is worth stressing that 90% meadow patch coverage could prompt more rainfall flowing as runoff and reduce sediment under different rainfall intensities. The complex mosaic-pattern formed by meadow and bald patches changed the hydrological response of the soil, decreasing runoff coefficient in 60% meadow patch coverage. The destruction, reduction or even disappearance of some mattic epipedons led to a higher sediment concentration in 30% meadow patch coverage. The meadow patch coverage exerted a greater influence on sediment yield than on runoff volume, although it was generally affected by rainfall intensity. Our findings highlight the importance of maintaining runoff and reducing sediment through the presence of mattic epipedons. Mattic epipedons appear as an effective soil erosion control feature, and this study offers a theoretical guidance for planning adaptive management strategies for degraded alpine meadows on the Qinghai-Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Based on daily mean temperature data from 32 meteorological stations in the study area, this paper discusses the relationship between the changes in the climatic growing season and altitude and the differences in the northern (NSQM) and southern (SSQM) slopes of the Qinling Mountains (QMs) from 1985 to 2015. Our analyses generated three primary results. First, the spatial distribution patterns of the growing season start (GSS), growing season end (GSE), and growing season length (GSL) exhibited an altitudinal gradient and differences between the NSQM and SSQM. The occurrence time of the GSS, GSE, and the GSL of the NSQM was approximately 15 days later, 10 days earlier, and 25 days shorter respectively than that of the SSQM. Second, the three factors exhibited regular changes with an increasing elevation gradient: the GSS, GSE, and GSL were gradually delayed, advanced, and shortened, respectively. In the area below 1800 m above sea level, the GSS, GSE, and GSL of the NSQM was later, earlier, and shorter, respectively, than that of the SSQM; while the changing trends in the three were opposite in the areas above 2700 m; and the three in the areas between 1800 and 2700 m varied little in the NSQM and SSQM. The sensitivities of the GSS, GSE, and GSL of the NSQM and SSQM to elevation also reflected in the trends of inter-annual variability. Third, among the different altitudinal vegetation belts from low-altitude to high-altitude areas, the occurrence time of the GSS and GSE and the duration of the GSL in the alpine meadow areas were all exchanged in the NSQM and SSQM. The GSS, GSE, and GSL of the NSQM were earlier, later, and longer respectively than that of the SSQM. [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]

• Effects of nitrogen and water addition on plant functional group were analyzed. • Grass' biomass increased while forbs' biomass decreased over year. • Biomass responses to nitrogen addition were stronger than to water addition. • N limitation transformed to P limitation in grass, while forbs remained N limited. The increase in atmospheric nitrogen (N) deposition and precipitation is obvious in the eastern Qinghai–Tibet Plateau. The response of different plant functional groups to increased N deposition and precipitation and the mechanism of N and phosphorus (P) stoichiometry are not yet clear. We examined the effects of the addition of N and water on plant diversity, community productivity and plant N:P stoichiometry of functional groups in an alpine meadow of the Qinghai-Tibet Plateau in China. Our results indicate that N and water additions significantly increased the total above-ground productivity and biomass of grasses in both years but decreased the biomass of forbs in 2018. In addition, plant diversity decreased with a high level of N addition, and the interactions of N and water had a weakening effect on the decline of plant diversity. Plant diversity was negatively correlated with the biomass of grasses. Our results demonstrate that the biomass of grasses showed a negative quadratic relationship with the N:P ratio of grasses, suggesting that addition of N and water shifted the grasses from N-limited to P-limited. The biomass of forbs showed significant positive correlations with the N:P ratio of forbs, implying the forbs still remained N limited. Overall, our study suggests that the response of grasses and forbs to water and N additions is inconsistent from the perspective of plant N:P stoichiometry. [ABSTRACT FROM AUTHOR]

The quantification of changes in long-term trends in grassland net primary productivity (NPP) and its large-scale driving forces are important for understanding terrestrial ecosystem changes in arid and semi-arid regions. Based on the MODIS-NPP dataset, this study investigated patterns in the spatiotemporal variations in NPP and its possible influencing factors in Inner Mongolia during 2000–2014 using the linear trend analysis method, correlation analysis, and an F test. The results show that grassland NPP had an annual rate of increase of 4.53 g C/(m2·a) with a significant increasing trend (p < 0.01). Spatial analysis results indicate that the average grassland NPP presented a gradual increasing trend from southwest to northeast, with an area of longitudinal zonality being identified. Grassland NPP presented a significant increase (p < 0.05) in more than 31.93% of the region. Grassland NPP and growing season precipitation (GSP) had a significant negative correlation in 54.78% of the study area. Grassland NPP and the growing season average land surface temperature (GSALST) had a significant negative correlation for 65.93% of the study area; growing season average temperature (GSAT) had no significant effect on the grassland NPP. For different grassland types, GSP had the greatest impact on alpine meadows (r = 0.73), and GSALST had the greatest impact on alpine steppes and alpine meadows (r = −0.81). Related ecological restoration projects such as fenced rangeland and planted grass played a positive impact on annual NPP in the study area. Image 1 • Spatial-temporal changes of NPP were analyzed in Inner Mongolia from 2000 to 2014. • Linear trend analysis and partial correlation analyses were used to this study. • There was different correlation between NPP and GSAT/GSP/GSALST. • The correlations between NPP and GSAT/GSALST in different grassland types were similar. • Human activities played a decisive role for the yearly increases of grassland NPP. [ABSTRACT FROM AUTHOR]

Interannual climate variation alters functional diversity through intraspecific trait variability and species turnover. We examined these diversity elements in three types of grasslands in northern China, including two temperate steppes and an alpine meadow. We evaluated the differences in community‐weighted means (CWM) of plant traits and functional dispersion (FDis) between 2 years with contrasting aridity in the growing season. Four traits were measured: specific leaf area (SLA), leaf dry matter content (LDMC), leaf nitrogen concentration (LNC), and the maximum plant height (H). CWM for SLA of the alpine meadow increased in the dry year while that of the temperate steppe in Qinghai showed opposing trends. CWM of LDMC in two temperate steppes became higher and CWM of LNC in all grasslands became lower in the dry year. Compared with the wet year, FDis of LDMC in the alpine meadow and FDis of LNC in the temperate steppe in Qinghai decreased in the dry year. FDis of H was higher in the dry year for two temperate steppes. Only in the temperate steppe in Qinghai did the multi‐FDis of all traits experience a significant increase in the dry year. Most of the changes in CWM and FDis between 2 years were explained by intraspecific trait variation rather than shifts in species composition. This study highlights that temporal intraspecific trait variation contributes to functional responses to environmental changes. Our results also suggest it would be necessary to consider habitat types when modeling ecosystem responses to climate changes, as different grasslands showed different response patterns. [ABSTRACT FROM AUTHOR]