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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]

• 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]

The maintaining mechanisms and potential ecological processes of species diversity in warm temperate- conifer-broadleaved-mixed forest are far from clear understanding. In this paper, the relative neighborhood density Ω was used to analyze the spatial distribution patterns of 34 species with ≥ 11 individuals in a warm- temperate-conifer-broadleaved-mixed forest, northern China. Then we used canonical correspondence analysis (CCA) and Torus-translation test (TTT) to explain the distribution of observed species. Our results show that aggregated distribution is the dominant pattern in warm-temperate natural forest and four species regular distribution at the spatial scale > 30 m. The aggregated percentage and intensity decline with spatial scale, abundance and size classes increasing. Rare species are aggregated more than intermediate and abundant species. These results prove sufficiently the effects existence of scale separation, self-thinning and Janzen-Connell hypothesis. In addition, functional traits (dispersal modes and shade tolerance) also have a significant influence on distribution of species. The results of CCA confirm that slope and convexity are the most important factors affecting the distribution of tree species distribution, elevation and slope of shrub species though the combination of topographic variables only explained 1% of distribution of tree species and 2% of shrub species. Most species don't have habitat preference; however 47.1% (16/34) species including absolutely dominant tree ( Pinus tabulaeformis and Quercus wutaishanica ) and shrub species ( Rosa xanthina ) and most other species with important value in the front, are strongly positively or negatively associated with at least one habitat. The valley and ridge are most distinct habitat with association of 12 species in the plot. However, high elevation slope with 257 quadrats is the most extensive habitat with only four species. Therefore, there is obvious evidence that habitat heterogeneity play an important role on shaping spatial distribution of species in warm temperate forest. Our research results provide significant evidence that dispersal limitation and habitat heterogeneity have a contribution jointly to regulating the spatial distribution pattern of species in warm-temperate-forest in China. [ABSTRACT FROM AUTHOR]

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

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

How climate change and human activities drive the evolution of the regional environment and where the quality of ecosystems improve or decline over time have become widespread concerns. In this study, we took the Three-River-Source (TRS) region of the Qinghai–Tibet Plateau as a case, aiming to identify and quantify the contribution of the natural and anthropogenic factors to the ecosystem changes over the past years from 1980 to 2018 using the methods of remote sensing and spatial statistical analysis. Based on the land cover map interpreted by reference to satellite remote sensing imagery data, we defined the Ecological Restoration Area Proportion (ERAP) as the bare land patch decrement to indicate the ecologically restored quantity in space. Assembling the restoration project information, we digitalized and vectorized the ecological Restoration Intensity (RI) including the spatial range and temporal duration. Combining the ERAP and the net primary productivity (NPP), which indicates the quantity and quality of ecosystems, respectively, the ecological asset Index (EAI) was developed and calculated. Having integrated the datasets of the vegetation monitoring, climatic factors, geographical factors, and human activities, we performed multi-variable analysis of the attribution of how the change in the EAI, the NPP, and the EAI have been affected by these factors together. The NPP of the middle and eastern parts of the TRS region has improved the most, as the average growth rate of NPP reached approximately 2.5 kg C/m2/10a. Due to such dynamic pattern, we found that human-induced re-vegetation has made limited contributions in our multi-regression model as the variance explained by the RI merely amounts to 4.4% to 8.8%, while the changes were mostly dependent on the regional temperature and the precipitation which contributed over 45% to the ecological restoration on average. It was summarized that "climate-help" overwhelms "human act" in such alpine grassland ecosystem. The regression results for the different aspects of the ERAP and NPP demonstrated that the ecological restoration project helped most in regard to ecosystem quality improvement rather than the restored ecosystem quantity. Our study has developed a comprehensive assessment methodology that can be reused to account for more ecological asset. The case is an example of an alpine ecosystem in which the success of ecological restoration needs favorable climatic conditions as supporting evidence for the nature-based solution. [ABSTRACT FROM AUTHOR]

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

Given the current situation that the research on the linguistic landscape in the tourism field is relatively insufficient, we try to carry out an investigation on the construction of linguistic landscape in the Fulai Mountain tourist area of Shandong Province, China, from the perspective of the tourism language landscape in domestic tourist areas. This study found that the language signs in the tourist area are mainly monolingual, supplemented by bilingual and trilingual signs. There are three languages in the Fulai Mountain tourist area: Chinese, English and Korean, among which Chinese is the preferred code, while English and Korean are marginalized in the linguistic landscape. The administrative department of the Fulai Mountain tourist area plays a decisive role in the construction of the linguistic landscape. We also find some problems with the linguistic landscape in the Fulai Mountain tourist area, such as insufficient construction of a diversified linguistic landscape, non-standard translation of language, and lack of design ideas and regional characteristics of the language signs. In the future, tourist area management departments should attach importance to the value of linguistic landscape construction, fully consider tourists' multi-language needs, improve linguistic landscape design, and regularly carry out linguistic landscape surveys. [ABSTRACT FROM AUTHOR]

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

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

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

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

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

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

• Near-hyperspectral measurements applicable to estimate plant biomass and cover of alpine grasslands. • Integrative approaches with multiple factors more accurate in estimating plant biomass and cover of alpine grasslands. • 66.55% and 64.58% increase in plant biomass and cover of alpine grasslands on Qinghai-Tibetan Plateau in past 20 years. • Sustainability of the alpine grasslands in dimensions of plant biomass and cover increase in future. Maintaining the aboveground biomass (AGB) and canopy cover (CC) of grassland is key for sustainable grassland management and rational conservation planning, especially for fragile regions of Qinghai-Tibetan Plateau (QTP). However, the estimation of AGB and CC with land use changes is often challenging due to poor availability of high-quality images of remote sensing or the large-scale field survey data. In this study, we used the transect survey method combining with quadrat measurements with 1200 plant samplings and near surface hyperspectral measurements at 180 sites to validate the MODIS data. An integrative approach combining the plant sampling, near surface hyperspectral measurements, remote sensing data interpretation, random forest modelling and Hurst phenomenon prediction was developed to accurately and efficiently estimate the CC and AGB of the alpine grasslands on the QTP from 2000 to 2017 and their future trends. The results showed: 1) estimation of AGB and CC in different land use types by integrating random forest with multiple factors (NDVI, latitude, longitude and altitude, grassland types) was more accurate; 2) the inter-annual changes of AGB and CC of the alpine grasslands presented significant fluctuations, with an increasing trend in the QTP; 3) the areas with improved vegetation conditions of AGB (66.55%) and CC (64.58%) were much larger than those with degraded vegetation conditions of AGB (33.45%) and CC (35.42%) in past 20 years. 4) there are 60.66% of the AGB and 59.87% of coverage showing sustainability and increasing in the future. Estimating the AGB and CC with multiple factors using the random forest and validated MODIS with the field spectrometer can improve the accuracy. The findings of this study can provide scientific basis for promoting the sustainability of grassland ecosystem through adaptive and rational management on the QTP and worldwide. [ABSTRACT FROM AUTHOR]

• No functional traits connected both phylogeny and environmental factors. • N addition at 8 kg N ha-1year−1 filtrated the species of the gramineae. • N addition at 72 kg N ha−1 year−1 filtrated the species of non-gramineae. • Potassium in normal year and phosphorus in warm year were main factors of environmental filtering. Nitrogen (N) deposition and warming leads to environmental gradients that shape plant communities and ecological diversity, space is treated as an equally important variable as the environmental variables in the environmental gradients. The Qinghai-Tibetan Plateau (QTP) is very sensitive to large increases in N deposition rates and warming. Environmental gradients caused by N deposition and spatial factors act as environmental filtering in community assembly by affecting plant functional traits and phylogeny. To investigate the effects of environmental filtering caused by N deposition on the community assembly in alpine meadows, we randomly placed and fertilized at 6 levels of N addition (no N addition, 8 kg N ha-1year−1, 24 kg N ha−1 year−1, 40 kg N ha−1 year−1, 56 kg N ha−1 year−1 and 72 kg N ha−1 year−1) both in a normal (normal precipitation and normal temperature) year and a warm (normal precipitation and warm) year. We used the fourth-corner analysis and extended RLQ (R stands for a matrix of environmental variables by samples, L stands for a species-cover-by-samples matrix and Q stands for a species-by-traits matrix) through multiple factors (soil factors, spatial heterogeneity, species traits, phylogenetic factor) to examine the effects of environmental filtering on the community assembly in alpine meadows. The results demonstrated that all soil variables showed a clear gradient and were affected by simulated N deposition; N addition at 8 kg N ha-1year−1 can filtrate the species of the gramineae, but N addition at 72 kg N ha−1 year−1 can filtrate the species of non-gramineae, the main factors of environmental filtering were potassium in normal year and phosphorus in warm year. With the increase of N deposition rate in alpine meadow of QTP, non-gramineous plants will be favored first, but eventually gramineous plants will occupy the dominant position in the QTP. Rational mitigation strategies should be developed for different climate change scenarios of alpine grasslands on the QTP according to their responses to the N addition gradients and climate change scenarios in the future. [ABSTRACT FROM AUTHOR]

• Biotic and abiotic factors significantly affected plant biomass-plant cover relationship in the alpine grasslands. • Plant diversity indices were negatively correlated with plant biomass in the alpine grasslands. • Plant biomass were positively correlated with soil N, P, Mg and OC in the alpine grasslands. • Soil nutrients played more critital roles than plant diversity played in regulating plant biomass accumulation. Biodiversity studies of grassland communities on Qinghai-Tibetan Plateau (QTP) produced dynamic results due mainly to environmental factors and anthropogenic activities. This study was designed to compare the plant diversity, plant biomass, plant tottal cover across different types of grasslands on the QTP. The various relationships between plant diversity indices such as Shannon-Weiner, Simpson, Evenness, and plant biomass, plant cover and soil elements were examined through correlation analysis. Further investigation was performed to examine the plant soil fertility-plant biomass and plant cover-plant biomass relationship using simple linear regression. We found a weak positive relationship between Evennes index and plant biomass, while a positive relationship was detected between plant cover and plant biomass. We suggested that grassland types and grazing affected the plant diversity-biomass-cover relationships on the QTP. Soil nitrogen (N), carbon (C), phosphorus (P) and Magnesium (Mg) were positively correlated with plant biomass, suggesting that soil nutrients rather than plant diversity played critical roles in regulating plant biomass accumulation in alpine grasslands. For a comprehensive understanding of the interconnections between plant diversity, plant cover, soil fertility and plant biomass, more studies should be done to probe into these relations and hence make a decision along this path. [ABSTRACT FROM AUTHOR]