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The rapid loss of global biodiversity can greatly affect the normal functioning of ecosystems. However, how biodiversity losses affect plant community structure and soil nutrients is unclear. We conducted a field experiment to examine the short‐ and long‐term effects of removing plant functional groups (Gramineae, Cyperaceae, legumes, and forbs) on the interrelationships among the species diversity, productivity, community structure, and soil nutrients in an alpine meadow ecosystem at Menyuan County, Qinghai Province. The variations in the species richness, above‐ and belowground biomass of the community gradually decreased over time. Species richness and productivity were positively correlated, and this correlation tended to be increasingly significant over time. Removal of the Cyperaceae, legumes, and other forbs resulted in fewer Gramineae species in the community. Soil total nitrogen, phosphorus, organic matter, and moisture contents increased significantly in the legume removal treatment. The removal of other forbs led to the lowest negative cohesion values, suggesting that this community may have difficulty recovering its previous equilibrium state within a short time. The effects of species removal on the ecosystem were likely influenced by the species structure and composition within the community. Changes in the number of Gramineae species indicated that they were more sensitive and less resistant to plant functional group removal. Legume removal may also indirectly cause distinct community responses through starvation and compensation effects. In summary, species loss at the community level led to extensive species niche shifts, which caused community resource redistribution and significant changes in community structure. [ABSTRACT FROM AUTHOR]

Grasslands support various ecological functions, such as climate regulation, soil and water conservation, carbon turnover, and nutrient cycling. However, nearly a half of global grasslands have been degraded to varying degrees, especially on the Qinghai–Tibet Plateau (QTP), an extremely fragile ecosystem. As a primary measure of grassland restoration, fertilization largely affects soil aggregate size distribution (ASD) and particle size distribution (PSD). Fractal theory provides a powerful tool for analysis and characterization of soil ASD and PSD. However, our current understanding of soil ASD and PSD responses to fertilization remains limited. Therefore, this study investigated the response of soil structure and fertility to long-term fertilization in alpine grasslands on the QTP based on fractal theory. Long-term fertilization caused significant changes in soil ASD, which varied depending on fertilization practice, particularly in the topsoil (0–5 cm). Soil texture, which is influenced by soil parent material, exhibited a continuous vertical distribution along the depth and was not altered by fertilization. In addition, the results further confirmed that large microaggregates with specific pore structures contributed more to soil organic carbon (SOC) sequestration than did other size aggregates. The generalized dimension spectra showed varying increases (6.27–34.93 %) in the complexity or fineness (ΔD) of the soil PSD after fertilization. Capacity dimension (D 0) decreased significantly with NP addition and was correlated strongly with plant species diversity and richness, whereas the information dimension (D 1), D 1 /D 0 , and correlation dimension (D 2) exhibited significant correlations with soil nutrients. During long-term fertilization, soil texture dominated the vertical distribution of the soil erodibility factor, and characteristic microaggregates were the key factors influencing change in soil microstructural stability. Overall, the findings highlight that selection of appropriate fertilization methods (single or combined applications) is vital for regulation and improvement of soil structure and fertility in alpine grasslands. • Long-term fertilization caused significant changes in soil aggregate size distribution. • Increased complexity (ΔD) of soil particle size distribution after fertilization. • Large microaggregates (0.05–0.25 mm) contributed more to SOC sequestration. • Soil texture dominated the vertical distribution of the soil erodibility factor. • Characteristic microaggregates were the key factors for soil microstructure stability. [ABSTRACT FROM AUTHOR]

Seasonal rhythms in biological and ecological dynamics are fundamental in regulating the structuring of microbial communities. Evaluating the seasonal rhythms of microorganisms in response to climate change could provide information on their variability and stability over longer timescales (>20-year). However, information on temporal variability in microorganism responses to medium- and long-term global warming is limited. In this study, we aimed to elucidate the temporal dynamics of microbial communities in response to global warming; to this end, we integrated data on the maintenance of species diversity, community composition, temporal turnover rates (v), and community assembly process in two typical ecosystems (meadows and shrub habitat) on the Qinghai-Tibet Plateau. Our results showed that 21 years of global warming would increase the importance of the deterministic process for microorganisms in both ecosystems across all seasons (R2 of grassland (GL) control: 0.524, R2 of GL warming: 0.467; R2 of shrubland (SL) control: 0.556, R2 of SL warming: 0.543), reducing species diversity and altering community composition. Due to environmental filtration pressure from 21 years of warming, the low turnover rate (v of warming: −3.13/-2.00, v of control: −2.44/−1.48) of soil microorganisms reduces the resistance and resilience of ecological communities, which could lead to higher community similarity and more clustered taxonomic assemblages occurring across years. Changes to temperature might increase selection pressure on specialist taxa, which directly causes dominant species (v of warming: −1.63, v of control: −2.49) primarily comprising these taxa to be more strongly impacted by changing temperature than conditionally (v of warming: −1.47, v of control: −1.75) or always rare taxa (v of warming: −0.57, v of control: −1.33). Evaluation of the seasonal rhythms of microorganisms in response to global warming revealed that the variability and stability of different microbial communities in different habitats had dissimilar biological and ecological performances when challenged with an external disturbance. The balance of competition and cooperation, because of environmental selection, also influenced ecosystem function in complex terrestrial ecosystems. Overall, our study enriches the limited information on the temporal variability in microorganism responses to 21 years of global warming, and provides a scientific basis for evaluating the impact of climate warming on the temporal stability of soil ecosystems. • Microbial community dynamics of grassland in response to global warming were examined • Global warming will reduce species diversity and alter community composition • High temperature might increase the dominance of the deterministic process • Plants mediate indirectly to differences of temperature response in temporal dynamics [ABSTRACT FROM AUTHOR]

• Warming decreased the stability of soil aggregate in shrubland. • Warming decreased the soil aggregate associated carbon storage in meadow but increased it in shrubland. • Warming enhanced the stability of soil aggregate associated carbon. • The associated carbon storage of macroaggregates is more sensitive to warming. Global warming is increasingly impacting the structure and functioning of the ecosystems in the Tibetan plateau. However, information about warming effects on the stability of carbon pools in soil aggregates is limited. Here, we implemented a 21-year long-term open-top-chamber (OTCs) warming experiment to reveal the warming effects on the stability of topsoil aggregate structure and carbon pools in a Tibetan alpine meadow and shrubland. The results demonstrated that long-term warming significantly reduced the soil aggregate stability of the shrubland, but had no significant effect on the alpine meadow. Although warming enhanced the stability of carbon pools in topsoil aggregate fractions for both the alpine meadow and shrubland, a negative response of the carbon management index (CMI) and carbon pool storage in the alpine meadow was found, while shrubland showed a positive response to warming. The response of carbon fractions to warming depended on soil aggregate size, with a reduction of labile C fraction 1 (C1) and stable carbon fraction (C4) in large (LMGA: >2 mm) and small macroaggregates (SMGA: 2–0.25 mm) of the alpine meadow, and unchanged carbon fractions in microaggregates (MIGA: <0.25 mm) for both the alpine meadow and shrubland. Long-term warming significantly decreased C-acquiring enzyme activity in shrubland, but had no significant effect on the meadow. Enzyme activity and glomalin-related soil protein (GRSP) concentration decreased as the size of soil aggregates increased in the alpine meadow and shrubland, which could be attributed to the structural characteristics of microaggregates, which have larger specific surface area and stronger microbial protection ability. Our findings provide a new perspective in understanding the response of alpine meadow and shrubland soil structure and carbon pool stability to long-term warming at the soil aggregate level. [ABSTRACT FROM AUTHOR]

The ecological linkage between above- and belowground parts of the terrestrial ecosystem is of interest to ecological and management fields. However, the knowledge on how the loss of plant functional groups impacts multitrophic interactions across soil biota and associated ecological functioning knowledge is lacking. This study aimed to evaluate responses of soil nematode communities to PFG (Gramineae, Cyperaceae, Leguminosae, and other Forbs) identity and richness loss after 9 years by comparing 15 treatments. Specifically, the loss of PFG richness significantly decreased carbon biomass and the abundance of bacterivores and negatively affected footprints of bacterivores and omnivore-predators (OP), leading to a decline in the enrichment and structure footprints. The response of nematode community structure and functional composition at different trophic levels to PFG richness loss varied with PFG identity. Gramineae removal reduced the community structural footprint positively associated with the biomass carbon and footprint of OP, suggesting carbon and energy enrichment are likely to be lower in soil micro-food webs. Although the removal of Cyperaceae reduced carbon biomass and the footprint of bacterivores, it did not cause significant shifts in carbon and energy enrichment and structural footprints in the soil food web, similar to the other two PFGs. Notably, Gramineae strongly controlled carbon and energy enrichment regulations in soil micro-food webs than other PFGs. The present study highlights the key role and influence of PFG richness and identification on food web ecosystem services. It provides a basis for the development of sustainable strategies for grazed alpine meadow ecosystem's management. [Display omitted] • The responses of nematodes community among trophic levels to the loss of PFG differ. • The negative effects of PFG loss on nematode community and functional conditions were conservative. • The positive effect of Gramineae on the soil carbon and energy enrichment over other PFG identities [ABSTRACT FROM AUTHOR]

Seeds often exhibit great plasticity of germination in response to environmental variability and uncertainty. The causes of this plasticity, however, remain poorly understood, and comparative phylogenic analyses of such plasticity are rare. Here, we analyzed a field germination dataset including 474 species exposed to three different levels of light availability, using comparative phylogenetic methods. We calculated the plasticity of germination in response to light availability (PG GP) based on the maximum germination proportion (GP max), PG T50 based on the time required to reach 50% of GP max , PG RGV based on the relative germination velocity (RGV), and PG Total based on all three of these germination traits. We found that closely related species shared similar light plasticity of germination behavior. Different aspects of germination plasticity in response to light availability were related to specific traits or local environment. PG GP was associated with adult longevity and local water habitat, while PG T50 was related to seed mass and local water habitat, and PG RGV was marginally significantly related to plant height. PG Total was significantly associated with adult longevity and water habitat. These results suggested that different aspects of germination plasticity were located at specific niche dimension, and local habitats with sufficient soil moisture induced great plasticity germination in response to light environment. As such, they can simplify our understanding of germination, promote the exploration of the general law of germination, and further increase our understanding of species diversity maintenance, adaptation, and evolution from the perspective of germination. [ABSTRACT FROM AUTHOR]

Finally, our phytochemical investigation led to the isolation of five anthraquinone derivatives and five flavonoid compounds (purity > 98%). Acknowledgment This work was supported by the China Spark Program (No. 2015GA870007), the Qinghai Provincial Applied Basic Research Project (2017-ZJ-749), the Qinghai Provincial Key Research and Development and Transformation Program (2019-NK-C04) and the Qinghai Innovation Platform Construction Project (No. 2017-ZJ-Y20). On the basis of the analysis of spectral data such as MS and SP 1 sp H and SP 13 sp C NMR, these compounds were determined as five common anthraquinone compounds present in the roots of I R. tanguticum i including, aloe-emodin ( B 1 b ) [[4]], rhein ( B 2 b ) [[5]], emodin ( B 3 b ) [[6]], chrysophanol ( B 4 b ) [[7]], and physcion ( B 5 b ) [[8]], as well as five flavonoid compounds, including tricin ( B 6 b ) [[9]], quercetin-3 I O i I i -Dglucoside ( B 7 b ) [[10]], kaempferol-3 I O i I i -L-rhamnopyranoside ( B 8 b ) [[11]], rhamnazin ( B 9 b ) [[12]], and tricin-7 I O i I i -D-glucopyranoside ( B 10 b ) [[13]]. [Extracted from the article]

• Warming significantly lowered soil nematode diversity. • Warming indirectly and directly affected vegetation to lead to soil nematodes diversity being changed. • Warming and litter removal significantly reduced external resource inputs to the food web. • Warming and litter removal lead to soil food web degradation. Both climate warming and litter removal alter soil nematode communities and the structure, stability, and function of soil food webs. The soil nematode metabolic carbon footprint, based on nematode biomass and respiration, can be used to indicate ecosystem function and the response of nematodes to nutrient enrichment in the ecosystem. However, it is unclear whether or how climate warming and litter removal affect the metabolic carbon footprint of soil nematodes and soil food webs. In this study, we investigated four warming and litter removal treatments in the Qinghai-Tibet Plateau, China, to determine the effects of climate warming and litter removal on soil microbial food webs. The treatments included: (1) control (CK), (2) warming, (3) litter removal, (4) warming + litter removal. We found that warming and litter removal had significant negative effects on the diversity and richness of soil nematodes. In addition, our results showed warming indirectly and directly affected vegetation diversity, thereby altering soil nematode diversity. Vegetation played an important role in the maintenance of soil nematode community diversity. The enrichment and structural footprints reflected nematodes that could respond most rapidly to resource enrichment and those with higher trophic levels in soil food webs, respectively. Overall, warming and litter removal significantly negatively affect the enrichment metabolic footprint, indicating they could significantly reduce the external resource inputs into the food web. Both warming and litter removal reduced the structural metabolic footprint of the soil food web, although the changes were not significant, indicating that the metabolic activity of nematodes of high nutrient levels decreased and the ability to regulate the food web from top-bottom effects was weakened under warming and litter removal. The nematode functional metabolic footprints indicated that litter removal could aggravate the effect of warming on the soil food web and result in more severe degradation. The combination of warming and litter removal significantly inhibited the connectance of the bacterial channel, but had no significant effect on the fungal channel. These results suggest that the soil food web enhanced resistance to the environment by increasing the proportion of the fungal channel. It is critical to understand the responses of soil food webs to climate warming and litter removal to better predict how ecosystem functions will change in the future. [ABSTRACT FROM AUTHOR]

Artificial grasslands have been regarded as an effective method to improve grass production and quality, especially on the Qinghai–Tibet Plateau. Soil ecosystem multifunctionality (EMF) plays an important role in sustainable regional development. However, few studies have investigated the impacts of artificial grasslands on soil EMF. Here, we constructed single-species artificial grasslands in a natural temperate steppe and investigated soil microbial communities, abiotic factors (soil moisture and pH), and functions related to biogeochemical cycles to explore (1) how the transformation from temperate steppe to artificial grasslands affected soil EMF and (2) the roles of species and phylogenetic microbial diversities, microbial community composition, and abiotic factors in driving differences in soil EMF. Our results showed that artificial grasslands decreased soil EMF regardless of planting species; that the bacterial and fungal community composition contributed more to soil EMF prediction than species and phylogenetic diversities; and that microbial phylogenetic diversities were negatively associated with soil EMF. Soil pH played an important role in the effects of artificial grasslands on soil EMF—artificial grasslands increased soil pH, which was negatively associated with soil EMF. Overall, the benefits of establishing artificial grasslands, for example, higher grass production and quality, might be at the expense of soil EMF. Further studies should explore mixed-species artificial grasslands. [ABSTRACT FROM AUTHOR]

• Long-term warming experiment showed the changes in environmental contexts. • Soil microbes of two ecosystems responded differently to warming. • Plants mediated the effect of global warming on microbial responses. Exploring the feedback of the soil microbial community and associated processes to global warming represents a major global challenge. To date, the focus has been placed on the direct effects of warming on soil microbial communities, overlooking how concurrent changes in plant communities may mediate these effects. Additionally, few studies have examined long-term effects of warming in more than one environmental context. In the present study, we conducted a long-term simulated warming experiment to investigate how changes to the plant community within two different environmental contexts affect the responses of soil microorganisms and their respiration to warming. We analyzed the abundance, diversity, and community composition of plants and soil microbes, in addition to soil microbial interaction networks and soil microbial respiration, in two typical ecosystems of the Qinghai–Tibet Plateau. Following long-term warming, the soil microbial composition, structure, and interactions changed, and the shifts depended on the aboveground plant type. Specifically, the co-occurring networks containing different microbial communities tended to be more complex in a shrubland than in a grassland after warming, leading to higher carbon use efficiency. Additionally, long-term warming changed the structure of soil microbial communities, increasing the relative abundances of oligotrophic taxa in the shrubland but not in the grassland. The shifts in community structure and interaction patterns could be explained by vegetation community attributes, highlighting the strong effect of plants on soil microbial responses. These plant-mediated effects on community structure and interactions subsequently could explain changes in soil microbial respiration rates. Microbial respiration showed a positive response to elevated temperature in the grassland but no response to temperature in the shrubland. These results indicate that interactions between soil microbial communities and plant communities determine how soil microbes respond to global warming. Therefore, future research on soil microbial community composition and associated carbon feedbacks to the climate change should include plant-mediated effects, which can provide a scientific basis for effectively mitigating global warming. [ABSTRACT FROM AUTHOR]

The meadow ecosystem on the Qinghai-Tibetan Plateau is considered to be sensitive to climate change. An understanding of the alpine meadow ecosystem is therefore important for predicting the response of ecosystems to climate change. In this study, we use the coefficients of variation (Cv) and stability (E) obtained from the Haibei Alpine Meadow Ecosystem Research Station to characterize the ecosystem stability. The results suggest that the net primary production of the alpine meadow ecosystem was more stable (Cv = 13.18%) than annual precipitation (Cv = 16.55%) and annual mean air temperature (Cv = 28.82%). The net primary production was insensitive to either the precipitation (E = 0.0782) or air temperature (E= 0.1113). In summary, the alpine meadow ecosystem on the Qinghai- Tibetan Plateau is much stable. Comparison of alpine meadow ecosystem stability with other five natural grassland ecosystems in Israel and southern African indicates that the alpine meadow ecosystem on the Qinghai-Tibetan Plateau is the most stable ecosystem. The alpine meadow ecosystem with relatively simple structure has high stability, which indicates that community stability is not only correlated with biodiversity and community complicity but also with environmental stability. An average oscillation cycles of 3-4 years existed in annual precipitation, annual mean air temperature, net primary production and the population size of consumers at the Haibei natural ecosystem. The high stability of the alpine meadow ecosystem may be resulting also from the adaptation of the ecosystem to the alpine environment. [ABSTRACT FROM AUTHOR]

Grassland shrub encroachment is known to change soil organic carbon (SOC) storage, but the effect of artificial thicketization on SOC in alpine grasslands of the Qinghai–Tibetan Plateau remains unclear. In this study, we investigated the effects of two common shrubs, leguminous Caragana korshinskii and non‐leguminous Hippophae rhamnoides, on SOC at a reforestation site on the Qinghai–Tibetan Plateau. While C. korshinskii had no significant effect on SOC content, H. rhamnoides significantly increased SOC content. In both shrub communities, there was a significant positive correlation between SOC content and the coverage, plant aboveground biomass, dominant plant species biomass, total and available nitrogen, total phosphorus, and proportion of water‐stable aggregate of greater than 250 μm. Structural equation modeling showed that the common path by which the two shrub communities affected SOC was that the dominant species affected soil structure and the available nitrogen content by influencing community biomass, which had indirect effects on SOC. Additionally, C. korshinskii participated in the regulation of SOC. This result provides an important empirical reference and key insights into the carbon cycling mechanisms of reforested grasslands on the Qinghai–Tibetan Plateau. [ABSTRACT FROM AUTHOR]

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

Plants can adapt to environmental changes by adjusting their functional traits and biomass allocation. The size and number of flowers are functional traits related to plant reproduction. Life history theory predicts that there is a trade‐off between flower size and number, and the trade‐off can potentially explain the adaptability of plants. Elevation gradients in mountains provide a unique opportunity to test how plants will respond to climate change. In this study, we tried to better explain the adaptability of the alpine plant Gentiana lawrencei var. farreri in response to climate change. We measured the flower size and number, individual size, and reproductive allocation of G. lawrencei var. farreri during the flowering period along an elevation gradient from 3200 to 4000 m, and explored their relationships using linear mixed‐effect models and the structural equation model. We found that with elevation increasing, individual size and flower number decreased and flower size increased, while reproductive allocation remained unchanged. Individual size positively affected flower number, but was not related to flower size; reproductive allocation positively affected flower size, but was not related to flower number; there is a clear trade‐off between flower size and number. We also found that elevation decreased flower number indirectly via directly reducing individual size. In sum, this study suggests that G. lawrencei var. farreri can adapt to alpine environments by the synergies or trade‐offs among individual size, reproductive allocation, flower size, and flower number. This study increases our understanding of the adaptation mechanisms of alpine plants to climate change in alpine environments. [ABSTRACT FROM AUTHOR]

Backgrounds: Climate change is well-known to alter the structure and function of grassland ecosystems, and multifunctionality contributes to a comprehensive understanding of the impacts of climate change on ecosystem functions. Warming and humidification are predicted to be the climate change trend on the northeastern Qinghai-Tibetan Plateau. However, understanding of how long-term warming and increased precipitation affect ecosystem multifunctionality in alpine meadows is still limited. Methods: Here, we conducted an 8-year field experiment involving warming and increased precipitation in an alpine meadow to explore how warming, increased precipitation, and their interaction affect ecosystem multifunctionality. Results: The results indicated that increased precipitation had a positive effect on ecosystem multifunctionality. However, warming and the interaction of warming and precipitation had no significant effects on it. Warming decreased species richness and plant coverage. Increased precipitation enhanced aboveground carbon (C), nitrogen (N), and phosphorus (P) pools of plant community, and soil moisture, but decreased soil pH. Aboveground P and N pools of plant community and microbial biomass nitrogen (MBN) were important predictors of ecosystem multifunctionality. Conclusion: This study demonstrated long-term increased precipitation can enhance ecosystem multifunctionality by indirectly affecting the individual functions (aboveground P and N pools of plant community and MBN), soil moisture, and pH in an alpine meadow. These findings highlighted that increased precipitation is more critical than warming for enhancing ecosystem multifunctionality in semi-arid alpine meadows. [ABSTRACT FROM AUTHOR]

• A meta-analysis on the degraded grasslands of the Qinghai-Tibetan Plateau. • More severe degradation for plant growth and soil quality than plant diversity. • Fertilisation improves plant growth and soil quality but limits plant diversity. • Optimal effect is found when jointly using phosphorus and nitrogen. • Climatic factors regulate degradation degree and fertilisers' effect. Climate warming and human disturbance are supposed to have severely affected the alpine grasslands on the Qinghai-Tibetan Plateau (QTP), a region where the extremely harsh and fragile ecological environment has attracted great attention because of its sensitivity to global change. However, there is still no unified understanding of the degree and magnitude of grassland degradation and the effectiveness of nutrient addition in this vast landscape, since most previous studies have focused on short-term observations at a single site. Here, we conducted a meta-analysis of 145 published studies on degraded alpine grassland along with 90 published studies, which concerning nutrient addition (nitrogen [N], phosphorus [P], and combined N and P [NP]) to quantitatively assess the responses of plant and soil characteristics to land degradation and restoration. Our results revealed that the response ratio (RR) of above-ground biomass (AGB), below-ground biomass (BGB), soil organic carbon (SOC), and soil total N (TN) decreased significantly (−47.23 %, −43.45 %, −32.35 %, and −37.97 %, respectively) in degraded grassland compared with non-degraded grassland. The RR of AGB was correlated with mean annual precipitation (MAP), while the RR of BGB was correlated with the interaction of MAP and mean annual temperature (MAT). Severely degraded grassland required additional nutrients to aid recovery. NP addition to severely degraded sites increased plant AGB (+32.44 %), TN (+10.99 %), soil total P (+32.25 %), and soil moisture (+9.21 %), but significantly decreased species richness (−45.46 %), diversity (−30.40 % for Shannon−Wiener index) and soil pH (−3.91 %). N addition increased the RR of AGB and grass biomass significantly by 28.77 % and 36.49 %, but had no significant effect on sedge and forb biomass. MAP influenced the RR of AGB, TN, TP under NP addition, the RR of BGB and the AGB of different function groups were significantly affected by MAT. We evidenced that the QTP has endured severe vegetation and soil degradation, which cannot be completely mitigated by supplementary fertilisation. Fertilisation could yield positive effects on plant performance and soil quality, but negative effects on biodiversity. Climate warming and associated precipitation change may regulate the effects of fertiliser on plant biomass and soil nutrients. [ABSTRACT FROM AUTHOR]

Beginning in the twentieth century, atmospheric deposition of N and P greatly increased in terrestrial ecosystems, including alpine grasslands. These inputs have profoundly affected soil microbial C and N cycles. Changes in the microbial environment are directly caused by changes in soil N and P availability and also indirectly through changes in vegetation in response to increased fertilization. The mechanisms involved in both the direct and indirect changes are not mutually exclusive and are poorly understood. Therefore, we investigated the responses of vegetation and soil microbes to a 9-year fertilization (N and P) experiment in an alpine grassland in the Qinghai–Tibetan Plateau in China. We found that N addition altered soil microbial community composition and processes regardless of P addition. To maintain stoichiometric homeostasis, soil microbes adjusted metabolic processes in response to changes in nutrient availability. High N availability enhanced microbial investment in C acquisition as indicated by β-1,4-Glucosidase activity. The abundance of microbial taxa that degrade labile C also increased. High N inputs also induced a proliferation of denitrifiers and increased the gaseous N loss potential. Partial least squares path modelling indicated that soil parameters (e.g., soil organic C and total N) and changes in the plant community played a key role in shaping soil microbial community structure and C and N cycling. Our results suggest that vegetation and stoichiometric differences between resource availability and soil microbial nutrient requirements collectively regulate the responses of soil microbial processes to N enrichment, which provides novel experimental insights into the mechanisms underlying the effects of nutrient inputs on microbial C and N cycles. Ultimately, our findings highlight the importance of plant traits in regulating microbial nutrient cycles, further promoting our comprehension about the mechanism of variation in the microbial nutrient cycles in an alpine grassland soils. • Microbial process was driven by stoichiometric relation between substrate and them. • Fertilization indirectly affects microbial processes mediated by vegetation. • Soil microbial community and functions correlated soil and plant parameters. [ABSTRACT FROM AUTHOR]

A detailed understanding of the molecular mechanisms of plant stress resistance in the face of ever-changing environmental stimuli will be helpful for promoting the growth and production of crop and forage plants. Investigations of plant responses to various single abiotic or biotic factors, or combined stresses, have been extensively reported. However, the molecular mechanisms of plants in responses to environmental stresses under natural conditions are not clearly understood. In this study, we carried out a transcriptome analysis using RNA-sequencing to decipher the underlying molecular mechanisms of Onobrychis viciifolia responding and adapting to the extreme natural environment in the Qinghai-Tibetan Plateau (QTP). The transcriptome data of plant samples collected from two different altitudes revealed a total of 8212 differentially expressed genes (DEGs), including 5387 up-regulated and 2825 down-regulated genes. Detailed analysis of the identified DEGs uncovered that up-regulation of genes potentially leading to changes in hormone homeostasis and signaling, particularly abscisic acid-related ones, and enhanced biosynthesis of polyphenols play vital roles in the adaptive processes of O. viciifolia. Interestingly, several DEGs encoding uridine diphosphate glycosyltransferases, which putatively regulate phytohormone homeostasis to resist environmental stresses, were also discovered. Furthermore, numerous DEGs encoding transcriptional factors, such as members of the myeloblastosis (MYB), homeodomain-leucine zipper (HD-ZIP), WRKY, and nam-ataf1,2-cuc2 (NAC) families, might be involved in the adaptive responses of O. viciifolia to the extreme natural environmental conditions. The DEGs identified in this study represent candidate targets for improving environmental stress resistance of O. viciifolia grown in higher altitudes of the QTP, and can provide deep insights into the molecular mechanisms underlying the responses of this plant species to the extreme natural environmental conditions of the QTP. [ABSTRACT FROM AUTHOR]

Captivity is an important and efficient technique for rescuing endangered species. However, it induces infertility, and the underlying mechanism remains obscure. This study used the plateau pika (Ochotona curzoniae) as a model to integrate physiological, metagenomic, metabolomic, and transcriptome analyses and explore whether dysbiosis of the gut microbiota induced by artificial food exacerbates infertility in captive wild animals. Results revealed that captivity significantly decreased testosterone levels and the testicle weight/body weight ratio. RNA sequencing revealed abnormal gene expression profiles in the testicles of captive animals. The microbial α-diversity and Firmicutes/Bacteroidetes ratio were drastically decreased in the captivity group. Bacteroidetes and Muribaculaceae abundance notably increased in captive pikas. Metagenomic analysis revealed that the alteration of flora increased the capacity for carbohydrate degradation in captivity. The levels of microbe metabolites' short-chain fatty acids (SCFAs) were significantly high in the captive group. Increasing SCFAs influenced the immune response of captivity plateau pikas; pro-inflammatory cytokines were upregulated in captivity. The inflammation ultimately contributed to male infertility. In addition, a positive correlation was observed between Gastranaerophilales family abundance and testosterone concentration. Our results provide evidence for the interactions between artificial food, the gut microbiota, and male infertility in pikas and benefit the application of gut microbiota interference in threatened and endangered species. [ABSTRACT FROM AUTHOR]

Objectives: Soil fauna plays a crucial role in contributing to litter breakdown, accelerating the decomposition rate and enhancing the biogeochemical cycle in terrestrial ecosystems. Comprehending the specific fauna role of functional species in litter decomposition is challenging due to their vast numbers and diversity. Climate and litter quality are widely acknowledged as dominant drives of litter decomposition across large spatial scales. However, the pattern of climate and litter quality modulates the effect of soil fauna on litter decomposition remains largely unexplored. To address this gap, we conducted an extensive analysis using data from 81 studies to investigate how climate and litter traits affects soil fauna in the decomposition. Data description: The paper describes fauna body size, climate zones (tropical, subtropical and temperate), ecosystem types (forest, grassland, wetland and farmland), soil types (sand, loam and clay), decomposed duration (< 180, 180–360, > 360 days), litter initial traits, average annual temperature and precipitation. The litter traits encompass various parameters such as concentrations of carbon, nitrogen, phosphorus, potassium, lignin, cellulose, total phenol, condensed tannin, hydrolysable tannin and other nutrient traits. These comprehensive datasets provide valuable insights into the role of soil fauna on the decomposition at global scale. Furthermore, the data will give researchers keys to assess how climate, litter quality and soil fauna interact to determine decomposition rates. [ABSTRACT FROM AUTHOR]

Over the last 40 years, a burrowing mammal eradication policy has been prevalent on the Qinghai–Tibetan Plateau (QTP). This policy is based on similar burrowing mammal eradication programs in other areas and is justified on the assumptions that burrowing mammals compete with livestock for forage and contribute to grassland degradation. However, there is no clear theoretical or experimental evidence supporting these assumptions.This paper synthesizes the ecological functioning of small burrowing mammals in natural grasslands and discusses the irrationality and consequences of burrowing mammal eradication for sustainable livestock grazing and grassland degradation.Past burrowing mammal eradication efforts have failed because increased food availability for the remaining rodents and reduced predator populations led to rapid population rebounds. Herbivores differ in diet, and there is clear evidence that burrowing mammals, especially plateau zokors Myospalax baileyi, have a different diet than livestock. In QTP meadows, burrowing mammal eradication induces a shift towards plant communities with fewer species preferred by livestock and more species preferred by burrowing mammals. Thus, eradicating burrowing mammals has the opposite effect, a reduction in livestock preferred vegetation. We suggest that the policy of poisoning burrowing mammals needs to be reconsidered and revoked as soon as possible.We argue that incorporating density‐dependent factors such as predation and food availability are essential for maintaining a low burrowing mammal density. For degraded grasslands, we suggest that the optimal sustainable approach is to decrease the intensity of livestock grazing. Lower grazing induces changes in vegetation structure and plant species composition that increases predation on burrowing mammals and decreases the abundance of plants preferred by burrowing mammals. Such a nature‐based grassland management system maintains the density of burrowing mammals at a low stable density while minimizing human management and interventions. [ABSTRACT FROM AUTHOR]

Deserts soils acted as important soil carbon pools in arid and semiarid regions. Soil organic carbon (SOC) contents and its driven factors remained unclear in alpine deserts on the Tibetan Plateau. In this study, we sampled 223 soil profiles, and analyzed SOC values under 0-30 cm. It was indicated that average and median of SOC were approximately 4.86 and 3.80 g/kg. SOC contents were divided into four groups. The largest group was approximately 3.32 g/kg (145 profiles, P<0.05) when air temperature and altitude were higher than 1.49°C and 2793 m with lower precipitation of 173.4 mm encircling with Qaidam basin. Future increasing precipitation scenario would be an effective countermeasure to increase SOC in this region. Furthermore, SOC of the smallest group was 13.7 g/kg when precipitation was over 371.5 mm in the south of Qinghai Lake. Alpine desert SOC were mainly controlled by total nitrogen and pH and precipitation with R2 of 0.87 (P<0.001). In addition, increasing nitrogen deposition and mineral decomposition significantly increased desert soils organic carbon storage. [ABSTRACT FROM AUTHOR]

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

Accurate information on grassland above-ground biomass (AGB) is critical to better understanding the carbon cycle and conserve grassland resources. As a climate-sensitive key ecological function area, it is important to accurately estimate the grassland AGB of the Tibetan Plateau. Sentinel-2 (S2) images have advantages in reducing mixed pixels and the scale effect for remote sensing, while the data volume is correspondingly larger. In order to improve the estimation accuracy while reducing the data volume required for AGB estimation and improving the computational efficiency, this study used the Recursive Feature Elimination (RFE) algorithm to find the optimal feature set and compared the performance of the Cubist, Gradient Boosting Regression Tree (GBRT), random forest (RF) and eXtreme Gradient Boosting (XGBoost) algorithms for estimating AGB. In this study, ten S2 bands, ten S2-derived vegetation indexes, 218 pieces of AGB field survey data, four types of meteorological data and three types of topographic data were used as the alternative input features for the AGB estimation model. The impurity and permutation importance were used as the feature importance calculation method input to the RFE, and the Cubist, GBRT, RF and XGBoost algorithms were used to construct the AGB estimation models. The results showed that the RF algorithm based on the monthly average temperature (T), elevation, Normalized Difference Phenology Index (NDPI), Normalized Difference Infrared Index (NDII) and Palmer Drought Severity Index (PDSI) performed best ( R 2 = 0.8838, RMSE = 35.05 g/m 2 , LCCC = 2.44, RPPD = 0.91). The above findings suggest that the RF model based on the features related to temperature, altitude, humidity and leaf water content is beneficial to estimate the grassland AGB on the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Background and aims: The ability of biological soil crusts (BSCs) to improve soil microenvironments is mainly due to microorganisms that form an integral component of the BSCs. We aimed to investigate the changes in bacterial communities within BSCs along climate gradients and explored factors and ecological processes that drive these variations. Methods: Algal and lichen BSCs were sampled along an aridity gradient in alpine grasslands from the Qinghai-Tibet Plateau, China. Bacterial communities in BSCs were determined using high-throughput sequencing, and soil beneath the BSCs (0–5 cm) was collected for macro-nutrient determination. Results: Algal BSCs consisted of more diverse bacterial communities than did lichen BSCs. Bacterial communities were significantly affected by the aridity index. With an increase in aridity index, bacterial diversity increased in algal BSCs but decreased in lichen BSCs. Additionally, lichen BSCs' bacterial communities were different from those of algal BSCs, especially in wetter areas, where Burkholderia dominated in lichen BSCs, but not in algal BSCs. Lichen BSCs' bacterial composition correlated significantly with soil pH and total nitrogen content, however that was not the case with algal BSCs. Stochastic processes governed the spatial variations of bacterial communities in lichen BSCs, which was different from the equivalent importance of stochastic and deterministic processes in algal BSCs. Conclusions: Changes in BSCs associated bacterial communities along an aridity gradient were different between algal and lichen BSCs. Additionally, stochastic processes were much more important for lichen BSCs than algal BSCs in shaping spatial variations of bacterial communities. [ABSTRACT FROM AUTHOR]

Boreal forests sequester massive amounts of atmospheric carbon dioxide (CO 2), and the contribution from the mid-high-latitude coniferous forests is considerable. This study quantified the net ecosystem exchange (NEE) of CO 2 flux and its driving factors in a spruce forest in the Qilian Mountains. The results indicated that the NEE presented a robust temporal pattern ranging from −26.09 to 12.35 g C m−2 on a day-to-day basis. Furthermore, cumulative monthly NEE flux varied between −194.61 g C m−2 and 33.56 g C m−2. Forest ecosystems are vital carbon sinks that sequester/store carbon dioxide from April to September, especially from June to August. The annual NEE flux was a robust carbon sink of 545.99 g C m−2. Forest NEE was significantly driven by latent heat flux, net radiation, air temperature, and precipitation (P < 0.001). Regression coefficient of fitting model was 49.2% using latent heat flux, air temperature, and precipitation. In addition, future warming and precipitation scenarios may have considerably negative and positive effects, respectively, on the carbon sink. • The annual NEE flux was a robust carbon sink of −545.99 g C m−2 on the Tibetan Plateau. • Forest NEE was significantly driven by latent heat flux, net radiation, air temperature, and precipitation. • Future warming and precipitation scenarios may have considerably negative and positive effects on the carbon sink. [ABSTRACT FROM AUTHOR]

While most studies yield positive relationships between biodiversity (B) and ecosystem functioning (EF), awareness is growing that BEF relationships can vary with ecological context. The awareness has led to increased efforts to understand how contemporary environmental context modifies BEF relationships, but the role of historical context, and the mechanisms by which it may influence biodiversity effects, remains poorly understood.We examined how historical context alters plant diversity–community productivity relationships via plant species interactions in alpine grassland. We also tested how historical context modifies interactions between plants and arbuscular mycorrhizal (AM) fungi, which can potentially mediate the above processes.We studied biodiversity effects on plant community productivity at two grassland sites with different histories related to grazing intensity—heavy versus light livestock grazing—but similar current management. We assembled experimental communities of identical species composition with plants from each of the two sites in disturbed soil from a contemporary heavily grazed grassland, ranging in species richness from one to two, three and six species. Moreover, we carried out a mycorrhizal hyphae‐exclusion experiment to test how plant interactions with AM fungi influence plant responses to historical context.We detected a significantly positive diversity–productivity relationship that was driven by complementarity effects in communities composed of plants from the site without heavy‐grazing history, but no such relationship in plant communities composed of plants from the site with heavy‐grazing history. Plants from the site with heavy‐grazing history had increased competitive ability and increased yields in low‐diversity communities but disrupted complementarity effects in high‐diversity communities. Moreover, plants of one species from the site with heavy‐grazing history benefitted more from AM fungal communities than did plants from the site without such history.Synthesis. Using the same experimental design and species, communities assembled by plants from two sites with different historical contexts showed different plant diversity–community productivity relationships. Our results suggest that historical context can alter plant diversity–community productivity relationships via plant species interactions and potentially plant–soil interactions. Therefore, considering historical contexts of ecological communities is of importance for advancing our understanding of long‐term impacts of anthropogenic disturbance on ecosystem functioning. [ABSTRACT FROM AUTHOR]

[Display omitted] • Alpine meadow degradation significantly changed soil microbial community composite. • Soil microbial diversity showed hump-shaped patterns with increasing degradation. • The changes in soil microbial diversity were greatly correlated with plant production. In recent decades, alpine meadows have experienced severe degradation owing to external disturbances. Although soil microorganisms are critical for ecosystem services, little is known about their responses to soil degradation and the potential patterns in alpine meadows. To solve this question, we collected and analyzed soil samples from three degraded alpine meadows situated on the Qinghai-Tibet Plateau. We aimed to examine the effects of degradation on soil microbial diversity and identify the ecological predictors for the diversity of bacteria and fungi. Our results showed that alpine meadow degradation significantly changed soil bacterial and fungal diversity and community composition. Specifically, the relationship between bacterial and fungal diversity and degradation intensity was a hump-shaped, with the highest diversity observed at a moderate degradation level. Additionally, alpine meadow degradation-induced changes in microbial diversity were strongly correlated with decreased plant production, with fungal diversity showing a closer link with below-ground biomass (BGB) than with bacterial diversity. Our findings offer empirical evidence that intermediate disturbance (i.e., moderate degradation) may be beneficial for supporting soil biodiversity. This has important implications for informing policy and management strategies meant to conserve soil biodiversity and ecosystem services when facing anthropogenic change. [ABSTRACT FROM AUTHOR]

The terrestrial methane budget varies between different vegetation types and soil conditions and is highly uncertain for alpine grasslands. This work used eddy covariance techniques to continuously measure CH4 flux (NEEm) over a semiarid alpine meadow on the northeastern Qinghai-Tibetan Plateau from January 2017 to August 2019. The diel NEEm averaged 0.14 ± 0.98 nmol CH4 m−2 s−1 (mean ± S.D.), with a rough pattern of daytime release and nocturnal uptake. The 8-day NEEm exhibited a similar sinusoid variation, with a peak of 6.8 mg CH4 m−2 d−1 at the end of April and a minimum of −1.5 mg CH4 m−2 d−1 at the end of August. The maximum release probably coincided with the thawing of frozen soil in the root zone, and the peak uptake may be related to high soil temperature. Monthly CH4 uptake was highest from June to September and consumed 51.7 mg CH4 m−2 from the atmosphere. CH4 production in the other months totaled 647.6 mg CH4 m−2. The semiarid alpine meadow thus acted as a weak net CH4 source, releasing ca 0.6 g CH4 m−2 year−1 to the atmosphere. The boosted regression trees analysis shows that the sensible heat flux (H) is positively related to half-hour NEEm and accounted for 34% of its variability. The piecewise structural equation models reveal that the magnitude of the effects from soil temperature and vapor pressure deficit on 8-day and monthly NEEm were almost equal, but acted in opposite directions. Vegetation growth and soil moisture exerted little direct influence on NEEm variability at half-hour, 8-day, or monthly scales. Our results show that CH4 emissions of the nongrowing season dominate the annual methane budget for this alpine meadow area. Methane consumption during the growing season was significantly constrained by low soil temperature and high soil water content. These findings imply that semiarid alpine meadows may consume more methane during the growing season if soil temperatures increase and soil moisture levels decrease as projected by future warming scenarios, thus constituting a climate change negative feedback. [ABSTRACT FROM AUTHOR]

The alpine meadow ecosystem on the Qinghai–Tibetan Plateau (QTP) is very sensitive to warming and plays a key role in regulating global carbon (C) cycling. However, how warming affects the soil organic carbon (SOC) pool and related C inputs and outputs in alpine meadow ecosystems on the QTP remains unclear. Here, we combined two field experiments and a meta‐analysis on field experiments to synthesize the responses of the SOC pool and related C cycling processes to warming in alpine meadow ecosystems on the QTP. We found that the SOC content of surface soil (0–10 cm) showed a minor response to warming, but plant respiration was accelerated by warming. In addition, the warming effect on SOC was not correlated with experimental and environmental variables, such as the method, magnitude and duration of warming, initial SOC content, mean annual temperature, and mean annual precipitation. We conclude that the surface SOC content is resistant to climate warming in alpine meadow ecosystems on the QTP. [ABSTRACT FROM AUTHOR]

Background and aims: Many meadows are experiencing severe degradation due to the effects of global climate change and other human-related activity, especially overgrazing. The impact of grazing may however vary in different sites, but the dynamics and mechanisms associated with grazing-related meadow degradation on soil microbial biomass structure and function in different locations are still unclear.To address this we examined three alpine meadows with different grazing sites in northwest China, which included grazing in winter and summer, in each of which there were four degradation gradients, varying from no degradation to severe degradation.At the Maqin site, grazing during the summer resulted in higher concentrations of microbial carbon (MBC), nitrogen (MBN), and phosphorus (MBP) compared to grazing during winter. Undegraded meadows (ND) also had higher MBC concentrations compared to low (LD), medium (MD), or severely degraded (SD) ones at the three sites. However, the homeostasis analysis revealed that the elemental stoichiometries were strictly controlled, despite significant degradation-related effects on the concentrations of MBC, MBN, and MBP, indicating relatively stable coupling relationships among C, N, and P.The random forest and partitioning variation analyses showed that edaphic factors play the more important roles in regulating microbial biomass and elemental composition in the different sites. Overall, these results suggest that the effects of degradation on soil microbial biomass concentrations and the stoichiometries are context dependent, particularly with regard to the impact of background soil properties, demonstrating that site conditions must be considered when predicting how grassland ecosystems will respond to grazing-related degradation.Methods: Many meadows are experiencing severe degradation due to the effects of global climate change and other human-related activity, especially overgrazing. The impact of grazing may however vary in different sites, but the dynamics and mechanisms associated with grazing-related meadow degradation on soil microbial biomass structure and function in different locations are still unclear.To address this we examined three alpine meadows with different grazing sites in northwest China, which included grazing in winter and summer, in each of which there were four degradation gradients, varying from no degradation to severe degradation.At the Maqin site, grazing during the summer resulted in higher concentrations of microbial carbon (MBC), nitrogen (MBN), and phosphorus (MBP) compared to grazing during winter. Undegraded meadows (ND) also had higher MBC concentrations compared to low (LD), medium (MD), or severely degraded (SD) ones at the three sites. However, the homeostasis analysis revealed that the elemental stoichiometries were strictly controlled, despite significant degradation-related effects on the concentrations of MBC, MBN, and MBP, indicating relatively stable coupling relationships among C, N, and P.The random forest and partitioning variation analyses showed that edaphic factors play the more important roles in regulating microbial biomass and elemental composition in the different sites. Overall, these results suggest that the effects of degradation on soil microbial biomass concentrations and the stoichiometries are context dependent, particularly with regard to the impact of background soil properties, demonstrating that site conditions must be considered when predicting how grassland ecosystems will respond to grazing-related degradation.Results: Many meadows are experiencing severe degradation due to the effects of global climate change and other human-related activity, especially overgrazing. The impact of grazing may however vary in different sites, but the dynamics and mechanisms associated with grazing-related meadow degradation on soil microbial biomass structure and function in different locations are still unclear.To address this we examined three alpine meadows with different grazing sites in northwest China, which included grazing in winter and summer, in each of which there were four degradation gradients, varying from no degradation to severe degradation.At the Maqin site, grazing during the summer resulted in higher concentrations of microbial carbon (MBC), nitrogen (MBN), and phosphorus (MBP) compared to grazing during winter. Undegraded meadows (ND) also had higher MBC concentrations compared to low (LD), medium (MD), or severely degraded (SD) ones at the three sites. However, the homeostasis analysis revealed that the elemental stoichiometries were strictly controlled, despite significant degradation-related effects on the concentrations of MBC, MBN, and MBP, indicating relatively stable coupling relationships among C, N, and P.The random forest and partitioning variation analyses showed that edaphic factors play the more important roles in regulating microbial biomass and elemental composition in the different sites. Overall, these results suggest that the effects of degradation on soil microbial biomass concentrations and the stoichiometries are context dependent, particularly with regard to the impact of background soil properties, demonstrating that site conditions must be considered when predicting how grassland ecosystems will respond to grazing-related degradation.Conclusion: Many meadows are experiencing severe degradation due to the effects of global climate change and other human-related activity, especially overgrazing. The impact of grazing may however vary in different sites, but the dynamics and mechanisms associated with grazing-related meadow degradation on soil microbial biomass structure and function in different locations are still unclear.To address this we examined three alpine meadows with different grazing sites in northwest China, which included grazing in winter and summer, in each of which there were four degradation gradients, varying from no degradation to severe degradation.At the Maqin site, grazing during the summer resulted in higher concentrations of microbial carbon (MBC), nitrogen (MBN), and phosphorus (MBP) compared to grazing during winter. Undegraded meadows (ND) also had higher MBC concentrations compared to low (LD), medium (MD), or severely degraded (SD) ones at the three sites. However, the homeostasis analysis revealed that the elemental stoichiometries were strictly controlled, despite significant degradation-related effects on the concentrations of MBC, MBN, and MBP, indicating relatively stable coupling relationships among C, N, and P.The random forest and partitioning variation analyses showed that edaphic factors play the more important roles in regulating microbial biomass and elemental composition in the different sites. Overall, these results suggest that the effects of degradation on soil microbial biomass concentrations and the stoichiometries are context dependent, particularly with regard to the impact of background soil properties, demonstrating that site conditions must be considered when predicting how grassland ecosystems will respond to grazing-related degradation. [ABSTRACT FROM AUTHOR]

Species employ seed dispersal and dormancy to mitigate competition and extinction risks in uncertain environments. Theoretical insights suggest a trade-off in that efficiently dispersed species tend to exhibit lower seed dormancy. This trade-off is hypothesized to be modified by life history traits and climatic factors. We collected data from 543 species, encompassing dormancy, dispersal capacities, climatic conditions (temperature and wind speed), plant height, seed mass, and shape from the Tibetan Plateau. We found that larger, non-spherical seeds favor strong dispersal and non-dormancy. Woody species demonstrate greater dispersal and lower dormancy compared to herbaceous species. A no-significant negative association between dispersal and dormancy was found, but the significance and magnitude of the trade-off depended on plant traits and climate. This trade-off amplifies with higher temperatures and non-spherical seed shapes. The trade-off strengthens as seed mass, plant height, and wind speed decrease in woody plants, but not in herbaceous plant. The interplay between climate factors and life-history traits affects the trade-off dynamics. Our results suggest that plants may not invest in a single dispersal or dormancy strategy to adapt to cold alpine environments. Distribution of species (herbaceous and woody), and plasticity of plant height, and seed traits are determined by environment and climate, which may limit the expression of dispersal or dormancy strategies. If dormancy is necessary under an altered climate, certain species that lack dormancy plasticity may face the risk of extinction, and thereby alter species coexistence status and community structure of alpine vegetation. • In alpine environments, species dispersal-dormancy trade-off strategies are not obvious and are mainly affected by plant traits and climate. • The trade-off between dispersal and dormancy is more pronounced and affected more strongly by plant height, seed mass, seed shape, mean annual temperature, and mean annual wind speed in woody plants than in herbaceous plants. • The strength of dispersal-dormant trade-off increases with increasing temperature and non-spherical seed shape. [ABSTRACT FROM AUTHOR]

Ribes himalense Royle ex Decne. (family Saxifraaceae, subfamily Grossulariaceae, genus Ribes) is a wild berry fruit with illustrated health‐promoting features, which widely distributed in Northwest China are deficiently exploited. This study aimed to assess the potential of a Ribes himalense as a source of natural bioactive compounds through characterizing its nutraceutical characteristics, phytochemicals properties, and antioxidant ability. Fresh berries were quantitatively analyzed for proximate composition, minerals, vitamins, amino acids, total polyphenols, total flavonoids, anthocyanins, procyanidin, and polysaccharides contents through China National Food Safety Standard; the characterization and identification of extracts of wild berries obtained with ethanol 30%, ethanol 50%, and ethanol 95% were firstly performed by UPLC‐Triple‐TOF‐MS2. Furthermore, antioxidant activity of the ethanol extract was evaluated via different assay methods such as DPPH, ABTS, and FRAP. The results indicated that the most important bioactive composition was procyanidin (0.72%), polyphenols (0.49%), total flavonoids (0.38%), vitamin C (64.6 mg/100g FW), and K (218.44 mg/100 g FW), and a total of 95 compounds were detected with polyphenols, flavonoids, and proanthocyanidins as the dominant, and also ethanol extract possessed stronger antioxidant activity. These results suggested that Ribes himalense fruit has great potential in protecting human health, with the focus on the development of functional products. [ABSTRACT FROM AUTHOR]

Aims: Plant diversity and coverage on the basidiomycete fungus Floccularia luteovirens fairy rings are higher than those outside of the fairy rings, indicating a favorable role of F. luteovirens in the growth of alpine meadow plants on the Qinghai-Tibet Plateau. However, the underlying physiological and molecular mechanisms of F. luteovirens-mediated plant growth and environmental adaptation remain largely unclear. Methods: Here, the growth and metabolic profiles of two alpine meadow plants which are the dominant plant species growing on F. luteovirens fairy rings (Kobresia humilis and Oxytropis coerulea), were investigated via physiological and metabolomic analyses. Results: F. luteovirens increases nutrient element accumulation in plants and improves the growth of the aboveground tissues but reduces the root growth of alpine meadow plants. Metabolomic analysis revealed that F. luteovirens reprograms carbohydrate and amino acid metabolism and affects the levels of organic acids and flavonoids, thereby modulating the growth and environmental adaptation of plants. Conclusions: Together, these results suggest that F. luteovirens promotes aboveground growth by modulating nutrient uptake and regulating metabolism in plants. These findings help to further elucidate the role of this edible mushroom fungus in influencing alpine meadow vegetation. [ABSTRACT FROM AUTHOR]

Background and aims: Long-term nitrogen (N) and phosphorus (P) fertilization could immensely alter plant-soil-microbial properties, thereby impacting the priming effect (PE). However, previous studies mostly simulated PE responses to fertilization by adding nutrient in the laboratory, which could not represent PE changes under long-term fertilization-induced ecosystem alteration. Our aim is to clarify the PE alteration in soils with long-term fertilization history in an alpine meadow.Soil samples (0–10 cm) were collected from a 9-year field fertilization experiment (including four treatments: control, + N with urea, + P with triple superphosphate, + NP with both fertilizers), and incubated for 30 days with 13C-labeled glucose amendment (2% SOC). Plant-soil-microbial properties were measured before/after incubation.Glucose addition induced a positive PE in all soils with a range from 0.56 to 1.37 mg C g−1 soil. N fertilization did not affect PE intensity due to the microbial adaptation and fast utilization of the added glucose for metabolic needs. P fertilization caused P accumulation in soils, and decreased available N and pH. Such changes inhibited microbes, and glucose activated microbial activities, causing higher PE intensity.Long-term N fertilization did not significantly affect PE, while P fertilization stimulated PE intensity. Overall, we highlight that P fertilization may induce higher risk of CO2 release, which deserves more attention when applying P fertilizers in this alpine meadow.Methods: Long-term nitrogen (N) and phosphorus (P) fertilization could immensely alter plant-soil-microbial properties, thereby impacting the priming effect (PE). However, previous studies mostly simulated PE responses to fertilization by adding nutrient in the laboratory, which could not represent PE changes under long-term fertilization-induced ecosystem alteration. Our aim is to clarify the PE alteration in soils with long-term fertilization history in an alpine meadow.Soil samples (0–10 cm) were collected from a 9-year field fertilization experiment (including four treatments: control, + N with urea, + P with triple superphosphate, + NP with both fertilizers), and incubated for 30 days with 13C-labeled glucose amendment (2% SOC). Plant-soil-microbial properties were measured before/after incubation.Glucose addition induced a positive PE in all soils with a range from 0.56 to 1.37 mg C g−1 soil. N fertilization did not affect PE intensity due to the microbial adaptation and fast utilization of the added glucose for metabolic needs. P fertilization caused P accumulation in soils, and decreased available N and pH. Such changes inhibited microbes, and glucose activated microbial activities, causing higher PE intensity.Long-term N fertilization did not significantly affect PE, while P fertilization stimulated PE intensity. Overall, we highlight that P fertilization may induce higher risk of CO2 release, which deserves more attention when applying P fertilizers in this alpine meadow.Results: Long-term nitrogen (N) and phosphorus (P) fertilization could immensely alter plant-soil-microbial properties, thereby impacting the priming effect (PE). However, previous studies mostly simulated PE responses to fertilization by adding nutrient in the laboratory, which could not represent PE changes under long-term fertilization-induced ecosystem alteration. Our aim is to clarify the PE alteration in soils with long-term fertilization history in an alpine meadow.Soil samples (0–10 cm) were collected from a 9-year field fertilization experiment (including four treatments: control, + N with urea, + P with triple superphosphate, + NP with both fertilizers), and incubated for 30 days with 13C-labeled glucose amendment (2% SOC). Plant-soil-microbial properties were measured before/after incubation.Glucose addition induced a positive PE in all soils with a range from 0.56 to 1.37 mg C g−1 soil. N fertilization did not affect PE intensity due to the microbial adaptation and fast utilization of the added glucose for metabolic needs. P fertilization caused P accumulation in soils, and decreased available N and pH. Such changes inhibited microbes, and glucose activated microbial activities, causing higher PE intensity.Long-term N fertilization did not significantly affect PE, while P fertilization stimulated PE intensity. Overall, we highlight that P fertilization may induce higher risk of CO2 release, which deserves more attention when applying P fertilizers in this alpine meadow.Conclusion: Long-term nitrogen (N) and phosphorus (P) fertilization could immensely alter plant-soil-microbial properties, thereby impacting the priming effect (PE). However, previous studies mostly simulated PE responses to fertilization by adding nutrient in the laboratory, which could not represent PE changes under long-term fertilization-induced ecosystem alteration. Our aim is to clarify the PE alteration in soils with long-term fertilization history in an alpine meadow.Soil samples (0–10 cm) were collected from a 9-year field fertilization experiment (including four treatments: control, + N with urea, + P with triple superphosphate, + NP with both fertilizers), and incubated for 30 days with 13C-labeled glucose amendment (2% SOC). Plant-soil-microbial properties were measured before/after incubation.Glucose addition induced a positive PE in all soils with a range from 0.56 to 1.37 mg C g−1 soil. N fertilization did not affect PE intensity due to the microbial adaptation and fast utilization of the added glucose for metabolic needs. P fertilization caused P accumulation in soils, and decreased available N and pH. Such changes inhibited microbes, and glucose activated microbial activities, causing higher PE intensity.Long-term N fertilization did not significantly affect PE, while P fertilization stimulated PE intensity. Overall, we highlight that P fertilization may induce higher risk of CO2 release, which deserves more attention when applying P fertilizers in this alpine meadow. [ABSTRACT FROM AUTHOR]

[Display omitted] • An ecosystem health-risk-services framework is developed to assess ecological security. • The credibility and reasonability of the assessment results are verified. • The ecological security of the GAPR was dominated by medium and above security levels. • The gravity centers of ecological security levels have changed from 2000 to 2020. Ecological security is a critical guarantor of human security and indeed human survival and is closely associated with sustainable development. Yet exploration of ecological security assessment in alpine pastoral regions is lacking, and many studies have failed to perform validation analyses on ecological security assessment results, weakening the reliability of their assessment results. In this study, an ecosystem health-risk-services framework is developed to assess the ecological security of the Gannan alpine pastoral region (GAPR) on the northeastern Tibetan Plateau from 2000 to 2020. Then, the remote sensing ecological index (RSEI) and high-resolution images are then introduced to verify and compare the results' reliability. Our study results indicate: (1) The assessment framework can better reflect the actual ecological security state in GAPR, and the correlation coefficient (R 2) of the comprehensive ecological security index (CESI) and RSEI is between 0.426 and 0.555 (p < 0.001). (2) The CESI value of GAPR shows a fluctuating and increasing trend from 2000 to 2020, with a spatial distribution pattern of high values in the south and low values in the north. The ecological security levels in GAPR are dominated by medium, medium-high and high security levels. (3) The centers of gravity of low and medium-low security levels show a northward movement trend, while that of medium-high and high security levels show a southward movement. Our framework provides a new perspective for ecological security assessment methods, which can be extended to other regions, and the results contribute useful references to decision-makers for socioeconomic development and eco-environmental protection in GAPR. [ABSTRACT FROM AUTHOR]

Animal carcass decomposition may bring serious harm to the environment, including pathogenic viruses, toxic gases and metabolites, and antibiotic resistance genes (ARGs). However, how wild mammal corpses decomposition influence and change ARGs in the environment has less explored. Through metagenomics, 16S rRNA gene sequencing, and physicochemical analysis, this study explored the succession patterns, influencing factors, and assembly process of ARGs and mobile genetic elements (MGEs) in gravesoil during long-term corpse decomposition of wild mammals. Our results indicate that the ARG and MGE communities related to wildlife corpses exhibited a pattern of differentiation first and then convergence. Different from the farmed animals, the decomposition of wild animals first reduced the diversity of ARGs and MGEs, and then recovered to a level similar to that of the control group (untreated soil). ARGs and MGEs of the gravesoil are mainly affected by deterministic processes in different stages. MGEs and bacterial community are the two most important factors affecting ARGs in gravesoil. It is worth noting that the decomposition of wild animal carcasses enriched different high-risk ARGs at different stages (bacA , mecA and floR), which have co-occurrence patterns with opportunistic pathogens (Comamonas and Acinetobacter), thereby posing a great threat to public health. These results are of great significance for wildlife corpse management and environmental and ecological safety. [Display omitted] • Resistome showed a differentiation first and then convergence pattern. • The wildlife-corpse degradation increased the temporal turnover of ARGs and MGEs. • The wildlife-corpse degradation enriched different high-risk ARGs and pathogens. • Deterministic processes dominated the ARG and MGE community assembly in gravesoil. [ABSTRACT FROM AUTHOR]

The human appropriation of net primary production (HANPP) was developed to estimate the intensity of human activities in natural ecosystems, which is still unclear in the Xinjiang grasslands. Using the Biome-Biogeochemical Cycle (Biome-BGC) grazing model in combination with field data, we assessed the HANPP and explored its spatiotemporal patterns in the Xinjiang grasslands. Our results showed that (1) the HANPP increased from 38 g C/m2/yr in 1979 to 88 g C/m2/yr in 2012, with an average annual increase of 1.47%. The HANPP was 80 g C/m2/yr, which represented 51% of the potential net primary production (NPPpot), and the HANPP efficiency was 70% in this region. (2) The areas with high HANPP values mainly occurred in northern Xinjiang and northwest of the Tianshan Mountains, while areas with low HANPP values mainly occurred in southern Xinjiang and southwest of the Tianshan Mountains. (3) Interannual variations in HANPP and NPPpot were significantly positively correlated (P<0.01). Interannual variations in HANPP efficiency and grazing intensity were negatively correlated (P<0.01). These results can help identify the complex impacts of human activities on grassland ecosystems and provide basic data for grassland management. [ABSTRACT FROM AUTHOR]

Aims: The volatile organic compounds (VOCs) produced by soil microbes modulated plant growth and development. Floccularia luteovirens, an edible mushroom, is beneficial to the growth of alpine meadow plants on the Qinghai-Tibet Plateau. We aimed to elucidate the physiological and molecular mechanisms underlying the mushroom fungal VOC-mediated plant growth and development. Methods: Here, we investigated the effects of VOCs produced by F. luteovirens on the root system development and seedling growth by integrating physiology, genetics, transcriptome and metabolome analysis using 1/2 MS medium-grown Arabidopsis thaliana seedlings. Results: Treatment with F. luteovirens VOCs reduce primary root growth by aggravating auxin accumulation through the repression of the abundance of auxin efflux carrier PIN-FORMED 2 (PIN2) protein, whereas it increases the lateral root number of A. thaliana seedlings. In addition to modulating root system architecture, treatment with F. luteovirens VOCs markedly increased aboveground growth. The transcriptome and metabolome analyses further supported the notion that F. luteovirens VOCs modulate plant growth and development through the induction of carbon/nitrogen metabolism and antioxidant defense while repressing several secondary metabolism and amino acid catabolism pathways. Conclusions: These results suggested that application of F. luteovirens VOCs promote growth by inducing changes in root system architecture through auxin pathway and regulating metabolism in plants. [ABSTRACT FROM AUTHOR]

The sharp rise in anthropogenic activities and climate change has caused the extensive degradation of grasslands worldwide, jeopardizing ecosystem function, and threatening human well‐being. Toxic weeds have been constantly spreading in recent decades; indeed, their occurrence is considered to provide an early sign of land degeneration. Policymakers and scientific researchers often focus on the negative effects of toxic weeds, such as how they inhibit forage growth, kill livestock, and cause economic losses. However, toxic weeds can have several potentially positive ecological impacts on grasslands, such as promoting soil and water conservation, improving nutrient cycling and biodiversity conservation, and protecting pastures from excessive damage by livestock. We reviewed the literature to detail the adaptive mechanisms underlying toxic weeds and to provide new insight into their roles in degraded grassland ecosystems. The findings highlight that the establishment of toxic weeds may provide a self‐protective strategy of degenerated pastures that do not require special interventions. Consequently, policymakers, managers, and other personnel responsible for managing grasslands need to take appropriate actions to assess the long‐term trade‐offs between the development of animal husbandry and the maintenance of ecological services provided by grasslands. [ABSTRACT FROM AUTHOR]

Biocrusts (biological soil crusts), which impact plant community characteristics and soil properties, are an important feature of soil surface in terrestrial ecosystem and called ecosystem engineers in arid and semi-arid habitats. The Qinghai-Tibet Plateau is located in arid and semi-arid regions, and the information on how biocrusts play a role in this ecosystem is still rare. In this study, the effects of different types of biocrusts (lichen-moss crusts, moss crusts, and bare ground as control) on plant diversity and soil physicochemical properties were evaluated and the key environmental factors associated with biocrust characteristics were analyzed in alpine steppe. The results showed that biocrusts affected the structure and diversity of plant community. The lichen-moss crusts were linked with lower plant diversity and plant species richness in degraded alpine steppe in the Qinghai-Tibetan Plateau. The cover of lichen crusts was positively correlated with plant cover while the cover and thickness of moss crusts were negatively correlated with plant cover. Moss crusts significantly reduced soil temperature and soil moisture content. Biocrusts significantly reduced the pH values of soil surface layer (0–1 cm) and deeper layer (5–10 cm). Soil total C (78.10 ± 6.53 g/kg), and total N (5.05 ± 0.21 g/kg) were highest in the soil surface layer (0–1 cm) where lichen-moss crusts were present. Our results indicated that the different types of biocrusts affect plant communities by changing the microenvironment and soil nutrients in the Qinghai-Tibetan Plateau. Further studies on the relationships between soil, biocrusts, and plants on a larger scale in the Qinghai-Tibetan Plateau are necessary. [ABSTRACT FROM AUTHOR]

Treatment with nitrification inhibitors, such as dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) have been strongly indicated to increase grassland biomass and mitigate soil N2O emission rates. However, the responses of both alpine meadow aboveground biomass and N2O emission rates to nitrification inhibitors remains unclear. We separately applied three doses of DCD and DMPP to alpine grassland soils with three duplicates. The biomass and N2O emission rates were subsequently measured by a clear-cut method and in-situ static chamber gas chromatography during the growing season. Our findings indicated that aboveground biomass increased significantly, and N2O emission rate decreased significantly at 6.8 kg ha−1 DCD and DMPP. Furthermore, the biomass increase effect was more significant than the N2O emission rate mitigation effect (p < 0.05). The highest ratios of DCD treatments on meadow production increase and N2O emission rate decrease were 27.2% and 36.3%, respectively. Our findings provide insight into the enhanced grassland primary production and decreased N2O flux by nitrification inhibitor treatment in alpine meadows, which may be beneficial to help mitigate global warming. [ABSTRACT FROM AUTHOR]

The melting of permafrost and the degradation of alpine meadow ecosystems caused by climate warming and high-intensity human activities have imposed serious threats to local and global ecological security. In order to estimate the effects of climate warming and grazing interference on the photosynthesis and respiration of alpine meadow plant community in permafrost regions, warming – infrared radiator is applied to simulate the climate warming (increasing temperature by +2°С). The winter grazing level is simulated by mowing the aboveground biomass of all plants. The responses of permafrost meadow community in terms of photosynthesis, respiration, surface soil temperature and moisture, as well as the carbon balance to simulated different climate warming and grazing level were analyzed and discussed. The results showed that: (1) the surface soil temperature in climate warming and grazing plots is significantly higher than in Ck plots (P < 0.01); (2) warming and warming + grazing plots enhanced community photosynthesis and respiration (P < 0.01); (3) warming and warming + grazing treatments increased community aboveground biomass (P < 0.05); (4) the photosynthetic rate increased in the second year, then decreased in the third year when both temperature and grazing level increased during the growing season. However, the ecosystem respiration increasingly increased year by year; (5) compared with the control groups, warming and grazing treatments resulted in an increase in carbon sequestration of the permafrost meadow community during the growing season. [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]