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

Recent studies proposed a convergence in the temperature sensitivity (Q 10 ) of soil respiration (R s ) after eliminating confounding effects using novel approaches such as Singular Spectrum Analysis (SSA) or the mixed-effects model (MEM) method. However, SSA has only been applied to eddy covariance data for estimating the Q 10 with air temperature, which may result in underestimations in responses of below-ground carbon cycling processes to climate warming in coupled climate-carbon models; MEM remains untested for its suitability in single-site studies. To examine the unconfounded Q 10 of R s , these two novel methods were combined with directly measured R s for 6 years in two Tibetan alpine ecosystems. The results showed that, 1) confounded Q 10 of R s estimated from seasonal R s -temperature relationship positively correlated with the seasonality of R s , and 2) estimates of unconfounded Q 10 of R s using SSA (mean = 2.4, 95% confidence interval (CI): 2.1–2.7) and MEM (mean = 3.2, 95% CI: 2.3–4.2) were consistent with the theoretical subcellular-level Q 10 (≈2.4). These results support the convergence in the Q 10 of R s and imply a conserved R s -temperature relationship. These findings indicate that the seasonality of R s has to be eliminated from estimating the Q 10 of R s , otherwise the estimates should be questionable. They also indicate that seasonal Q 10 and its responses to warming should not be directly used in carbon-climate models as they contain confounding effects. [ABSTRACT FROM AUTHOR]

The distributions of many species show climate-driven shifts towards higher elevations, but evidence for elevational shifts is scarce for the alpine grasslands on the Qinghai-Tibetan Plateau. The upward shift of alpine grassland distribution from 2000 to 2014 was assessed with field measurements and satellite remote sensing data obtained across six elevational transects on the Qinghai-Tibetan Plateau. The aboveground biomass (AGB) of alpine grasslands varied with altitude and its data produced a bell-shaped curve. This was mainly due to the elevational dependency of climate change at the surface (i.e., producing drier climate at low elevations and wetter climate at middle elevations). The normalized difference vegetation index (NDVI) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) exhibited a positive exponential relationship with the AGB of alpine grasslands. Overall, MODIS NDVI initially increased, then peaked at median altitude sites, then decreased with altitude on each elevational transect. MODIS NDVI at the upper limit of alpine grassland distribution did not show a significant increasing trend from 2000 to 2014, even though land surface temperature increased and precipitation remained approximately constant. High spatial resolution Landsat data supported this result. Further analyses of MODIS NDVI at all other sites found no general increase in AGB towards higher elevations. The results suggest that the distribution of alpine grasslands on the Qinghai-Tibetan Plateau did not show an upward shift despite rapid climate warming having occurred from 2000 to 2014. [ABSTRACT FROM AUTHOR]

Pastoralists on Eurasian rangeland often believe that traditional management practices involving moderate rotational grazing ensure sustainable yield, increase plant digestibility and promote biodiversity. To assess the generality of these suppositions we compared biomass production, community leaf C, N and P stoichiometry, leaf trait diversity and carbon and nutrient pools in root and soil for moderately grazed vs. ungrazed plots in Tibetan alpine meadows. We used five leaf traits (leaf C, leaf N and leaf P concentrations; SLA: specific leaf area, and LDMC: leaf dry matter content) as indicators of plant digestibility and rangeland quality. We measured these foliar traits and the ramet numbers for component species in moderately grazed plots as well as in exclosures (3–11 years) at five sites across the Qinghai-Tibetan plateau. Community weighted mean (CWM) trait values and functional dispersion (FDis) were used to quantify the mean and the variance in the distribution of trait values, respectively. Both the leaf P CWM and leaf P FDis generally increased under grazing and the LDMC CWM decreased, leading to improved plant digestibility and rangeland quality (e.g. high, community-wide leaf nutrients). The leaf C CWM , leaf N CWM and SLA CWM increased under grazing but the FDis of these traits tended to decrease. Grazing generally increased species diversity but decreased aboveground biomass, organic carbon, and nutrient concentrations in soil and root, especially decreasing root nitrogen and soil available phosphorus. Both root biomass and the leaf C:N CWM decreased in grazed plots at wet sites, but increased at dry sites. The community-wide increase and greater interspecific diversity in leaf nutrient concentrations coupled with decreasing LDMC CWM show that grazing induced an increase in plant digestibility, nutrient concentrations, and nutrient diversity in these alpine meadows. However, this increase in forage quality comes at the cost of losses in both carbon stock and nutrient availability that depress biomass production. Our findings and a review of related literature suggest that traditional grazing practices involve a trade-off between short-term yield and sustainability, a management challenge that must be addressed on rangelands with low soil fertility. [ABSTRACT FROM AUTHOR]

Traits that favor rapid plant growth are expected to have an important influence on species relative abundance (SRA) in semi-natural grasslands where competitive exclusion is reduced by grazing. However, which traits are more strongly associated with variation in SRA remains largely unknown, especially in P-limited but species-rich grasslands. We assessed the relative importance of traits predicting SRA in P-limited Tibetan alpine meadows subject to long term grazing. We assessed abundance in terms of both aboveground biomass and ramet numbers in relation to seven traits (specific leaf area, LDMC: leaf dry matter content, leaf carbon concentration, leaf nitrogen concentration, LPC: leaf phosphorus concentration, mature height, and seed size) for all component species in grazed and ungrazed plots in each of three contrasting sites on the Tibetan Plateau. We used CATS regression ( i.e. regression for Community Assembly through Trait Selection) to quantify the relative importance of different traits in predicting SRA, and tested dependence of trait importance values on both environmental context and alternative measures of abundance. Species were primarily differentiated along a trade-off axis involving traits promoting nutrient acquisition for fast growth vs resource conservation and competitive ability. A higher LPC consistently was the most important trait predicting species abundance in grazed plots, while species with low LPC but higher LDMC held an advantage in ungrazed plots. This suggests that in competition-released communities, species with a high ability to uptake soil available P tend to become abundant, while in competition-dominated communities, species using fixed P efficiently do better. The relative importance of traits in ungrazed plots did not change across sites, but in grazed plots species that have traits associated with nutrient conservation were favored in colder and drier conditions. The results highlight the importance of traits affecting acquisition of soil available P in these Tibetan alpine meadow communities. Species tradeoffs in nutrient acquisition versus conservation are a primary determinant of SRA, but the relative importance of traits depended on both environmental context and whether SRA was estimated as above-ground biomass or as number of ramets. [ABSTRACT FROM AUTHOR]

The functional structure of plant communities can be altered by grazing through two main mechanisms: species turnover (i.e. changes in species occurrence and relative abundance) and intraspecific trait variability ( ITV), which is driven by phenotypic responses of individual plants and shifts in the relative abundance of genotypic variants within species. Studies of grassland ecosystem function under grazing often focus on community changes induced by species turnover, which ignores the effects of ITV on biomass productivity, soil carbon or nutrient availability. By quantifying the relative contribution of both effects on shifts in community-wide traits, we highlight the role of ITV in community functional response to grazing and its implications for ecosystem function in Tibetan alpine meadows., We measured three chemical traits ( LC: leaf carbon, LN: leaf nitrogen and LP: leaf phosphorus concentrations) and two morphological traits ( SLA: specific leaf area, LDMC: leaf dry matter content) that are critical components of plant production and forage quality in grazed and ungrazed plots. Using variance decomposition of community-weighted means ( CWM) for these foliar traits, we distinguished the relative importance of ITV vs. change in species occurrence and abundance in response to grazing and the associated changes in soil carbon and nutrient availability., The CWM for foliar nutrients and SLACWM increased in response to grazing together with decreases in soil carbon and nutrient stores, especially LPCWM enrichment and loss of available soil P. The LPCWM was strongly negatively correlated with LDMCCWM, which was significantly higher in ungrazed plots. These community-wide trait responses to grazing were generally best captured by ITV and not changes in species occurrence and abundance, although ITV was consistently correlated with species turnover for all traits., Synthesis and applications. In response to continuous grazing, plants in Tibetan alpine meadows increase specific leaf area and foliar nutrients but tend to have lower leaf dry matter content, a response consistent with faster growth and regrowth under grazing. This intraspecific trait variability response drives a shift in community function from conservative, slow-growing resource use in ungrazed meadows to exploitative resource use under grazing. This community-wide functional response enhances forage quality, in turn favouring the secondary productivity of small herbivorous mammal communities, but also contributes to accelerated depletion of soil available phosphorus. We discuss the implications of these results for biodiversity conservation, ecosystem function and rangeland sustainability in the Qinghai-Tibetan Plateau, especially with regard to managing grazing rotation to strike a balance between favouring secondary productivity of domesticated stock vs. small herbivorous mammals. [ABSTRACT FROM AUTHOR]

Background and aims: Tree diversity is considered to influence decomposition either by changing environmental conditions or by non-additive litter mixture effects. Thus, we examined the influence of tree species richness, forest age and environmental factors on single-species decomposition, and tested the hypothesis that high litter species diversity induces predominantly positive non-additive mixture effects on decomposition processes. Methods: Decomposition trials using litter bags were performed in subtropical forests in China. Plot-specific decompositions rates of the abundant species Schima superba were related to environmental factors across 27 forest stands differing in age and tree species richness. Effects of litter species diversity on decomposition and N loss was assessed based on 27 plot-specific litter mixtures comprising 7 to 17 species. Results: Decomposition rate of Schima superba leaf litter was mainly affected by stand characteristics and microclimate but not tree diversity. Two thirds of plot-specific litter mixtures showed a positive non-additive mixture effect whose strength was marginally positively influenced by litter species richness. Conclusions: Tree diversity at stand level does not directly influence decomposition of a common litter substrate. However, our results suggest that tree species richness in the litter layer can indirectly promote decomposition and nutrient cycling via positive non-additive mixture effects. [ABSTRACT FROM AUTHOR]

China is very rich in biodiversity, however, it is also characterized by a long history of civilization. As a result, China has a large number of threatened species. Recently the Chinese government evaluated the living status of plants, and published the China Biodiversity Red List: Higher Plants. However, little is known about how threatened plants are distributed and conserved in China. In this study, we developed a fine resolution distribution database for 3244 threatened plants, explored richness patterns and evaluated the in situ conservation status of the threatened plants by overlapping the species distribution with terrestrial national and provincial nature reserves (NNRs and PNRs) in China. We found the greatest richness of threatened plants in the southwestern region of mainland China (mainly Yunnan, southeastern Xizang and western Sichuan), northwestern Guangxi, northern Guangdong, Hainan Island and the mountainous region of Taiwan, while the lowest richness was found in Qinghai, Hebei, Shandong, Jiangsu and Chongqing Provinces. On average, NNRs covered 18.8%, and NNRs and PNRs together covered 27.5%, of threatened plant distribution areas. However, 827 threatened plants (including 627 species endemic to China) were not covered by NNRs and 397 threatened plants (including 293 endemic to China) were not covered by either NNRs or PNRs. We proposed that nature reserves specifically designed for threatened plants need to be established in South China, especially in the Yunnan, Guizhou, Guangxi, Xinjiang Hainan, and Zhejiang Provinces. [ABSTRACT FROM AUTHOR]

Grassland degradation is challenging the health of grassland ecosystems globally and causing biodiversity decline. Previous studies have demonstrated the impact of grassland degradation on the abundance and behavior of small mammals. Little is known about how it affects the genetic structure of gregarious mammals in the wild. This study explores the effects of grassland degradation on the genetic structure of a small burrowing mammal, plateau pika (Ochotona curzoniae). We used nine microsatellite loci to analyze the genetic diversity and genetic differentiation between colonies and genetic relatedness between individuals within the colony. We found that pikas in severely degraded grasslands had a significantly higher genetic diversity within colonies, a higher level of gene flow between colonies, and a lower genetic differentiation between colonies compared to pikas in less degraded grasslands. Individuals within colonies had a significantly lower genetic relatedness in severely degraded grasslands than in less degraded grasslands. This study has provided potential evidence of a significant impact of grassland degradation on the genetic structure of pikas, which has caused a breakdown of their kin‐selected colony structure. [ABSTRACT FROM AUTHOR]

Abstract: Monitoring soil respiration (R s) at regional scales using images from operational satellites remains a challenge because of the problem in scaling local R s to the regional scales. In this study, we estimated the spatial distribution of R s in the Tibetan alpine grasslands as a product of vegetation index (VI). Three kinds of vegetation indices (VIs), that is, normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and modified soil adjusted vegetation index (MSAVI), derived from Landsat Thematic Mapper (TM) and Moderate-resolution Imaging Spectroradiometer (MODIS) surface reflectance product were selected to test our method. Different statistical models were used to analyze the relationships among the three VIs and R s. The results showed that, based on the remote sensing data from either MODIS or Landsat TM, exponential function was the optimal fit function for describing the relationships among VIs and R s during the peak growing season of alpine grasslands. Additionally, NDVI consistently showed higher explanation capacity for the spatial variation in R s than EVI and MSAVI. Thus, we used the exponential function of TM-based NDVI as the R s predictor model. Since it is difficult to achieve full spatial coverage of the entire study area with Landsat TM images only, we used the MODIS 8-day composite images to obtain the spatial extrapolation of plot-level R s after converting the NDVI_MODIS into its corresponding NDVI_TM. The performance of the R s predictor model was validated by comparing it with the field measured R s using an independent dataset. The TM-calibrated MODIS-estimated R s was within an accuracy of field measured R s with R 2 of 0.78 and root mean square error of 1.45gCm−2 d−1. At the peak growing season of alpine grasslands, R s was generally much higher in the southeastern part of the Tibetan Plateau and gradually decreased toward the northwestern part. Satellite remote sensing demonstrated the potential for the large scale mapping of R s in this study. [Copyright &y& Elsevier]

Summary: Recent in vitro and in vivo data show that acid-sensing ion channel 1a (ASIC1a) activation enhances neuronal excitability in the hippocampus and neocortex, indicating that ASIC1a might play a role in the generation and maintenance of epileptic seizures. The aim of this study was to investigate association of the ASIC1a gene with temporal lobe epilepsy (TLE) for the first time. Six tag single-nucleotide polymorphisms (SNPs) of the ASIC1a gene were selected and genotyped using polymerase chain reaction-restriction fragment length polymorphism in 560 TLE patients and 401 healthy controls. There was a significant allelic and genotypic association between rs844347:A>C and TLE compared with controls. The rs844347-A allele frequency was 88.1% in the patients and 83.0% in control subjects (OR=1.516, 95% CI 1.142–2.013, p =0.004). Furthermore, the haplotype analysis revealed a significant association with TLE. The results of this study demonstrate for the first time an association between an ASC1a variant allele and TLE in a Han Chinese population. [Copyright &y& Elsevier]

Abstract: A recent study suggests that the P86L polymorphism (rs2986017) in the calcium homeostasis modulator 1 (CALHM1) gene interferes with calcium homeostasis and increases amyloid β (Aβ) levels. Moreover, in vitro and in vivo data show that both calcium homeostasis and high levels of Aβ play an important role in the induction and maintenance of epileptic seizures in hippocampus, indicating CALHM1 might play a potential role in pathophysiological pathways involved in temporal lobe epilepsy (TLE). The aim of this study was to investigate the genetic contribution of CALHM1 to TLE. Five single-nucleotide polymorphisms (SNPs) of CALHM1 were selected and genotyped using polymerase chain reaction restriction fragment length polymorphism in 560 patients with TLE and 401 healthy controls. We found a positive association between rs11191692 and TLE, but a negative result between rs2986017 and TLE. The rs11191692-A allele frequency was found in 32.4% of the patients and in 26.2% of control subjects (OR=1.35, 95% CI=1.10–1.65, uncorrected P =0.003, corrected P =0.015). Furthermore, the positive association between rs11191692 and TLE independent of apolipoprotein E ε4 was supported by five SNPs haplotype analysis. The results of this study provide the first evidence that the SNP rs11191692 in CALHM1 confers highly increased susceptibility to TLE. [Copyright &y& Elsevier]

Abstract: Human respiratory syncytial virus (RSV), for which no clinically approved vaccine is available yet, is globally a serious pediatric pathogen of the lower respiratory tract. Several approaches have been used to develop vaccines against RSV, but none of these have been approved for use in humans. An efficient vaccine-enhancing strategy for RSV is still urgently needed. We found previously that oral SL7207/pcDNA3.1/F and intranasal FGAd/F were able to induce an effective protective immune response against RSV. The heterologous prime–boost immunization regime has been reported recently to be an efficient vaccine-enhancing strategy. Therefore, we investigated the ability of an oral SL7207/pcDNA3.1/F prime and intranasal (i.n.) FGAd/F boost regimen to generate immune responses to RSV. The SL7207/pcDNA3.1/F prime–FGAd/F boost regimen generated stronger RSV-specific humoral and mucosal immune responses in BALB/c mice than the oral SL7207/pcDNA3.1/F regimen alone, and stronger specific cellular immune responses than the i.n. FGAd/F regimen alone. Histopathological analysis showed an increased efficacy against RSV challenge by the heterologous prime–boost regimen. These results suggest that such a heterologous prime–boost strategy can enhance the efficacy of either the SL7207 or the FGAd vector regimen in generating immune responses in BALB/c mice. [Copyright &y& Elsevier]

Abstract: Helper-dependent adenoviral (HDAd) vectors were developed primarily for genetic disease therapy by deleting all coding regions for attenuating the host cellular immune response to adenovirus (Ad) and long-lasting gene expression. Recently Harui et al. reported that HDAd vaccine could stimulate superior transgene-specific cytotoxic T lymphocyte (CTL) and antibody responses via the intraperitoneal route, compared to first-generation adenoviral (FGAd) vaccine. This prompted us to explore the potential of HDAd as a vaccine vector administrated intranasally. In this study, we prepared HDAd and FGAd vectors expressing enhanced green fluorescent protein (EGFP), respectively, and compared their efficacy in mice. Mice were immunized intranasally with 5×109 vp HDAd or FGAd vector particles. Despite stimulating similar anti-Ad antibody responses with FGAd vaccine in the prime/boost strategy, HDAd vector expressing EGFP displayed superior transgene-specific serum IgG, mucosal IgA and cellular immune response, with the characterization of balanced or mixed Th1/Th2 CD4+ T-cell responses. Meanwhile, a single dose of intranasal (i.n.) vaccine of HDAd–EGFP induced a serum IgG response with more efficacy than FGAd–EGFP. In addition, i.n. boost immunization enhanced transgene-specific humoral and cellular responses, compared to single i.n. HDAd–EGFP immunization. Our results suggest that HDAd has potential for a mucosal vaccine vector via i.n. route, which will be useful for the development of vaccines against respiratory viruses, such as respiratory syncytial virus and influenza virus. [Copyright &y& Elsevier]

Soil phosphorus (P) is essential for plant growth and influences biological processes. Determining the amounts of available P to plants has been challenging, and many different approaches exist. The traditional Hedley sequential extraction method and its subsequent modification are applied to determine different soil P forms, which is critical for understanding its dynamics and availability. However, quantifying organic and inorganic P (Po & Pi) in different extracts is labor-intensive and rarely used with large sample numbers. As an alternative, near-infrared spectroscopy (NIRS) has been employed to determine different P fractions at reasonable costs in a short time. This study aimed to test whether the analysis of P fractions with NIRS is an appropriate method to disentangle the effects of P limitation on high-altitude grassland ecosystems, particularly with fertilizer amendments. We explored NIRS in soils from the grassland soil samples on the northern Tibetan Plateau. First, we extracted the P fractions of 191 samples from the Haibei Alpine Meadow Ecosystem Research Station at four depth increments (0–10 cm, 10–20 cm, 20–40 cm, and 40–70 cm), including nutrient additions of nitrogen (N) and P. We compared the results of the Hedley extraction with the laboratory-based NIRS model. The fractionation data were correlated with the corresponding NIRS soil spectra; the coefficient of determination (R2) of the NIRS calibrations to predict P in P fractions ranged between 0.12 and 0.90; the ratio of (standard error of) prediction to the standard deviation (RPD) ranged between 1.07 and 3.21; the ratio of performance to inter-quartile distance (RPIQ) ranged from 0.3 to 4.3; and the model prediction quality was higher for Po than Pi fractions, and decreased with fertilizer amendment. However, the external-validation results were not precise enough for the labile P fractions (RPD < 1.4) due to the limited number of samples. The results indicate that using NIRS to predict the more stable P pools, combined with Hedley fractionation focusing on the labile P pool, can be a promising approach for soils in alpine grasslands on the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Globally, grassland degradation is an acute ecological problem. In alpine grassland on the Tibetan Plateau, increased densities of various small mammals in degraded grassland are assumed to intensify the degradation process and these mammals are subject to lethal control. However, whether the negative impact of small mammals is solely a result of population size or also a result of activity and behavior has not been tested. In this study, we use plateau pika as a model to compare population size, core area of colony, and the number of burrow entrances and latrines between lightly and severely degraded grassland. We test whether the alleged contribution of pika to grassland degradation is a result of increased population size or increased burrowing activities of individuals in response to lower food abundance. We found that grassland degradation resulted in lower plant species richness, plant height, and biomass. Furthermore, the overall population size of pika was not significantly affected by location in lightly and severely degraded grassland. However, pika core areas in severely grassland degradation were significantly larger and had significantly higher densities of burrows and latrines. Our study provides convincing evidence that habitat‐induced changes in the behavior of small, burrowing mammals, such as pika, can exacerbate grassland degradation. This finding has significant implications for managing small mammals and restoring degraded grassland ecosystems. [ABSTRACT FROM AUTHOR]

Biodiversity serves as the fundamental underpinning for ecosystem functions and services. As a result of human‐induced global change, there is a growing awareness of the substantial alterations in terrestrial above‐ground biodiversity, particularly within alpine regions. However, it remains uncertain whether below‐ground biodiversity will exhibit similar responses, both in terms of magnitude and manner, to anthropogenic global changes as above‐ground biodiversity.Here, we conducted a meta‐analysis to assess the impacts of warming, nutrient addition and grazing on plant and soil microbial biodiversity in alpine grasslands on the Qinghai–Tibetan Plateau, which are known to be climate‐sensitive and vulnerable. The analysis included 819 experimental observations from 152 studies, focussing on species richness, Shannon diversity and Pielou's evenness.We found that plant biodiversity exhibited greater sensitivity to climate warming and anthropogenic activities compared with soil microbial biodiversity. Specifically, plant richness and Shannon diversity were reduced by warming and nutrient addition, while plant evenness was increased by grazing. However, only microbial richness was increased by grazing and microbial evenness was increased by warming slightly.The responses of biodiversity to climate warming and anthropogenic activities were modulated by multiple factors. Specifically, the negative effects of warming on plant biodiversity were more pronounced in long‐term experiments under warmer or drier environmental conditions. The negative effects of nitrogen addition on biodiversity were enhanced by the intensity and duration of nitrogen treatment. Appropriate intensity and frequency of grazing were beneficial to sustaining plant biodiversity. Soil microbial biodiversity was weakly regulated, where bacterial Shannon diversity was more sensitive to nutrient addition, while fungal species richness was sensitive to grazing.Synthesis. Our findings reveal a mismatch between above‐ground plant and below‐ground microbial biodiversity in response to climate warming and anthropogenic activities in alpine grasslands, with plant biodiversity being more sensitive. In the context of future global change, plant biodiversity may be at greater risk than soil microbial biodiversity. In addition, biodiversity responses of different experimental and environmental conditions should be distinguished, and more attention is needed on biodiversity conservation in alpine steppe, or areas with warmer and drier environmental conditions, high‐intensity fertilization or heavy grazing. [ABSTRACT FROM AUTHOR]

Anthropogenic eutrophication is known to impair the stability of aboveground net primary productivity (ANPP), but its effects on the stability of belowground (BNPP) and total (TNPP) net primary productivity remain poorly understood. Based on a nitrogen and phosphorus addition experiment in a Tibetan alpine grassland, we show that nitrogen addition had little impact on the temporal stability of ANPP, BNPP, and TNPP, whereas phosphorus addition reduced the temporal stability of BNPP and TNPP, but not ANPP. Significant interactive effects of nitrogen and phosphorus addition were observed on the stability of ANPP because of the opposite phosphorus effects under ambient and enriched nitrogen conditions. We found that the stability of TNPP was primarily driven by that of BNPP rather than that of ANPP. The responses of BNPP stability cannot be predicted by those of ANPP stability, as the variations in responses of ANPP and BNPP to enriched nutrient, with ANPP increased while BNPP remained unaffected, resulted in asymmetric responses in their stability. The dynamics of grasses, the most abundant plant functional group, instead of community species diversity, largely contributed to the ANPP stability. Under the enriched nutrient condition, the synchronization of grasses reduced the grass stability, while the latter had a significant but weak negative impact on the BNPP stability. These findings challenge the prevalent view that species diversity regulates the responses of ecosystem stability to nutrient enrichment. Our findings also suggest that the ecological consequences of nutrient enrichment on ecosystem stability cannot be accurately predicted from the responses of aboveground components and highlight the need for a better understanding of the belowground ecosystem dynamics. [ABSTRACT FROM AUTHOR]

Carbon‐focused climate mitigation strategies are becoming increasingly important in forests. However, with ongoing biodiversity declines we require better knowledge of how much such strategies account for biodiversity. We particularly lack information across multiple trophic levels and on established forests, where the interplay between carbon stocks, stand age, and tree diversity might influence carbon–biodiversity relationships. Using a large dataset (>4600 heterotrophic species of 23 taxonomic groups) from secondary, subtropical forests, we tested how multitrophic diversity and diversity within trophic groups relate to aboveground, belowground, and total carbon stocks at different levels of tree species richness and stand age. Our study revealed that aboveground carbon, the key component of climate‐based management, was largely unrelated to multitrophic diversity. By contrast, total carbon stocks—that is, including belowground carbon—emerged as a significant predictor of multitrophic diversity. Relationships were nonlinear and strongest for lower trophic levels, but nonsignificant for higher trophic level diversity. Tree species richness and stand age moderated these relationships, suggesting long‐term regeneration of forests may be particularly effective in reconciling carbon and biodiversity targets. Our findings highlight that biodiversity benefits of climate‐oriented management need to be evaluated carefully, and only maximizing aboveground carbon may fail to account for biodiversity conservation requirements. [ABSTRACT FROM AUTHOR]

Climate projection requires an accurate understanding for soil organic carbon (SOC) decomposition and its response to warming. An emergent view considers that environmental constraints rather than chemical structure alone control SOC turnover and its temperature sensitivity (i.e., Q10), but direct long‐term evidence is lacking. Here, using compound‐specific radiocarbon analysis of soil profiles along a 3300‐km grassland transect, we provide direct evidence for the rapid turnover of lignin‐derived phenols compared with slower‐cycling molecular components of SOC (i.e., long‐chain lipids and black carbon). Furthermore, in contrast to the slow‐cycling components whose turnover is strongly modulated by mineral association and exhibits low Q10, lignin turnover is mainly regulated by temperature and has a high Q10. Such contrasts resemble those between fast‐cycling (i.e., light) and mineral‐associated slow‐cycling fractions from globally distributed soils. Collectively, our results suggest that warming may greatly accelerate the decomposition of lignin, especially in soils with relatively weak mineral associations. [ABSTRACT FROM AUTHOR]

Climate warming is changing plant sexual reproduction, having consequences for species distribution and community dynamics. However, the magnitude and direction of plant reproductive efforts (e.g., number of flowers) and success (e.g., number and mass of fruits or seeds) in response to warming have not been well‐characterized. Here, we generated a global dataset of simulated warming experiments, consisting of 477 pairwise comparisons for 164 terrestrial species. We found evidence that warming overall decreased fruit number and increased seed mass, but little evidence that warming influenced flower number, fruit mass, or seed number. The warming effects on seed mass were regulated by the pollination type, and insect‐pollinated plants exhibited a stronger response to warming than wind‐pollinated plants. We found strong evidence that warming increased the mass of seeds for the nondominant species but no evidence of this for the dominant species. There was no evidence that phylogenetic relatedness explained the effects of warming on plant reproductive effort and success. In addition, the effects of warming on flowering onset negatively related to the responses in terms of the number of fruits and seeds to warming, revealing a cascading effect of plant reproductive development. These findings provide the first quantification of the response of terrestrial plant sexual reproduction to warming and suggest that plants may increase their fitness by producing heavier seeds under a warming climate. [ABSTRACT FROM AUTHOR]

The Omicron variant is currently ravaging the world, raising serious concern globally. Monitoring genomic variations and determining their influence on biological features are critical for tracing its ongoing transmission and facilitating effective measures. Based on large-scale sequences from different continents, this study found that: (i) The genetic diversity of Omicron is much lower than that of the Delta variant. Still, eight deletions (Del 1–8) and 1 insertion, as well as 130 SNPs, were detected on the Omicron genomes, with two deletions (Del 3 and 4) and 38 SNPs commonly detected on all continents and exhibiting high-occurring frequencies. (ii) Four groups of tightly linked SNPs (linkage I–IV) were detected, among which linkage I, containing 38 SNPs, with 6 located in the RBD, increased its occurring frequency remarkably over time. (iii) The third codons of the Omicron shouldered the most mutation pressures, while the second codons presented the least flexibility. (iv) Four major mutants with amino acid substitutions in the RBD were detected, and further structural analysis suggested that the substitutions did not alter the viral receptor binding ability greatly. It was inferred that though the Omicron genome harbored great changes in antigenicity and remarkable ability to evade immunity, it was immune-pressure selected. This study tracked mutational signatures of Omicron variant and the potential biological significance of the SNPs, and the linkages await further functional verification. [ABSTRACT FROM AUTHOR]

The alpine grasslands of the Tibetan Plateau store 23.2 Pg soil organic carbon, which becomes susceptible to microbial degradation with climate warming. However, accurate prediction of how the soil carbon stock changes under future climate warming is hampered by our limited understanding of belowground complex microbial communities. Here, we show that 4 years of warming strongly stimulated methane (CH4) uptake by 93.8% and aerobic respiration (CO2) by 11.3% in the soils of alpine grassland ecosystem. Due to no significant effects of warming on net ecosystem CO2 exchange (NEE), the warming‐stimulated CH4 uptake enlarged the carbon sink capacity of whole ecosystem. Furthermore, precipitation alternation did not alter such warming effects, despite the significant effects of precipitation on NEE and soil CH4 fluxes were observed. Metagenomic sequencing revealed that warming led to significant shifts in the overall microbial community structure and the abundances of functional genes, which contrasted to no detectable changes after 2 years of warming. Carbohydrate utilization genes were significantly increased by warming, corresponding with significant increases in soil aerobic respiration. Increased methanotrophic genes and decreased methanogenic genes were observed under warming, which significantly (R2 =.59, p <.001) correlated with warming‐enhanced CH4 uptakes. Furthermore, 212 metagenome‐assembled genomes were recovered, including many populations involved in the degradation of various organic matter and a highly abundant methylotrophic population of the Methyloceanibacter genus. Collectively, our results provide compelling evidence that specific microbial functional traits for CH4 and CO2 cycling processes respond to climate warming with differential effects on soil greenhouse gas emissions. Alpine grasslands may play huge roles in mitigating climate warming through such microbially enhanced CH4 uptake. [ABSTRACT FROM AUTHOR]

Most experimental biodiversity-ecosystem functioning research to date has addressed herbaceous plant communities. Comparably little is known about how forest communities will respond to species losses, despite their importance for global biogeochemical cycling. We studied tree species interactions in experimental subtropical tree communities with 33 distinct tree species mixtures and one, two, or four species. Plots were either exposed to natural light levels or shaded. Trees grew rapidly and were intensely competing above ground after 1.5 growing seasons when plots were thinned and the vertical distribution of leaves and wood determined by separating the biomass of harvested trees into 50 cm height increments. Our aim was to analyze effects of species richness in relation to the vertical allocation of leaf biomass and wood, with an emphasis on bipartite competitive interactions among species. Aboveground productivity increased with species richness. The community-level vertical leaf and wood distribution depended on the species composition of communities. Mean height and breadth of species-level vertical leaf and wood distributions did not change with species richness. However, the extra biomass produced by mixtures compared to monocultures of the component species increased when vertical leaf distributions of monocultures were more different. Decomposition of biodiversity effects with the additive partitioning scheme indicated positive complementarity effects that were higher in light than in shade. Selection effects did not deviate from zero, irrespective of light levels. Vertical leaf distributions shifted apart in mixed stands as consequence of competition-driven phenotypic plasticity, promoting realized complementarity. Structural equation models showed that this effect was larger for species that differed more in growth strategies that were characterized by functional traits. In 13 of the 18 investigated two-species mixtures, both species benefitted relative to intraspecific competition in monoculture. In the remaining five pairwise mixtures, the relative yield gain of one species exceeded the relative yield loss of the other species, resulting in a relative yield total ( RYT) exceeding 1. Overall, our analysis indicates that richness-productivity relationships are promoted by interspecific niche complementarity at early stages of stand development, and that this effect is enhanced by architectural plasticity. [ABSTRACT FROM AUTHOR]

Permafrost soils store enormous quantities of organic carbon. Especially on the alpine Qinghai-Tibet Plateau, global warming induces strong permafrost thawing, which strengthens the microbial decomposition of organic carbon and the emission of the greenhouse gas carbon dioxide (CO 2 ). Enhanced respiration rates may intensify climate warming in turn, but the magnitude of future CO 2 emissions from this data-scarce region in a changing climate remains highly uncertain. Here, we aim at an area-wide estimation of future potential CO 2 emissions for the permafrost region on the Qinghai-Tibet Plateau as key region for climate change studies due to its size and sensitiveness. We calculated four potential soil respiration scenarios for 2050 and 2070 each. Using a regression model, results from laboratory experiments and C stock estimations from other studies, we provide an approximation of total potential soil CO 2 emissions on a regional scale ranging from 737.90 g CO 2 m −2 y −1 –4224.77 g CO 2 m −2 y −1 . Our calculations as first estimate of thawing-induced CO 2 emissions (51.23 g CO 2 m −2 y −1 –3002.82 g CO 2 m −2 y −1 ) from permafrost soils of the Qinghai-Tibet Plateau under global warming appear to be consistent to measurements of C loss from thawing permafrost soils measured within other studies. Thawing-induced soil CO 2 emissions from permafrost soils with a organic C content ranging from 2.42 g C kg −1 to 425.23 g C kg −1 increase general soil respiration by at least about one third on average at a temperature of 5 °C. Differences between scenarios remain < 1% and thawing-induced CO 2 emissions generally decrease over time comparing 2015, 2050 and 2070. With this spatial approximation at a regional scale, a first area-wide estimate of potential CO 2 emissions for 2050 and 2070 from permafrost soils of the Qinghai-Tibet Plateau is provided. This offers support of assessing potential area-specific greenhouse gas emissions and more differentiated climate change models. [ABSTRACT FROM AUTHOR]

Subsoils of alpine grasslands on the Qinghai-Tibetan Plateau represent a tremendous yet poorly investigated reservoir of soil organic carbon (SOC) on a global “hotspot” of warming. Compared with the temperature sensitivity of SOC decomposition, microbial anabolism of new carbon and priming of native SOC remain poorly constrained under warming-enhanced labile carbon input in these subsoils. Here we employed an innovative approach to investigate the sequestration of freshly added carbon in microbial necromass versus SOC priming in the top- (0–10 cm) and subsoils (30–40 cm) from a field experiment that simulated varied warming scenarios in an alpine grassland on the Qinghai-Tibetan Plateau. The 13 C composition of microbial necromass-derived amino sugars was analyzed in tandem with respired CO 2 and dissolved SOC components (including dissolved lignin) in an 86-day laboratory incubation with 13 C-labeled glucose. A higher fraction of freshly added carbon was respired while a smaller proportion was stabilized as amino sugars in the subsoil relative to the topsoil, leading to a much lower microbial carbon accumulation efficiency at depth. Meanwhile, a higher relative priming effect was observed in the subsoil (47± 14%) compared to the topsoil (14± 4%), suggesting a higher vulnerability to substrate-induced SOC loss at depth, although such changes may be associated with higher glucose addition rate (relative to SOC) in the subsoil. Furthermore, enhanced winter warming significantly reduced degradable SOC (assessed by SOC mineralization and dissolved lignin content) in the subsoil and potentially intensified nitrogen limitation under labile carbon additions, which further decreased microbial carbon accumulation (in the form of amino sugars) in the subsoil without affecting the topsoil. These results collectively indicate a limited microbial carbon sequestration potential and a higher vulnerability to warming-induced substrate changes in the subsoil of this alpine grassland, which warrants better understanding to predict soil carbon responses to climate warming on the Qinghai-Tibetan Plateau. [ABSTRACT FROM AUTHOR]

The alpine meadow on the Qinghai-Tibetan Plateau (QTP), which is sensitive to global climate change and human activities, is subjected to addition of nutrients such as nitrogen (N) and phosphorus (P) in the soil. The impacts of N or P on ecosystem structure and function depend at least partly on the response of soil fungal communities, although few studies have compared the effects of N and P addition, both separately and together. We examined the responses of composition of the soil fungal community to 3-year experimental nutrient additions (control, N, N plus P, and P) in a typical alpine meadow of the QTP. We found that P addition, regardless of N addition, significantly reduced fungal species richness and changed fungal community composition, while the effect of N was undetectable. Nitrogen plus phosphorus caused a more distinct community than either N or P addition alone. Multivariate regression tree, canonical correspondence analysis, and distance-based multivariate linear model analyses all suggested available P was a key parameter determining the diversity and composition of the fungal community. Other parameters such as dissolved organic N, aboveground net primary productivity of forbs, and dissolved organic C played important but secondary roles. The results indicated an important role of P in structuring soil fungal communities in the alpine meadow. Our results suggest that fungal diversity loss and long-term changes in ecosystem stability can result from fertilization management in the fragile alpine environment. [ABSTRACT FROM AUTHOR]

A growing body of work examines the direct and indirect effects of climate change on ecosystems, typically by using manipulative experiments at a single site or performing meta‐analyses across many independent experiments. However, results from single‐site studies tend to have limited generality. Although meta‐analytic approaches can help overcome this by exploring trends across sites, the inherent limitations in combining disparate datasets from independent approaches remain a major challenge. In this paper, we present a globally distributed experimental network that can be used to disentangle the direct and indirect effects of climate change. We discuss how natural gradients, experimental approaches, and statistical techniques can be combined to best inform predictions about responses to climate change, and we present a globally distributed experiment that utilizes natural environmental gradients to better understand long‐term community and ecosystem responses to environmental change. The warming and (species) removal in mountains (WaRM) network employs experimental warming and plant species removals at high‐ and low‐elevation sites in a factorial design to examine the combined and relative effects of climatic warming and the loss of dominant species on community structure and ecosystem function, both above‐ and belowground. The experimental design of the network allows for increasingly common statistical approaches to further elucidate the direct and indirect effects of warming. We argue that combining ecological observations and experiments along gradients is a powerful approach to make stronger predictions of how ecosystems will function in a warming world as species are lost, or gained, in local communities. [ABSTRACT FROM AUTHOR]

Besides overgrazing by livestock, browsing by small native mammals, such as plateau pikas, is considered an important cause of alpine grassland degradation on the Qinghai-Tibetan Plateau (QTP). Preference of pikas for degraded grasslands, resulting in increased population density, has been proposed as the most accepted hypothesis. However, few studies have explored the mechanisms underlying the habitat preferences of pikas. Herein, we analyzed aboveground biomass, community composition, forage quality of lightly and severely degraded alpine grasslands, and the diet and nutritional intake of pikas living there to test whether the plant community structure and associated nutrient composition of severely degraded grasslands are more suitable for pikas in terms of dietary and nutritional requirements. Our results showed that the plant community structure differed between lightly and severely degraded grasslands, with lightly degraded grasslands containing more food plants preferred by pikas. The nutritional composition of plants in severely degraded grasslands was less suitable for pikas than that in lightly degraded grasslands. Our results reject the nutritional hypothesis that severely degraded grasslands meet the dietary and nutritional needs of pikas better. We conclude that food and nutrient selection are not drivers of population increase in pikas in the severely degraded grasslands of the QTP. • Severely degraded grasslands (SDG) contain fewer pikas' favorite foods. • Plants in SDG have lower nutritional suitability for pikas. • Pikas' population growth on SDG is unlikely due to food and nutrient choices. [ABSTRACT FROM AUTHOR]

Alpine ecosystems like the Qinghai-Tibet Plateau strongly respond to global warming. Their soils, containing large carbon stocks, release more carbon dioxide as a possible consequence. Reciprocally, this may intensify climate warming. The Qinghai-Tibet plateaús large and almost inaccessible terrain results in a general data scarcity for this area making the quantification of soil carbon dynamics challenging. The current study provides an area-wide estimation of soil respiration for the Qinghai-Tibet Plateau, which is a key region for climate change studies due to its size and sensitivity. We compared the ability of six regression models to predict soil respiration that were developed within different studies and are based on mean annual air temperature, mean annual precipitation and belowground biomass. We used the WorldClim data sets to approximate annual soil respiration on a regional scale. Compared to field measurements of soil respiration at single spots in different vegetation zones on the Qinghai-Tibet Plateau (max. 1876.63 g C m −2 year −1 ), our predicted results (max. 1765.13 g C m −2 year −1 ) appear to be consistent. The basic difference between grasslands and forests in soil respiration is indicated by all regression models, however, a more precise differentiation between vegetation types is only exhibited by the regression model based on mean annual precipitation. Overall, this model performs best for most and the largest vegetation zones. Nevertheless, the approximations of the model based on mean annual temperature by Raich and Schlesinger (1992) with a lower constant better represent the vegetation zone of the alpine steppe. With this spatial estimation of soil respiration at a regional scale, a basis for assessing an area-specific potential of greenhouse gas emissions on the Qinghai-Tibet Plateau is provided. Moreover, we quantify a complex soil ecological process for this data-scarce area. [ABSTRACT FROM AUTHOR]

Aim: An important research question in ecology is how climate and the biodiversity of aboveground plants and belowground microbiomes affect ecosystem functions such as nutrient pools. However, little is studied on the concurrent role of above‐ and belowground species composition in shaping the spatial distribution patterns of ecosystem functions across environmental gradients. Here, we investigated the relationships between the taxonomic composition of plants, soil bacteria and soil fungi and spatial turnover in nutrient pools, and assessed how species composition–nutrient pool relationships were mediated by contemporary climatic conditions. Location: Qinghai‐Tibetan Plateau. Time period: Current. Major taxa studied: Plants, soil bacteria and soil fungi. Methods: We surveyed plant assemblages, sampled the taxonomic composition of soil bacteria and soil fungi, and measured plant‐ and soil‐mediated nutrient pools at 60 alpine grasslands on the Qinghai‐Tibetan Plateau. Using Mantel tests, structural equation models and general linear models, we investigated the relative importance of the taxonomic composition of plant, soil bacterial, and soil fungal communities on the spatial turnover of alpine grassland nutrient pools. Results: We found that the taxonomic composition of plant, soil bacterial, and soil fungal communities was associated with local climate. However, the effects of local climate on the spatial turnover of plant‐ and soil‐mediated nutrient pools were mainly indirect and mediated through plant and soil bacterial species composition, but not through soil fungal species composition. We further found that the replacement component of soil bacterial β‐diversity and the richness difference of plant β‐diversity were the direct predictors of nutrient pools in the alpine grasslands. Main conclusions: These results highlight that belowground bacterial composition together with aboveground plant species composition are related to spatial turnover in nutrient pools, perhaps even driving it. Conserving above‐ and belowground biodiversity may therefore safeguard against the impacts of local climate on the functions of climate‐sensitive alpine grasslands. [ABSTRACT FROM AUTHOR]

As a crucial property for assessing the stability of soil organic carbon (SOC), the mineralization potential of SOC (R SOC) is often considered vital for soil carbon (C) dynamics. Previous studies have investigated the responses of R SOC and the corresponding regulation of increased nitrogen (N) and phosphorus (P) inputs, among which, the response of R SOC would affect SOC accumulation directly, emphasizing the significance of investigating R SOC. Hence, based on a long-term nutrient addition experiment in a Tibetan alpine grassland, this study assessed R SOC using a 45-day soil incubation experiment with 13C-glucose labeling method and explored the underlying mechanisms. The results demonstrated bacterial richness and diversity decreased in the topsoil due to the lower pH caused by the continuous N addition, whereas fungal richness and diversity had no significant change. And R SOC decreased with N addition in the topsoil because of suppressing the physiological process of microbes for N. Our results highlighted the crucial role of C availability (indicated by dissolved organic carbon) and N availability (indicated by total nitrogen) in controlling R SOC with long-term nutrient addition in the top- and subsoil, respectively. Overall, this study elucidated the impact of N and P addition on R SOC and offered the regulatory mechanisms of R SOC by considering soil, plant and microbial properties. These findings can serve as a basis for anticipating the changes in SOC dynamics in response to enhanced N and P deposition. A conceptual diagram depicting the influence of the 10-year N and P addition on R SOC and the underlying mechanisms in the top- and subsoil in alpine grasslands. The short arrow (↑ and ↓) represent increase and decrease in the variables. The arrow containing letters (including N, P and N + P) represent N addition, P addition and N + P addition of the field experiment. [Display omitted] • Soil mineralization in the topsoil decreased with long-term N addition. • Soil properties, not microbial community properties, controlled R SOC. • C and N availability dominated R SOC in the alpine grassland. [ABSTRACT FROM AUTHOR]

Highlights: [•] Virus challenge has been investigated following s.l. vaccination with HDAd-sFsyn. [•] We investigate the immune responses induced by HDAd-sFsyn. [•] We assess the utility of the sublingual mucosa as a site for immunization with HDAd-sFsyn. [ABSTRACT FROM AUTHOR]

Satellite‐derived normalized difference vegetation index (NDVI) data are increasingly relied on to reveal the growth responses of vegetation to climate change, yet the vegetation growth tracking accuracy of these data remains unclear due to a lack of long‐term field data. Here, we adopted a unique field‐measured seasonal aboveground biomass dataset from 1982–2014 to assess the potential of using satellite‐derived NDVI data to match field data in regard to the interannual variability in seasonal vegetation growth in a Tibetan alpine grassland. We revealed that Global Inventory Monitoring and Modeling System (GIMMS) NDVI data captured the advancement of field‐measured vegetation growth throughout the entire study period but not from 2000–2014, while MODIS NDVI data still observed this advancing trend after 2000 to a limited extent. However, satellite‐derived NDVI data consistently underestimated the advancement degree of field‐measured vegetation growth, regardless of whether GIMMS or MODIS NDVI data were considered. We tentatively attribute this underestimation to an increased ratio of grass biomass to forb biomass, which could delay the advancement of NDVI development but not affect that of field‐measured biomass development. Our results suggest that satellite‐derived NDVI data may miss critical responses of vegetation growth to global climate change, potentially due to long‐term shifts in plant community composition. [ABSTRACT FROM AUTHOR]

The extent to which key factors at the global scale influence plant biomass allocation patterns remains unclear. Here, we provide a theory about how biotic and abiotic factors influence plant biomass allocation and evaluate its predictions using a large global database for forested communities. Our analyses confirm theoretical predictions that temperature, precipitation, and plant height and density jointly regulate the quotient of leaf biomass and total biomass, and that they have a much weaker effect on shoot (leaf plus stem) biomass fractions at a global scale. Moreover, biotic factors have larger effects than abiotic factors. Climatic variables act equally on shoot and root growth, and differences in plant body size and age, as well as community species composition, which vary with climate in ways that drown out the variations in biomass fractions. The theory and data presented here provide mechanistic explanations of why climate has little effect on biomass fractions. [ABSTRACT FROM AUTHOR]

Background and aims: Root-associated fungi link resource fluxes between the soil and roots, thus influencing plant growth and ecosystem function. However, at present, the impact of global warming on these fungi and their plant host specialization, especially in ecosystems on the Qinghai-Tibetan Plateau is obscure. Methods: Here, pot experiments were conducted to examine the root-associated fungal community structure of 14 host plant species undergoing two years of experimental warming on the Qinghai-Tibetan Plateau. Infrared heaters were used to raise the soil temperature to 2.0 ℃ higher than the relative ambient temperature. Subsequently, the endophytic and rhizoplane fungal communities were explored by sequencing the fungal internal transcribed spacer (ITS) region. Results: A total of 1564 OTUs were identified, which were dominated by ascomycetes (82.71%). Similar root-associated fungal diversity and community composition were identified under ambient and warming environments. The root-associated fungal community composition significantly varied among different host plant species, and this dissimilarity was enhanced under experimental warming. Root N concentration was essential in shaping the structure of the root-associated fungal community. Conclusions: Although the root-associated fungal community was resilient to short-term warming, our study highlights that climate warming can induce higher host specificity of root-associated fungal communities in the alpine meadow ecosystem. [ABSTRACT FROM AUTHOR]

Phenology is critical to ecosystem carbon quantification, and yet has not been well modeled considering both aboveground and belowground environmental variables. This is especially true for alpine and pan-arctic regions where soil physical conditions play a significant role in determining the timing of phenology. Here we examine how the spatiotemporal pattern of satellite-derived phenology is related to soil physical conditions simulated with a soil physical model on the Tibetan Plateau for the period 1989-2008. Our results show that spatial patterns and temporal trends of phenology are parallel with the corresponding soil physical conditions for different study periods. On average, 1 °C increase in soil temperature advances the start of growing season (SOS) by 4.6 to 9.9 days among different vegetation types, and postpones the end of growing season (EOS) by 7.3 to 10.5 days. Soil wetting meditates such trends, especially in areas where warming effect is significant. Soil thermal thresholds for SOS and EOS, defined as the daily mean soil temperatures corresponding to the phenological metrics, are spatially clustered, and are closely correlated with mean seasonal temperatures in Spring and Autumn, respectively. This study highlights the importance and feasibility of incorporating spatially explicit soil temperature and moisture information, instead of air temperature and precipitation, into phenology models so as to improve carbon modeling. The method proposed and empirical relations established between phenology and soil physical conditions for Alpine ecosystems on the Tibetan plateau could also be applicable for other cold regions. [ABSTRACT FROM AUTHOR]

Amyloid β-protein (Aβ) has been causally implicated in the neurodegenerative processes that accompany Alzheimer's disease. Soluble oligomers of the Aβ1-42 fragment are thought to be significantly more neurotoxic than higher molecular weight aggregates. We report the isolation and characterization of a mouse monoclonal antibody (MAb) directed against soluble Aβ1-42 oligomers. Synthetic Aβ1-42 oligomers were assembled in vitro; these were used to immunize mice, and hybridomas were isolated following myeloma fusion of splenocytes from immunized animals. Screening for reactivity against AAβ1-42 resulted in the identification of MAb A8 with high affinity for soluble oligomers. The isotype of A8 was found to be IgG2b. Experiments using sub-peptides of AAβ1-42 revealed that the epitope identified by A8 lies within the 1-6 region of Aβ. The antibody displays high affinity for soluble AAβ1-42 oligomers in the molecular weight range of 16.5-25 kDa, and detected target antigen in brain sections from senescence-accelerated SAMP 8 mice. The sensitivity and optimal titers for the detection of soluble AAβ1-42 oligomers were determined to be 0.625 µg/mL in indirect ELISA, and 1:106, 1:4000, and 1:150 for ELISA, Western blotting, and immunohistochemistry, respectively. The A8 antibody specific for soluble AAβ1-42 oligomers will provide a valuable tool for Alzheimer's disease research. [ABSTRACT FROM AUTHOR]

Aim: Most existing studies that examined the biotic mechanisms of ecosystem stability have focused on aboveground biodiversity. Whether and how belowground biodiversity affects the stability of natural ecosystems is largely unknown. In the present study, we investigated the relationships between above‐ and belowground biodiversity and the temporal stability of grassland biomass production across a large gradient of soil and climatic conditions. Location: Tibetan Plateau. Time period: 2001–2016. Major taxa studied: Alpine grass and soil bacteria, arbuscular mycorrhiza (AM) fungi and fauna. Methods: We coupled a field biodiversity survey conducted in 54 alpine grassland ecosystems across the Tibetan Plateau with a satellite‐sensed proxy (enhanced vegetation index, EVI) of ecosystem productivity during 2001–2016. The temporal stability of primary productivity was calculated as the ratio of the mean annual peak EVI to the standard deviation of the annual peak EVI over this period. Plant diversity was determined using a classic vegetation survey approach, soil bacterial and AM fungal diversity were measured using a high‐throughput sequencing approach, and soil fauna was counted and identified at the order level after being extracted using a modified Berlese–Tullgren method. Results: Our results demonstrated that both above‐ and belowground biodiversity were positively associated with ecosystem stability. Belowground biodiversity not only affected ecosystem stability directly, but also influenced it indirectly through plant diversity and soil fertility. Furthermore, soil pH, climate and its variability strongly influenced soil biodiversity, which in turn influenced ecosystem stability. Main conclusions: Our study demonstrates the indispensable role of belowground biodiversity in regulating ecosystem stability, emphasizing the necessity of conserving this 'hidden' biodiversity in fragile alpine ecosystems facing ongoing environmental change. [ABSTRACT FROM AUTHOR]

Human respiratory syncytial viruses (RSVs) are classified into two major groups (A and B) based on antigenic differences in the G glycoprotein. To investigate circulating characteristics and phylodynamic history of RSV, we analyzed the genetic variability and evolutionary pattern of RSVs from 1977 to 2019 in this study. The results revealed that there was no recombination event of intergroup. Single nucleotide polymorphisms (SNPs) were observed through the genome with the highest occurrence rate in the G gene. Five and six sites in G protein of RSV-A and RSV-B, respectively, were further identified with a strong positive selection. The mean evolutionary rates for RSV-A and -B were estimated to be 1.48 × 10–3 and 1.92 × 10–3 nucleotide substitutions/site/year, respectively. The Bayesian skyline plot showed a constant population size of RSV-A and a sharp expansion of population size of RSV-B since 2005, and an obvious decrease 5 years later, then became stable again. The total population size of RSVs showed a similar tendency to that of RSV-B. Time-scaled phylogeny suggested a temporal specificity of the RSV-genotypes. Monitoring nucleotide changes and analyzing evolution pattern for RSVs could give valuable insights for vaccine and therapy strategies against RSV infection. [ABSTRACT FROM AUTHOR]

Subsoils contain >50% of soil organic carbon (SOC) globally yet remain under‐investigated in terms of their response to climate changes. Recent evidence suggests that warmer, drier conditions in alpine grasslands induce divergent responses in SOC decomposition and carbon accrual in top‐ versus subsoils. However, longer term effects on microbial activity (i.e., catabolic respiration vs. anabolic growth) and belowground carbon cycling are not well understood. Here we utilized a field manipulation experiment on the Qinghai‐Tibetan Plateau and conducted a 110‐day soil incubation with and without 13C‐labeled grass litter to assess microbes' role as both SOC "decomposers" and "contributors" in the top‐ (0–10 cm) versus subsoils (30−40 cm) after 5 years of warming and drought treatments. Microbial mineralization of both SOC and added litter was examined in tandem with potential extracellular enzyme activities, while microbial biomass synthesis and necromass accumulation were analyzed using phospholipid fatty acids and amino sugars coupled with 13C analysis, respectively. We found that warming and, to a lesser extent, drought decreased the ratio of inorganic nitrogen (N) to water‐extractable organic carbon in the subsoil, intensifying N limitation at depth. Both SOC and litter mineralization were reduced in the subsoil, which may also be related to N limitation, as evidenced by lower hydrolase activity (especially leucine aminopeptidase) and reduced microbial efficiency (lower biomass synthesis and necromass accumulation relative to respiration). However, none of these effects were observed in the topsoil, suggesting that soil microbes became inactive and inefficient in subsoil but not topsoil environments. Given increasing belowground productivity in this alpine grassland under warming, both elevated root deposits and diminished microbial activity may contribute to new carbon accrual in the subsoil. However, the sustainability of plant growth and persistence of subsoil SOC pools deserve further investigation in the long term, given the aggravated N limitation at depth. [ABSTRACT FROM AUTHOR]

As crucial carbon (C) and energy sources for soil microorganisms, neutral sugars are essential component of the labile soil organic carbon (SOC) pool derived from plants and microorganisms and can directly affect the accumulation of SOC. However, the changes in labile SOC components with elevated soil nitrogen (N) and phosphorus (P) inputs remain unclear. Taking advantage of a 10-year field N and P addition experiment in an alpine grassland on the Tibetan Plateau, we analyzed the compositions and concentrations of neutral sugar in plant versus soil, coupled with soil nutrient properties and plant biomass, we assessed factors affecting the preservation of neutral sugars in soil. We found that the concentrations of neutral sugar were lower in plant shoots than those in roots. The concentrations of neutral sugar and the GM/AX ratio (GM: galactose and mannose; AX: arabinose and xylose) in shoots and roots were insensitive to nutrient addition. The concentrations of neutral sugar in the topsoil were significantly lower than those in the subsoil, and both significantly decreased with N alone and P alone addition. The GM/AX ratio was significantly higher in the topsoil than that in the subsoil and both increased with nutrient addition (except for NP addition in the topsoil). Additionally, SOC was negatively correlated with soil neutral sugar concentrations but positively correlated with the GM/AX ratio. This result emphasizes the important role of microbial transformation of neutral sugars in regulating the relative magnitude of the labile SOC pool versus the stable SOC pool, which is consistent with the concept of "microbial carbon pump" (MCP). This study demonstrates differential compositions and concentrations, as well as responses of neutral sugars to N and P addition in plant versus soil, providing new information to understand the effect of nutrient addition on the SOC pool in the plant-soil system. [Display omitted] • Neutral sugar in shoots and roots was insensitive to N and P addition. • Neutral sugar in the top- and subsoil both declined with N or P alone addition. • The GM/AX did not change in plant but increased in soil with N or P alone addition. • Neutral sugar was negatively correlated with SOC. [ABSTRACT FROM AUTHOR]

Nutrient cycling in alpine grasslands is susceptible to climate change and anthropogenic activities, which can affect soil phosphorus (P) availability. Despite the crucial role of soil P availability in maintaining stability and productivity of grassland ecosystems, limited research has been conducted on the effects of nitrogen (N) addition and winter grazing on P transformation on the Qinghai-Tibet Plateau. In an 8-year experiment, we applied four different N addition rates (0, 25, 50, and 100 kg urea ha−1 year−1) in combination with winter grazing to investigate the effects of N addition and winter grazing on the soil P fractions. The results reveal that increasing the N addition gradually reduced the resin-Pi and NaOH-Pi contents in the soil by increasing the plant P uptake and promoting the release of carboxylates in the rhizosheath, regardless of grazing. Winter grazing decreased the NaHCO 3 -Pi and NaOH-Pi contents compared with the no-grazing treatment by increasing the P uptake of the plants. In contrast, neither grazing nor N addition affected the HCl conc. -P or residual-P content. In the no-grazing plots, the soil NaHCO 3 -Po content exhibited a gradual increase in response to N addition, whereas N addition had no discernible effect on the NaOH-Po content. In the grazing plots, the NaHCO 3 - and NaOH-Po contents gradually decreased with N addition, which was associated with the increased acid phosphatase activity in the rhizosheath and the export of forage. Thus, we conclude that N addition promotes the dissolution of NaOH-Pi to more available inorganic P forms. Under winter grazing conditions only, the transformation of P from inorganic to organic forms gradually decreased with increasing N additions. • N addition promotes the dissolution of NaOH-Pi to more available inorganic P forms. • Winter grazing reduces the P transformation from inorganic to organic forms. • N addition only decreases the organic P accumulation in the presence of grazing. [ABSTRACT FROM AUTHOR]

Grazing is the most important disturbance to grasslands, especially on the Tibetan Plateau, which sustains the livelihoods of tens of thousands of herders. However, the effects of grazing intensity and associated changes in vegetation on freeze–thaw processes (FTPs) in seasonal permafrost regions remain unclear. Here, two years of continuous in situ observations from a controlled grazing intensity experiment were used to examine FTPs and influencing factors in an alpine meadow on the Eastern Tibetan Plateau. Our results showed that a higher grazing intensity led to a shorter frozen period, extended freezing and thawing periods, and earlier initiation of freezing and thawing periods. Furthermore, grazing increased soil temperature and active (> 0 °C) and effective (> 10 °C) accumulated temperatures. The soil diurnal temperature range increased linearly with grazing intensity, whereas soil moisture did not vary with soil temperature. Our results demonstrated that the freezing and frozen periods were mainly influenced by soil temperature and the diurnal temperature range, whereas soil moisture played a critical role in the variation in the thawing period. The reduction in aboveground biomass elicited changes in FTPs, including shortening of the frozen period and lengthening of the thawing and freezing periods. Collectively, our results highlight that the combination of grazing-induced changes in vegetation and changes in subsurface temperature and moisture leads to changes in freezing and thawing processes. • Grazing changed freeze–thaw processes, causing shorter frozen and extended freezing and thawing periods. • Grazing increased soil temperature, accumulated temperature, and diurnal temperature range. • Freezing and frozen periods were affected by soil temperature, whereas thawing period were affected by soil moisture. • Grazing affected freeze–thaw processes by changing aboveground biomass. [ABSTRACT FROM AUTHOR]

Background: Future ecosystem structure and function will largely depend on root responses to climate change. However, few studies have explored the responses of root production and decomposition to simultaneous warming and altered precipitation in high-latitude and high-altitude ecosystems. Methods: Using ingrowth core and root bag methods, we investigated root production and decomposition dynamics from 2013 to 2015 in a full-factorial warming (control, 1.5 ~ 1.8 °C warming) and precipitation (dry (−50% precipitation), ambient, and wet (+50% precipitation)) experiment established in 2011 in a Tibetan alpine grassland. Results: Warming and precipitation effects on root production were independent. Dry plus warming treatments increased root production, while wet treatments did not significantly affect root production. In contrast, root decomposition accelerated along the increasing precipitation gradient. Warming tended to decrease root decomposition under dry treatments but did not affect root decomposition under wet treatments. The different responses of root production among the treatments were mainly driven by changes in soil moisture, whereas those of root decomposition were mainly due to the changes in the root carbon nitrogen ratio, soil microbial biomass and soil moisture. Conclusions: Given that altered precipitation had contrasting effects on root production and decomposition, our findings indicate that root-derived carbon may accumulate in soils on the Tibetan Plateau where precipitation decreases but not in the areas with projected increasing precipitation under future warming. [ABSTRACT FROM AUTHOR]

Background and aims: Soil respiration (Rs) is expected to positively feedback to climate warming. The strength of this feedback is uncertain as numerous environmental factors, such as precipitation and soil moisture, can moderate the warming response of Rs. Methods: We combined seven-year Rs measurements in a warming experiment in the Tibetan alpine grassland with a meta-analysis on grassland warming experiments globally to investigate how precipitation and soil moisture influences the warming response of Rs. We further analyzed the warming responses of heterotrophic (Rh) and autotrophic (Ra) components of Rs. Results: Warming enhanced growing-season Rs in the wet years but decreased it in the dry years in the field experiment at the Tibetan grassland. Precipitation modulated the warming responses of growing-season Rs via Rh, but not Ra. Consistent with the field experiment, a positive relationship between precipitation and the warming response of growing-season Rs was also observed in the global-scale meta-analysis on grassland warming experiments. Conclusions: Precipitation influences the warming effects on Rs and could result in variation in warming response of Rs across years and experimental systems. Empirical functions provided by this study could be used to reduce the uncertainty in predicting Rs in a warmer future. [ABSTRACT FROM AUTHOR]

Monitoring the mutation and evolution of the virus is important for tracing its ongoing transmission and facilitating effective vaccine development. A total of 342 complete genomic sequences of SARS-CoV-2 were analyzed in this study. Compared to the reference genome reported in December 2019, 465 mutations were found, among which, 347 occurred in only 1 sequence, while 26 occurred in more than 5 sequences. For these 26 further identified as SNPs, 14 were closely linked and were grouped into 5 profiles. Phylogenetic analysis revealed the sequences formed 2 major groups. Most of the sequences in late period (March and April) constituted the Cluster II, while the sequences before March in this study and the reported S/L and A/B/C types in previous studies were all in Cluster I. The distributions of some mutations were specific geographically or temporally, the potential effect of which on the transmission and pathogenicity of SARS-CoV-2 deserves further evaluation and monitoring. Two mutations were found in the receptor-binding domain (RBD) but outside the receptor-binding motif (RBM), indicating that mutations may only have marginal biological effects but merit further attention. The observed novel sequence divergence is of great significance to the study of the transmission, pathogenicity, and development of an effective vaccine for SARS-CoV-2. [ABSTRACT FROM AUTHOR]

Grassland ecosystems account for more than 10% of the global CH4 sink in soils. A 4‐year field experiment found that addition of P alone did not affect CH4 uptake and experimental addition of N alone significantly suppressed CH4 uptake, whereas concurrent N and P additions suppressed CH4 uptake to a lesser degree. A meta‐analysis including 382 data points in global grasslands corroborated these findings. Global extrapolation with an empirical modelling approach estimated that contemporary N addition suppresses CH4 sink in global grassland by 11.4% and concurrent N and P deposition alleviates this suppression to 5.8%. The P alleviation of N‐suppressed CH4 sink is primarily attributed to substrate competition, defined as the competition between ammonium and CH4 for the methane mono‐oxygenase enzyme. The N and P impacts on CH4 uptake indicate that projected increases in N and P depositions might substantially affect CH4 uptake and alter the global CH4 cycle. [ABSTRACT FROM AUTHOR]