Due to the impact of climate change, significant alterations in snowmelt have already occurred, which have been demonstrated to play a crucial role in photosynthetic carbon sequestration processes in vegetation. However, the effect of changes in snowmelt on light use efficiency (LUE) of grassland remain largely unknown in the permafrost region of Qinghai-Tibetan Plateau (QTP). By utilizing remote sensing data from 2000 to 2017, we conducted an analysis on the spatial and temporal patterns of LUE for various types of permafrost and grassland on the QTP. The LUE of the growing season was 1.1588 g CMJ(-1), displaying variations among different ecosystems: alpine steppe of seasonally frozen ground (ASS) > alpine meadow of seasonally frozen ground (AMS) > alpine meadow of permafrost (AMP) > alpine steppe of permafrost (ASP). Furthermore, our study demonstrated that decreasing snowmelt during the growing season had a negative impact on LUE through meteorological factors, elucidating its influence on LUE for approximately 40.65%, 34.06%, 41.05%, and 32.68% of ecosystems studied. Reduced snowmelt indirectly affects LUE by lowering air temperatures, vapor pressure deficit and solar radiation, while replenishing soil moisture. Additionally, changes in snowmelt can directly affect LUE by reducing the insulating properties of snow cover. Therefore, when estimating gross primary productivity (GPP) using remote sensing data based on LUE, it is essential to consider the impact of snowmelt. This will better represent vegetation phenology's response to climate change.

Alpine grasslands are vital in regulating carbon balance on the Qinghai-Tibetan Plateau (QTP) because of the large soil organic carbon (SOC) stocks, while persistent disturbance from the endemic small semifossorial herbivore, plateau pika (Ochotona curzoniae, hereafter pika), may break this balance. Pika affect the soil microclimate by creating a heterogeneous underlying surface, which is expected to alter soil microbial communities and eventually SOC stocks. However, our knowledge regarding the potential influence mechanism is still limited. Here, we investigated vegetation biomass, soil properties and soil microbes among 4 different surfaces (i.e., original vegetation, new pika pile, old pika pile and bare patch) of typical alpine grasslands to reveal soil microbial communities and the associated effect on SOC in response to pika bioturbation. Our results showed that pika bioturbation increased both bacterial and fungal diversity and their phyla abundance for SOC decomposition. Vegetation biomass, electrical conductivity and NH4+-N accounted for the variation in both bacterial and fungal community compositions and diversity. SOC stocks were 15-30% lower in pika piles and bare patches than in the original vegetation, which was mainly attributed to the reduced soil organic matter input from vegetation and the enhanced SOC consumption by soil microbial communities. Overall, we conclude that pika bioturbation altered the diversity and composition of soil microbial communities, which was associated with SOC loss and positive carbon feedback in alpine grasslands. Our findings provide insights into the role of small semifossorial herbivores in the carbon cycle of global grasslands.

The burrowing activity of plateau pikas (Ochotona curzoniae; hereafter, pikas) may profoundly influence vegetation species composition on the Qinghai-Tibetan Plateau (QTP). Although significant efforts have been made to examine the relationship between vegetation species composition and pikas disturbance, our knowledge regarding the direct influence of pikas activity on vegetation species diversity is still limited. We conducted field observations on pikas burrows and surrounding vegetation patches at 23 alpine grassland sites to investigate this effect. When compared to vegetation patches, pikas burrowing activity decreased soil hardness, thus improving water infiltration, while caused the less reduction of soil nutrition and soil moisture when compared to adjacent vegetation patches. Vegetation species composition on pikas burrows significantly differed from that on vegetation patches. Common plant species between pikas burrows and vegetation patches were fewer than three in all types of grasslands, and ten species were found exclusively on pikas burrows. The total species richness, including both pikas burrows and vegetation patches, was approximately 1.3-2.5 times higher than that on each single patch type (pikas burrows or vegetation patches). A conceptual framework was proposed to synthesize the evolution of vegetation species composition under a disturbance regime resulting from pika's burrowing. Overall, we concluded that pika's burrowing activity enhanced vegetation species richness by loosening the soil, creating safe sites for seed settling and germination, which provided a novel habitat for vegetation invasion.

Background The bacterial mechanisms responsible for hydrogen peroxide (H2O2) scavenging have been well-reported, yet little is known about how bacteria isolated from cold-environments respond to H2O2 stress. Therefore, we investigated the transcriptional profiling of the Planomicrobium strain AX6 strain isolated from the cold-desert ecosystem in the Qaidam Basin, Qinghai-Tibet Plateau, China, in response to H2O2 stress aiming to uncover the molecular mechanisms associated with H2O2 scavenging potential. Methods We investigated the H2O2-scavenging potential of the bacterial Planomicrobium strain AX6 isolated from the cold-desert ecosystem in the Qaidam Basin, Qinghai-Tibet Plateau, China. Furthermore, we used high-throughput RNA-sequencing to unravel the molecular aspects associated with the H2O2 scavenging potential of the Planomicrobium strain AX6 isolate. Results In total, 3,427 differentially expressed genes (DEGs) were identified in Planomicrobium strain AX6 isolate in response to 4 h of H2O2 (1.5 mM) exposure. Besides, Kyoto Encyclopedia of Genes and Genomes pathway and Gene Ontology analyses revealed the down- and/or up-regulated pathways following H2O2 treatment. Our study not only identified the H2O2 scavenging capability of the strain nevertheless also a range of mechanisms to cope with the toxic effect of H2O2 through genes involved in oxidative stress response. Compared to control, several genes coding for antioxidant proteins, including glutathione peroxidase (GSH-Px), Coproporphyrinogen III oxidase, and superoxide dismutase (SOD), were relatively up-regulated in Planomicrobium strain AX6, when exposed to H2O2. Conclusions Overall, the results suggest that the up-regulated genes responsible for antioxidant defense pathways serve as essential regulatory mechanisms for removing H2O2 in Planomicrobium strain AX6. The DEGs identified here could provide a competitive advantage for the existence of Planomicrobium strain AX6 in H2O2-polluted environments.

Plant biomass reveals the productivity and stability of a biotic community and is extremely sensitive to climate warming in permafrost regions, such as the Qinghai-Tibetan Plateau (QTP) in China. However, the response of the plant biomass of different functional groups to rising temperatures in such alpine zones remains unclear. Here, infrared radiators were used to simulate year-round warming on the QTP from 2011 to 2018. During the 8-year warming experiment, air temperature increased by 0.16 degrees C, while humidity tended to increase by 0.27 % at 20 cm above the ground. However, the rate of the increase in air temperature declined with an increasing number of years. Soil temperature and moisture increased by 1.28 degrees C and 3.61 %, respectively, on average from 0 to 100 cm below the ground, and the increment of soil moisture tended to rise with increasing depth. At the depths from 0 cm to 20 cm below the ground, soil organic carbon and total phosphorus tended to decrease by 0.79 g/kg and 0.04 g/kg, respectively, while soil total nitrogen tended to increase by 0.04 g/kg. Plant biomass had non-significant responses to warming, but the variation among different plant functional groups was greatest for forbs with the increment being 12.50, 147.97, and 160.47 g/m(2) for plants aboveground, belowground, and total biomass, respectively. The ratios of plant total biomass tended to decrease by 2.29 %, increase by 0.60 %, and increase by 1.70 % for grasses, sedges, and forbs, respectively, so warming greatly decreased the proportion of grasses and increased the proportion of forbs in community. Warming weakened the positive correlation of grass biomass with soil temperature and enhanced the negative correlation of grass biomass with soil N and P content, along with weakening the positive correlation of sedge biomass with soil moisture and N content, while enhancing the negative correlation between sedge biomass and soil temperature. Meanwhile, forb biomass was greatly increased by soil temperature in the effects of warming. In conclusion, the 8-year warming produced negative effects on grasses and sedges by increasing soil temperature and N content and thus promoted the growth of forbs, which might induce a shift toward forbs in this community.

With the global warming, the permafrost on the Qinghai-Tibetan Plateau (QTP) is degrading significantly, which brings potential threats to the major engineering projects built in or on it, e. g., the Qinghai-Tibet Highway, Qinghai-Tibet Railway, and Xinjiang-Tibet Highway. This study uses advanced survey and statistical methods to reveal the spatial distribution characteristics, development patterns, influencing factors, and formation mechanisms of the damages on the pavement induced by permafrost thawing and freeze-thaw cycles to identify their development process, evolution patterns, and different types of underlying permafrost. This will provide suggestions and guidance to the relevant departments in the decision-making, planning, design, and construction and maintenance of the running or future engineering projects on the QTP.

Some sloping peatlands in northern regions often develop surface microtopographic patterns to maintain their water balance and ecosystem functioning. However, we do not know whether and how spatial patterning would influence the water balance and peat formation of permafrost-affected peatlands in relatively dry regions. Here we used data from the field observations and Unmanned Aerial Vehicle (UAV) survey of a slope peatland at an elevation of around 4800 m in the hinterland of the Qinghai-Tibetan Plateau (QTP) to document and understand the topographic controls of water balance and vegetation growth. Our terrain analysis result shows that the peatland-located on the middle of a hillslope-has a gentle slope of 5.6 degrees +/- 2.5 degrees, while the non-peatland upper has a steep slope of 12 degrees +/- 4.5 degrees. The great upstream catchment area and the presence of shallow impermeable permafrost likely create a saturated condition for peat formation. Our UAV results show obvious spatial patterning of abundant pools and ridges across this peatland, and pool sizes and ridge abundance increase with increasing slopes, suggesting that slope-controlled water flow gradient is the main driver of ridge formation and that ridges is to slow down the runoff. UAV-derived greenness values show a positive relationship with the total pool extent locally (R2 = 0.60) and decrease with increasing distance from the individual pools, suggesting sensitive responses of vegetation growth to surface moisture. Thus, enhanced vegetation growth and likely resultant great peat accumulation immediately around pools potentially further differentiate surface micro-topography, strengthening the pool stability. We conclude that the local slope gradient, surface patterning (pools and ridges) and permafrost interact together to regulate water flow and maintain water balance, which in turn regulate the vegetation growth, peat accumulation and peatland stability. Our study implies that the delicate water balance maintained partly by microtopography is sensitive to climate change-especially potential extreme hydroclimate events-and natural and human-induced disturbances that may modify the surface patterning and weaken the peatland's stability, affecting the carbon sequestration ability of this type of peatlands.

A bacterial strain, designated GEM5(T), was isolated from sand soil samples from the Qinghai-Tibet Plateau. The polyphasic study confirmed the affiliation of the isolate with the genus Massilia. GEM5(T) had Gram-stain-negative, non-spore-forming and rod-shaped cells and grew at 4-30 degrees C. pH 6-8 and with 0-2% (w/v) NaCl. Its cell wall contained ribose. Q8 was the predominant respiratory quinone, and summed feature 3 (C-1(6:1), omega 6c/w7c) and C-16:0 were the major components of the fatty acids. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unidentified phospholipid, an unidentified aminolipid and four unidentified lipids. The DNA G+C content was 65.1 mol%. The phylogenetic analysis based on the 16S rRNA gene showed a stable Glade being formed by GEM5(T), Massilia timonae CCUG 45783(T) (97.94%) and Massilia oculi CCUG 43427A(T) (97.58%). The average nucleotide identity (ANIb) values between GEM5(T) and M. timonae CCUG 45783(T), M.oculi CCUG 43427A(T) were 91.3 and 91.7%, respectively. On the basis of the morphological, physiological and chemotaxonomic pattern, it was proposed that strain GEM5(T) (=JCM 32744(T)=CICC 24458(T)) should be classified as representing a member of the genus Massilia with the name Massilia arenae sp. nov.

As the basic units of soil structure, soil aggregate is essential for maintaining soil stability. Intensified freeze-thaw cycles have deeply affected the size distribution and stability of aggregate under global warming. To date, it is still lacking about the effects of freeze-thaw cycles on aggregate in the permafrost regions of the Qinghai-Tibetan Plateau (QTP). Therefore, we investigated the effects of diurnal and seasonal freeze-thaw processes on soil aggregate. Our results showed that the durations of thawing and freezing periods in the 0-10 cm layer were longer than in the 10-20 cm layer, while the opposite results were observed during completely thawed and frozen periods. Freeze-thaw strength was greater in the 0-10 cm layer than that in the 10-20 cm layer. The diurnal freeze-thaw cycles have no significant effect on the size distribution and stability of aggregate. However, 0.25 mm) and reduced aggregate stability. Our study has scientific guidance for evaluating the effects of freeze-thaw cycles on soil steucture and provides a theoretical basis for further exploration on soil and water conservation in the permafrost regions of the QTP.

Permafrost areas are sensitive to climate change and have a significant impact on energy and water cycles. Ground ice is a crucial component on the Qinghai-Tibetan Plateau (QTP). Understanding the environmental characteristics of ground ice is vital for accurately modeling its distribution and evolution. In this study, we analyzed 15 environmental characteristics of high ice-content permafrost sites. These attributes were extracted from 400 high ice-content permafrost datasets including 300 drilling boreholes and 100 thaw slumps collected throughout the entire plateau using large-scale remote sensing data and their products. The results are as follows: The mean annual air temperature in areas where high ice-content permafrost exists ranges from -5 to -3.5 & DEG;C, with an average warming rate of 0.08 & DEG;C/a. Additionally, there was an average increase in precipitation of about 25 mm/10a and an increase in soil moisture of about 4%/10a. Geomorphology strongly influences the occurrence of high ice content permafrost, with 85% of high ice-content permafrost development at altitudes between 4400 and 5100 m. Approximately 86% of high ice-content permafrost were developed in lowland or relatively flat areas, preferably in gently sloping and shady slope regions. Soils exhibit less variability in clay particles and more variability in silt and sand. Key indicators in the high ice content permafrost region include warming rate, active layer thickness, elevation, bulk density, soil thickness, clay content, precipitation, soil moisture, and NDVI. High ice-content permafrost is the result of a combination of environmental factors and is expected to undergo significant changes in the future. This study provides a foundation for comprehending the environmental changes in the high ice-content permafrost areas and modeling the distribution of ground ice. It underscores the urgent need to address the significant environmental changes faced by high ice-content permafrost regions.