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Continuous CO2 flux observation with eddy covariance method conducted in the alpine shrub on the Qinghai-Tibet Plateau indicates that there are distinct diurnal and monthly variations for COz fluxes in the alpine shrub on the plateau. As for diurnal variation, with net CO2 influx from 08:00 to 19:00 and net CO2 efflux from 20:00 to 07:00, peak CO2 flux during warm season (July) appears around 12:00 (-1.19 g CO2 η m-2 η h-l); there is no obvious horary fluctuation for CO2 flux during cold season (January), and horary CO2 flux during most hours in a day is close to zero except for a small amount of net efflux (about 0.11 g CO2 · m-2 · h-1) from 11:00--17:00. As for monthly variation, with net CO2 influx from June to September and net CO2 efflux from January to May and October to December, the peak monthly CO2 influx and CO2 efflux appear in August and April, respectively. The total net COz influx from June to September and total net CO2 efflux from February to May and October to December in the alpine shrub on the Qinghai-Tibet Plateau are estimated to be 673 and 446 g CO2 · m-2. Results show that the alpine shrub on the Qinghai-Tibet Plateau is remarkable carbon dioxide sink under no grazing conditions and the total yearly CO2 influx is estimated to be 227 g CO2 · m-2. [ABSTRACT FROM AUTHOR]

Simple Summary: The Qinghai–Tibetan plateau is considered as the third Pole of the world and is characterized by low oxygen, high altitude, extreme cold weather and strong ultraviolet radiation. Yak, as the main domestic animals raised on the plateau, play various roles in local herdsmen's lives by supplying necessities such as meat, milk and fuel. Yak are adapted to the harsh environment on the plateau; microbiota in gut equip the hosts with special abilities including adaptability, as illustrated by numerous research projects. Accordingly, the microbes in the gastrointestinal tract of yak must be characteristically profiled as a strategy to adapt to the environment. However, little is known about the microbial community in whole tract of yak; almost all of reported researches focused on rumen. Therefore, in the current study the bacterial community in the gastrointestinal tract of yak was explored using 16S rDNA amplicon sequencing technology, and the community profiling characteristic in each section was clearly elucidated. In the current research, samples of yak gastrointestinal tracts (GITs) were used to profile the bacterial compositional characteristics using high through-put sequencing technology of 16S RNA amplicon. A total of 6959 OTUs was obtained from 20,799,614 effective tags, among which 751 OTUs were shared by ten sections. A total of 16 known phyla were obtained in all samples—the most abundant phyla were Firmicutes (34.58%), Bacteroidetes (33.96%) and Verrucomicrobia (11.70%). At the genus level, a total of 66 genera were obtained—Rikenellaceae_RC9_gut_group (7.24%), Akkermansia (6.32%) and Ruminococcaceae_UCG-005 (6.14%) were the most abundant. Species of Observed (Sob), Shannon and Chao values of the Stomach were the greatest, followed by the large intestine, while small intestine had the lowest diversity (p < 0.05). Bacteroidete were more abundant in sections from rumen to duodenum; while Firmicutes were the most abundant in sections from jejunum. ABC transporters (7.82%), Aminoacyl-tRNA biosynthesis (4.85%) and Purine metabolism (3.77%) were the most abundant level-3 pathways in all samples. The results of associated correlation analysis indicated that rectum samples might be used as an estimator of rumen bacterial communities and fermentation. The results of this research enrich the current knowledge about the unique animals of the QTP and extend our insight into GITs microecology of various animals. [ABSTRACT FROM AUTHOR]

• Rumen bacteria community of Tibetan sheep was predominated by phyla Bacteroidetes, Firmicute and Verrucomicrobia at phylum level, as to genus , Rikenellaceae_RC9_gut_group and Prevotella_1 predominated. • Sex and age were two important factors which shaping the rumen bacterial composition of Tibetan sheep as previous reported on mice and human. • Most of predicted function genes significantly enriched in adult female sheep compared with adult male sheep and yearling female sheep, respectively. In this study, 18 Tibetan sheep were assigned into four groups by age and sex, namely young ewes (E1, n = 5), young rams (R1, n = 3), adult ewes (EA, n = 5) and adult rams (RA, n =5) to profile the bacterial composition of Tibetan sheep and to explore the impacts of sex and age on rumen microbiota using high-throughput sequencing method of amplicon of 16S rRNA V3–V4 region. The results indicated that all effective tags for 18 samples were clustered into 5429 OTUs (Operation taxonomic Units, OTUs) with an absolute abundance > 1 at a similarity level > 97%. The rumen bacterial composition of female adult sheep was more diverse than male adult sheep and yearling female sheep. SILVA database was used to annotate taxonomic information for each representative sequence using the RDP classifier, the results showed that Bacteroidetes, Firmicutes, Verrucomicrobia and Proteobacteria were the most dominant phyla, representing 56.68%, 28.81%, 6.71% and 1.73% of reads from all samples on average, respectively. At the genus level, Rikenellaceae_RC9_gut_group , and Prevotella_1 were most abundant with relative abundance of 12.98% and 11.19%, respectively. Relative abundance of Bacteroidetes in EA was greater than RA (p = 0.014), relative abundance of Firmicutes in RA was greater than EA (p < 0.001), and the relative abundance of Spirochaetae in E1 was greater than R1 (p = 0.038). Shifting genera between the sexes belonged to Order Bacteroidales and Clostridiales , both changed substantially across sex in adult sheep (p < 0.01). The abundance of Bacteroidetes in female sheep and Firmicutes and Planctomycetes in male sheep significantly increased with age (p < 0.05), while the abundance of Spirochaetae in female sheep and Cyanobacteria in male sheep decreased with age (p < 0.05). Shifting genera between age groups belonged to order Bacteroidales and Clostridial. The abundance of order Bacteroidales in female sheep increased with age (p = 0.046), and the abundance of order Clostridiales in male sheep increased with age (p = 0.006), while it decreased with age in female sheep (p = 0.030). In summary, this study profiled the bacterial composition characteristics of Tibetan sheep and concluded that physiological factors, e.g. sex and age, shaped the bacterial composition, which expands our knowledge of the rumen of ruminant animals residing on the Qinghai-Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Structural information of grassland changes on the Tibetan Plateau is essential for understanding alterations in critical ecosystem functioning and their underlying drivers that may reflect environmental changes. However, such information at the regional scale is still lacking due to methodological limitations. Beyond remote sensing indicators only recognizing vegetation productivity, we utilized multivariate data fusion and deep learning to characterize formation-based plant community structure in alpine grasslands at the regional scale of the Tibetan Plateau for the first time and compared it with the earlier version of Vegetation Map of China for historical changes. Over the past 40 years, we revealed that (1) the proportion of alpine meadows in alpine grasslands increased from 50% to 69%, well-reflecting the warming and wetting trend; (2) dominances of Kobresia pygmaea and Stipa purpurea formations in alpine meadows and steppes were strengthened to 76% and 92%, respectively; (3) the climate factor mainly drove the distribution of Stipa purpurea formation, but not the recent distribution of Kobresia pygmaea formation that was likely shaped by human activities. Therefore, the underlying mechanisms of grassland changes over the past 40 years were considered to be formation dependent. Overall, the first exploration for structural information of plant community changes in this study not only provides a new perspective to understand drivers of grassland changes and their spatial heterogeneity at the regional scale of the Tibetan Plateau, but also innovates large-scale vegetation study paradigm., Competing Interests: Conflict of interest The authors declare that they have no conflict of interest., (Copyright © 2023 Science China Press. Published by Elsevier B.V. All rights reserved.)