The upper Yellow River basin over the Tibetan Plateau (TP) is an important ecological barrier in northwestern China. Effective LULC products that enable the monitoring of changes in regional ecosystem types are of great importance for their environmental protection and macro-control. Here, we combined an 18-class LULC classification scheme based on ecosystem types with Sentinel-2 imagery, the Google Earth Engine (GEE) platform, and the random forest method to present new LULC products with a spatial resolution of 10 m in 2018 and 2020 for the upper Yellow River Basin over the TP and conducted monitoring of changes in ecosystem types. The results indicated that: (1) In 2018 and 2020, the overall accuracy (OA) of LULC maps ranged between 87.45% and 93.02%. (2) Grassland was the main LULC first-degree class in the research area, followed by wetland and water bodies and barren land. For the LULC second-degree class, the main LULC was grassland, followed by broadleaf shrub and marsh. (3) In the first-degree class of changes in ecosystem types, the largest area of progressive succession (positive) was grassland–shrubland (451.13 km²), whereas the largest area of retrogressive succession (negative) was grassland–barren (395.91 km²). In the second-degree class, the largest areas of progressive succession (positive) were grassland–broadleaf shrub (344.68 km²) and desert land–grassland (302.02 km²), whereas the largest areas of retrogressive succession (negative) were broadleaf shrubland–grassland (309.08 km²) and grassland–bare rock (193.89 km²). The northern and southwestern parts of the study area showed a trend towards positive succession, whereas the south-central Huangnan, northeastern Gannan, and central Aba Prefectures showed signs of retrogressive succession in their changes in ecosystem types. The purpose of this study was to provide basis data for basin-scale ecosystem monitoring and analysis with more detailed categories and reliable accuracy.

The extensive accumulation of spent mushroom substrate (SMS) owing to the large-scale production of edible fungi is causing environmental problems that cannot be ignored. Co-composting is a promising method for agricultural and animal husbandry waste disposal. In this study, the composition and function of microbial communities in the process of cattle manure–maize straw composting with SMS addition were compared through an integrated meta-omics approach. The results showed that irrespective of SMS addition, the predominant fungi were Ascomycota, while the dominant bacteria were Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes. High temperature promoted the evolution from Gram-negative bacteria (Bacteroides, Proteobacteria) to Gram-positive bacteria (Firmicutes, Actinomycetes). The composting process was accelerated by SMS addition, and the substrate was effectively degraded in 14 days. Metaproteomics results showed that the dominant microorganism, Planifilum fulgidum, secreted large amounts of S8, M17, and M32 proteases that could degrade macromolecular protein substrates in the presence of SMS. Planifilum fulgidum, along with Thermobifida fusca and Melanocarpus albomyces, synergistically degraded hemicellulose, cellulose, and protein. In addition, the dominant microorganisms related to the initial raw materials such as Pichia, Lactobacillus in the microbial agent and Hypsizygus in SMS could not adapt to the high-temperature environment (>60 °C) and were replaced by thermophilic bacteria after 5 days of composting.

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

The influence of Quaternary climate fluctuation on the geographical structure and genetic diversity of species distributed in the regions of the Qinghai–Tibet Plateau (QTP) has been well established. However, the underlying role of the East Asian monsoon system (EAMS) in shaping the genetic structure of the population and the demography of plants located in the arid northwest of China has not been explored. In the present study, Nitraria tangutorum, a drought-tolerant desert shrub that is distributed in the EAMS zone and has substantial ecological and economic value, was profiled to better understand the influence of EAMS evolution on its biogeographical patterns and demographic history. Thus, the phylogeographical structure and historical dynamics of this plant species were elucidated using its five chloroplast DNA (cpDNA) fragments. Hierarchical structure analysis revealed three distinct, divergent lineages: West, East-A, and East-B. The molecular dating was carried out using a Bayesian approach to estimate the time of intraspecies divergence. Notably, the eastern region, which included East-A and East-B lineages, was revealed to be the original center of distribution and was characterized by a high level of genetic diversity, with the intraspecific divergence time dated to be around 2.53 million years ago (Ma). These findings, combined with the data obtained by ecological niche modeling analysis, indicated that the East lineages have undergone population expansion and differentiation, which were closely correlated with the development of the EAMS, especially the East Asian winter monsoon (EAWM). The West lineage appears to have originated from the migration of N. tangutorum across the Hexi corridor at around 1.85 Ma, and subsequent colonization of the western region. These results suggest that the EAWM accelerated the population expansion of N. tangutorum and subsequent intraspecific differentiation. These findings collectively provide new information on the impact of the evolution of the EAMS on intraspecific diversification and population demography of drought-tolerant plant species in northwest China.

The water level of Qinghai Lake, the largest saltwater lake in China, has been rising consistently, which has altered the lake’s ecosystem service patterns and produced an unpredictable impact on local ecological security and sustainable development. To explore the changes in the area around Qinghai Lake’s ecosystem provisioning services that respond to the rise in water level, the spatial and temporal changes of three ecosystem services (water yield, soil conservation, and habitat quality) from 2000 to 2020 were calculated by the InVEST model. Then, the ecosystem service transformation of the rise in Qinghai Lake’s underwater level was evaluated, and the trade-off and synchrony among the three ecosystem services were discussed. Finally, Random Forest and Geographically and Temporally Weighted Regression models were used, to reveal the driving factors and spatial differentiation of ecosystem service change. Results showed that: (1) Although three ecosystem provisioning services were increased by 3.21%, 31.67%, and 6.19%, respectively, in 2000–2020, an overall change trend was observed that they increased first and then decreased. After reaching their peak values in 2005 (444.68 mm), 2015 (341.89 t·hm⁻²·a⁻¹) and 2015 (0.67), three ecosystem provisioning services decreased to 349.27 mm, 271.82 t·hm⁻²·a⁻¹, and 0.66 in 2020, respectively. (2) Three ecosystem provisioning services, as well as ecosystem services among different land use types, presented a synchronous relationship during the research periods. (3) Natural factors, such as precipitation and NDVI (Normalized Difference Vegetation Index), accounted for 30.0% of ecosystem services changes, and Social-economic factors, such as GDP (Gross Domestic Product) and population accounted for 28.0% of three ecosystem provisioning services changes. These driving factors exhibited significant spatial heterogeneity (adjusted R² > 0.6). There were limitations in the scope of ecosystem services evaluation and insufficient consideration of the value of aquatic habitats, which deserved further exploration. This study may provide a scientific basis for the evaluation and management of the plateau lake ecosystem under the background of climate change.

The alpine grasslands account for approximately 54.5% of the total carbon in China’s grasslands, and carbohydrate-active enzymes (CAZymes) play key roles in the turnover of carbon. However, the variation and factors influencing gene-encoding enzymes for plant- and microbial-derived carbon decomposition in alpine steppes and alpine meadows remain unclear. Here, the trends in microbial carbohydrate-active enzymes (CAZymes) and their responses to the decomposition of biomass of different origins were studied using metagenomics in the alpine steppes and alpine meadows on the Tibetan Plateau. Our results revealed the abundance of GTs and CBMs was higher in the alpine steppes than in the alpine meadows, whereas AAs were higher in the alpine steppes than in the alpine meadows. Soil properties (i.e., soil water content, soil ammonium nitrogen, and nitrate nitrogen) highly related to CAZyme genes (GTs, CBMs, and AAs) showed an abundant pattern between the alpine steppes and alpine meadows. Moreover, our results indicated that the relative abundance of genes encoding CAZymes involved in the decomposition of plant- (indicated by cellulose, hemicellulose, and lignin) and fungal-derived carbon (indicated by chitin and glucans) was higher by 8.7% and 10.1%, respectively, in the alpine steppes than in the alpine meadows, whereas bacterial-derived carbon (indicated by peptidoglycan) was lower by 7.9% in the alpine steppes than in the alpine meadows. Soil water content (SWC), nitrate nitrogen (NO₃⁻), and pH influenced on the abundance of CAZyme genes involved in the decomposition of plant-, fungal-, bacterial-derived carbon. In addition, the dominant microbial phyla (Actinobacteria, Protebacteria, and Acidobacteria) mineralized carbon sources from plant- and microbial-derived carbon through their corresponding CAZyme families. In conclusion, our study compared plant- and microbial-derived carbon decomposition potentials and influencing factors to illustrate the contribution of dead biomass to carbon accumulation in alpine grasslands.