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A vast portion of the surface of the Earth is desert and desertified land, where, due to the harsh natural environment, vegetation is generally scarce. Soil microbes play important roles in ecosystems and have been used as indicators of soil quality and health. However, microbial interactions in desert ecosystems remain poorly understood. In this study, we collected soil samples from 12 deserts in northern China, spanning four climate types representing distinct aridity gradients, to evaluate bacterial and eukaryotic co‐occurrence networks, and analyze environmental factors determining microbial interactions and their relationships with these factors. At the regional scale, bacterial and eukaryotic interactions strengthened with increasing mean annual precipitation (MAP). They were also influenced by soil total phosphorus and the normalized difference vegetation index. At the local scale, although soil‐, climate‐, and plant‐related factors significantly constrained bacterial and eukaryotic networks, their relative effects varied. Overall, eukaryotic communities formed smaller and less complex networks than bacterial communities. Both bacterial and eukaryotic networks were more complex in deserts with higher MAP, suggesting that they are more stable and play more important roles in biogeochemical cycling in these areas than in lower MAP deserts. Our results provide further evidence that altered precipitation gradient probably leads to unstable and vulnerable microbial communities. This study enhances our understanding of microbial community organization in desert ecosystems, while providing novel insights into soil health. These findings should prove valuable in the evaluation of land development and degradation processes. [ABSTRACT FROM AUTHOR]

Xeric shrubs often play an important role in reversing desertification and promoting ecological restoration of degraded dryland ecosystems. However, how shrubs affect their associated herbaceous species and environmental conditions remains largely unknown. In this study, we conducted a removal experiment along with stable isotope analysis to determine the water use strategy of a shrub species (Artemisia ordosica) and its associated perennial graminoids (PG) in the Mu Us Desert, northern China. We observed that in the intact plots, both shrubs and PG predominantly utilized water from the shallow soil layer (0–20 cm, 54.36%, and 63.63%, respectively). Compared to this, when shrubs were removed, soil water content decreased, the main water source of PG switched to the middle soil layer (20–60 cm, 48.25%), and their water use efficiency (WUE) increased. However, the removal of PG had no significant impacts on the soil water content in any layer or on the water source of shrubs but for slightly decreased WUE. We highlighted that rather than hydraulic lift, shade‐induced evaporation decline is the primary mechanism by which shrubs facilitate the growth of associated herbaceous plants in desert ecosystems, indicating that the facilitated herbaceous plants have more flexible water use strategies than shrubs, which probably drives the community succession from being shrub‐dominated to herb‐dominated. [ABSTRACT FROM AUTHOR]

BACKGROUND: The threshold of the lower limit of the normal range of lung function has been suggested to be more accurate than the 0.7 fixed ratio (FEV1/FVC < 0.7) for a diagnosis of COPD. We aimed to explore the health status and risk factors of patients overdiagnosed with COPD when using the lower limit of the normal range as a diagnostic reference. METHODS: Subjects with COPD diagnosed by a pulmonologist according to guidelines of the Global Initiative for Chronic Obstructive Lung Disease were recruited from October 2016 to April 2018. Overdiagnosed COPD was defined as FEV1/FVC that meets the criterion of the 0.7 fixed ratio but not the the lower limit of the normal range criterion. Spirometry and questionnaires were performed by eligible subjects. RESULTS: Of the 513 subjects included in the final analysis, 20 (3.9%) were overdiagnosed when using the lower limit of the normal range as the diagnostic reference. The subjects who were overdiagnosed were older, weighed more, had better lung function, lower modified Medical British Research Council scores, and higher St. George's Respiratory Questionnaire and 36-item Short Form Survey scores than the subjects who were correctly diagnosed. Older age, heavier weight, exposure to cooking oil fumes, or a new-built or newly renovated home were associated with an increased risk of overdiagnosis of COPD (age adjusted odds ratio (OR) 1.17, 95% CI 1.09–1.26; weight adjusted OR 1.08, 95% CI 1.03–1.13; exposure to cooking oil fumes adjusted OR 3.00, 95% CI, 1.04–8.68; exposure to new-built or newly renovated home adjusted OR 10.88, 95% CI 1.46–80.87. CONCLUSIONS: The subjects with overdiagnosed COPD had a better health status and lung function than the subjects who were correctly diagnosed. Older age, heavier weight, and exposure to cooking oil fumes or a new-built or newly renovated home were factors associated with the overdiagnosis of COPD. These findings may help reduce overdiagnosis of COPD [ABSTRACT FROM AUTHOR]

Soils harbour highly diverse bacterial communities that are essential for nutrient cycling and carbon storage. However, this diversity impedes the efforts to characterize individual taxa and their ecological attributes. In particular, comprehensive assessments of soil bacterial communities in drylands in China are limited. In this study, soil samples were collected across 12 deserts, covering four climatic regions (dry sub‐humid, semi‐arid, arid and hyper‐arid) in northern China to examine the dominant phylotypes, and their environmental preferences and functional traits. Only 3.2% of the bacterial phylotypes (913 phylotypes) were dominant. These dominant phylotypes can be grouped into six major ecological clusters based on high pH, high elevation, low aridity index, high aridity index, low mean annual temperature and low soil water content, each with multiple phyla. Based on the association between diversity indexes for dominant and subdominant phylotypes, these dominant bacteria might be the drivers or indicators of key soil processes across desert soils in northern China. Genes involved in carbon fixation and decomposition and nitrogen metabolism varied across desert soils, suggesting functional differences. These findings provide deeper insights into soil bacterial communities, which are critical for forecasting the ecological consequences of ongoing global environmental change and for a better mechanistic understanding of the biogeochemical cycle. Highlights: 3.2% of the bacterial phylotypes were dominant across 12 deserts in northern China.The dominant phylotypes were grouped into six major ecological clusters.Carbon fixation, decomposition and nitrogen metabolism genes varied across desert soils.Some northern China desert soils might undergo nitrogen and carbon loss in the near future. [ABSTRACT FROM AUTHOR]

Revegetation using xerophytic plants in drylands can alter soil microbial community diversity and composition; however, information about the microbial communities and their genetic repertoires that are involved in soil organic carbon (SOC) processes in drylands remain unclear. This study aimed to characterize soil microbial genes and their potential to mediate SOC decomposition in three revegetation shrublands (Artemisia ordosica, Salix psammophila and Caragana microphylla) in the Mu Us Desert of northern China using an SOC mineralization experiment and shotgun metagenome sequencing. Among the three shrublands, the S. psammophila shrubland had the highest cumulative CO2 emissions and highest rates of mineralization of the slow SOC pool. The mineralization rate of the slow SOC pool and the microbial taxonomic and functional composition displayed a significant correlation. Most C‐degradation genes were assigned to three bacterial phyla, Actinobacteria, Proteobacteria and Acidobacteria. The relative abundance of microbial functional genes involved in degrading recalcitrant C‐complexes was significantly higher in the S. psammophila shrubland, resulting in the slow accumulation of recalcitrant SOC. These results suggest that the microbial functional genes that regulate the decomposition of the SOC pool in dryland shrubland soils may be influenced by shrub species selection. These findings highlight the importance of understanding how microbial catabolic potential mediates the potential for SOC sequestration in different revegetation shrublands in drylands. Highlights: We studied SOC mineralization and soil microbial functional genes in three revegetation shrublands.S. psammophila shrubland had the highest CO2 emissions and highest mineralization rates of the slow C pool.Slow SOC pool mineralization rate was related to microbial taxonomic and functional composition.Different dryland shrubs may mediate soil microbial functional genes that regulate SOC pool decomposition. [ABSTRACT FROM AUTHOR]