Soil fungal taxonomic diversity along an elevation gradient on the semi-arid Xinglong Mountain, Northwest China.

Elevation gradients, often regarded as "natural experiments or laboratories", can be used to study changes in the distribution of microbial diversity related to changes in environmental conditions that typically occur over small geographical scales. We exploited this feature by characterizing fungal composition and diversity along an elevation gradient on Xinglong Mountain, northwest China. For this, we used MiSeq sequencing to obtain fungal sequences and clustered them into operational taxonomic units (OTUs). In total, we obtained 1,203,302 reads, 133,700 on average in each sample of soil collected at three selected elevations (2807, 3046, and 3536 m). The reads were assigned to 2192 OTUs. Inconsistent variations were observed in fungal alpha-diversity in samples from the three elevations. However, Principal Coordinate Analysis based on Bray-Curtis and UniFrac (weighted and unweighted) distance metrics revealed that fungal communities in soil samples from 3046 and 3536 m elevations were most similar. Principal Component Analysis based on relative abundances of shared OTUs confirmed that OTUs in samples from 3536 m elevation were more closely related to OTUs from 3046 m than samples from 2807 m elevation. Ascomycota, Basidiomycota, Glomeromycota, Cercozoa and Chytridiomycota were the most abundant fungal phyla across the elevation gradient. Our study also provides valuable indications of relations between fungal communities and an array of soil chemical properties, and variations in fungal taxonomic diversity across a substantial elevation gradient.

Ecohydrological effects of biocrust type on restoration dynamics in drylands.

Global climate change influences not only vascular plants, but also biological soil crusts (biocrusts), which play important roles in dryland vegetation dynamics by redistributing rainfall in soils. Different types of biocrusts, spanning a spectrum from cyanobacteria-dominated and moss-dominated, have distinct roles in rainfall redistribution patterns, but the ecohydrological effects of different biocrust types on dryland ecosystem dynamics remain largely unclear. This study developed an ecohydrological model with biocrust as a system state variable to explicitly explore the effects of different biocrust types on dryland vegetation dynamics in Shapotou region in northern China, particularly after restoration. The results indicated that both cyanobacteria- and moss-dominated biocrusts could support high grass cover (approximately 40%) after restoration. Cyanobacterial, but not moss biocrusts, could also maintain a high level of shrub cover (13 and 3%, respectively). Shifting from cyanobacteria to mosses gradually increased the biocrust cover from approximately 40% to 80%. The biocrust's water-holding capacity (the volume of water it can intercept per unit area) is likely be able to explain the dynamics of biocrust and shrub cover (with correlation efficiency of R2 = 0.972 and 0.987, respectively), but not grass cover (R2 = 0.224). The findings suggest that biocrust type may significantly affect coverage of biocrusts and shrubs, but not grass coverage, and global climate change may influence dryland restoration by altering biocrust types.

Nanohybrid of Carbon Quantum Dots/Molybdenum Phosphide Nanoparticle for Efficient Electrochemical Hydrogen Evolution in Alkaline Medium.

The exploration of highly efficient non-noble metal electrocatalysts for hydrogen evolution reaction (HER) under alkaline conditions is highly imperative but still remains a great challenge. In this work, the nanohybrid of carbon quantum dots and molybdenum phosphide nanoparticle (CQDs/MoP) has been firstly demonstrated as an efficient alkaline HER electrocatalyst. The CQDs/MoP nanohybrid is readily prepared through a charge-directed self-assembly of CQDs with phosphomolybdic acid (H3PMo12O40) at the molecular level, followed by facile phosphatizing at 700 °C. The introduction of CQDs greatly helps to alleviate the agglomeration and surface oxidation of MoP nanoparticles and ensures each MoP nanoparticle to be electronically addressed, thus significantly enhancing the intrinsic catalytic activity of MoP. The optimized CQDs/MoP exhibits high-efficiency synergistic catalysis toward HER in 1 M KOH electrolyte with a low onset potential of -0.08 V and a small Tafel slope of 56 mV dec-1 as well as high durability with negligible current loss for at least 24 h.