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.
The present paper makes an approach to the methodology of soil erosion mapping in the region lack of field observations by the use of TM satellite images and topographic map in combination with soil erosion type and intensity, correlation of vegetation cover rate with slope established by previous data and field typical investigation.
Plant communities of the geologic past can be reconstructed with high fidelity only if they were preserved in place in an instant in time. Here we report such a flora from an early Permian (ca. 298 Ma) ash-fall tuff in Inner Mongolia, a time interval and area where such information is filling a large gap of knowledge. About 1,000 m 2 of forest growing on peat could be reconstructed based on the actual location of individual plants. Tree ferns formed a lower canopy and either Cordaites , a coniferophyte, or Sigillaria , a lycopsid, were present as taller trees. Noeggerathiales, an enigmatic and extinct spore-bearing plant group of small trees, is represented by three species that have been found as nearly complete specimens and are presented in reconstructions in their plant community. Landscape heterogenity is apparent, including one site where Noeggerathiales are dominant. This peat-forming flora is also taxonomically distinct from those growing on clastic soils in the same area and during the same time interval. This Permian flora demonstrates both similarities and differences to floras of the same age in Europe and North America and confirms the distinct character of the Cathaysian floral realm. Therefore, this flora will serve as a baseline for the study of other fossil floras in East Asia and the early Permian globally that will be needed for a better understanding of paleoclimate evolution through time.
Soil priming is a microbial-driven process, which determines key soil-climate feedbacks in response to fresh carbon inputs. Despite its importance, the microbial traits behind this process are largely undetermined. Knowledge of the role of these traits is integral to advance our understanding of how soil microbes regulate carbon (C) emissions in forests, which support the largest soil carbon stocks globally. Using metagenomic sequencing and 13 C-glucose, we provide unprecedented evidence that microbial traits explain a unique portion of the variation in soil priming across forest biomes from tropical to cold temperature regions. We show that microbial functional profiles associated with the degradation of labile C, especially rapid simple sugar metabolism, drive soil priming in different forests. Genes involved in the degradation of lignin and aromatic compounds were negatively associated with priming effects in temperate forests, whereas the highest level of soil priming was associated with β-glucosidase genes in tropical/subtropical forests. Moreover, we reconstructed, for the first time, 42 whole bacterial genomes associated with the soil priming effect and found that these organisms support important gene machinery involved in priming effect. Collectively, our work demonstrates the importance of microbial traits to explain soil priming across forest biomes and suggests that rapid carbon metabolism is responsible for priming effects in forests. This knowledge is important because it advances our understanding on the microbial mechanisms mediating soil-climate feedbacks at a continental scale.
Since the establishment of geological prospecting fund initiated in Decision of State Council on Strengthening Geological Work,the total size of geological prospecting fund from central and provincial level has reached 13 billion RMB,which is playing an increasingly important role in the reform and development of geological exploration.However,different mechanisms and objectives have been emerged from various places during the operation of geological prospecting fund.On account of this,the paper offers the strategic conception on how to strengthen the coordinated development of the two-level geological prospecting fund effectively and giving full play to the geological prospecting fund so as to promote breakthroughs in geological exploration.
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