Although microorganisms play a key role in the carbon cycle of the Poyang Lake wetland, the relationship between soil microbial community structure and organic carbon characteristics is unknown. Herein, high-throughput sequencing technology was used to explore the effects of water level (low and high levels above the water table) and vegetation types (Persicaria hydropiper and Triarrhena lutarioriparia) on microbial community characteristics in the Poyang Lake wetland, and the relationships between soil microbial and organic carbon characteristics were revealed. The results showed that water level had a significant effect on organic carbon characteristics, and that soil total nitrogen, organic carbon, recombinant organic carbon, particle organic carbon, and microbial biomass carbon were higher at low levels above the water table. A positive correlation was noted between soil water content and organic carbon characteristics. Water level and vegetation type significantly affected soil bacterial and fungal diversity, with water level exerting a higher effect than vegetation type. The impacts of water level and vegetation type were higher on fungi than on bacteria. The bacterial diversity and evenness were significantly higher at high levels above the water table, whereas an opposite trend was noted among fungi. The bacterial and fungal richness in T. lutarioriparia community soil was higher than that in P. hydropiper community soil. Although both water level and vegetation type had significant effects on bacterial and fungal community structures, the water level had a higher impact than vegetation type. The bacterial and fungal community changes were the opposite at different water levels but remained the same in different vegetation soils. The organic carbon characteristics of wetland soil were negatively correlated with bacterial diversity but positively correlated with fungal diversity. Soil water content, soluble organic carbon, C/N, and microbial biomass carbon were the key soil factors affecting the wetland microbial community. Acidobacteria, Alphaproteobacteria, Verrucomicrobia, Gammaproteobacteria, and Eurotiomycetes were the key microbiota affecting the soil carbon cycle in the Poyang Lake wetland. Thus, water and carbon sources were the limiting factors for bacteria and fungi in wetlands with low soil water content (30%). Hence, the results provided a theoretical basis for understanding the microbial-driven mechanism of the wetland carbon cycle.

Background: Abandoned mining sites are becoming increasingly common due to anthropogenic activities. Consequently, external-soil spray seeding technology has attracted increasing attention as a strategy to remediate them. However, significant challenges remain that greatly inhibit the efficacy of such technologies, such as insufficient nutrients available for plants. Methods: For this study, we designed an experiment, which involved the addition of mineral-solubilizing microorganisms and R. pseudoacacia seedlings to the external-soil spray seeding (ESSS) substrate, and measured the soil nutrients, enzyme activities, and root growth of R. pseudoacacia. Results: First, the combination of certain mineral-solubilizing microorganisms with ESSS advanced its efficiency by increasing the availability of soil nutrients and soil enzymatic activities in association with R. pseudoacacia. Furthermore, the improvement of root growth of R. pseudoacacia was intimately related to soil nutrients, particularly for soil total nitrogen (TN) and total sulfur (TS). In general, the effects of the J2 (combined Bacillus thuringiensis and Gongronella butleri) treatment for soil nutrients, enzyme activities, and plant growth were the strongest. Conclusion: In summary, the results of our experiment revealed that these mineral-solubilizing microorganisms conveyed a promotional effect on R. pseudoacacia seedlings by increasing the soil nutrient content. These results provide basic data and microbial resources for the development and applications of mineral-solubilizing microorganisms for abandoned mine remediation.

Canopy transpiration is an important component of evapotranspiration, integrating physical and biological processes within the water and energy cycles of forests. Quercus acutissima and Cunninghamia lanceolata are two important, fast‐growing and commercial tree species that have been extensively used for vegetation restoration, water conservation and building artificial forests in the Yangtze River Delta region of China. The primary objective of this study was to characterize sap flow densities of the two species by comparing daytime and nocturnal sap flow patterns and their relationships with environmental factors. Sap flow densities (Sd) were measured between September 2012 and August 2013 using the commercially‐available thermal dissipation probes. Hourly meteorological data were measured in an open field, located 200 m away from the study site, including photosynthetically‐active radiation (Par), air temperature (Ta), relative air humidity (Rh), vapor pressure deficit (Vpd) and precipitation (P). Soil water content (Swc) data were logged hourly in different layers at Q. acutissima and C. lanceolata forests. Results indicated that the mean Sd in summer was higher than that in spring and autumn. Both the Sd of Q. acutissima and C. lanceolata showed distinct diurnal patterns. Nocturnal sap flow densities (Sdn) were noticeable, and both species followed similar declining patterns during our study period. The daytime sap flow density (Sdd) was more sensitive to environmental factors than Sdn. Sap flow density was significant linearly correlated with Par, Vpd and Ta, and Par and Vpd explained the greatest amount of variation in daytime sap flow of Q. acutissima and C. lanceolata, respectively. Our study will enrich knowledge of plantation forest physical and biological processes and provide valuable information for plantation forest management in the Yangtze River Delta region of China.

Urban plants have been proven to mitigate ambient particulate matter (PM), which can benefit urban planners in their attempts to control urban air pollution. In this study, PM depositions on the leaves of 8 tree species were quantitatively analysed in 7 functional areas of the city of Nanjing, China, over the course of one year. The results demonstrated that leaf PM included different particle size fractions (PM10 and PM2.5), and differed among seasons and species. The highest amounts of total PM, PM10, and PM2.5 were found in the industrial area, and the mean values were 80.24 μg/cm2, 52.14 μg/cm2, and 15.51 μg/cm2, respectively, and the highest accumulation of total PM (60.65 μg/cm2), PM10 (37.29 μg/cm2), and PM2.5 (11.23 μg/cm2) occurred in winter. Significant differences were found between the tree species tested. Cedrus deodara exhibited high amounts of the total PM, PM10, and PM2.5 accumulations. This study examined the mass and quantity distribution of PM among tree species, and identified the particles combined with a scanning electron microscope (SEM). In terms of particle mass, 48% of the identified particles had a diameter of 10 μm, and only 18.3% of them had a diameter of 2.5 μm. In terms of particle number, the results indicated that 73% of them had a diameter of 2.5 μm, and only 5.5% of them had a diameter of 10 μm. To test the relationship between leaf traits and PM2.5 accumulation, results showed that stomata size, density, and hair were significantly related to the PM2.5 capture quantity. As far as we know, this is the first paper to present the mass and quantity distribution of the PM of different tree species in Nanjing. The results not only give comprehensive insights into the dust-retaining capability of tree species but also offer a selection of species for urban green areas where the goal is to mitigate urban airborne PM.