Castanopsis fargesii is a good afforestation plants and various microorganisms play important roles in mediating the growth and ecological functions of this species. In this study, we evaluated changes in microbial communities in soil samples from C. fargesii forests. The phospholipid fatty acid (PLFA) biomarker method was used to obtain bacteria, fungi, actinomycetes, gram-positive bacteria (G+), gram-negative bacteria (G−), aerobic bacteria, and anaerobic bacteria to investigate spatiotemporal changes in microbial communities during the growing season. The results show that soil microorganisms were mainly concentrated in the upper 20-cm layer, demonstrating an obvious surface aggregation (P < 0.05). Large amounts of litter and heavy rainfall during the early growing season resulted in the highest PLFA contents for various microorganisms, whereas relatively low and stable levels were observed during other times. The dominant species during each period were bacteria. G+ or aerobic bacteria were the main bacterial populations, providing insights into the overall trends of soil bacterial PLFA contents. Due to the relative accumulation of refractory substances during the later stages of litter decomposition, the effects of fungi increased significantly. Overall, our findings demonstrate that the main factors influencing microbial communities were litter, rainfall, and soil field capacity.

To achieve efficient simulation for surface shallow-water flows in large-scale basin irrigation, a semi-Lagrangian numerical solution for two-dimensional shallow-water equations in unstructured spatial cells was developed. In this numerical solution, all state variables were defined at the finite-volume cells and presented piecewise constant distribution. A redistribution method of the state variable values for the inner node of a spatial cell was developed and can strictly preserve mass conservation. Then, a simple displacement formula along a characteristic-line was applied to connect the variable values between a unknown and its adjacently known time steps of the semi-Lagrangian form of two-dimensional shallow-water equations. The water level gradient term was specially treated to accurately balance the water level distribution at the wet or wet–dry spatial cell interface. Simultaneously, an existing finite-volume method with a fully implicit temporal solution for the Eulerian form of two-dimensional shallow-water equations in a triangular spatial cell was selected as a comparative model. Finally, a performance comparison between the semi-Lagrangian and Eulerian numerical solutions was analyzed based on three basin irrigation experiments. The results show that the semi-Lagrangian and Eulerian numerical solutions presented similar average relative errors between the observed and simulated data. The semi-Lagrangian numerical solution exhibited lower mass conservation ability, but its water quantity balance errors were less than 0.3% for three experiments. The semi-Lagrangian numerical solution was six times more computationally efficient than the Eulerian numerical solution in central processing unit (CPU) time. Thus, the semi-Lagrangian numerical solution is more suitable to simulate shallow-water flows in basin irrigation.

Phyllostachys edulis plays an important role in maintaining carbon cycling. We examined the effects of soil properties on organic carbon content in a P. edulis forest on Dagang Mountain, Jiangxi Province, China. Based on correlation and stepwise multiple regression analyses, the effects of seven soil factors on organic carbon and their sensitivities to change were studied using path and sensitivity analyses. The results revealed differences in the interconnections and intensities of soil factors on organic carbon. Soil porosity, field capacity, and ammonium nitrogen levels were the main factors affecting organic carbon in the ecosystem. Soil porosity had a strong direct effect on organic carbon content and a strong indirect effect through field capacity. Field capacity and ammonium nitrogen levels mainly affected organic carbon directly. Field capacity, soil porosity, and ammonium nitrogen content, as well as bulk density, β-glucosidase activity, and invertase activity, were sensitive factors. Polyphenol oxidase activity was insensitive. Our study provides a theoretical basis for understanding the effects of soil factors on organic carbon, which can be utilised to improve P. edulis forest management strategies and promote carbon sequestration capacities.