Liu M.,Fujian Normal University |
Liu M.,State Key Laboratory of Humid Subtropical Mountain Ecology Funded by Ministry of Science and Technology and Fujian Province |
Chen X.,Fujian Normal University |
Chen X.,State Key Laboratory of Humid Subtropical Mountain Ecology Funded by Ministry of Science and Technology and Fujian Province |
And 3 more authors.
Estuarine, Coastal and Shelf Science | Year: 2015
To simulate impacts of nitrogen retention in the reservoir on nitrogen nutrient transported from the upland watershed to the ocean, a coupled watershed-reservoir modeling system, consisting of a watershed distributed model (SWAT) and a two-dimensional water quality model (CE-QUAL-W2), was developed. The coupled modeling system was well calibrated, and simulated values mainly agreed with observed data, demonstrating that the SWAT and CE-QUAL-W2 coupled modeling system can be used to assess hydrodynamic and water quality processes in a complex watershed comprised of an upland watershed and a downstream reservoir. Applying the coupled model, a long time simulation was conducted to analyze the temporal characteristics of nitrogen exported from the watershed and to reveal the effect of nitrogen retention in the reservoir at annual, monthly and daily scales. The results showed that nitrogen export from the watershed is closely associated with precipitation and runoff. The wet season was the critical period of nitrogen loss, whereas the dry season is the critical period for water quality management. The reservoir serves mainly as a nitrogen sink at annual scale due to the effect of nitrogen retention, but within the year, it may act as a sink during the wet season and a source during the dry season, which is significantly influenced by inflow runoff, nitrogen load and reservoir regulation. © 2015 Elsevier Ltd.
Han S.-Z.,Fujian Normal University |
Gao R.,Fujian Normal University |
Gao R.,State Key Laboratory of Humid Subtropical Mountain Ecology Funded by Ministry of Science and Technology and Fujian Province |
Li A.-P.,Fujian Normal University |
And 9 more authors.
Chinese Journal of Applied Ecology | Year: 2015
Soil microbial community structures were analyzed by biomarker method of phospholipid fatty acid (PLFA) for a natural forest dominated by Castanopsis fabri (CF) and an adjacent plantation of Cunninghamia lanceolata (CL) in the mid-subtropics of China. The results showed that the amounts of total PLFAs, bacterial PLFAs, fungal PLFAs, gram-positive bacterial PLFAs and gramnegative bacterial PLFAs in the 0-10 cm soil layer were higher than in the 10-20 cm soil layer, and each type of PLFAs in CF were higher than in CL. In either soil layer of the two forest types, the contents of bacterial PLFAs were significantly higher than those of fungal PLFAs. In the two forests, the contents of bacterial PLFAs accounted for 44%-52% of total PLFAs, while the contents of fungal PLFAs just accounted for 6%-8%, indicating the bacteria were dominant in the soils of the two vegetation types. Principal component analysis showed that the influence of vegetation types was greater than soil depth on the microbial community structures. Correlation analysis showed that gram-negative bacterial PLFAs, gram-positive bacterial PLFAs and bacterial PLFAs were significantly negatively correlated with pH, positively with water content, and the PLFAs of main soil microorganism groups were significantly positively correlated with soil total nitrogen, organic carbon, C/ N and ammonium. ©, 2015, Editorial Board of Chinese Journal of Applied Ecology. All right reserved.