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In order to study the the this stage the Dianshan eutrophication inherent reason, according to the results of the 2008-2009 survey of the the Dianshan Lake District of living aquatic resources and the historical survey data, the use of Ecopath with Ecosim 6.1 software to build the Dianshan ecosystem nutrition channel model , Dianshan water ecosystem structure and energy flow characteristics. Model involving the 21 functional components of the the Dianshan ecosystem waterfowl, fish, shrimp, mollusks, benthos, zooplankton, phytoplankton, and detritus, covering the the Dianshan ecosystem energy flow process. Nutrition streams merge from different functional groups several trophic levels, in order to simplify the complexity food gateway Department of called trophic level of the ecosystem structure, this study will eventually Dianshan ecological systems into five trophic levels, the first of which the Ⅰ-level detritus, phytoplankton and higher aquatic plants, Ⅱ grade pictographic zooplankton, cladocerans, copepods, molluscs and other benthic animals, herbivorous fish, level Ⅲ to including knife brachygnathus, gloss yellow catfish and other fish, including red, white fish and other meat-type fish Ⅳ grade Ⅴ grade, including waterfowl, red, white fish and other meat-type fish. Found neurotrophic level conversion efficiency the Dianshan ecosystem III, IV trophic level higher conversion efficiency of 14.6%; Dianshan ecosystem grazing food chain conversion efficiency of 12.3%, the conversion efficiency of the detrital food chain 11.3%; five trophic levels between the average energy conversion efficiency of 11.7%, higher than the surrounding Taihu Lake and Qiandao Lake and other lakes mean the energy flow of the system. Ecological network analysis, the Dianshan ecosystem energy flow, biomass and production distribution pyramid-type trophic level of each functional group ranges from 1 to 3.92, waterfowl occupy the highest level of the trophic level. The mixotrophic effect analysis of the impact of the different functional groups of Food Network the other corresponding functional group. The mixed nutritional effects analysis, Dianshan ecosystem, each functional group on its own mixed nutritional effect is generally negative effect, predator of its the mixed nutritional effects of catch their bait, fishing generally negative effect. Phytoplankton and detritus as the producer of the food web has positive effects on most other types of. Top predators obvious negative effects of their bait. Integrated analysis, the the Dianshan Lake fishing intensity will be a negative effect on the ecosystem of fish functional groups. Circulation flow rate is the total amount of nutrient flow re-enter the recycling system, the the Dianshan Lake ecosystem circular flow 77.65 t km-2 · a-1, the value is much smaller than the adjacent Taihu, currently Dianshan ecosystem lower overall recycling rates, energy efficiency needs to be improved and enhanced. TPP / TR (primary productivity of the system than the total respiration), an important indicator of the maturity of the system is described, and a mature ecosystem TPP / TR value should be close to 1, the results of this study show the Dianshan ecosystem TPP / TR value 2.80. The connection index Cl and omnivorous index SOI is reaction within the system indicators Contact complexity. More maturing ecosystem, the more complex the links between the various functional groups in their systems, the Dianshan ecosystem connectivity index and omnivorous index of 0.19 and 0.07, respectively, two values ??are less than the adjacent Taihu. Finn's loop index is the circulation flow rate and the ratio of the total flow in the system, Dianshan the Finn's value is 1.89%, while the Finn's average path length refers to the average length of each cycle through the food chain, of Dianshan the Finn's average path length was 2.37. Comprehensive analysis of of Dianshan the ecosystem parameters primary productivity / respiration (TPP / TR), to connect index (CI) and the energy cycle index FCI (2.80,0.19 and 0.0189) Dianshan ecosystem is still in the immature state ecosystem state.
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