Study On The Restoration Model Of Aquatic Vegetation In The Lake Connect To The Yangtze River

In order to explore the aquatic vegetation restoration model of shallow water in the lakes along the river,the group cooperated closely with the Shengjin Lake National Nature Reserve Administration in 2017.According to the requirements of the Shengjin Lake Wetland Ecological Benefit Compensation Project,Jinbaowei in Dongliu Town,Dongzhi County 2 area which closed the Shengjin Lake,Niutoushan Town,Guichi District,has implemented aquatic vegetation restoration project in Shengjin Lake Lake Pass,2 of which were used for fisheries.The project lasts for three years.Experimental research on the effects of different aquatic vegetation restoration models on water quality and the competitive relationship between aquatic plants is conducted in Jinbaowei.Yanwowei are mainly used to study aquatic plant cultivation techniques for aquatic vegetation restoration.Jinbaowei used as aquatic vegetation restoration test area,Water quality of three types of aquatic vegetation restoration models:water plants,submerged plants+floating plants,submerged plants+floating plants+emergent plants.Water quality data are regularly monitored during plant growth from 2017 to 2019.The separate analysis results of the six water quality indicators shows that the annual change trends of TN,TP,COD_Mnn and NH₃-N in the water bodies under the three aquatic vegetation restoration models are close to each other,and they all show a significant downward trend.During the plant growth period of the TN,TP,COD_Mnn and NH₃-N in the water body of the test area of submerged plants+floating leaf plants+emergent plants recovered the fastest decline.According to the Grey-mode Identification Model,Comprehensive calculation of water quality indicators showed that the comprehensive index of water quality in the submerged plant restoration area decreased from 2.37 in the early recovery period in 2017 to 2.24 in the later recovery period in 2019,compared with The D area in the photo area decreased by 20%.The comprehensive index of water quality in the submerged plants+floating plants+emergent plants area showed an upward trend,from 2.65 to 3.11.Therefore,the water quality improvement in the submerged vegetation restoration area was the most significant.Significantly,the restoration of submerged vegetation is suitable as the first mode of restoration of aquatic vegetation in degraded lakes,achieving rapid purification of water quality.The results of coverage of aquatic plants show that the coverage of aquatic plants of Vallisneria natans,Potamogeton wrightii Mor.,Ceratophyllum demersum and Hydrilla verticillata among four aquatic plants of submerged aquatic plants,diarrhea,Vallisneria natans,Potamogeton wrightii Mor.has been decreasing in three years and disappeared basically after July;while Ceratophyllum demersum and Hydrilla verticillata were basically dominant species,with a coverage of 80%.Among the five aquatic plants in the submerged plants+floating plants area,such as Vallisneria natans,Hydrilla verticillata,Nymphoides peltata and Trapa incisa,the dominant species in May 2017 was Nymphoides peltata,and the dominant species in July were Hydrilla verticillata,Nymphoides peltata and Trapa incisaare associated with Vallisneria natans,and after2019,Vallisneria natans can only be monitored in April and not detected after July,while Hydrilla verticillata and Trapa incisaare can reach 75%.50%.Among the five aquatic plants in the submerged plants+floating water plants+emergent plants area,such as Vallisneria natans,Potamogeton wrightii Mor.,Trapa incisaare,Zizania latifolia and Nelumbo nucifera,the dominant species in July 2017 were Zizania latifolia and Nelumbo nucifera.they have reached 85%.In 2019,the main dominant species are still were Zizania latifolia and Nelumbo nucifera,while Nelumbo nucifera coverage is over 90%and Zizania latifolia is 80%.Vallisneria natans and Potamogeton wrightii Mor.can only be detected in April,and basically disappeared in July.The test results of aquatic plant cultivation technology in the Yanwowei showed that under 5 different cultivation densities,the cultivation density of 3m×3m and 1m×1m can reach more than 60%in July,and The water level of the bird's nest in the test area of short than 2m in July,and the coverage of aquatic plants is the highest.The degree can reach 80%in July and is not limited by water depth;the coverage of Zizania latifolia and Nelumbo nucifera can reach 85%in July under the cultivation density of 5m×5m and 1m×1m,and it is about 3m in high water season.Deep water area is less than 1.5m in shallow water area.Therefore,in the restoration of aquatic vegetation,not only the effect of water quality restoration must be considered,but in order to complete the vegetation restoration more efficiently,the competition relationship between aquatic plants needs to be considered.That is,avoid co-cultivation of submerged plants Vallisneria natans and Potamogeton wrightii Mor.with Ceratophyllum demersum and Hydrilla verticillata;avoid the use Nelumbo nucifera and Trapa incisa.Aquatic plant cultivation In order to reduce the waste of manpower and material resources,a more efficient cultivation density should be selected,and the cultivation density of Vallisneria natans and Potamogeton wrightii Mor.weeds should be set to 3m×3m.It should be set to a density of 5m×5m for cultivation.