Jiuduansha Wetland National Nature Reserve

Shanghai Jiuduansha Wetland National Nature Reserve Located between 121 ° 46 '- 122 ° 15' e and 31 ° 03 '- 31 ° 17' n, the reserve is 46.3 km long from east to west and 25.9 km wide from north to south. It is composed of Shangsha, Zhongsha, Xiasha, Jiangya Nansha and the shallow waters nearby. It is adjacent to the East China Sea in the East, the Yangtze River in the west, Pudong and Hengsha Island in the southwest and northwest, respectively About 420.2 square kilometers. Jiuduansha Wetland is affected by both marine climate and continental climate, with prevailing monsoon, abundant rainfall, sufficient sunshine and four distinct seasons.

Jiuduansha Wetland is the only estuarine wetland in the Yangtze River Estuary, which is an important part of China's natural ecological protection network.

On July 23, 2005, the State Council approved the establishment of "Shanghai Jiuduansha Wetland National Nature Reserve".

Shanghai Jiuduansha Wetland National Nature Reserve

synonym

Jiuduansha Wetland National Nature Reserve generally refers to Shanghai Jiuduansha Wetland National Nature Reserve

Shanghai Jiuduansha Wetland National Nature Reserve is located in the lanmensha river section between the north and South channels of the Yangtze River Estuary. It is located between 121 ° 46 '- 122 ° 15' e and 31 ° 03 '- 31 ° 17' n, 46.3 km long from east to west and 25.9 km wide from South to north. Established on March 8, 2000, the nature reserve is a national nature reserve. The main protected objects of the reserve are rare animals and plants and their wetland environment.

Historical evolution

On March 8, 2000, Shanghai Municipal People's Government approved the establishment of "Shanghai Jiuduansha Wetland Nature Reserve".

On September 29, 2003, Shanghai Municipal People's government promulgated the administrative measures of Jiuduansha Wetland Nature Reserve in Shanghai.

On July 23, 2005, the State Council approved the establishment of "Shanghai Jiuduansha Wetland National Nature Reserve".

geographical environment

position

Shanghai Jiuduansha Wetland National Nature Reserve is located in the lanmensha river section between the north and South channels of the Yangtze River Estuary. It is located between 121 ° 46 '- 122 ° 15' e and 31 ° 03 '- 31 ° 17' n, 46.3 km long from east to west and 25.9 km wide from South to north.

topographic features

Jiuduansha is located in the mouth of the Yangtze River. It is mainly due to the deposition of sediment, forming three main sandbanks: upper sandbank, middle sandbank and lower sandbank. According to the environmental characteristics and sediment distribution in different areas of Jiuduansha, the sediments of Jiuduansha can be divided into fine sand, silty fine sand, sandy silt, silt and clay silt. The sediment of Jiuduansha is mainly composed of fine particles. The sediment of tidal flat has obvious zonation phenomenon. With the increase of hydrodynamic strength, the particle size of sediment increases from small to large, the size of clay decreases from variable, and the size of silt and fine sand increases from small to large. The vertical variation of Jiuduansha tidal flat sediments is from top to bottom, from fine to coarse.

Jiuduansha is an estuary sandbank with an altitude of 2.5-3.5m. According to the topography, it can be divided into high tide beach, middle tide beach, low tide beach and underwater shoal. The micro geomorphic forms can be divided into the near radial ebb drainage system composed of tidal gullies of different scales and the swampy shallow depression in the middle of the sandbank, while the micro geomorphic forms of the beach at the edge of the sandbank are also different due to the scouring and silting effects of the upwelling tide and downwelling tide.

climate

The nature reserve is located in the north subtropical zone. Affected by the marine climate and continental climate, the monsoon is prevailing, mild and humid, with abundant rainfall, sufficient sunshine and four distinct seasons. Jiuduansha Wetland is spring from mid March to early June, summer from mid June to late September, autumn from early October to mid November and winter from late November to next March. Winter and summer are longer, spring and autumn are shorter, northwest wind is more in winter, southeast wind is more in summer, cold and dry in autumn and winter, warm and rainy in spring and summer.

air temperature

The average annual temperature of Hengsha station near Jiuduansha is 15.7 ℃, the lowest in January, with an average of 4.2 ℃, the extreme minimum temperature is - 7.7 ℃, the highest in July, with an average of 27.3 ℃, the extreme maximum temperature is 36.6 ℃, and the frost free period is 254 days.

illumination

The annual sunshine hours of Hengsha station from 1980 to 1989 were 1798hr, accounting for 41% of the annual sunshine hours, and the average radiation was 362.7mj/m2.

precipitation

The average annual precipitation is about 1145mm, with the largest in summer (480.2mm) and the smallest in winter (100.8mm). The average precipitation from April to September is generally more than 100 mm. Although there is snow in winter, there is no snow.

Wind condition

Jiuduansha is located in the south of the Yangtze River Estuary, on the edge of the north subtropical zone, which belongs to the East Asian monsoon prevailing area. The seasonal variation of wind direction is very obvious. Southerly wind prevails in summer, northerly wind prevails in winter, and spring and autumn are transitional seasons. Due to the frequent occurrence of local convective weather in spring and summer, typhoons in summer and autumn, and cold waves and cold air in autumn and winter, strong winds may appear in Jiuduansha area every month of the year. The annual average wind speed is 3.7 ~ 4.0m/s.

From 1960 to 1989, there were 201 tropical cyclones affecting the Yangtze River Estuary and its adjacent waters, with an average of 3.4 per year. The impact of tropical cyclones is mainly concentrated in July to September. The rainstorm, storm surge and big wave brought by the invasion of typhoon caused a strong scouring effect on Jiuduansha beach.

hydrology

Due to the flood and dry season variation of runoff and sediment transport, the periodic variation of tide and tidal current, the seasonal variation of wave and its randomness, the hydrological elements of Jiuduansha water area are complex and changeable, showing the unique hydrological characteristics of tidal estuary.

Jiuduansha hydrology is mainly controlled by Yangtze River current, tide and storm surge. There is an irregular semidiurnal shallow tide near Jiuduansha, with an average tidal range of 2.67M and a maximum tidal range of 4.62m. The average annual water temperature (Gaoqiao station) is 17.3 ℃, the highest in August, the average 28.9 ℃, the extreme highest 33.1 ℃, the lowest in February, 5.6 ℃, the extreme lowest 2.0 ℃.

Jiuduansha carries the water and sediment from the Yangtze River and is affected by the sea tide. The annual average sediment concentration of the Yangtze River is 0.518kg/m3, and the annual average sediment transport of the sea is 4.86 × 108t. In addition to depositing part of the huge amount of sediment in the estuary, which provides a rich material source for the formation of the major Sand Islands, the rest diffuses and deposits outside the estuary under the action of waves and tidal currents. The frequency of wave direction and wind direction are basically the same, and the seasonal variation is very obvious.

soil

Jiuduansha is a new estuarine sandbank, which is affected by climate, parent material, hydrological and sediment conditions, vegetation and other factors, forming a soil type with short development process and primitive soil forming process. Jiuduansha soil can be divided into coastal saline soil and fluvo aquic soil.

vegetation

According to the vegetation regionalization of China vegetation, Jiuduansha should belong to subtropical evergreen deciduous broad-leaved forest area, Eastern (humid) evergreen broad-leaved forest sub area, north subtropical evergreen and deciduous broad-leaved mixed forest area, Jiang Huai plain, cultivated vegetation and aquatic vegetation area. The vegetation zonality of Jiuduansha is not obvious, and all of them are hidden components.

Regional scope

Shanghai Jiuduansha Wetland National Nature Reserve is composed of Shangsha, Zhongsha, Xiasha, Jiangya Nansha and the shallow waters nearby. It is adjacent to the East China Sea in the East, the Yangtze River in the west, Pudong and Hengsha Island in the southwest and northwest, with a total area of 420.2 square kilometers.

Protection target

Botany

There are 17 species of higher plants in Jiuduansha nature reserve, which are angiosperms, belonging to 7 families and 15 genera. Among them, there are 3 species of dicotyledons in 3 families and 3 genera, and 14 species of monocotyledons in 4 families and 12 genera.

phytoplankton

A total of 118 species and varieties of algae belonging to 57 genera and 7 phyla were recorded in the reserve. Among them, Bacillariophyta is the most abundant with 85 species of 37 genera, accounting for 72.0% of the total, followed by Chlorophyta with 18 species of 9 genera, accounting for 15.3% of the total, and Cyanophyta with 7 species of 7 genera, accounting for 5.9%. A total of 102 species and varieties of algae were recorded, belonging to 5 phyla and 47 genera. Among them, Bacillariophyta is the most abundant, with 76 species of 30 genera, accounting for 74.5% of the total; followed by Chlorophyta, with 17 species of 8 genera, accounting for 16.7% of the total; Cyanophyta, with 5 species of 5 genera, accounting for 4.9%; dinoflagellate, with 17 species of 8 genera, accounting for 16.7% of the total

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