Poyang Lake is a member of the world life lake network, the largest river and lake in the Yangtze River basin, the largest freshwater lake in China and an important wetland in the world. Poyang Lake is located in the south bank of the middle and lower reaches of the Yangtze River and the north of Jiangxi Province, involving Nanchang, Jiujiang and Shangrao 12 counties (districts).
The fluctuation of water level in Poyang Lake is influenced by the water from five rivers (Ganjiang, Fuhe, Xinjiang, Raohe and Xiushui) and the Yangtze River. During the flood season, the water level is high and the lake is wide and endless. Hukou Hydrological Station covers an area of 3955km2 when the highest water level is 21.80m.. During the dry season, the water level drops, the beach is exposed, and the lake returns to the trough, winding a line. There is a big difference between flood and low water level. "High water is a lake, low water is a river" and "a flood, a dry line" are the natural geographical characteristics of Poyang Lake.
Poyang Lake wetland includes waters, beaches, islands and other landforms. Beach refers to the vast area between high and low water levels, with an area of about 3 130 km2. There are 4 1 islands with an area of about 103 km2.
Due to the seasonal variation of water level in Poyang Lake, many shallow lakes and beaches are formed in winter, which become the main habitats of migratory birds in winter. In summer, beaches and hills around bare islands and lakes are the main habitats of summer migratory birds.
Second, abiotic environment.
1, surface water runoff of Poyang Lake wetland
Poyang Lake wetland is the convergence center of Poyang Lake convergence water system, and its water environment is subject to the whole water system environment. Poyang Lake water system consists of Poyang Lake and its connected Ganjiang River, Fuhe River, Xinjiang River, Raohe River, Xiushui River, Qingfeng Mountain Stream, Jintong River, Zhang Tian River and Boyang River, with a drainage area of 162225 km2 and an average annual runoff of 1950- 1984.
2. Water level
From 1956 to 2000, the average water level of each hydrological station in Poyang Lake was12.86 ~15.19 m, with the highest water level of 22.43~22.98 m and the lowest water level of 5.90 ~12.00 m. The lowest water level in 78.8% years appeared in 65438+February and 65438+1October.
3. Water temperature
The annual average water temperature of Poyang Lake wetland is about 18℃, with the highest temperature of 29.9℃ in August and the lowest temperature of 5438+0 of 5.9℃ in June. The extreme maximum water temperature of the whole lake is 38.2℃, and the extreme minimum water temperature is 0℃. During the day, the highest water temperature appears in 15~ 17, and the lowest water temperature is 6~8. Due to the water depth of Poyang Lake and the influence of wind, waves and lake currents, the vertical distribution of water temperature is relatively small, and the difference between the upper and lower layers is about 65438 0℃.
4. Water quality
The results of water quality evaluation of Poyang Lake show that the water quality of the whole lake basically maintains Class II ~ III water standards, and the water quality is good. Judging from the over-standard situation, in the selected 12 evaluation project, the indexes of total phosphorus, volatile phenol, ammonia nitrogen and permanganate exceeded the standard in some monitoring sections in different water periods. From the pollution sharing rate, the pollution proportion of total phosphorus, volatile phenol, ammonia nitrogen and permanganate index is significant at the entrance of the lake, and the pollution proportion of total phosphorus and permanganate index is significant at the exit of the lake. From the pollution load ratio, the pollution in the south branch of Jiangxi and the east branch of Xinjiang is heavier, while the pollution in Xiuhekou and Fuhekou is lighter. The pollution of Hamashi and Duchang in the lake area is relatively heavy, while that of Xing Zi and Park Mountain is relatively light. Although the water quality of Poyang Lake is still good at present, the amount of organic pollutants and nutrients entering the lake is relatively large, especially nutrients such as total phosphorus, which have obvious influence on the water quality of Poyang Lake. The results of pollution trend analysis show that ammonia nitrogen, volatile phenol and comprehensive pollution index in the whole lake are mainly increasing, while permanganate index is mainly decreasing. Boyang, Longkou, Piaoshan, Kangshan and Hamashi in the lake area are mainly rising, while Zhuxi Estuary and Banghu Lake are mainly falling.
Third, benthic animal resources.
Benthic animals are natural food for fish and birds, and are also indicators of water environment quality monitoring. Benthic animals include freshwater sponges of Polypoda, Hydra of Coelenterata, nematodes and caterpillars of Plants, oligochaetes and leeches of Annelida, gastropods and branchiopods of Mollusca, crustaceans, water mites and insects of Arthropoda, and feather insects of Bryophyta. According to the investigation of 198 1~ 1992, there are altogether 106 species of benthos in Poyang Lake, including 87 species of molluscs, 8 families 17 species of 5 orders in aquatic insects, and 0/2 species of oligochaeta. The average total biomass of benthos is 246.42 g/m2, and the average density is 72 1 /m2. Molluscs account for 99.34% of the average total biomass, aquatic insects accounts for 0.42%, and Oligochaeta accounts for 0.24%. Chironomid larva is the dominant population in aquatic insects, and earthworm is the dominant population in Oligochaeta.
Among 87 species of shellfish in Poyang Lake, there are 40 species of Gastropoda, belonging to 8 families 16 genus, and 47 species of bivalve, belonging to 4 families 17 genus (40 species of which are endemic to China). The species of gastropods in Poyang Lake mainly include China round snail, copper rust ring snail, square ring snail, long horn snail, China marsh snail, big marsh snail, square short hook snail, radish snail and so on. However, the number of river snail, bowman snail, long river snail, short groove snail and pointed cyst snail is scarce. The weighted average values of the distribution density and biomass of gastropods in the whole lake are 15 /m2 and 55g/m2, respectively. The distribution density and biomass of Banghu Lake are the largest, which are 549. 12 /m2 and150g/m2 respectively. . The distribution density of South Jianghu is the smallest, which is 13 /m2. The main species of bivalves are lake mussels, pearl mussels, sword mussels, Ai Le mussels, Hyriopsis cumingii, river mussels, toothless mussels, crested mussels and Corbicula fluminea, which are widely distributed and numerous, and are the dominant species. There are relatively few species, such as tomato, ring bee, China bee, oval bee, Pleurotus eryngii, Pleurotus eryngii, SINONOVACULA SINONOVACULA, SINONOVACULA olivaceus. SINONOVACULA SINONOVACULA keel is distributed in Hexiu River in Wucheng, which is in an endangered state. In recent years, with the development of pearl nuclear industry in lakeside area, the population of mussels has dropped sharply due to overfishing. The weighted average values of distribution density and biomass of bivalves are 65438 0.3 /m2 and 7g/m2, respectively. They are. The distribution density and biomass of Dacha Lake are the largest, which are 89 /m2 and 73g/m2； respectively. . The minimum values are 0. 1 /m2 and 0.4 g/m2, respectively, near Piaoshan.
The distribution of zoobenthos in Poyang Lake is significantly different due to the species and quantity of water depth, current, sediment and aquatic plant ecological types. Submerged plants are dominated by bivalves, followed by Oncomelania hupensis (the intermediate host of Schistosoma japonicum), Oncomelania sinensis and Oncomelania striata. Shrub areas mainly include Gastropoda pear-shaped snails, Chinese snails and Chinese snails. In estuaries and rivers, there are a large number of carved clams, toothless clams, short-hooked ticks, copper-rusted snails, Aileria mussels and so on. In the zone with rich organic matter at the bottom, there are more snails in quadratus and China. There are few molluscs in the lake water level fluctuation area. Oligochaeta and Chironomid larvae are distributed in the whole lake, but the area of water shrub is larger than that of submerged plants, and the density in the northwest of the lake is larger than that in the southeast of the lake. The biomass of zoobenthos in Poyang Lake is 2 464.26 kg/hm2, of which molluscs are 2 448.03 kg/hm2. According to the calculation of 3 1.8× 104hm2, the zoobenthos in the whole lake are about 76.7× 104t, of which molluscs are about 76.2× 104t.
Hyriopsis cumingii and Hyriopsis plicata are excellent freshwater pearl mussels, which are mainly distributed in the rivers leading to the lake. From 1970 to 1974, the average annual output of Hyriopsis cumingii and Cremastra plicata in Poyang Lake was 6 999 t, from 1975 to 1979 was 5 206 t, and from 1980+0988 was 4 458 t.
Four, shrimp and crab resources
There are 8 species of shrimps in Poyang Lake, accounting for 80% of the known species of shrimps 10 in Jiangxi, among which white shrimp and Japanese prawn are the dominant species, accounting for 40%~50% and 30%~40% of the total annual output respectively. In addition, there are Chinese gibbon, Macrobrachium macrobrachium, and excellent crabs, such as Macrobrachium macrobrachium, Macrobrachium neoformans, crayfish and Procambarus clarkii (exotic species). The average annual output of prawns in Poyang Lake 1949~ 1958 was 2 474 t, that in 1959~ 1968 was 2 65425 t, and that in 1969~ 1978 was/kloc.
There are 4 species of crabs in Poyang Lake, accounting for 28.57% of known crabs 14 in Jiangxi. Eriocheir sinensis is distributed in the Yangtze River and Poyang Lake. Since the 1950s, the resources of Eriocheir sinensis have been sharply reduced due to the dam-building of rivers, the obstruction of the upstream passage of juvenile crabs and the increase of fishing intensity. Poyang Lake used to produce a lot, but now the Chinese mitten crab in the Yangtze River basin is no longer produced. Instead, it is cultivated artificially in lakes, ponds and even rice fields along the lake, becoming the main breeding species in Poyang Lake area.
Verb (abbreviation of verb) fish resources
1, fish species
There are 40 species of fish/kloc-0 in Poyang Lake, belonging to 2 1 family, with 75 species of CYPRINIDAE as the main species, accounting for 53.5% of the fish species in Poyang Lake. The main dominant species are carp, crucian carp, bream, bighead carp, bighead carp, carp, silver carp and bighead carp. The national first-class protected animals are Chinese sturgeon and Chinese sturgeon, and the second-class protected animals are mullet. There are more than 800 species of freshwater fish in China, more than 300 species of fish in the Yangtze River system and 205 species of fish in Jiangxi. The fish species in Poyang Lake account for 17.50% of the freshwater fish species in China, 46.67% of the fish species in the Yangtze River system and 68.29% of the fish species in Jiangxi.
2. Distribution of spawning grounds and feeding grounds.
The settled fishes in Poyang Lake mainly include carp, crucian carp, bream, bream, yellow catfish, catfish, mandarin fish, snakehead, whitebait in Taihu Lake, whitebait in Qiaokou and so on. Migratory (river-sea migratory) fish include Chinese sturgeon, bonito, eel, European eel, Cynoglossus semilaevis, fugu arcuatus and fugu obscurus. Semi-migratory (river and lake migratory) fish include green grass, silver carp, bighead carp, mandarin fish, mandarin fish and so on. Mountain stream fish include mandarin fish, China striped breastfish, bearded catfish and moon fish. The waters of Boyang and Yugan counties in the southeast of Poyang Lake are the concentrated producing areas of carp and crucian carp. In the south of the lake area, Chengjiahu Zhaohe, Huanglaohu Xiangzikou and Caowan Hulingkou are spawning grounds for bonito. The centipede mountain area north of Songmen Mountain in Wucheng County, Yongxiu County is the main feeding ground for juvenile shad, and the areas around Zhuhu Lake, West Lake Ferry, Qinglan Lake and Dayuchi are the main feeding ground for whitebait.
3. Catch, catch composition and age composition
1995, the total catch of Poyang Lake was 34852.2t, an increase of 1% over the previous year. Among them, the output of whitebait 133.4 t decreased slightly compared with the previous year; The output of bonito 1 358.5 t was the same as last year. Shrimp output 1 63 1.3 t, the same as last year. The catch mainly includes carp, crucian carp, catfish, green grass, silver carp, bighead carp, bighead carp, snakehead, mandarin fish, bighead carp and yellow catfish. Carp accounts for 25%, crucian carp accounts for 20%, catfish accounts for 10%, grass, silver carp and bighead carp account for 10%, and silver carp, catfish and Pelteobagrus fulvidraco account for 35%. The fish caught in that year was more than that in the second year, and the fish in the second year was less, which led to the younger and smaller individuals. The catch yield of Poyang Lake accounts for 2.74% of the annual output of aquatic products in Jiangxi Province127.1×104t.
4. Protection and rational utilization of fishery resources
In order to protect and make rational use of the fishery resources in Poyang Lake, Jiangxi Provincial People's Government has designated a closed fishing area and a closed fishing period in Poyang Lake. Every year from March 20th to June 20th, the fishing season is closed, including: yugan county Beikou Bay, Chengjiachi, Carassius auratus Lake and Sanzhou Lake (Changhuzi); Dashafang (Square), Sanhu, Tuantan Lake and Jinxian County (Qinglan Lake) in Nanchang County; East Lake, Shangbeizha (a) Lake, Xiabeizha (a) Lake, Shangxin Lake, Xiaxin Lake and Changhu Lake in Xinjian County; Shahu Lake in Yongxiu County, Great Lakes and Marshes, Banghu Lake in Xing Zi County, Hanchi Lake in Poyang County, Dalianhu Lake, Huyun Lake, Xihu Lake in duchang county, etc. ***20 places. The elevation of Cao Zhou in the fishing area is12.3 ~14.7m. In winter, the ports are closed in turn to protect fish from overwintering.
Intransitive verb bird resources
(1) Birds in Poyang Lake
There are 365,438+00 known bird species in Poyang Lake, including 65,438+059 typical wetland birds. According to the habitat types, there are 45 resident birds, 0/55 winter migratory birds, 0/07 summer migratory birds and 3 lost birds. There are 13 species of endangered birds in the world. There are 54 species of national protected animals, including Class I protected animals 10 species: white crane, white-headed crane, great bustard, oriental white stork, black stork, Chinese merganser, white-shouldered eagle, golden eagle, white-tailed sea eagle and seagull; There are 44 species of second-class protected animals, such as cygnet, curly pelican, white-naped crane, gray crane, dune crane, white goose and white spoonbill. China-Japan migratory bird protection agreement protects 153 species, accounting for 67.4% of the 227 species protected by the agreement. The Agreement on the Protection of Migratory Birds between China and Australia protects 46 species of birds, accounting for 56.8% of the number of birds protected by the agreement.
(2) the number and distribution of waterfowl
The total number of waterfowl in Poyang Lake is about 40× 104, among which the wintering waterfowl is about 10-20× 104, and the maximum number is 30× 104. There are tens of thousands of geese among wintering waterfowl. The most important ones are white crane, white-naped crane, grey crane, oriental stork, black stork, great bustard, white goose, white spoonbill and cygnet. The total number is greater than 3× 104. There are 15 species of cranes in the world, including 9 species in China and 5 species in Poyang Lake. Among them, white cranes, white-headed cranes, white-naped cranes and gray cranes are winter migratory birds, and Grus canadensis in Canada is a bird that occasionally gets lost. Poyang Lake is an important wintering habitat for white cranes, with more than 2,500 wintering population, accounting for more than 95% of the world total. It is also the largest wintering flock in the world (more than 30,000 geese). Since 1998, Poyang Lake has become an important habitat for oriental storks. More than 2,800 oriental storks wintered in Poyang Lake, accounting for about 80% of the world total.
There are 1 889 species of breeding birds and subspecies in China, 24 1 species of breeding birds and subspecies in hilly plains of eastern central China, and 1 species of breeding birds and subspecies in Poyang Lake, accounting for 8.05% of the country and 63.07% of the sub-region of eastern central China.
The investigation results of birds in Poyang Lake from 65438 to 0983 show that the areas around Ruihong and Kangshan in the east of Poyang Lake are mainly geese and ducks, and they are also one of the distribution areas of great bustards. Cygnets, geese and ducks are mainly distributed in Tanxiao Lake, Broad Bean Lake, Chengjia Lake and Caowan Lake in the south of Poyang Lake. Wucheng and Jishan areas in the west of Poyang Lake are dominated by rare waterfowl such as cranes, bustards, cygnets, mandarin ducks, geese and ducks. The islands of Sanshan, Sishan and Jewellery Mountain in the north of Poyang Lake are mainly geese and ducks.
In recent years, the results of many aerial surveys and synchronous surveys around Poyang Lake show that the distribution of white cranes in Poyang Lake is centered on Poyang Lake National Nature Reserve, with Dayanlian Lake, Qingnan Lake and Nanjishan Provincial Nature Reserves as important habitats, and satellite lake Jiujiang Saicheng Lake in Poyang Lake as more important habitats.
To sum up, the distribution characteristics of birds in Poyang Lake area are as follows:
Yugan and Boyang areas to the east of Poyang Lake used to be dominated by geese and ducks, which have become more important wintering habitats for cranes, storks, cygnets, spoonbills and geese and ducks. Nanji Mountain Provincial Nature Reserve, Nanchang, Xinjian and Jinxian in the south of Poyang Lake used to be dominated by cygnets, geese and ducks, and the protected areas have expanded into important habitats for cranes, storks, cygnets, spoonbills, raptors, geese and ducks, gulls and snipes. In the winter of 200 1 year, more than one black-faced spoonbill was first discovered in Nanji Mountain Provincial Nature Reserve. Poyang Lake National Nature Reserve, Yongxiu in the west of Poyang Lake and Xing Zi are still important wintering habitats for rare waterfowl such as cranes, bustards, cygnets, white geese, geese and ducks. Wild goose, duck, heron, cormorant, etc. Mainly distributed in Lushan area and Hukou area in the north of Poyang Lake. Duchang Miaoxin Lake, Sanshan Mountain, Sishan Mountain, Jewel Mountain and other islands have expanded from geese and ducks in the past to more important habitats with white cranes, oriental storks, cygnets, geese and ducks and herons.
In addition, Chihu (Jiujiang, Ruichang), Husai (Lushan), Taibai Lake and Fangze Lake in northern Jiangxi have also become the wintering habitats of rare waterfowl since the flood of 1998.
Every March, summer migratory birds migrate to Poyang Lake to breed, and in June, 5438+00, they leave Poyang Lake. * * * Qingcheng Yaobang Cemetery, Henghu Comprehensive Reclamation Field, Xinjian Xiangshan Forest Park, Nanchang Tianxiangyuan, Nanchang Global Park, Nanchang 5 10 and 828 Guest House, Hukou Xieshan and other places are breeding grounds for egrets, with nearly 10× 104 egrets and cows every year. A small number of yellow-billed egrets (national second-class protected animals) and great egrets breed in the lake area. Due to the change of global ecological environment, some night herons gradually become resident birds and also inhabit Poyang Lake area in winter.
Seven, Poyang Lake National Nature Reserve
Jiangxi Poyang Lake National Nature Reserve is located in the northwest corner of Poyang Lake. It is an internationally important wetland with rich biodiversity, the main wintering place for global white cranes and oriental white storks, and one of the most important wintering places for migratory birds in Asia.
Poyang Lake Nature Reserve was established with the approval of Jiangxi Provincial People's Government in June, 1983, formerly known as "Poyang Lake Migratory Birds Reserve in Jiangxi Province", and was upgraded to a national nature reserve with the approval of the State Council in May, 1988, renamed as "Poyang Lake National Nature Reserve in Jiangxi Province", and its management organization was "Poyang Lake National Nature Reserve Administration in Jiangxi Province". The reserve has jurisdiction over nine lakes, namely, Wuhu, Hu Sha, Banghu, Zhu Shi, Meixi, Wuhu, Dacha, Hu Xiang and Changhuchi, spanning the three counties of Xinjian, Yongxiu and Xing Zi under the jurisdiction of Nanchang and Jiujiang, involving 16 townships (towns and fields) with a total area of 22400hm2.
This reserve is rich in animal and plant resources. According to the investigation, there are 50 species of phytoplankton, 476 species of higher plants, 47 species of zooplankton, 40 species of shellfish, 227 species of insects, 22 species of fish 122, 48 species of amphibians 13, reptiles, 3 species of birds10 and 47 species of mammals in the nature reserve. Among them, there are 10 species under national first-class protection, 44 species under national second-class protection, and 153 species under Sino-Japanese migratory bird protection agreement, accounting for 67.4% of the total number of agreed birds. There are 46 species of birds protected by the Agreement on the Protection of Migratory Birds between China and Australia, accounting for 56.8% of the total number of birds in the agreement.
White crane is an important protected object in Poyang Lake National Nature Reserve, accounting for more than 95% of the world total. At the same time, the nature reserve is also an important wintering place for cranes, storks, swans and other waterfowl, a breeding ground for herons, some wild ducks and passerine birds, and an important post station and food supply place for migratory birds. "Birds in Poyang Lake, knowing how much, cover Yun Zheyue when flying, but don't see the grass by the lake when setting", which is a true portrayal of the spectacular scene of migratory birds wintering in Poyang Lake. Every autumn and winter, a large number of migratory birds from the north, with their children, go through difficulties and obstacles, not far from Wan Li, and come to Poyang Lake for winter. In the core lakes and marshes of the nature reserve, there are often spectacular scenes where 50,000 to 60,000 birds of all kinds gather together.
1February, 1992, the former Ministry of Forestry and the World Wide Fund for Nature (WWF) listed Poyang Lake Nature Reserve as one of the 40 A-level protected areas in China. In July of the same year, the government of China applied to join the Convention on Wetlands of International Importance Especially as Waterfowl Habitat, and Poyang Lake Nature Reserve, as one of the first six nature reserves to join the Convention, was included in the List of Wetlands of International Importance. 1997 was appointed by the former Ministry of Forestry to join the Northeast Asia Crane Protection Network. Poyang Lake Nature Reserve is also the only protected area with 1 wetland type among the five demonstration protected areas of "China Nature Reserve Management Project" funded by Global Environment Facility (GEF).
The rivers of Jiangxi and Hexiu meet here and then flow into the vast Poyang Lake. In the rainy season, the rivers and lakes are integrated, and the water and the sky are the same, and people seem to be in the sea; In dry season, the water falls out of the beach, forming a vast wetland grassland and forming a beautiful Jiangnan prairie; The sand dunes in this area are undulating and stretch for more than ten miles, forming a spectacular water desert. Wucheng town, where the reserve is located, was once listed as one of the four famous towns in Jiangxi along with Jingdezhen, Zhangshu and Hekou. After the establishment of the reserve, it attracted many domestic and foreign guests to visit. Prins Carl Philip, England and Prince Henrik of Denmark made a special trip here to watch birds, leaving good memories.