| The Poyang lake is the largest wetland of China and one of the international important wetland, which was famous for the important bird wintering habitat, with about300000-400000migratory birds wintering in the Poyang lake each year. During1998-2011, we conducted simultaneous land survey each year to investigate the species composition, number, and distribution of waterbirds. We also surveyed the summer bird species diversity in the Poyang lake, and used logistic equation to fit the correlation between sample intensity and bird species numer to certainfy the minimum sample intensity of bird survey on large scale in the wetland system.We collected the data on climate, land cover, topography, NDVI, net primary production and human population density, and analyzed the correlation of those environment variables and the population number and distribution of Siberian crane, oriental white stork, common crane, tundra swan wintering in the Poyang lake. Furthermore, we assessed the importance of lakes for wintering birds and conducted gap analysis for rare bird species conservation on the basis of the current status of nature reserves in the Poyang lake.1. In Dec.2009and Jun.2010, using transect method and simultaneous survey methods, we studied the structure of bird community in Duchang Migratory Birds Nature Reserve of Poyang Lake in Jiangxi Province. We totally recorded169bird species, which belong to43families of14orders, in which there are17species listed as national protected species and5endemic species in China. There were96bird species of36families recorded in summer and135bird species of36families, The bird community was mainly composed of the species of Passeriformes, Charadriiformes, and Anseriformes, accounting for47.4%,13.3%, and9.6%of total number of bird species respectively in winter; in summer, the bird community was mainly composed of the species of Passeriformes, Charadriiformes, and Ciconiiformes, accounting for58.3%,8.3%, and10.4%. There is a significant seasonal shift of bird composition between winter and summer in Duchang Migratory Birds Nature Reserve. In low water period, bird species diversity was highest in the habitat of farmland, followed by grassland, swamp and water area, and lowest in farmland, and Acridotheres cristatellus, Pycnonotus sinensis, sturnus cineraceus, Passer montanus, Streptopelia orientalis were the dominant bird species; in summer, there is no difference between farmland and water area, and Egretta garzetta, Acridotheres cristatellus were the dominant bird species. Combined with the history bird records, there were totally338bird species in the Poyang lake, with56species under national protection.2. The population of common crane wintering in Poyang lake constantly increased from 1998to2011, and the average population size was2335±651, with maximum7640in winter of2011. There was a significantly positive correlation between the change of common crane population size and the precipitation in flood seasons in Poyang lake (r=-0.399, p=0.036), but no significant correlation between the change of common crane population size and the average monthly water level of the wucheng monitoring station either in flood seasons or draught seasons. The wintering common cranes clustered in Poyang lakes. The lakes of Dahuchi, Dalianzihu, Sanhu, Hanchihu, Qihu, Zhuhu, Nanhu (gongqing), Dachahu were the hotspots of wintering common crane. Averagely74.9±5.6%of common cranes wintered outside nature reserves. The spatial distribution of common crane was significantly positively correlated with the area of mudflat habitat, and was negatively correlated with area of agriculture land, human density, village count, net primary productivity of August and November. Mudflat area was an important factor determining the spatial distribution of common cranes, which accounted for15%of the spatial change of occurrence frequency, and combined with the factor of NPP in Nov. accounted for24.6%of spatial change of average number of common cranes.3.52lakes were inhabited by wintering oriental white stork, with farthest distance between these lakes about180km, and in38of those, the number of wintering storks accounted for more than1%of the oriental white stork’global population. The average yearly population of the wintering oriental white storks in the Poyang lakes was2305±326, with the maximum of3789individuals in winter2005. The wintering population in2004,2005,2010and2011exceed the estimated global population size. The number change inside the Poyang Lake Nature Reserve can significantly reflected the dynamic of the whole population dynamic of wintering storks in Poyang lakes (r=0.797, n=13,P=0.001). The number of the wintering storks in Poyang lake showed a significant linear increase (R2=0.443, F=20.708, p=0.000), but exhibited obviously interannual fluctuation. In winter, orient white storks were clumpedly distributed in Poyang lakes. Shahu, Dahuchi, Banghu and Hanchihu were most frequently used lakes and often clustered large crowd of the storks. There was a significantly weak correlation between the occurrence frequency and annual average number of the storks (r=0.274, p=0.049,n=52). We also found most of the inhabited lakes are covered in existing nature reserves, though some lakes outside the reserve were also considerably used by orient white storks.4.The average population size of tundra swan wintering in Poyang lake was53964±8502, with maximum112514in winter of2005. Most of the tundra swan were distributed in such lakes as Dahuchi, Dachahu, Saihu, Zhuhu, Hanchihu, Qihu, with average number about4000in one lake each year. Averagely65.9±5.3%of tundra swans wintered outside nature reserves. There was a significantly correlations between the change of tundra swan population size and the average relative humidity of September, rainy days in September, average water level of August, the highest water level of June, July, August and Octember. Based on the population size trend of the tundra swan wintering in the Poyang Lake National Nature Reserve during1987-2011, the climate and water level exerted the same impact as on the population size trend on the whole Poyang lake during1998-2011. The population number dynamics of tundra swan was significantly correlated with annual highest water level (r=-0.630, p=0.001,n=25), the average water level of Oct.(r=-0.483, p=0.015,n=25), the average water level of Dec.(r=-0.430, p=0.032, n=25), the average water level of July (r=-0.576, p=0.003, n=25) and August (r=-0.530, p=0.006, n=25). The annual highest water level and average water level of December totally accounted for52.4%of the population change of tundra swan in the Poyang National Nature Reserve.5. There were46lakes inhabited by wintering Siberian crane. Of them,25lakes with the number of wintering Siberian crane are more than1%of the population number of Siberian crane over the world; the lakes where over40.0%, e.g.1280individuals of Siberian crane inhabited in winter included Dachahu Lake in Jiujiang region, Banghu Lake and Candouhu Lake in the Poyang Lake Nature Reserve. The average yearly population number of the wintering Siberian crane in the Poyang Lakes was3108±849, with the maximum4004individuals in2002winter. On the whole, there was no drastic fluctuation, but the population number showed considerable fluctuation since2003. The Poyang Lake Nature Reserve was the major wintering area of Siberian crane. Since2002, over60%of Siberian crane wintered in the nature reserve (except for2006). Most of the lakes inhabited by Siberian crane have been covered in the nature reserve, where66.0±27.3%of Siberian crane were recorded. However, some lakes outside nature reserve were also considerably used by Siberian crane. The population size dynamic of Siberian crane in the Poyang Lake National Nature Reserve during1983-2011was significantly correlated with annual highest water level (r=-0.389, p=0.037, n=29), annual lowest water level (r=-0.414,p=0.026, n=29), the average water level of July (r=-0.526,p=0.003, n=29). Aug (r=-0.382,p=0.041, n=29). Oct (r=-0.404,p=0.030. n=29). However, only the average water level of July was a significant predictor factor, and accounted for27.7%of the population number dynamics (R2=0.277,df=28, F=10.322, P=.003).6. According to the occurrence frequency and number of6rare bird species during1998-2011, we used fuzzy assessment method to assess the importance of80lakes as wintering habitat, find the hotspots of bird species diversity, make gap analysis for rare bird species conservatioin. Banghu, Dachahu and Dahuchi were the most important lakes for wintering waterbirds, all located inside the Poyang Lake National Nature Reserve. In the Poyang lake,70.1%f lakes were covered inside the nature reserves; of them,22.5%f lakes were inside the national nature reserves,18.8%ere inside the province nature reserves,28.8%ere inside the county nature reserves. Of the most important30lakes,12lakes were inside the Poyang Lake National Nature Reserve and the Nanji Wetland National Nature Reserve, that is, about40.0%f these lakes were inside the National Nature Reserves. |
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