Guan L.,Beijing Forestry University |
Jia Y.,Beijing Forestry University |
Jia Y.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research |
Saintilan N.,Macquarie University |
And 4 more authors.
Freshwater Biology | Year: 2016
The species-area relationship, which is closely linked with the more general species-energy theory, is one of the most well-known patterns in geographical ecology, but the underlying causes remain contentious. The more individuals hypothesis (MIH) articulates a causal path from resource availability to population abundance to species richness. The MIH has been tested with a range of taxa including plants, invertebrates and land birds but never with migratory waterbirds. Using multiyear simultaneous survey data of wintering waterbirds in 10 lakes at Poyang Lake, China, and remotely sensed habitat condition measurements, we applied structural equation modelling (SEM) to test three causal paths: (A) good habitat conditions (e.g. habitat availability and heterogeneity) attract more species (high richness); (B) habitat conditions promote abundance (more individuals); and (C) habitat conditions promote abundance, which in turn increases richness. We also modelled responses of species richness and abundance to habitat conditions using generalised additive mixed modelling (GAMM) to assess their co-variation. While our analysis confirmed the first two paths, we found no support for the third, which is the central postulate of the MIH. In addition, in agreement with GAMM, SEM indicated that species richness was more closely related to habitat quality than to abundance. Our findings suggest that wintering waterbird species richness and abundance are two intrinsic community indices that covary with environmental variables. © 2016 John Wiley & Sons Ltd.
Cong P.,Anhui University of Science and Technology |
Cao L.,Anhui University of Science and Technology |
Fox A.D.,University of Aarhus |
Barter M.,Anhui University of Science and Technology |
And 5 more authors.
Bird Conservation International | Year: 2011
Approximately 75% of the East Asian Flyway Tundra Swan Cygnus columbianus bewickii population winters in the Yangtze River floodplain, China. Historically the species was more widely distributed throughout the floodplain but now most of the population is confined to five wetlands in Anhui Province and to Poyang Lake in Jiangxi Province, where the majority (up to 113,000 birds) occur. Within-winter counts suggest that swans congregate at Poyang Lake before dispersing to other sites later in the winter. Counts show large between-year fluctuations, but suggest declines at Shengjin and Fengsha Lakes (both in Anhui) during the last five years. Declines at Shengjin Lake are likely due to decreases in submerged vegetation (particularly tuber-producing Vallisneria, a major food item) perhaps linked to eutrophication. Range contractions throughout the floodplain may also be linked to reductions in submerged vegetation coverage elsewhere. Changes in water quality and lake hydrology post-Three Gorges Dam may have adversely affected submerged vegetation productivity. Key information needs for the effective implementation of conservation measures for Tundra Swans include: (1) annual surveys of all major wintering sites throughout each winter to establish the importance of different sites during the non-breeding period; (2) more information on swan diets at important sites; and (3) an assessment of adverse effects of water quality and lake water levels post-Three Gorges Dam on submerged vegetation productivity at Poyang Lake and other important sites. Copyright © 2011 BirdLife International.
Wu J.-D.,Jiangxi Poyang Lake National Nature Reserve |
Li F.-S.,International Crane Foundation |
James B.,University of Wisconsin - Madison
Wetland Science | Year: 2013
Poyang Lake is the largest freshwater lake in China and globally famous for its birdlife. The rich food resources provided by this wetland's emergent and submerged aquatic plant diversity is a major reason that hundreds of thousands of migratory birds travel to Poyang Lake every winter; on average more than 400 000 water-birds make Poyang Lake their winter home. Poyang Lake is extremely important to Critically Endangered Siberian Cranes Grus leucogeranus, as 3 000-4 000 Siberian Cranes, or over 98% of the world's population of this species spend winter here each year. The International Crane Foundation and the Poyang Lake National Nature Reserve collaborated to carry out a monitoring program from 1999 to 2010 in Sha Hu, one of nine sub-lakes of the Poyang Lake National Nature Reserve in Jiangxi Province of China. The objectives of the monitoring were to: record the number and location of the Siberian Cranes; determine the biomass of their aquatic food plants; and better understand relationship between foraging Siberian Cranes and their aquatic food plants as well water depth. Tubers of Vallisneria spp. were the main food of the Siberian Cranes during winter. Vegetation transects were set up to record numbers and biomass of Vallisneria spp. and their tubers. High vantage points that covered the whole Sha Hu were used to record number of Siberian Cranes and the water depth where the birds were foraging throughout the winter. The location of the birds was also mapped. During the 12 years, overall average number of Siberian Cranes was 46 birds, with winters in 2002, 2006 and 2009 over 90 birds. Within a winter, numbers of Siberian Cranes from November to January were relatively stable and the peak number of cranes occurred in December (120 birds). Siberian Cranes were seen mostly in the middle part by south of the lake, while very few recorded in northern and southern parts. The cranes were almost exclusively seen in the submerged vegetation communities dominated by Vallisneria spp. and Potamogeton spp. From 1999 to 2010, the average dry weight of Vallisneria tubers at Sha Hu was 5.92 g/m2, in 2005, 2006 and 2008 about or over 12.00 g/m 2, while was 0.10 g/m2 in 2010. For the 12 years of data, the correlation between the number of Siberian Cranes during December and January and tuber dry weight was not significant, with r=0.231, indicating Vallisneria tubers, at least alone, were likely not a limiting factor to the wintering Siberian Cranes. Areas with water depth of 5-27 cm had the highest number of the cranes (58%), followed by areas with water depth of 40-45 cm (31%). In total, 91% of the Siberian Cranes were found in areas with water depth of 5-45 cm. The big flood at Poyang Lake in summer of 2010 had a significant impact on aquatic plant food, forcing Siberian Cranes seeking alternative food sources in sedge/grass zones.
Chen B.,Nanjing Institute of Environmental Sciences |
Chen B.,Chinese Research Academy of Environmental Sciences |
Cui P.,Nanjing Institute of Environmental Sciences |
Xu H.,Nanjing Institute of Environmental Sciences |
And 8 more authors.
Polish Journal of Ecology | Year: 2016
Poyang lake area (1000–3246 km2) is the most important wintering ground for the globally critically endangered Siberian crane (Leucogeranus leucogeranus). More than 98% of the Siberian crane population overwinters in Poyang lake area. Remote-sensing and the spatial analysis tools of geographic information system (GIS) technology were used to assess the suitability of the habitat for wintering Siberian cranes in Poyang lake area at different water levels. The results demonstrated that as the water level increased within the range of 7.93–12.16 m, the area of unsuitable habitat increased gradually, but the areas of good, fair and poor habitat decreased. When the water level reached 12.16 m, good habitat for Siberian cranes covered an area of only 3005 ha, which is only 0.93% of the area of the total lake area. When human disturbance factors including vehicles, fishing and construction activities were added to the analysis of the current distribution of Siberian crane habitat, the results again indicated that the area of good habitat decreased with an increase in water level within the range of 7.93–12.16 m. Additionally, the areas of good habitat occurred primarily in the region of two national nature reserves, which are the Poyang Lake National Nature Reserve and the Nanjishan National Nature Reserve. Our study provides important data and an important theoretical basis for water level management and nature reserve construction in Poyang lake area. © 2016, Polish Academy of Sciences. All rights reserved.
Cui P.,Nanjing Institute of Environmental Sciences |
Zhou D.,Nanjing Institute of Environmental Sciences |
Wu Y.,Nanjing Institute of Environmental Sciences |
Wu J.,Nanjing Institute of Environmental Sciences |
And 7 more authors.
Pakistan Journal of Zoology | Year: 2014
The highly pathogenic avian influenza H5N1 virus (here after H5N1) still produces devastating effects in humans, poultries and wild birds. Migratory birds were thought to play a role in the long-distance spread of H5N1. This study identified 7 high-risk species and 18 potential high-risk species that may transmit H5N1 into Poyang Lake and determined four resident bird species as "bridge species" that may disperse H5N1 around the lake. The high-risk species were selected according to the following behavioral and ecological factors: migratory status, abundance, degree of mixing of species and gregariousness, migration from or stopovers at epidemic areas, and previous infection status. Among the 25 high-risk and potential high-risk species, 22 belonged to the orders Anseriformes (n = 11) and Charadriiformes (n = 11). The risk of intra-species transmission was high for Anseriformes (ducks and geese) and Charadriiformes birds, and was relatively low for Gruiformes and Ciconiiformes birds. This study can be informative and useful in the surveillance of avian influenza epidemics at breeding, stopover, and wintering sites other than Poyang Lake along the East Asian-Australian Flyway. Copyright 2014 Zoological Society of Pakistan.