In the last decades, the East Dongting Lake wetlands in the middle reaches of the Yangtze River, one of the major overwintering region for migratory herbivorous geese in the East Asian–Australasian Flyway (EAAF), suffered dramatically changes in hydrological regimes and physical habitats caused by the Three Gorges Dam project (TGD), which would inevitably result in a lack of suitable wintering habitats for migratory herbivorous geese.
      Changes in herbivorous goose populations in relation to changes in their wintering habitat are of great concern in the major overwintering region in EAAF. The spatio-temporal evaluation of the waterbird-habitat relationship not only directly reflects the wintering herbivorous goose population pattern and their habitat quality but also promotes the development of wetland management strategies for protecting these valuable species in the middle reaches of the Yangtze River from the effects of human intervention, and in particular, the Three Gorges dam project.
      Researchers in the Institute of Subtropical Agriculture, Chinese Academy of Sciences (ISA) employ remote sensing, geographic information systems (GIS) and statistical techniques to analyze the relationship between three herbivorous goose abundance dynamics and the changes in their habitats within the past decades in the East Dongting Lake wetlands.
      The team found that the fluctuations in three herbivorous goose abundances exhibited negative correlations with changes in interval duration (i.e., days between complete sedge meadow exposure and goose arrival in the study areas), but positive correlations with the the normalized difference vegetation index (NDVI) of sedge meadow in late wintering seasons. Comparing to Eastern Tundra Bean Goose, Lesser White-fronted Geese and Greater White-fronted Geese were more sensitive to habitat changes. No significant correlations were observed between goose abundances and both mean water levels and sedge meadow areas.
      In conclusion, the variations in herbivorous goose abundances may be caused by changes in the NDVI of sedge meadows and the interval durations between sedge meadow exposure and goose arrival. The earlier flood recession can accelerate the exposure, growth, and withering of sedge meadows (low NDVI in late January), thereby creating unsuitable feeding conditions for the geese in the wintering seasons.
      This research was supported by funding from the National Key Technology Research and Development Program of China (2014BAC09B03), the National Basic Research Program of China (2012CB417005), the Open Foundation of Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences (ISA2015304) and the Project funded by China Postdoctoral Science Foundation (2016M592436).
      The study entitled “Response of herbivorous geese to wintering habitat changes: Conservation insights from long-term population monitoring in the East Dongting Lake, China” has been published in issue 3, Vol. 17 of Regional Environmental Change, details could be found at http://link.springer.com/article/10.1007/s10113-016-1087-z
Contact: XIE Yonghong
E-mail: xyh@isa.ac.cn
Institute of Subtropical Agriculture, Chinese Academy of Sciences