Study On The Model Of Overwintering Geese Habitats And Carrying Capacity In Poyang Lake

Geese are the dominant species among those waterbirds overwintering along the middle and lower Yangtze River.As one of two large lakes connected to the Yangtze River,Poyang Lake is greatly affected by hydrological factors.The growth of the wetland vegetation in Poyang Lake is closely related to the exposure time of the meadow.Clarifying the relationship between flood recession and the growth process of Carex spp.and the carrying capacity of overwintering geese habitats is the key to determine the spatial-temporal pattern of suitable habitats so as to geese's conservation.In this study,Changhuchi Lake,a typical sub-lake of Poyang Lake National Nature Reserve,was chosen as the study area.This study undertook in-situ experiment as well as lab analysis to Carex spp.during the growth season and numbers of overwintering geese.Combining remote sensing data,temperature data,and field survey data,the time window suitable for feeding on and the carrying capacity of overwintering geese habitats were obtained.The main results are as follows:1.There was a significant correlation between the plant height and aboveground biomass(P<0.01);hydrological regime and temperature jointly affect the growing process of Carex spp.Delayed flood recession will influence the vegetation's pattern for geese to feed due to low temperature limit.2.The exposure time of Carex spp.could reach 12~28 days in autumn while it could reach 83~182 days in spring,which is appropriate for geese to feed.The study proposed a method to uncover the time window of Carex spp.fit for overwintering geese and has proved that a 20-day delay of flood recession would cause a great mismatching between the growth patterns of Carex spp.and fail to meet the food requirements of geese in their peak season.3.Carex spp.is the main food resource for overwintering geese,and geese are selective for height of food source vegetation.During the wintering period,the moss biomass of the habitat and the carrying capacity of the geese increased exponentially.When the number of geese in the habitat is higher than the carrying capacity,the habitat will not be able to meet the feeding needs of the geese,and the geese migrate to other habitats where food resources are abundant.