关键词: 渗透势, 种子萌发, 生理特性, 紫花苜蓿

Abstract: In order to find out the micro-habitat use of water birds in Poyang Lake and its response to water level, a survey on the number of water birds and the use of microhabitat was carried on with a fixed-radius point count method in 52 locations of 5 regions of Poyang area from October, 2014 to April, 2015. The results showed that 8 species such as tundra swan (Cygnus columbianus), spotted redshank (Tringa erythropus) and Eurasian spoonbill (Platalea leucorodia) mostly inhabited in shallow water. Bean goose (Anser fabalis), swan goose (A. cygnoides) and ruddy shelduck (Tadorna ferruginea) mostly inhabited in grassland and shallow water. Greater whitefronted goose (A. albifrons) and common crane (Grus grus) mostly inhabited in grassland. Common coot (Fulica atra) and great crested grebe (Podiceps cristatus) mostly inhabited in deep water. Blackheaded gull (Larus ridibundus) and little grebe (Tachybaptus ruficollis) mostly inhabited in both deep and shallow water. According to the analysis of the relationship between water birds’ number and the water level of Xingzi hydrological station, the total amount of water birds in Lake Poyang was negatively correlated with the water level. The numbers of water birds peaked at the water level of 8 m in Wucheng area of Poyang Lake National Nature Reserve, Duchang Migratory Birds Provincial Nature Reserve and Jinxian area, while they peaked at the level of 10-12 m in Hengfeng area of Poyang Lake National Nature Reserve, Nanji Wetland National Nature Reserve and East Poyang Lake National Wetland. Generally, a negative correlation was found between the water level in each region and the number of water birds of different families and species, whereas there existed a significant positive correlation between the water level and the number of Podicipediformes birds in some regions because Podicipediformes birds dived for foraging demanding for certain depth of water level.

Key words: osmotic potential, physiological characteristics, seed germination, Medicago sativa.