| Lashihai Lake is an important wintering and stopover site for migratory waterbirds in West China,and it has important value in the ecological location for the conservation of rare and endangered waterbirds and bird diversity.From September 2011 to September 2013,this research made uninterrupted observations and records for 105 times(once a week)on waterbird species and their individual numbers at Lashihai Lake,and carried on sample surveys on the relative environmental factors,such as hydrologic features,wetland vegetation and aquatic organisms.The main conclusions are as follows:1.In this research,336,115 individuals of waterbirds were recorded,belonging to 59 species,12 families and 6 orders.In these 59 species,tundra swan,oriental pratincole,pied avocet and whimbrel are new records at Lashihai Lake,and whimbrel is a new record in Yunnan Province.5 species are the state key protection birds,of which 1 species is the national first-grade protection birds,4 species are the national second-grade protection birds.Based on the comprehensive analysis of historical records,we find,compared to records made at the start of this century,the waterbird diversity at Lashihai Lake has been reduced significantly,and part of rare and endangered waterbird species recorded disappeared from this wetland.This research shows that the waterbird diversity of Lashihai Lake is very rich,and this wetland has important value in ecological location for the conversation of rare and endangered waterbirds.2.This research reveals there exist some annual differences and significant seasonal variations of waterbird diversity at Lashihai Lake.The wintering period of waterbirds at this Lake is from September to April of the next year,and the breeding season is from May to August.And with the replacement cycle of the wintering period and the breeding season,the waterbird diversity of the wetland presents a reciprocating dynamic model between increasing and decreasing.The research suggests that the waterbird diversity at Lashihai Lake has been decided by the diversity of migratory waterbirds,and the root cause of seasonal variations of waterbird diversity can be explained by the migrating and wintering process of migrating waterbirds at Lashihai Lake.3.The research reveals that the temporal dynamics of the wintering waterbirds at Lashihai Lake shows obvious periodic characteristics with the migrating process,and finds that there is an obvious relation between the immigrating,staying,emigrating duration and their interannual variations during the wintering periods and different species of wintering waterbirds and their population size.The interannual variations of species numbers and individual numbers maintain relatively stable,and show a basic rule of seasonal changes with the process of migrating and wintering of wintering waterbirds at Lashihai Lake.Through the analysis,it is considered that the seasonal changes of species numbers reflect the immigration and emigration timing of different species of wintering waterbirds at Lashihai Lake,and the dynamic pattern of the total individual number is the results overlaid by individual numbers of different species of wintering waterbirds in the temporal distributions.4.This study has carried on a correlation analysis of the influence of 8 kinds of climatic factors on the variations of species numbers and individual numbers of wintering waterbirds in the immigration and emigration phases by the stepwise regression method.The results discover that the weekly average temperature and weekly average wind speed are the main factors affecting individual numbers of wintering waterbirds in these two phases,and the weekly minimum temperature,weekly average temperature and weekly average relative humidity are the main factors affecting species numbers.5.The research has studied the waterbird community characteristics of 3 habitat types in 3 phases of the wintering periods.The research findings demonstrate that the change pattern of species numbers and individual numbers of waterbird community at Lashihai Lake is high at both sides and low in the middle,and the diversity and evenness indexes are high in the middle and low at both sides with the time sequence.And the results also show that the waterbird community characteristics in 3 habitat types have significant differences.During the wintering periods,the main species numbers and individual numbers of waterbirds at Lashihai Lake appear on water surfaces and in swamp areas,and the diversity and evenness indexes of waterbird community are found to be the highest in swamp areas.In terms of different ecological types of waterbirds,there also exist significant differences between the community characteristics of swimming birds and waders in the 3 habitat types at Lashihai Lake.There exist the highest species numbers and individual numbers of swimming birds on water surfaces,and the highest diversity index in swamp areas.And waders have only been recorded in swamps and abandoned farmlands.The research suggests that,in order to keep the conservation of waterbird diversity at Lashihai Lake,it is very important to protect the habitat qualities of water surfaces and swamp areas.6.Based on the conditions of 3 habitat types in different phases of the wintering periods at Lashihai Lake,this study has also carried on a correlation analysis of the influence of 6 kinds of habitat factors on the community characteristics of waterbirds.The results show that the influence of different habitat factors is different to the community characteristics of waterbirds,and the influence of habitat factors affecting the same community characteristics in different phases of the wintering periods is also different.Specifically,in the autumn immigration phase,food resources are the key determinant to species numbers of waterbirds,the average water level is the important environmental condition affecting individual numbers of waterbirds,and the percentage of vegetation area is more important than other habitat factors for the diversity index of waterbirds.The existence of benthic animals is the key reason that restricts species numbers and the diversity index of waterbirds in the wintering staying phase,and the expansion of water area is more favorable to the increase of the waterbird population size in this phase.Benthic animals are also the restricting factor in the spring emigration phase to species numbers of waterbirds,but the individual numbers are more closely related to the water level factor in this stage.7.Based on the current situations of waterbird diversity and spatio-temparol dynamic characteristics of Lashihai Lake,the research further discusses the problems of the waterbird diversity conservation at Lashihai Lake.And the conservation strategies have been proposed on the basis of the current ecological conditions and characteristics of habitat factors.The research fully reveals the current situations of diversity characteristics,species composition and population of waterbirds,explores the seasonal and annual change rules of waterbird diversity in depth,and systematically analyzes the influence and inherent correlation of climate and habitat factors on the spatio-temporal variation of waterbird diversity at Lashihai Lake.And the results provide the important theoretical basis and scientific data for the correct understanding of the regional importance of Lashihai Lake and the international status of waterbird diversity in this wetland,and for the effective development of the conservation of waterbird diversity at Lashihai Lake. |
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