The Characteristics Of Several Dominant Plant Populations In Meadow Grassland In The North Shore Of Qinghai Lake And Its Correlation With Climate Factors

There is a close relationship between plant population characteristics and meteorological conditions. The variation of plant above-ground biomass, height, vegetation coverage and growth period presents to be a sensitive with meteorological conditions, and it will do some reactions in one year. In order to provide the scientific bases for grassland climatic resources and pasture yield assessment, based on collected the above-ground biomass, the height, the coverage degree and the growth stages of species populations of meadow grassland in the north shore of Qinghai Lake, in combination of climate materials, such as air temperature, rainfall etc., the climatic change since 1976 and the plant population characteristics are analyzed at first. And then, the variation of the above-ground biomass, the height, and the coverage degree and growth stages of five dominant plants in this region were analyzed. At last, the relationships between the above-ground biomass, the height, the coverage degree and growth stages of five dominant plants and climatic factors were explored. Climatic effect and major and minor climatic factors affecting on five dominant plants were analyzed at the same time. The results are as follows:1.In the last 33 years, annual mean temperature has elevated 0.48℃/10a; annual mean rainfall and annual mean sunshine hours have increased 9.39mm/10a and24.6h/10a in the north Shore of Qinghai Lake. But annual evaporation has dropped about 17.57mm/10a.2.Between 1997 and 2008, the above-ground biomass of four dominant species, i.e. Stipa. krylovii Roshev, Poa crymophila, Koeoeria cristata, Kobresia humilis was increasing. The above-ground biomass of plant community ,i.e. Poa crymophila Koeleria cristata, Kobresia humils was presented by an increased trend year by year. The height of most of dominant species showed that there were increasing trends year by year. The coverage degrees of plant community showed a decreasing tendency. The growth season of most of dominant species, i.e. Stipa. krylovii Roshev, Poa crymophila, Koeoeria cristata, Artemisia scoparia had prolonged, such as returning green stage became early and yellow period date became late.3.Moisture regime was a major climatic factor to impact above-ground biomass of natural plant by analysis on relationship between natural plant and meteorological conditions. The more the rainfall was, the more the above-ground biomass got.4.Returning green stage of vegetation was subjected to moisture regime. There was a positive correlation between returning green stage of vegetation and the last year rainfall (p<0.01), and a negative correlation between returning green stage of vegetation and evaporation (p<0.01). Wilting date of vegetation was subjected to thermal condition.5.According to the Canonical Correlation Analysis,the height of Stipa. Krylovii has a close relationship with the annual mean temperature; the key factor affecting the above-ground biomass of Poa crymophila was the annual mean temperature. Annual mean rainfall and annual mean sunshine hours have played a main role in the above-ground biomass of Koeleria cristata. The relationship between annual mean sunshine hours and the height of Kobresia humils was significant. Annual evaporation was major climatic factors affecting on the height of Artemisia scoparia.6.The annual mean evaporation was a main factor to impact the cover degree of plant populations of meadow grassland in July and August, and there was a negative correlation between them (P<0.01).