2.1 | Site Description
The research site was selected at the Haibei National Field Research Station of Alpine Grassland Ecosystem. The site is located in the northeastern part of QTP, south of Lenglong Mountain in the eastern part of the northern branch of Qilian Mountains and northwest of Datong River Valley in Menyuan County, Haibei Prefecture, Qinghai Province. The ecosystem represents the special ecological environment type of the QTP and is an excellent field support platform for alpine meadow ecological research. The region within the site is dominated by low mountains and mudflats with an elevation between 3400-4500m. The complex and varied terrain, including river valley mudflats, mountains and marshes, is distributed in a typical continental plateau climate. There is no obvious division into four seasons in a year, and the climate is cold and dry with little rainfall. The average annual temperature is -1.7℃, with a range of -0.9 -2.5℃. The average temperature in July, the hottest month, is 9.9℃, with a range of 8.9 -10.5℃. The average temperature in January, the coldest month, is -15.2℃. The annual temperature difference is 22.0-22.7℃, with an average of 25.1℃. The annual precipitation ranges from 425.36㎜ to 850.4㎜, with an average of 582.1㎜, of which 80% is distributed in May to September in the growing season and 20% in the cold season. Precipitation in November-February accounts for only 4% of the annual precipitation. Alpine meadow soil is the most widespread in the Haibei Station area, and its vegetation types are diverse, withKobresia plants, mainly including Kobresia , Kobresia humilis , Carex capillifolia , etc., different regional associated species are different, the proportion is also uneven, mainly a variety of Carex chinensis Retz., Poa annua L. , and cushion plants. The vegetation is low and dense. In this study,Stipa aliena Keng and Kobresia humilis were selected as the established species in the alpine meadow of hilly land, common companion species are Elymus nutans Griseb, Poa annua L.,Saussurea superba Anthony f.Pygmaea Anthony, Medicago archiducis-nicolai Sirj., Gentiana straminea Maxim. And so on.