2.1 | Site description
The research plots were carried out in Qinghai Haibei alpine grassland
ecosystem national observation and research station (Haibei Station,
37°39.876′ N, 101°10.748′ E), with an altitude of 3227.6 m. The sample
plot is a winter pasture. The grazing period is from the beginning of
October to the end of April of the following year, so the plant growth
season is not disturbed by grazing. It belongs to typical plateau
continental climate, the annual average precipitation and temperature
are 560 mm and -1.7 °C, respectively. The precipitation from May to
September during the growing season accounts for about 80% of the total
annual precipitation.
The plant growing season has rain and heat at the same time, and soil
type is alpine meadow soil. Since the 1980s, the three pastures and
grazing channel grasslands have carried relatively stable grazing
intensity, and formed obvious grazing gradients in terms of surface
characteristics and species composition (Table 1, Fig. 1).
The native vegetation of the alpine meadow in this area is cold
mesophytic, wet mesophytic and dry mesophytic perennial Kobresia as a
constructive vegetation type. The community structure is relatively
complex and the species composition is rich. There are about 30 species
m-2, and the dominant species are mainly includingKobresia humilis, K. pygmaea, Elymus nutants, Festuca rubra, Poa
annua, Oxytripis ochrocephala, Gentiana straminea, Potentilla nivea,
Saussurea superba, Thermopsis lanceolate . Coexisting species includingStipa aliena, Poa annua, Kobresia humilis, Kobresia pygmaea,
Oxytropis ochrocephala, Thermopsis lanceolata, Saussurea superba,
Leontopodium nanum, Gentiana straminea, Potentilla nivea, Anaphalis
lactea Maxim. Among them, Stipa aliena and Poa annuabelong to Gramineae, Kobresia humilis and Kobresia pygmaeabelong to Cyperaceae, Oxytropis ochrocephala and Thermopsis
lanceolata belong to Leguminous, Saussurea superba, Leontopodium
nanum, Gentiana straminea, Potentilla nivea and Anaphalis lactea
Maxim belong to Forb group.