Table 1 Basic information of the sample plot
In order to study the response of alpine meadow soil ecosystems to
grazing disturbance under environmental constraints, alpine meadows
located on mountain slopes within the study area were selected for
grazing experiments of different intensities. This sample site is
located on the middle slope of a semi-positive mountain slope with low
soil moisture content and weak vegetation growth, which is one of the
representative types of alpine meadows under environmental constraints,
detailed information of which is given in Table1. The selected
experimental land was fenced and prohibited from grazing in 2009 as a
grazing experiment, which included one closed grazing group and three
grazing groups of different intensities. The closed grazing group was
CK, and three grazing groups of different intensities were light
grazing, moderate grazing and heavy grazing as experimental groups to
form a grazing gradient. The geographical location and layout of the
experimental plots are shown in Figure 1. The area of the closed grazing
group was 3×15 m² and there was no human intervention except for
sampling throughout the year. The area of the other three grazing
treatment groups with different intensity was 9 × 9 m. In the grazing
group, the warm season grazing experiment was carried out from June to
September each year. The grazing animals were Tibetan sheep. The grazing
intensity treatment groups of light, heavy and heavy grazing intensity
were grazed continuously for 48 hours at the beginning of each month.
According to the gradient grazing intensity treatment, 3, 5 and 12
Tibetan sheep of the same age and body size were grazed in the mild,
moderate and heavy grazing groups, respectively. The sheep were allowed
to eat and move freely during the grazing period and were released from
the experimental area 48 hours later. Soil samples were taken 15 days
after the grazing experiment.