2.2 Site selection and data collection
In late July 2019, eight P. kansuensis infected sites and eight non-infected sites were set up based on the different dominant and constructive species in Bayanbulak alpine grassland. A total of three 1 m × 1 m quadrats were placed in each site. The elevation and spatial geographical coordinates at each site were recorded using a GPS (GPSMAP®60CSx, Garmin, Olathe, Kansas, USA). The species compositions and other detailed information are shown in Table 1. Plant species composition, canopy cover, and species number and abundance were recorded in each quadrat. Five to ten individual fresh and mature plant leaves from each species in each quadrat were collected and then separately stored in labeled paper bags.
All the plant samples were collected and brought back to the laboratory and dried at 105ºC for 30 min to avoid losses due to respiration and decomposition. Then, the plant samples were dried at 65ºC for 48 h, weighed and ground with ball mill, and stored in sample bags for N, P, and K determination. In addition, 0–10 cm surface soil samples were obtained using a hand auger from the infected and non-infected sites with five replicates taken at each site. One part of the soil subsample was used to measure SW, and the other was evenly mixed and stored at 4ºC for the measurement of SOC, N, P, and K.
Plant community composition was measured as species richness (number of plant species); plant abundance was the number of individuals per square meter; and plant canopy cover was defined as the proportion of the ground occupied by a perpendicular projection of the aerial parts of individuals.