2.1 Study area
The experiment was conducted on a karst alpine grassland in the
Liangshuigou sheep breeding farm in Guizhou, which is located on the
Yunnan-Guizhou Plateau, China
(103º36′–104º45′E, 26º36′–27º26′N;
2200 m a.s.l.). It has a subtropical
monsoonal humid climate with an annual average temperature of 10–12 °C
and precipitation of 962 mm. The grassland is a perennial Lolium
perenne +Trifolium repens grassland. The main plant species areLolium perenne , Trifolium repens , Festucaovina ,Poa annua , Carex liparocarpos , and Potentilla
chinensis . The soil type in the study site is
alpine yellow-brown loam (H. Sun,
2014).