2.1 Vegetation characteristics
From TS, TSD to TD, the total coverage, AGB, Shannon-Weiner index and richness were decreased (Table2). There were significant differences among different treatments. Compared with TS, the coverage under TSD and TD decreased by45.31% and 60.41%, respectively, and the AGB decreased by 58.90% and 70.24%, respectively, and the Shannon-Weiner index decreased by 38.94% and 55.43%, respectively, and the richness decreased by 51.08% and 58.77%, respectively. The changes in dominance was the opposite of total coverage. The grass layer height was in order of TSD>TD >TS and evenness was in order of TD >TS >TSD.