Effect of two new herbicides on important values and plant diversity of Stellera chamaejasme-Kobresia humilis grassland communities

A field survey was conducted to determine the effect of two new herbicides on important values and plant diversity of Stellera chamaejasme-Kobresia humilis grassland communities. This study showed that two herbicides (Langdujing and Mielangdu) greatly affected the important values of plant species of S. chamaejasme-K. humilis grassland communities, indicating that the important values of K. humilis, Stipa purpurea, Poa crymophila, Leymus secalinus increased gradually and these plant species became the dominant, but the S. chamaejasme and Thermopsis lanceolata disappeared. LangDujing and Mielangdu caused one and five plant species to disappear, respectively. Two herbicides decreased the plant diversity of grassland communities, indicating that the Langdujing and Mielangdu reduced the richness index by 15.2% and 31.4% respectively in the coming year. The Mielangdu significantly decreased the dominant index (P0.05) but Langdujign did not affect the dominant index. The evenness index was significantly different between Langdujingd and Mielangdu (P0.05). This study suggested that Mielangdu had stronger influence than Langdujing on plant diversity and important values of grassland community.