Effect of Pedicularis kansuensis invasion on plant community characteristics in Bayanbulak grassland

Invasive species often repel other species in the community through competition, alter species composition and structure of the invasive community, and destroy the stability of the ecosystem. Pedicularis kansuensis is a typical invasive plant which spreads rapidly in the Bayanbulak Grassland and poses a serious threat to the local ecosystem. In this study, we investigated the species composition and community characteristics of the P. kansuensis community with four invasive classes (no invasion, low invasion, medium invasion, and high invasion), and analyzed the differences in species diversity under the different classes of invasion. The results showed that: 1) 30 species of vascular plants were recorded in the three invasive communities of P. kansuensis, and 27 species were recorded in the no invasive communities. These three invasive communities contained three additional species compared with the no invasive communities, however the three species were different in the invasive communities. 2) The invasion of P. kansuensis decreased the important values of Potentilla bifurca, Oxytropis lapponica, Stipa purpurea, Koeleria litvinowii, and Leontopodium leontopodioides. With an increase in invasion degree, the proportion of Poaceae density in the communities exhibited a downward tendency after initially increasing, while the proportion of Fabaceae and Poaceae density and coverage decreased significantly under medium and high invasion (P < 0.05). 3) With an increase in invasion degree, species richness and Margalef richness index increased initially and then decreased, and the Shannon-Wiener diversity index, Simpson dominance index, and Pielou evenness index all demonstrated a downward－up－down trend. This study can provide a scientific basis for the conservation of biodiversity in Bayanbulak Grassland.