Effects of invasion of Coreopsis grandiflora on vegetation diversity

Five representative habitats invaded by Coreopsis grandiflora were investigated in Qingdao city. The variety and quantity of the indigenous vegetation were studied by using the square intercept method in five habitats. Ninetytwo indigenous species belonged to sixteen families were recorded, the number of Asteraceae and Poaceae were the most. The pattern of local community biodiversity was analyzed by species richness, diversity index and Pielou evenness index. The importance value of each species was calculated. The results showed that the invasion of C. grandiflora reduced species richness, Simpson diversity index, ShannonWiener diversity index and Pielou evenness index of the sample plots. The most reductions of four indexes were 34.75%, 60.53%, 58.22% and 41.98%. By calculating, the average important value of C. grandiflora was 56.92%, which was more than other vegetations in communities. Analysis of relationship between the average important value of C. grandiflora and the species richness of communities revealed that when the important value of C.grandiflora was 20.25%, with increase of the former, the latter was on the decrease. These results clearly showed that the invasion of C. grandiflora had a negative effect on biodiversity.