Study on the diversity of Vitex negundo var. heterophylla community in Taihang Mountain of Shanxi Province

The plant species diversity of 13 associations in the Vitex negundo var. heterophylla communities in Taihang Mountain was studied by using richness index (R1), Simpson index （）, ShannonWeiner index (H) and evenness index (E4). The results indicate that the quantity of populations and species was obviously uneven among 13 associations, which lead to variation of and H. R1 and H increased and then decline slowly with the increase of elevation and reached the peak value at 760 m while E4 slightly varied. With the disturbing of traveling and grazing, diversity indices decreased with the increase of disturbance degree. Affected by the natural factors and human activities, the dominance of V. negundo var. heterophylla reduced and showed a tendency of negative succession, while those under fewer disturbances of human activities showed xerosere character.