Comparison of Species Diversity of Platycladus orientalis Forests under Three Types of Disturbance

The influence of human-caused disturbance on plant diversity of natural Platycladus orientalis forests was studied based on field etho-botanical and ecological survey in Adong village, Deqin County in Northwest of Yunnan Province. The results indicated that the diversity and evenness index in the shrub and herb layers inmoderately and heavily disturbed plots were larger than those of slightly disturbed plots. While the analyses on the species either increased or decreased in the disturbed plots showed that the major species increased in the moderately and heavily disturbed plots were secondary, heliophilous and wide-distributive ones, but lacking of peculiar species in China. And the increased species did not contribute substantially to keep relative steadiness in Platycladus orientalis communities.