Abstract: With the method of sample plot investigation,plant species diversity of southern slope on Zixi Mountains was studied.Four indicators including Margalef index,Shannon index,Simpson diversity index and Pielou index were chosen for analyzing the diversity of plant,woody plant and shrub plant one by one.The results showed that (1)as altitude increasing,Margalef index,Shannon and Simpson diversity index of plant species diversity all increased first and then decreased,presenting a single-peak distribution pattern,while Pielou index increased all the time with altitude increasing,appearing a positive correlation pattern;(2)the four indexes of woody plant species diversity were all increasing at first and then decreasing,showing a single-peak distribution pattern,the four indexes of tree species diversity all appeared a single-peak distribution pattern as well;(3)the four indexes of shrub and herb species diversity all increased first and then decreased,and then increased and decreased again,appearing a pattern of bimodal distribution.

Key words: Zixi Mountains, species diversity, elevation gradient, distribution pattern