Abstract:The Karst peak-cluster landform forest in Maolan is a rare non-zonal forest ecosystem with strong originality and less human disturbance, which is quite different from the normal landform zonal forest ecosystem. In this study, the typical sample plot survey method was used to 11 vertical transect plots in the Maolan Karst forest with an altitude of 620-910 m. We analyzed the vertical gradient variation characteristics of the species richness of the top community in the study area, and used redundancy analysis (RDA) method to analyze the effects of environmental factors on species richness, so as to clarify the relationship between species richness and environmental factors on the vertical gradient, and provide a theoretical basis for the maintenance and restoration, protection and management of Karst natural forest ecosystem. The results showed that: (1) a total of 511 species of vascular plants belonging to 124 families and 272 genera were recorded in the Maolan karst peak cluster. (2) One-way ANOVA analysis showed that the richness of different life forms in the community was very significantly different (P<0.01); Multiple comparison analysis of LSD showed that the richness level of community was overall > shrub layer > herb layer > tree layer. (3) With the increase of altitude gradient, the total species richness of community and the species richness of herb layer were significantly negatively correlated with altitude (P<0.05), while the tree layer richness and shrub layer richness were no obvious regularity with altitude. (4) Redundancy analysis showed that the contribution rate of soil C/N/P reached 58%, which was the main factor affecting species richness.