To explore the spatio-temporal distributional patterns of the vegetation in a Karst cluster- peak-depression region, we investigated the species composition and diversity characteristics of three forests inside 200 m × 40 m dynamic monitoring plots in Huanjiang County of Guangxi. Results showed that plant communities changed from plantation to secondary forest to primary forest with increasing diversity associated with reduced disturbance intensity. We recorded 65 woody species belonging to 26 families and 52 genera, 100 woody species belonging to 33 families and 68 genera, and 123 woody species belonging to 43 families and 91 genera in the plantation, secondary, and primary forests, respectively. Evergreens accounted for 41.5%, 47.0%, and 52.9% of species in the plantation, secondary, and primary forests, respectively. Meanwhile, the families characterized with one species accounted for 39.46%, 36.36%, and 53.66% of the total families in the plantation, secondary, and primary forests, respectively. The dominant families and species with an IV (importance value) > 10.00 numbered 6 families and 6 species (23.1% and 9.2% of total), 6 families and 5 species (18.1% and 5%), and 10 families and 7 species (23.3% and 5.7%) in the plantation, secondary, and primary forests, respectively. While the proportions of these IVs were up to 76.1% and 65.2%, 81.0% and 66.2%, and 64.4% and 32.5% of the sum IVs of respective families and species in the corresponding forests. Two-way indicator species analysis (TWINSPAN) divided the plantation, secondary forest, and primary forest into 8, 9, and 8 community groups at the third level, respectively. Diversity and structure indices were significantly higher in the primary forest than in the plantation and secondary forests, except for crown breadth and Simpson index in the plantation. The values of Simpson index and evenness in the plantation were highly significantly higher than in the secondary forest. And the values of density and coverage in the plantation were highly significantly lower than in the secondary forest. Thus, variable disturbance intensity resulted in variation in communities’ composition and diversity characteristics in these forests. Our results may be informative for choosing forest management strategies in the Karst cluster-peak-depression region.