Abstract: Clausena dunniana, a dominant species in the subtropical karst forests, is widely distributed across all successional stages, making it an ideal indicator species for understanding forest dynamics. In this study, we investigated C. dunniana populations across different successional stages in the Maolan National Nature Reserve, including tree-shrub mixed forest (SC), secondary growth forest (SG), and old-growth forest (OG). By integrating static life tables, survival analysis, time-series forecasting, and competition indices, we analyzed population structure and dynamics. The results showed that: (1) Population age structure varied across successional stages, with SC exhibiting a typical increasing reverse J-shaped pattern, SG showing a pyramid-shaped distribution, and OG displaying a spindle-shaped structure with insufficient recruitment of young individuals. (2) The population dynamic index (V_pi) revealed the highest theoretical growth potential in SC (53.03%), but the actual regeneration index (V_pi′) under disturbance approached zero across all stages (SC: 0%, SG: 1.01%, OG: 3.29%). (3) Survival curves conformed to Deevey Type II in SC and SG, and shifted to Deevey Type I in OG. (4) Survival analysis demonstrated that mortality risk in SC was concentrated in early life stages, increased gradually with age in SG, and peaked during middle to late life stages in OG. (5) Time-series projections indicated a long-term decline in population size across all successional stages due to insufficient recruitment. (6) Interspecific competition emerged as the dominant limiting factor, with competitive intensity decreasing as diameter at breast height increased, and reaching the peak at the sapling stage. By elucidating the population dynamics of C. dunniana and highlighting the constraining effects of competitive pressure on population development in the fragile karst habitat, our results provide a scientific foundation for forest restoration and biodiversity conservation.

Key words: karst, population structure, population dynamics, static life table