Keywords: 
• botany /
• matrix model /
• Oxalis griffithii /
• population dynamics /
• life-cycle stage

Abstract: To elucidate the population dynamics of the perennial understory herb and explore the critical life-cycle stage affecting the population growth，the perennial herb，Oxalis griffithii，was selected and investigated. Total eight long-term plots with 2.0 m 1.6 m area were set up in three habitats （evergreen broadleaf forest，Chamaecyparis obtuse plantation，conifer and broadleaf mixed forest）. The life history of Oxalis griffithii was divided into four stages（seed stage，seedling stage，juvenile stage and mature stage） according to its individual morphological characteristics. Next，Lefkovitch structural matrix models of these populations in three habitats were established based on field investigation data. Then，population dynamics and their structural changes were analyzed by mean matrix models of three given habitats. Also，critical life-cycle stage affecting population dynamics was estimated using sensitivity analysis and elasticity analysis. Results of developmental trends for population dynamics in the three habitats，given by the dominant eigenvalue of the matrices，showed that in the evergreen broadleaf forests population was stable，whereas in the other habitats population was decayed. Survival，growth and reproduction varied significantly through stage，and sensitivity parameters （sensitivity and elasticity） also varied through stage. Also，population growth rate was significantly correlated with the sensitivity and elasticity of larger stage survival. This result indicated that the plants at a larger stage were the most important to population dynamics. Therefore，conserving the plants at a larger stage is very important for protecting and conserving the perennial herb population.［Ch，2 fig. 5 tab. 19 ref.］