基于Lefkovitch矩阵模型的山酢浆草种群动态分析

Population dynamics of Oxalis griffithii using the Lefkovitch matrix model

依据林下多年生草本植物山酢浆草Oxalis griffithii的形态学特征,将其生活史划分为4个阶段,并根据3种生境下山酢浆草种群的野外调查资料建立了不同种群的Lefkovitch结构矩阵模型,在此基础上预测了山酢浆草种群的动态及其阶段结构的变化;同时,运用敏感度、贡献率指标分析了影响种群动态的关键生活史阶段。结果表明:不同生境下山酢浆草种群的动态发展趋势不尽相同,常绿阔叶林下的种群(MD)呈稳定发展状态,其他2种生境下种群表现出衰退的发展趋势;种群的动态变化过程受个体的生长、残存、萎缩和繁殖等的综合影响;不同生活史阶段对种群动态的影响差异显著,种群动态过程及其发展趋势主要受种群内较大阶段个体的影响。

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.]