川黔地区濒危植物红豆树种群结构与数量动态特征

Population structure and number dynamic characteristicsof endangered plant Ormosia hosiei inSichuan and Guizhou provinces, China

红豆树(Ormosia hosiei)是我国南方特有珍稀濒危植物,具有极高的经济价值和人文价值。为了解红豆树种群在川黔山区的生存现状及制约种群发展的原因,该文以川黔4个区域红豆树自然种群为调查对象,采用典型样地调查的方法,根据不同种群的分布特征,每个种群分别设置2个面积为20 m×20 m的具有代表性的样地进行调查,通过编制种群静态生命表、绘制存活曲线、计算数量动态指数、利用生存函数及时间序列模型分析了川黔山区不同红豆树种群的结构与动态特征。结果表明:(1)河株村和干耳盘村种群龄级结构呈倒“J”型结构,陈家湾村和绒春村种群呈不规则“哑铃”型结构,红豆树种群自然更新能力强,但中龄级个体容易缺失。(2)4个种群均为增长型,存活曲线接近于Deevey-Ⅱ型,其中河株村、陈家湾村和绒春村种群消失率和死亡率呈“多峰型”,种群在生长中期容易受到外界干扰。(3)红豆树种群数量动态变化表现为幼龄级个体死亡率高,成熟龄级个体数量动态稳定的特点,其形成原因与山区地形特点和红豆树种子传播特性有关。(4)RDA排序结果显示,海拔和坡度是影响幼龄个体数量结构的主导因子,干扰强度是影响种群中高龄个体数量结构的主要因素。综上表明,川黔山区红豆树天然种群结构与数量特征的形成受制于山区地形特点、红豆树自身繁殖特性以及环境压力;通过对种群幼龄个体密度控制和中龄个体生长空间进行管理,可以提高种群幼苗存活率,促进中龄个体健壮生长,维持红豆树天然种群稳定性。

Ormosia hosiei is a rare and endangered plant that is narrowly distributed in South China,with important economic and humanistic values.In order to find out its survival status and the reasons that restrict its development,we investigated the natural populations of O.hosiei in four regions of Guizhou and Sichuan provinces.According to the distributive characteristics of different populations,we set up two 20 m×20 m for each population by using the method of plot investigation and conducted a community survey in each plot.The structural characteristics of O.hosiei populations were analyzed by establishing population static life tables and drawing populations survival curves.Four survival functions,number dynamic index,and time series model analysis were used to describe survival status.The results were as follows:(1)The age-class structure of O.hosiei populations were in the shape of“J”at Hezhu Village and Ganerpan Village,in the shape of“Dumbbell”at Chenjiawan Village and Rongchun Village,the populations had strong natural renewal ability,but middle-aged individuals were easily missing.(2)The four populations belonged to the increasing type,the survival curves of populations are close to Type Deevey-Ⅱ,the disappearance rate and mortality rate of O.hosiei populations showed a“Multimodal”pattern in Hezhu Village,Chenjiawan Village and Rongchun Village,indicating that the populations were susceptible to external disturbances in the middle period.(3)All O.hosiei populations in different regions appeared to decrease in the early stage and keep dynamically stable in the medium-late stage,and the formation reasons were related to the topographic characteristics of mountainous areas and the seed dispersal characteristics of O.hosiei.(4)RDA analysis showed that altitude and slope were the dominant factors affecting the populations structure of young individuals,and interference intensity was the main factor affecting the number structure of older individuals.All the above results indicate that the structural and number characteristics of O.hosiei populations in different regions are restricted by the topographic characteristics of mountainous areas,the reproductive characteristics of O.hosiei and the environmental pressure;By controlling the density of young individuals and managing the growth space of middle-aged individuals,we can increase the survival rate of the seedlings,promote the healthy growth of middleaged individuals,and maintain the stability of the natural populations of O.hosiei.