石羊河中下游沙蒿种群年龄结构与动态分析

对石羊河流域中下游沙蒿(Artemisia arenaria)种群进行了调查，利用体积结构理论划分沙蒿种群冠级结构，绘制静态生命表及存活曲线，分析沙蒿种群年龄结构与动态，主要结果如下：（1）沙蒿种群幼龄级个体数目多，中龄级的个体数稳定，而高龄级个体由于种间竞争及环境因子的影响，个体数少； （2）沙蒿种群的存活曲线趋于Deevey-Ⅱ型，动态表现为前期增长，中期稳定，后期衰退；（3）沙蒿种群的生存率函数单调下降, 累积死亡率函数单调上升，死亡密度函数曲线表现的较为平缓，而危险率函数表现出随着龄级的增加而逐渐增大的趋势。

Population Age Structure and Dynamic Analysis of Artemisia arenaria in Middle and Lower Reaches of Shiyang River Area

This research investigated the Artemisia arenaria population in the middle and lower reaches of Shiyang River basin. By using the volume structure theory, we classified the age structure of Artemisia arenaria population, mapped the survival curve and static life table, and analyzed the age structure and dynamic condition of Artemisia arenaria population. The main results are as follows: (1) the individual number of young Artemisia arenaria population is large, of middle-age class is stable, whereas of senior-age is less due to the effects of interspecific competition and environmental factors; (2) the survival curve of Artemisia arenaria population exhibits a tendency of Deevey-Ⅱ type; with regard to the dynamic performance, it shows an early-stage growth, medium -term stable condition and late-stage recession; (3) the function of survival rate of Artemisia arenaria population decreases monotonically, whereas the function of cumulative mortality increases monotonically. The curve of morality density is relatively flat，and the function of hazard rate demonstrates a progressively increasing trend with the increasing age class.