独叶草种群年龄结构及动态分析

对太白山不同生境条件下的独叶草种群年龄结构、生命表及存活曲线进行了研究，结果表明，不同生境的独叶草种群在3～6年生阶段个体数量最多。幼年个体和老年个体数量较少，生命表中。幼龄级的dx、qx、Kx等为负数，可以反映种群幼龄个体缺乏程度．以无性繁殖独叶草不同与以有性生殖为主的植物，它可产生不同龄级的无性系分株，幼龄个体少的年龄结构并不代表种群必然衰退．随海拔升高，种群密度增加，个体寿命延长，反映了种群在适应性方面的调整．独叶草种群根状茎生存于腐殖质层中，仅有叶片露出地面；种群所在的牛皮桦、巴山冷杉和太白红杉群落人为干扰较少。生境相对稳定，种群可以长期维持．对种群保护应注重所处的环境及森林群落保护。

Analysis on age structure and dynamics of Kindonia uniflora populations

Kindonia uniflora is a perennial clone herbaceous plant, and also, a native endangered plant in China. This paper studied its age structure, life table and survivorship curve in different habitats in Taibai mountain area. The results indicated that the age structure and dynamics of K. uniflora populations in the Betula utilis forest at altitude 2500-2700 m, in the Abies fargesii forest at altitude 2700-2900 m, and in the Larix chinensis forest at altitude 2900-3100 m had the similar pattern and developing tendency. The number of younger ramets at 1-2 years old or older than 5 years was less, and the number of ramets at 3-5 years old was the highest in the age structures. The negative values of dx (dead number), qx (mortality rate) and Kx (Killing rate) in the life table showed the increasing rate of the population sizes during the age stage. The survivorship curve of K. uniflora populations in different habitats belonged to Deevey C after 3-5 years old. The mortality rate of populations during 5-10 years stage was higher, and was stable after 10 years old. As for the characters of asexual propagation and clone growth, the rhizomes of the populations were in humus of soil, and developed and expanded as guerilla line style. During growth season, only one leaf grew above ground at every inter-node, and the population growth and development were rarely influenced by external factors. The forest communities, such as Betula utilis, Abies fargesii and Larix chinensis forest, in which K. uniflora populations lived, were at middle or higher mountain, where there were rarely disturbance from human being. Therefore, the habitats for K. uniflora populations to live were relatively stable. As the altitude increased, the disturbances from human being became less, the density of K. uniflora populations increased, the life cycle expanded, the peak of population death delayed, and the population living strategy changed to adapt to the habitats. K. uniflora populations preferred to live in cool climate, thick humus of soil and under shaded forest, therefore, the habitat of communities of Abies fargesii, Larix chinensis forest at altitude 2700-3100 m were better than that in Betula utilis forest. The growth and development of K. uniflora populations depended on the habitats; therefore, the communities in which K. uniflora population lived should be conserved firstly. The in-situ conservation of the populations should be encouraged.