塔里木盆地灰叶胡杨种群数量动态

Quantity and Dynamic of Populus Pruinosa Population in Tarim Basin

[目的]了解塔里木盆地灰叶胡杨种群的数量及动态。[方法]以林木径级结构代表年龄结构,绘编灰叶胡杨种群结构图;采用分段匀滑技术,编制灰叶胡杨种群的生命表、存活曲线、死亡率及亏损率曲线,分析灰叶胡杨种群结构与动态趋势。[结果]塔里木盆地灰叶胡杨种群年龄结构呈双曲线型,幼苗数及成年个体数都较丰富,1龄向2龄过渡时死亡率较高,达71.9%,致使2龄级个体偏少,4龄以后各龄级比例协调。灰叶胡杨种群存活数随年龄的增加而降低,幼龄与老龄的生命期望较低。种群的存活曲线趋于DeeveyⅢ型,死亡率和亏损率曲线均有2个高峰期,与树种生物生态学特性及环境恶化有关。[结论]灰叶胡杨种群呈增长型,死亡率高峰出现在1～2龄级和6龄级附近。幼苗到中龄级个体的不足是胡杨种群濒危的重要原因。

Objective The study aimed to learn the population quantity and dynamic of Populus pruinosa in Tarim basin.Method With diameter class structure of forest trees as age structure,the population structure chart of P.pruinosa was drawn.The life table,survival curve and the curves of mortality and deficiency rate of P.pruinosa population were drawn by segmentation smoothness technique to analyze the population structure and dynamic trend of P.pruinosa.Result The age structure of P.pruinosa population in Tarim basin showed to be double-curve type,with richer seedlings number and adult individual number.The mortality during the transition from the 1st instar to the 2nd was higher,being up to 71.9 %,which caused that the 2nd instar individuals were less and the proportion of age classes was harmonious after the 4th instar.The survival number of P.pruinosa population reduced along with the increment of age,and the life expectations of the young and old population were lower.The survival curve of population tend to be DeeveyIII type and the curves of both mortality and deficiency rate had 2 peak stages,relating to the biological and ecological characteristics of the tree species and environmental worsening.Conclusion The P.pruinosa population showed to be increase type,the mortality peak occurred near the 1st～ 2nd and the 6th age classes.The shortage of seedling individuals reaching middle age class was the important reason for P.pruinosa population being in severe danger.