水蚀风蚀交错带黑沙蒿灌丛斑块种群结构及动态特征研究

Structure and Dynamic Characteristics of Shrub Patch of Artemisia ordosicain the Cross Areas of Wind-water Erosion

黑沙蒿(Artemisia ordosica)作为黄土高原水蚀风蚀交错带沙地植被演替的先锋植物,对维护该地区生态系统的稳定性起到重要的作用。该研究以黄土高原水蚀风蚀交错带黑沙蒿灌丛斑块作为研究对象,通过对灌丛斑块的样地调查和数据统计,编制了黑沙蒿灌丛斑块的静态生命表,绘制其存活曲线和生存分析函数的曲线,并采用时间序列模型对种群的数量动态进行预测,以揭示水蚀风蚀交错带黑沙蒿灌丛斑块种群结构和动态特征。结果表明:(1)黑沙蒿灌丛斑块数量结构属于增长型,但Ⅰ、Ⅱ级灌丛数目少于Ⅲ级数目。(2)数量变化动态指数(V′pi)趋于零,说明灌丛斑块对外界干扰比较敏感。(3)存活曲线趋于Deevey-Ⅱ,表明黑沙蒿斑块种群各大小级的死亡率基本接近。(4)生存分析和时间序列预测表明,黑沙蒿小灌丛斑块个体的缺乏是未来中灌丛斑块数量衰减的主要原因。研究认为,黄土高原黑沙蒿灌丛斑块在研究区内生长更新良好,能够适应水蚀风蚀交错带的气候环境,种群处于稳定增长状态,为其他植物种群的定居和恢复创造了水养生境条件。

Artemisia ordosicais the pioneer plant in the cross areas of wind-water erosion in Loess Plateau in China,which plays an important role in the stability of the ecosystems in the regions.We chose the shrub patches as the research objects.Based on the plot investigations in the cross areas of wind-water erosion,the static life table was established,survival curves and the function curves derived from the survival analysis were also constructed to evaluate the A.ordosicashrub patch population characteristics.The A.ordosicapopulation dynamics were predicted by a time-sequence model.The results showed that：（1）the age structure of the A.ordosicashrub patch was a pyramid,but there were fewer individuals in classes I andⅡthan in class Ⅲ;（2）The number dynamics index（V′p i）was close to zero,so the A.ordosica shrub patches were sensitive to environment disturbances;（3）The survival curve of the A.ordosicashrub patch appeared to approach the Deevey-Ⅱ type,which indicated that the mortality rate in different sizeclasses was similar;（4）The survival analysis and the time-sequence model demonstrated that the lack of young individuals could be the major cause for the decrease of middle size class shrub patches.Therefore,the research suggested that the A.ordosicashrub patch,in Loess Plateau in China,could grow,renew,and adapt well in the cross areas of wind-water erosion climate environment,and the population was in stable increasing the situation,which created the water and nutrient condition for the settle and recover of other plants.