干旱区生态环境知识资源中心

This study investigated the age class structure of H. persicum populations in different edaphic types in Gurbanttinggtit desert and analyzed the survival rate, mortality rate and spectral analysis characteristics. The results showed that the survival curve of H. persicum populations tended to be the type of Deevey-III, the mortality rate of H. persicum was high at early stage and low at late stage, There existed 2-4 death peak phases in the whole population life span. The natural regeneration process of the H. persicum population can be represented by the fluctuation of the distribution of the number of trees in different age classes. Spectral analysis showed that the fluctuation of H. persicum population was multi-harmonic superposition with large periodic containing small periodic, and had more than two periodic fluctuation. Upscaling process of spectral analysis indicated that the periodic fluctuation of H. persicwn population becomes constant in relatively small sampling plot (4400-5600 m(2)), when it is growing under relatively good environmental conditions in the Gurbanttinggilt desert. On the other hand, when the growing conditions are poor, large plot (4000-9200 m(2)) is needed to obtain constant population. Accordingly, different plot sizes should be used for spectral analysis to reveal the periodic fluctuation on the optimal scale.