麦蚜混合种群发生的分形性质初探

Analysis on fractal characters of wheat aphids mixed populations

运用分形理论,对1987～2006年间麦蚜混合种群发生的田间系统调查资料进行分析,对麦蚜混合种群发生的性质进行探讨.结果表明:麦蚜发生具有分形性质,其分维值为0.338 7,分维值较小,说明发生程度较重.4月、5月份每隔5 d的时间序列分维值中.4月份至5月15号分维值下降,然后上升.5月10日至20日分维值较小,说明此时段麦蚜集中发生.

The mixed population of wheat aphids occurrence was investigated by means of fractal theory based on the systematic field investigation data of wheat aphids occurrence in 1987～2006.The results indicated that wheat aphids occurrence had a fractal property with the D value 0.338 7,the less of the fractal dimension value showed the lighter of the wheat aphids occurrence.The fractal dimension value was degressive from April to fifteen May,then ascending.The minimum fractal dimension value in 10～20 May indicated wheat aphids concentrated occurrence in this period.