纸坊沟流域植被恢复区灌木林昆虫群落时间结构及动态

通过对纸房沟流域不同植被恢复区昆虫进行调查,结果表明:昆虫种类数以天然灌木林最高,混交林次之,单纯林分较低,个体数量以柠条林昆虫数量最高,其次为混交林和沙棘林,天然灌木林变化幅度最小。各植被昆虫种类和数量季节变化符合y=ax3 bx2 cx d函数变化规律。从特征指数来分析:昆虫群落多样性指数5～9月份大小次序均为天然灌木林>混交林>单纯林分,均匀度以单纯林和混交林的昆虫群落变化幅度较大,天然灌木林变化幅度最小。群落的优势度与均匀度值的变化呈相反趋势。主分量分析表明:植物类型不同的昆虫群落,其主导因素和时间格局不同,且结构越复杂,主导因素和时间格局越明显;相反,则主导因素和时间格局分化不明显;通过排序植食性昆虫、捕食性昆虫、寄生性昆虫在各植被昆虫群落变化的不同时期占主导因素。

The time structure and dynamic of insect communities in the bush vegetation restoration areas of Zhifanggou watershed in Loess hilly region

The insects were investigated from March 2004 to November 2004 at Zhifanggou watershed in hilly area of loess plateau..The result showed that the insect species varied spatially in the following order:the natural bush forests,the mixed forests,and the simple forests.The number of the insect individuals in Caragana korshinskii were the highest,followed by mixed forests and Hippaphae rhamnoides,and the number of the insect individuals in the natural bush forests were the smallest.The season changes of number of the insect species and individuals in various vegetations can be described by a function y=ax3 bx2 cx d.The order of diversity value of the insect community in various vegetations from May to September were the natural bush forests,the mixed forests and the simple forests.The evenness value's change range of the simple forests and mixed forests are higher,and the natural bush forests are smaller.Contrary trend are assumed in the dominance values and the evenness values in time course.The principal component analysis were used for studying main factors and the temporal patterns of the insect communities in different time,and the insect commuonty in the natural bush forests had a more complicated composition,less fluctuation,more obvious mian factors and temporal patterns.However,in the mixed forests and the simple forests,the composition of the insect commuonty were simple and fluctuated greatly,their mian factors and temporal patterns were not obvious.