Investigation of Vertical Structure of Insect Community in Picea crassifolia Forest

The insects in different layers of the spruce(Picea crassifolia) forest in difgerent latitude area in Qilian Mountains Nature Reserve were investigated and analysed,using connection survey as the main method combining with tread survey and sift survey and with manpower collection and light collection.The results showed that the phytophagous insects in the spruce forest in Qilian Mountains exhibited obvious vertival stratification structure.According to the amounty of species of each structure,it could be divided into 6 insect communities,namely the insects community of fhe shrub and herbage(928 species),of the soil and root(780 species),of the tender end and needle(117 species),of the stem phloem and xylem(66 species),of the branch thin end twig shin(38 species),of the blossom and seed and fruit(14 species).According to the degree of infestation,from heavy to light,the insect communities followed the order of the tender end and tender needle,the stem phloem and xylem,the soil and root.The majority of the insects feeding on or parasitizing in Picea crassifolia were monophagous or oligophagous;the minority of them were polyphagous.The insects feeding on or parasitizing in the bush layer and grass layer were largely polyphagous,a few were oligophagous,the oligophagous insects were very few.The feeding parts on the tree of the majority of the insects were relatively fixed,but there were many insects feeding on several parts of trees.