Abstract: The community diversity of arthropod was investigated in forest-steppe ecotone in southeast edge of Inner Mongolia tableland. Totally, 15 orders, 77 families and 326 species were recorded, and they belonged to Insect, Arachnoida and Myriapoda. The individual numbers of Araneae, Diptera, Homoptera and Hymenoptera accounted for more than 10% of the total,and they were considered as dominant groups. The individual number, species number, H¹ and J increased gradually with the environment gradients from forest to steppe, with maximum in forest-meadow or meadow-steppe ecotone and minimum in steppe. The individual numbers, species numbers and H¹ of the ecotones were maximum, and they were significantly higher than that in forest and steppe. The result indicated that the edge effect was obvious in the large-scale forest-steppe ecotone. The arthropod community composition in different vegetation zones varied considerably. Their similarity gradually reduced from the forest zone to forest-meadow region, to meadow-steppe region and to steppe zones, which suggested that the similarity varied with the environmental gradient changes. The composition of arthropod community in ecotone and steppe zones had apparent differentiation from the forest zone, and the differentiation was gradually increasing. Multiple linear regression analyses showed that forest patch number and vegetable coverage were the most important factor determining the species diversity and evenness of arthropod community, and forest patch number, average forest patch size and vegetable coverage affected the individual number and species number. The percentage of nature enemy entities in different vegetation zones were (0.363 1±0.041 6)%～{(0.524 9}±0.036 5)%. The nature enemies played an important role in maintaining ecosystem balance of the forest-steppe ecotone.

Key words: arthropod, community diversity, forest-steppe ecotone, Inner Mongolia tableland