Abstract: In desertified region in Yanchi County,Ningxia,a field investigation on terrestrial arthropods was carried out by taking the pitfall trapping method in and out-of the Caragana Korshinskii shrubberies under different site conditions with and without mobile sand cover in spring,summer and autumn.It was found that: ① There was a remarkably seasonal difference in the activity distribution of dominant groups including Melolonthidae,Tenebrionidae and Formicidae families between the two kinds of sites conditions; ② In spring and autumn,there was a similar distribution of total abundance between the shrub microhabitats under the same site conditions,but a significantly (P<0.05) difference in total abundance between shrub microsites under the distinctive site conditions.In summer,there was a reverse distribution of total abundance between the shrub microhabitats under two kinds of site conditions; ③ In summer and autumn,there were no significant (P>0.05) differences in group richness and Shannon index between the shrub microhabitats under both kinds of site conditions,but a significant (P<0.05) different distribution of group richness between the shrub microhabitats from one kind of site conditions to another in spring.Likewise,the distribution of dominance index between the shrub microhabitats was found to be affected by the site conditions in each season; ④ The seasonal Sorenson index between the shrub microhabitats showed a reverse pattern between the two kinds of site conditions with and without mobile sand cover; ⑤ It was suggested that the individual distribution of taxonomical groups and related total abundance and dominance index was affected by the site conditions,shrub microhabitat and seasonal change.It was found that the shrub canopy facilitated the diversity of terrestrial arthropods.

Key words: site condition, terrestrial arthropod, community structure, shrub canopy, microhabitat, Yanchi, Ningxia