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Abstract: Crofton weed (Ageratina adenophora) is a highly invasive weed that has spread into several provinces of southern China. This study compares carabid assemblages originating from native pastures with assemblages in Crofton weed dominated communities in the Lancang County, Yunnan Province, to assess how the invasion of this neophyte impacts the community structure of ground-dwelling arthropods. Over a period of 16 months, a total of 1574 carabid beetles representing 28 species were collected at two types of pasture, and 679 carabid beetles representing 34 species at stands of Crofton weed. The most common carabid species, Tetragonoderus arcuatus and Harpalus indicus, were mostly found in the pastures, while four of the five rarest species were present exclusively under Crofton weed. Alpha-diversity and evenness of carabid assemblages were greater under Crofton weed. Three distinct groups of carabid species were separated according to indicator values and a characterization of habitats: habitat generalists, Crofton weed specialists and native pasture specialists. The distribution of carabid species was related to environmental parameters such as depth of litter layer, total phosphorus, height of vegetation, amount of fresh biomass and pH of the soil. According to this study, the invasion of Crofton weed will alter the structure of carabid communities, but will not necessarily reduce the alpha-diversity of carabid assemblages. [Copyright &y& Elsevier]

Abstract: Diversity and species composition of carabid beetles were investigated at Quzhou county in the North China Plain. The study area was originally affected by high salinity and desalinized in three stages in 1973, 1978 and 1982. At sites desalinized in 1982, carabids were sampled at field margins as well as inside fields to investigate the role of field margins as refuge habitats. Furthermore, samples were taken from field margins desalinized in 1973 and 1978, respectively, to explore long-term developments of carabid assemblages following desalinization. At margins, soil salinity, N contents and the number of plant species as well as the height of dominant plants were recorded and their correlation with the species composition of carabids explored. Overall carabid diversity at Quzhou was low compared to areas not affected by high salinity. Field margins yielded significantly higher numbers of both species and individuals, whereas assemblages within the field had a low diversity and a homogeneous species composition. Carabid diversity slightly increased in relation to decreased soil salt contents and time elapsed since desalinization. These results may be explained by field margins serving as refuge to many carabid species and by an overall low species pool of carabids in Quzhou due to former high salinity, current high levels of fertilizer and pesticide applications, and by a comparatively low colonization rate of carabids to the area. As different carabid species varied strongly in their reaction to environmental parameters, the preservation of a diverse set of habitats will best protect the current diversity of these beetles in the agricultural landscape of Quzhou. [Copyright &y& Elsevier]