Temporal and spatial distribution of ground beetle (Coleoptera : Carabidae) assemblages in grasslands and adjacent wheat fields

Ground beetles were captured during winter wheat growing season in 1993-199 4 at four sites and in 1996-1997 at two sites using pitfall traps positione d in grasslands, wheat fields, and along grassland-wheat field edges. Of 69 species collected, six species accounted for 75.5 % of the total number of beetles captured. The numbers of these species captured varied among years , seasons, and habitats. Species composition was most strongly influenced b y season, followed by year, and then habitat (wheat vs. grassland). Ground beetles that reproduce in spring were separated from those producing young in autumn along the first axis of a canonical correspondence analysis (CCA) . With the effects of season and year removed, ground beetles were classifi ed with respect to habitat preference along axes one and two of a partial C CA. Based on the ordination by partial CCA, ground beetles were classified as either habitat generalists, wheat specialists, grassland specialists, or boundary specialists. Landscape structure was an important component in de termining the spatial distribution of ground beetles.