Ground dwelling beetles and forest vegetation change over a 17-year-period, in western Oregon, USA

Regrowth and old-growth Douglas-fir stands were sampled for ground dwelling beetles using pitfall traps in 1982, 1983 and 1999. Species richness and abundance was compared within and among years, plots, and age of forest using multivariate techniques. Representatives of 49 families and 224 taxa were collected for a total of 11,191 specimens. The abundance and species richness of ground dwelling beetles suggested four notable relationships. First, different ages of forest had significantly different beetle communities. For instance, the herb stage regrowth stands supported a number of seral specialists including: Microlestes nigrinus Mannerheim and Trachypachus holmbergi Mannerheim. Second, specifically defined plant communities were associated with unique beetle communities. Ordination analysis showed that the grouping of stands, based on beetle communities, was correlated with differences in vegetative characteristics. Third, over a 17-year-period, beetle communities in old-growth stands remained relatively stable while beetle communities in regrowth stands exhibited a high degree of change. Ordination analysis grouped old-growth stands regardless of year sampled, while young seral stands changed significantly in regards to their ordination position depending on sampling year. Fourth, beetle communities in regrowth stands changed in a manner that paralleled the predictable transformation of young plant communities into mature forest stands. Ordination analyses found that beetle communities in the herb stage regrowth stands of 1982 had changed significantly and exhibited characteristics of beetle communities in tree stage regrowth stands. (C) 2002 Elsevier Science B.V. All rights reserved.