Ground beetle community structure as a bioindicator of forest health

The controversy over the definition of forest health has been attributed to the lack of criteria to design and evaluate forest management objectives within societal and environmental goals. A widely accepted both societal and environmental goal could be the maintenance of habitat for native species which contribute to ecosystem function. The ground beetle (Coleoptera: Carabidae) guild has been suggested as a suitable bioindicator taxon. This study was undertaken with the general objective of determining the effect of different disturbance levels on ground beetle community structure. A literature review was done to search for patterns of ground beetle response to forest fire and logging. Field experiments were also carried out. One study was done in Nevado de Colima National Park, Mexico to evaluate the effects of bark beetle attack and sanitation logging to pine stands using time since disturbance as a factor. Residual tree vigor, basal area estimates and ground beetle assemblages were used as forest health criteria. Stands previously attacked and sanitized resulted in good healthy condition as indicated by stand structure and vigor. Overall low diversity of ground beetle was found with overwhelming dominance of the species Calathus aztec Ball and Negre. Changes due to time since disturbance suggest ground beetle as potential bioindicator of forest health. Another field experiment was carried out in northern Arizona ponderosa pine to determine the effect of four stand treatments (unmanaged, thinning only, thinning plus prescribed burn and wildfire) on ground beetle species assemblage, and to identify candidate indicator species. The unmanaged forest condition had the lowest diversity of ground beetles and thinning only did not significantly change this low diversity. Both conditions were dramatically dominated by the species Synuchus dubius Kirby. A prescribed burn applied to previously thinned stands significantly increased ground beetle diversity. The indicator species was Cyclotrachelus constricus Say. Wildfire resulted in the most diverse assemblage, however, it was dominated by open-habitat species on the genus Amara and Harpalus . The relative abundance of indicator species and the presence or absence of functional groups is suggested as a parameter to assess forest health.