Fuel reduction treatment and wildfire influence on carabid and tenebrionid community assemblages in the ponderosa pine forest of northern Arizona, USA

We investigated the response of community assemblages of carabids (Coleoptera: Carabidae) and tenebrionids (Coleoptera: Tenebrionidae) from June to August in 2003 and 2004 on ponderosa pine forest stands of various conditions that were created by fuel reduction treatments (thinning, and thinning plus prescribed burning) and wildfires between 1987 and 1996 in northern Arizona. We found that richness and abundance increased for carabids but decreased for tenebrionid significantly from June (the driest season of the year) to August (wet monsoon season of the year), a temporal partition for ecological niches in ponderosa pine forests. For both taxa, wildfire burned stands had the highest species richness and diversity; whereas the thinned stands had the highest species evenness. Both fuel reduction treatment and wildfire resulted in significantly different community assemblages of carabids and tenebrionids compared to unmanaged stands. Results showed that carabids from the genera of Amara, Anisodactylus, Cicindela, Harpalus, Radine, and tenebrionids in the genus of Eleodes were ecological indicators for wildfire stands. However, Synuchus dubius, and Coelocnemis spp.1 were indicator species for thinned stands, and unmanaged stands, respectively. We concluded that the richness and diversity of both taxa tended to increase after fuel reduction treatment and wildfire, and that some species from both taxa were suitable as ecological indicators for the structural change of ponderosa pine forests. Creating a mosaic of heterogeneous landscape through mechanical fuel reduction treatments is an important management strategy to maintain high invertebrate species diversity in ponderosa pine forest ecosystems in the southwestern US.