Effects of invasive eastern redcedar on capture rates of Nicrophorus americanus and other Silphidae

Because of fire suppression and improper land management, native eastern redcedar, Juniperus virginiana L., is invading many grassland areas. Among these areas are the Loess Canyons of southeastern Lincoln County, NE, which support a large population of the federally endangered American burying beetle, Nicrophorus americanus Olivier. In the past 30 yr, cedar encroachment has covered >30% of this landscape and is increasing at a rate of 2% per year. The effects of cedar trees on remaining populations of American burying beetle are currently unknown. In this study, we sampled two sites in Lincoln County, NE, by placing paired baited pitfall traps (N = 16) in cedar-dominated and open grassland habitats during June and August 2004 and 2005. We collected significantly more Silphidae, including American burying beetle in open habitats. All American burying beetle were marked and released. The recapture rate of these beetles was two times higher in cedar sites than in open sites. Among the Silphidae, only Nicrophorus orbicollis Say was collected significantly more often in cedar areas. The results of this study indicate that cedars reduce numbers of most silphid species, likely by limiting their ability to forage for carrion, a required resource for feeding and reproduction. This is the first study to directly examine the impact of cedar on Silphidae, and our results have important implications in the Great Plains and beyond. However, future studies must examine the impacts of cedar management, including mechanical control or prescribed fire, on American burying beetle and other silphid species.