Document: ERI-3-64-21

Changes in semi-desert grassland plant communities 10 years following cessation of grazing and reintroduction of fire.

GEIGER, E.L.* and G.R.MCPHERSON

University of Arizona, Tucson, AZ 85721, USA ¹

Abstract:
Invasive non-native species, livestock overgrazing, and fire suppression have been blamed for the changes in structure of semi-desert grasslands in the southwestern United States. Specifically, these factors are thought to have reduced native species diversity and hindered restoration and conservation efforts. Management targeted at restoration of native vegetation and reduction of non-native populations has included removal of cattle and reintroduction of frequent prescribed fires. The Buenos Aires National Wildlife Refuge (BANWR) was established in southeastern Arizona in 1985 to provide habitat for the recovery of the masked bobwhite quail (Colinus virginianus ridgwayi), a federal endangered species. Much of BANWR is dominated by Eragrostis lehmanniana Nees (Lehmann lovegrass), an undesirable introduced grass from South Africa. We analyzed data collected as part of a long-term vegetation monitoring survey in 1987, 1989, 1993, and 1997 on 38 permanent transects at BANWR using repeated-measures analysis of variance, and determined that basal cover of native species and non-native species have not changed substantially in ten years. We assessed the influence of fire regime on basal cover of native species and non-native species in 1993 and 1997; neither fire frequency nor time since fire affected cover or species composition. However, average cover of E. lehmanniana increased in 1993 on soils with low clay content, likely in response to above-average annual rainfall. This study suggests that climatic and edaphic factors may outweigh management efforts.

Keywords: fire, grazing, nonnative, invasive, Eragrostis lehmanniana

This abstract is being presented at: 8:45 AM in session:
Oral Session #19: Grassland Restoration.