PARENT SESSION
Poster Session #59: Fire Ecology II.
Thursday, August 8. Presentation from 8:00 AM to 9:30 AM. Exhibit Hall B & C, TCC

The effects of fire and grazing on an arid grassland ecosystem.

Nordell, Shawn^*,1, Valone, Thomas¹, Ernest, Morgan², ¹ St. Louis University, St. Louis, MO² University of New Mexico, Albuquerque, NM

ABSTRACT- Disturbances can strongly affect ecological systems but few studies have examined how multiple, potentially interacting disturbances might affect community structure and biodiversity. Grasslands are subjected to multiple disturbances such as grazing, fire, and drought and thus are ideal settings to study both the effects of single disturbance types and potential interaction effects. We examined short-term responses of grasses, shrubs and rodents on experimental plots to determine how manipulations of livestock grazing and prescribed fire affect individual species and community structure in a shrub-invaded arid grassland. Protection from grazing for 2 years did not affect the vegetation of the study site. However, burning significantly reduced total grass basal cover by 20%. Thirteen perennial grasses were recorded and two grasses (Aristida sp. and Eragrostis intermedia) and Broom Snakeweed (Gutierrezia sarothrae) were found in lower abundance on burned plots in the growing season after plots burned. All honey mesquite (Prosopis glandulosa) survived the fire. Twelve species of rodents were captured. Total rodent captures and the number of Banner-tailed Kangaroo Rats (Dipodomys spectabilis) did not differ among treatments. No significant interaction between burning and grazing was observed. Fire appears to have few short-term negative effects on species in this system.

KEY WORDS: fire, grazing, grassland, disturbance