Bromus tectorum (cheatgrass) is one of the most widespread invasive species in the western United States. In sagebrush steppe rangeland it alters fire frequency, soil moisture, and nutrient dynamics, decreasing the value of rangeland for wildlife and livestock and increasing costs associated with fire remediation and habitat restoration. Land managers have observed cheatgrass expansion into areas that were previously uninvaded in the Southern Rocky Mountain region. Currently cheatgrass invasion has been shown to exhibit positive feedbacks on plant community change, however, it is possible that management intervention soon after disturbance may restore negative feedbacks and promote recovery to a pre-disturbance community. We ask whether herbicide application can be used to avoid the process changes that cheatgrass can cause and promote desirable plant communities resistant to reinvasion. We collected baseline data on plant functional group cover in 8 burned sites in southeast Wyoming, 4 of the sites burned within 3 years of plot establishment (NB) and 4 sites burned between 3 and 12 years of plot establishment (OB). Paired unburned (UB) plots were established in 7 of the 8 sites to assess whether plant communities are recovering to pre-disturbance communities. Half of the plots were treated with imazapic) herbicide applied at a rate of 5oz/ac (148ml/0.4ha) in the fall.

Results/Conclusions

Cover of plant functional groups was reassessed the following summer. Preliminary results indicate that cheatgrass cover was reduced in treated plots. There was no significant difference in cheatgrass cover in treated NB plots versus treated OB plots. We detected no difference difference in cheatgrass cover between NB and OB control plots, indicating untreated plots were not recovering to pre-disturbance levels through natural processes. Assessment of underlying ecosystem processes in semiarid systems subject to nonlinear plant community change following disturbance such as this will provide a better understanding of mechanisms underlying observed changes in species composition.