Cheatgrass (Bromus tectorum) is an exotic invasive grass now found in most western states. Becky Kerns, a research ecologist with the Forest Service’s Pacific Northwest Research Station, and her colleague Michelle Day with Oregon State University, investigated how cheatgrass responded to both the frequency and season of prescribed burning over a 10-year period in stands of ponderosa pine in the Malheur National Forest in eastern Oregon. They created a model to explain cheatgrass dynamics at different invasion stages, from local cheatgrass establishment to broader scale invasions.They found: Cheatgrass cover increased with fall burning regardless of burn frequency (1 burn versus 3 burns) between 2002 and 2012. At fine scales, initial burn coverage helped cheatgrass establishment while native annual forb cover (biotic resistance) constrained spread. Initial cheatgrass abundance in 2002 was key in explaining the extent of cheatgrass by 2012. Abiotic and biotic processes that affected cheatgrass expansion varied with invasion stage, but ultimately, biotic factors such as native plant diversity and cover were not enough to totally mitigate the spread of cheatgrass. These findings will be helpful to resource managers planning restoration and conservation efforts in ponderosa pine forests.