Cheatgrass (Bromus tectorum) is one of the most prolific invaders of western rangelands, increasing fire frequency, decreasing wildlife and livestock habitat value and limiting the use of prescribed fire as a management tool. Once cheatgrass becomes established, it modifies the environment to create an ecologically stable state that is resilient to both successional processes and management intervention. The objective of the study reported here is to evaluate landscape scale constraints on conversion of perennial grass/shrublands to cheatgrass dominated stable states. Study sites were located in southeastern Wyoming and stratified by aspect and slope position along a fire chronosequence. Circular nested plots (CNP’s) were randomly located within these strata to measure effects on plant community.

Results/Conclusions

Field observations and preliminary analysis indicate that cheatgrass is more likely to persist on south facing aspects at low to mid elevations than on other aspects. Additional CNP’s were established in areas prone to persistent infestation to test plant community and ecosystem process response to cheatgrass invasion, fire history, chemical control, seeding, and grazing. Future field work will assess the effectiveness of treatments to reduce the rate of N turnover and rate of soil moisture depletion. Researchers have identified these factors as key processes that promote alternative stable states dominated by cheatgrass.