Fire and Drought Effects on Kentucky Bluegrass in a Northern Great Plains Grassland

Kentucky bluegrass, a mid-stature, C3, invasive grass, has dramatically increased in northern Great Plains rangelands since the 1990s and has displaced many native species. Changing precipitation regimes have the potential to affect the ecology and agricultural rangeland productivity of this area. There is a need to understand how the current Kentucky bluegrass-invaded vegetation community will respond to extreme changes in precipitation regimes and the effects these changes might have on the overall species composition, productivity, structure, and function of these ecosystems. A 5-y drought experiment was initiated in 2017 near Mandan, North Dakota, to evaluate differences between ambient precipitation, an intercept of 30%, and an intercept of 60% of ambient precipitation using passive rain intercept shelters. The experiment included a sub-plot prescribed burning treatment. Canopy cover measurements and plant counts were used to determine drought and fire effects. Our results show that prescribed burning reduces Kentucky bluegrass and that the interactive effects of drought, either simulated or meteorological, and fire, can reduce Kentucky bluegrass. If a producer's objective is to reduce Kentucky bluegrass, conducting prescribed burns in drought years or before predicted drought years is an effective way to do so. This knowledge will help develop sustainable management options for natural areas in the northern Great Plains and for livestock producers in Kentucky bluegrass-dominated rangelands of the northern Great Plains.