Understanding spatial dynamics of Tallgrass prairie dominated by tall fescue

This study was conducted on restored tallgrass prairie and invaded tallgrass prairie located in the Grand River Grasslands of southern Iowa to determine differences in heterogeneity of plant structure and functional group composition at different scales. Restored tallgrass prairies were seeded with a species-rich seeding mixture and managed by burning the entire prairie, every three years. Data were collected in August 2014 and 2015 to compare heterogeneity of restoration of native plant structure and functional group composition to the heterogeneity of invaded tallgrass prairies that were managed with patch burning and conventionally grazed. Invaded tallgrass prairies were managed with patch-burning to create a fire-grazing interaction where grazers preferentially grazed patches of the landscape that had been recently burned. We quantified structural heterogeneity in invaded landscapes managed with patch burn grazing under two different grazing strategies. The grazing strategies we compared were 1) season-long stocking (April – September) and 2) intensive early stocking (April – July). Data were collected early, late, and after the growing season in 2014 and 2015 to determine how heterogeneity changed throughout the year. Heterogeneity was higher in invaded patch-burned sites than in restored tallgrass prairie. Patch burning created patch-level heterogeneity in litter and bare ground measurements but not in structure or plant functional group composition. IES did not increase among-patch heterogeneity compared to SLS, but it did increase within-patch heterogeneity. Tall fescue forage quality is higher than many native grasses, and has low amounts of standing dead post-fire. These characteristics shifted grazers focus from recently burned patches, as is typically seen in native grasslands managed with patch-burning, and created conditions whereby grazers patchily grazed throughout the pasture. Advisers: Walter H. Schacht and Dirac Twidwel