COS 130-5 - Native species recover slowly after yellow bluestem removal

Abstract: Yellow bluestem (Bothriochloa ischaemum) is one of the major threats to grasslands in the southern United States. Grasslands invaded by yellow bluestem have lower diversity and abundance of native plants, arthropods, and birds. Yellow bluestem can be killed or removed in some circumstances, but the responses by native species after removing yellow bluestem are still unclear. To test for recovery after invasive species removal, we used clipping to remove yellow bluestem from replicated plots in an invaded grassland and tracked the recovery of the native plant community for 8 years, comparing removal plots to plots without removal. Before removal, all plots had high cover of yellow bluestem (average = 73% cover) and low species richness (3 species). Species richness in removal plots remained low for the first two years but increased to 12 species by year 8. Total plant cover was lower in removal plots through year 5 and similar to controls by year 8 but total grass cover always remained lower in removal plots. It is unclear whether the slow recovery of native plants is due to the lack of seed (no seed bank and/or low seed rain) or whether yellow bluestem has a long-lasting legacy on soil conditions. In fall 2022, we initiated a new experiment to test whether seed addition will increase native plant recovery. We will share preliminary data to be collected in spring 2023.