Rehabilitating Invaded Rangeland in Central South Dakota with Grazing, Seeding, and Herbicides

Rangelands in the northern Great Plains are threatened by invasive C3 annual and perennial grasses that displace native C4 grasses. Rehabilitating these rangelands by reintroducing native C4 grass species could extend the season in which relatively higher-quality forage is available for livestock grazing and improve wildlife habitat. Three seeding treatments, four herbicide treatments, and two stocking densities were applied to a pasture in central South Dakota, United States, that was dominated by invasive C3 grasses. Grazing and herbicide treatments were designed to suppress exotic cool season grasses. Drought limited establishment during the first 2 yr, but C3 grasses were successfully controlled during this time. Plots drill-seeded and sprayed with glyphosate established a mean of 1.0 seeded grasses m-2 by the third yr. Unseeded plots and plots that did not receive glyphosate failed. This trend continued into yr 5, when the most successful treatments were composed of 10-14% seeded C4 grasses, as determined by a modified step-point count technique. Stocking density did not affect establishment success. It is possible to suppress C3 invasive grasses with herbicide and establish native C4 tallgrasses in central South Dakota, but drought makes it a risky proposition in this semiarid region. (c) 2023 The Society for Range Management. Published by Elsevier Inc. All rights reserved.