Strip-seeding is a proposed cost-effective tool to reestablish native communities in highly invaded grasslands. The method involves seeding species in horizontal patches across a landscape and relying on natural dispersal for colonization of unseeded areas. However, a previous study found high invasive cover and low native diversity in unseeded patches five years after seeding, indicating a need for additional management.
Targeted grazing and prescribed burns can reduce competition from invasive species and increase native diversity. However, the community changes are transient without a sufficient native seedbank. With strip-seeding, seeded patches provide a native seed source adjacent to unseeded patches, and therefore may facilitate longer-term increases in native abundance and diversity. We ask 1) how targeted grazing, prescribed burns, and strip-seeding affect the plant community and 2) how initial strip-seeding configuration interacts with the management treatments to alter community outcomes.
We seeded native perennial bunchgrasses in horizontal strips of three varying widths (N =4) across fields in Fall 2011. In Spring 2016, we applied targeted sheep grazing and small-scale prescribed burning, alone and in combination to the strip seeding plots. We measured native and non-native diversity and abundance within unseeded patches to determine the effects of the treatments on the community.
Results/Conclusions
Native diversity was highest in treatments that were burned and grazed, followed by treatments that were only burned. Grazed treatments did not have significantly higher native diversity than control plots. Non-native cover was 22% lower on average in the burned and grazed treatment compared to controls. Burned treatments and grazed treatments were not as effective at reducing non-native cover as the combination treatment with only 13% and 10% average reductions, respectively. This suggests that combining these management approaches in the context of strip seeding can increase effectiveness of establishing desired plant communities and controlling non-natives.
Effects of treatments on native diversity and non-native cover varied slightly by strip-seeding treatment. Non-native cover was significantly higher in strip-seeding treatments with wider unseeded areas and native diversity was significantly higher in treatments with narrower unseeded areas, regardless of burning and grazing treatment. This suggests that spatial configuration of seeded patches is an important determinant of community composition following management treatments, and should be considered when planning restoration seeding treatments. Continuation of this project in subsequent years will provide insight into whether combining burning, grazing, and strip-seeding is an effective strategy for long-term maintenance a diverse native plant community.