Adaptive, multipaddock grazing management increased C3 and reduced C4 graminoids without changing total forage production in shortgrass steppe

Authors: Augustine, David; Porensky, Lauren; Hoover, David; KEARNEY, SEAN - Thunder Basin Grasslands Prairie Ecological Association; Wilmer, Hailey; RITTEN, JOHN - Colorado State University; Derner, Justin; MURPH, RACHEL - Natural Resources Conservation Service (NRCS, USDA); KOEPPEL, SARA - Natural Resources Conservation Service (NRCS, USDA); HARTUNG, JOHN - Natural Resources Conservation Service (NRCS, USDA); MAGNUSON, STEPHANIE - Us Forest Service (FS); ADLER, STEVEN - Us Forest Service (FS); BARBER, CASEY - Us Forest Service (FS); POLLART, MATT - Department Of Natural Resources; TURNER, RACHEL - Department Of Natural Resources; SCHULZ, TERRI - The Nature Conservancy; TOOMBS, TED - Environmental Defense Fund; LAVALLEE, JOCELYN - Environmental Defense Fund; DWYER, ANGELA - Bird Conservancy Of The Rockies; OVERLIN, ANNIE - Colorado State University; ANDERSON, STEVE - Crow Valley Livestock Cooperative; BOWMAN, DANA - Crow Valley Livestock Cooperative; LAWRENCE, ANDY - Crow Valley Livestock Cooperative; WAHLERT, JEFF - Crow Valley Livestock Cooperative

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/16/2025
Publication Date: 5/26/2026
Citation: Augustine, D.J., Porensky, L.M., Hoover, D.L., Kearney, S., Wilmer, H.N., Ritten, J., Derner, J.D., Murph, R., Koeppel, S., Hartung, J., Magnuson, S., Adler, S., Barber, C., Pollart, M., Turner, R., Schulz, T., Toombs, T., Lavallee, J., Dwyer, A., Overlin, A., Anderson, S., Bowman, D., Lawrence, A., Wahlert, J. 2026. Adaptive, multipaddock grazing management increased C3 and reduced C4 graminoids without changing total forage production in shortgrass steppe. Rangeland Ecology and Management. 107:74-84. https://doi.org/10.1016/j.rama.2026.04.003.
DOI: https://doi.org/10.1016/j.rama.2026.04.003

Interpretive Summary: Many rangelands—especially those in semi-arid areas—have big year-to-year and place-to-place differences in rainfall. These differences strongly affect how much forage grows and which plant species are present. Because of this natural variability, the effects of grazing management on vegetation can take many years to show up. We studied how a collaborative, adaptive multi-paddock rotational grazing system (CARM) changed vegetation compared to traditional season-long grazing (TRM) over 10 years in the semi-arid shortgrass steppe. Each year, the CARM herd grazed paddocks on the Sandy Plains ecological site (mostly cool-season grasses) at the beginning and end of the growing season, and grazed paddocks on the Loamy Plains ecological site (mostly warm-season grasses) during the middle of the season. The exact grazing schedule changed each year based on current growing conditions. Some paddocks in CARM were also given full-season rest (no grazing) from time to time. On the Loamy Plains site, CARM increased the amount and productivity of cool-season grasses compared to warm-season grasses, starting in year 5 and continuing through year 10. Species that contributed to this shift included the cool-season grasses western wheatgrass and needle and thread, and the warm-season grasses, blue grama and buffalograss. On the Sandy Plains site, CARM did not change the relative abundance or productivity of herbaceous plants. but did increase cover of the dominant shrub, four-wing saltbush. Although repeated differences in grazing timing changed the balance of perennial grass functional groups on the Loamy Plains site within 10 years, these changes did not affect total forage production because gains in some species were offset by losses in others. Overall, our results suggest that adaptive multi-paddock grazing can increase the abundance of perennial cool-season grasses, but this improvement may come with trade-offs—such as reducing habitat for grassland birds that prefer shorter vegetation.

Technical Abstract: Many rangelands, particularly those in semi-arid climates, experience dramatic spatial and temporal variability in precipitation, which drives variation in forage production and plant species composition. With such variability, the influence of grazing management on vegetation dynamics may only be detectable over long time periods. We examined the degree to which collaborative, adaptive multi-paddock rotational grazing management (CARM) influenced vegetation dynamics relative to traditional season-long grazing management (TRM) over a 10-year time frame in the semi-arid shortgrass steppe. Each year, CARM herd(s) grazed paddocks with the Sandy Plains ecological site (dominated by C3 graminoids) early and late in the growing season, and grazed paddocks primarily comprised of the Loamy Plains ecological site (dominated by C4 grasses) during the middle of the season. Current growing season conditions were used to determine the exact timing of rotations. Additionally, CARM incorporated periodic season-long rest (without grazing) for select paddocks. On the Loamy Plains ecological site, CARM increased the cover and production of C3 relative to C4 graminoids, beginning in year 5 and persisting through year 10. Multivariate analyses of relative cover by species identified Pascopyrum smithii, Hesperostipa comata, Elymus elymoides and Carex duriuscula as the C3 species and Bouteloua gracilis and B. dactyloides as the C4 species responsible for the shift on Loamy Plains. In contrast, for the Sandy Plains ecological site, CARM had no detectable effects on the relative abundance or productivity of herbaceous plants, and the shrub Atriplex canescens was the only species identified that increased in cover in CARM relative to TRM. While sustained shifts in grazing timing (associated with the rotation sequences) across years altered the relative abundance of perennial grass functional groups within a decade on Loamy Plains, these shifts were offsetting such that total forage production was unaffected. Our findings can be explained by the greater sensitivity of C3 vs. C4 perennial graminoids to early-season grazing, and highlight the challenges associated with enhancing total forage production via multi-paddock rotations in semi-arid rangelands. Our results suggest progress towards the objective to enhance perennial C3 graminoid abundance with adaptive multi-paddock grazing, but this progress came at the expense of other ecosystem service objectives such as short-structured grassland bird habitat.