Professor University of Oregon Eugene, Oregon, United States
Traditionally, ecological restoration has focused on rebuilding “reference ecosystems” that seemingly conflict with human-dominated landscapes. However, restoration and agricultural production can exist as complimentary land use goals. In the Willamette Valley of western Oregon, native prairies are a disturbance-adapted ecosystem that were historically widespread and maintained by indigenous burning practices. Following Euro-American settlement, fire suppression and land conversion contributed to the loss and modification of these ecosystems. Today, agricultural lands now dominate the region and most remaining native prairie habitat lacks regular disturbance regimes necessary for their persistence.To address this, our study tests whether native prairie restoration can be successful in conjunction with agricultural practices. Specifically, we partnered with My Brothers’ Farm, a 320-acre organic farm in Creswell, Oregon with a herd of approximately 50 bison, to use rotational grazing as a disturbance tool to convert a field formerly used for annual ryegrass (Lolium multiflorum) seed production into a livestock pasture that provides sustainable forage while also supporting a diversity of native species. In fall 2021, we implemented an experiment consisting of 48 grazed/ungrazed plots (8-m2 each) divided across six paddocks. We seeded 10 native prairie species in October 2021 and began a rotational grazing prescription in February 2022. Within each plot, we collected monthly measurements of species richness, cover, vegetation height, and flower counts, and collected soil samples in April 2023.Preliminary results from 2022 suggest that grazing improves native seedling establishment by reducing the abundance of annual ryegrass: grazing had a significant positive effect on native richness and percent cover while simultaneously reducing ryegrass cover. Native cover was also significantly correlated to percent bare ground when seeded in fall 2021. As of March 2023, native richness and cover continue to be greater in the grazed compared to the ungrazed plots. Preliminary soil health analyses indicate that soil conditions are poor across the pasture, with high compaction, inadequate nutrients, and low pH likely resulting from decades of conventional annual ryegrass production. Rotational grazing is slowly improving soil health, but management actions including disking, chisel ripping, and harrowing will likely be necessary to accelerate the pasture restoration process before adding more native seed. In conclusion, this study suggests that grazing may be used as a disturbance tool to help establish native prairie plant species within an agricultural landscape in western Oregon. Through collaborative partnerships and the development of sound management practices, we can create win-win scenarios with agroecological restoration.
