Written by Doug Warnock
Members of the Pacific Northwest Section of the Society for Range Management recently toured four livestock operations in southwestern Washington, where animal grazing is being used to positively impact situations that had been detrimental to other animals or plants.
Reed canary grass (Phalaris arundinacea) has invaded much of the lowland riparian and wetland ecosystems in the Pacific Northwest. This has been detrimental to the Oregon Spotted Frog by threatening its ability to reproduce. Oregon Spotted Frogs (OSF) need short vegetation in the wet meadows to successfully deposit their eggs. Reed canary grass reduces OSF breeding because it has tall, dense plants that suppress the shorter native plants, which are much better suited for OSF egg production.
Various methods have been used to control canary grass, with mixed results. Attempts have included mowing, burning, herbicide applications, livestock grazing, and native planting. A group of local people came together and designed a plan to find a method that would produce good results for the OSF and cause no harm to other creatures or plants. Jake Yancey of the Tracking Ranch provided cattle for the grazing. In the spring of 2019, they established three treatment paddocks, each of five to seven acres, on the Mima Creek Preserve in South Thurston County. One paddock was assigned short-term, high-density grazing; the second paddock was assigned continuous grazing, and the third was not grazed and functioned as a control. This study was conducted over a five-year period, during which a substantial amount of data was collected. OSF egg mass counts were conducted during the oviposition period, which is in February and March, each year.
Those involved in the study were Melissa Habenicht and Sarah Hamman of Ecostudies Institute, Sanders Freed of the Center for Natural Land Management, and Jake Yancey.
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The conclusions from the study were: (1) Grazing improves vegetation structure for OSF breeding habitat by reducing plant height, with similar outcomes for both continuous and rotational regimes. (2) Grazing should be applied while reed canary grass is still palatable, but late enough in the season so that regrowth remains short through the OSF breeding period. If this critical window is missed, mowing or brush cutting should be used as a follow-up to the grazing to reduce standing dead vegetation and thatch. (3) Grazing prescriptions for OSF habitat maintenance will vary by site, depending on forage availability, environmental conditions, and the growth phase of the reed canary grass. (4) Grazing once per year in late summer did not affect reed canary grass cover in this study. Multiple rounds of grazing, both early and late in the season, may be a more effective control strategy; however, it may be difficult to graze cattle early in the season when conditions are wet. Sheep could be utilized for short time periods. Further research is needed to evaluate the effectiveness of this strategy.
Visiting this project showed us a good example of what can be accomplished by local people working together to overcome a problem threatening an endangered species. This program demonstrates how creative thinking, achieved through the collaboration of a group of dedicated individuals, solves problems.
Doug Warnock, retired from Washington State University Extension, is one of the founding members of Roots of Resilience.