Sheep Grazing as a Tool for Vernal Pool Stewardship

2007 Annual Report for GW06-029

Project Type: Graduate Student
Funds awarded in 2006: $8,813.00
Projected End Date: 12/31/2008
Grant Recipient: Sonoma State University
Region: Western
State: California
Graduate Student:
Major Professor:
J. Hall Cushman
Sonoma State University

Sheep Grazing as a Tool for Vernal Pool Stewardship


In 2007 we continued experimental spring sheep grazing, completed data analysis for 2005-2007, and presented results in a written thesis, an oral public defense, and at two conferences. Sheep grazing at the experimental site did not significantly increase native plant cover or richness. Sheep grazed heavily in pool bottoms once pools dried, contrary to management goals. Sheep grazing may be more effective at enhancing natives if done while pools are still inundated, or after natives have senesced. A companion study showed that high-productivity vernal pools grazed by cattle did have greater native richness and cover than ungrazed pools.

Objectives/Performance Targets

Our objectives for 2007 were to: continue experimental sheep grazing, monitor vegetation of grazed and ungrazed plots, monitor vernal pool hydrology, analyze the resulting new data, begin manuscript preparation, and plan for an educational field session.


From analysis of our 2005-07 data, we found that sheep grazing was not increasing overall native species richness or cover. We considered altering the grazing regime at our experimental site in order to encourage natives. However, we decided that continuing the experiment with a consistent regime for the remainder of the grant period would yield more useful, readily interpretable and publishable results. Spring sheep grazing did reduce one problematic pool bottom invader, pennyroyal (Mentha pulegium), and appeared to increase one rare early-blooming, aquatic native (Lobb’s buttercup, Ranunculus lobbi).

In February 2007, I presented my work in a public thesis defense at Sonoma State University, as well as submitting it in written form. I have also presented my work in several other venues. In April 2007, I was invited to and spoke at the State of the Laguna conference held by a local non-profit, the Laguna Foundation. In August, I spoke at the joint annual meeting of the Ecological Society of America and the Society for Ecological Restoration.

Preparations for an educational workshop on February 8, 2008 are well underway. The workshop is intended to bring local livestock producers together with land managers and biologists to educate producers about opportunities for conservation grazing of vernal pools, and discuss how to make livestock grazing of vernal pools more effective, from both the livestock production and conservation perspectives. Local sheep rancher Kerry Williams has been helping to plan and recruit for the session, and the Sotoyome Resource Conservation District is helping plan and host the session. The City of Santa Rosa is providing a venue for the meeting free of charge, as well as access to their lands for a field trip. Western United Dairymen has assisted us with publicity. We have recruited a broad array of experts to speak at the meeting, including two range management specialists, a Nature Conservancy ecologist, and several highly respected local ranchers and dairymen with experience on vernal pool landscapes (including the President of the Sonoma County Farm Bureau).

Impacts and Contributions/Outcomes

My work has contributed to growing local interest in using grazing–both cattle and carefully timed sheep–as a vernal pool management tool. Several publicly owned preserves in the study area are now going to be grazed by livestock to manage for native species. I have received inquiries from land managers asking for referrals to additional producers.

The Laguna Foundation, a local non-profit, is seeking funding for further research into effective grazing regimes for vernal pools, with my collaboration.

Despite skepticism from some quarters that biologists and ranchers could come together for a grazing workshop, I have found both groups to be receptive, enthusiastic, and willing to participate. I think the workshop itself will contribute to closer relations and better communication between the producer and conservation communities.


J. Hall Cushman

Sonoma State University
1801 E. Cotati Ave.
Rohnert Park, CA 94928
Office Phone: 7076642142