Drill-seeding blue oak acorns: a new method for restoration in California’s rangelands.

View the project final report

Commodities

• Animals: bovine

Practices

• Animal Production: rangeland/pasture management
• Natural Resources/Environment: carbon sequestration, habitat enhancement

Our project: "Drill-seeding blue oak acorns: a new method for restoration in California rangelands," will quantify the feasibility and cost-effectiveness of drill-seeding as a technique for restoring blue oak (Quercus douglasii) woodlands in California rangelands.

California's blue oak woodlands are rich resources for agriculture and wildlife, accounting for one-third of the grazed land in California and harboring more wildlife than any other ecosystem in California (Borchert et al.1991, Pavlik et al.1991). However, in both cleared and existing woodlands, there is a lack of new oak recruitment (Adams et al.1992, Swiecki and Bernhardt 1998). This lack of recruitment throughout the blue oak range (3-million hectares (Bollsinger 1988)) requires that a restoration solution be cost-effective and scalable. Existing restoration techniques use irrigation, caging, tree tubes, and weed control, which is effective but costly and unfeasible on a large scale. We propose to test and demonstrate the application of drill-seeding to “farm” oaks in rangelands. Restoration of blue oak woodlands will benefit ranchers by providing invaluable shade and increasing the quantity and quality of forage beneath the trees (Frost et al.1991). Also, restoration at scale will be an important factor in mitigating the impacts of climate change on rangelands, and could play a significant role in helping California meet climate mitigation goals (Cameron et al. 2017).

We will test the efficacy of drill-seeding blue oak acorns under varying conditions, combining drill-seeding with the following variables in a paired nested block study: cattle grazing, shade, and seeding rate. Germination will be quantified in the late spring. Survivorship will be measured for two years, taking place once in the summer and once in the fall after the first rains.

Data will be analyzed, prepared for publication, and shared with agency and landowner partners via two workshops and a pamphlet about the practice.

1. Create a prototype of an acorn-seeding implement and conduct field testing and trials
2. Demonstrate a viable technique for seeding acorns at scale with germination rates similar to other direct -seeding applications.
3. Perform a complete cost-benefit analysis of the this drill seeding technique relative to current industry standards.
4. Introduce 30-50 individuals (landowners, land managers, agency partners, non-profit partners) to the concept of applying large-scale agricultural techniques to rangeland restoration through a field workshop.
5. Submit a manuscript for publication based on the findings, in an applied science journal.
6. Create an acorn drill-seeding pamphlet, including plans for the implement that is written in plain English, free of scientific jargon, for distribution to the ranching community.