Ten Years of Oak Restoration in City of Walnut Creek Open Spaces

Oaks ‘n’ Folks – Volume 18, Issue 1 – February 2002

The Oak Habitat Restoration Project in City of Walnut Creek Open Spaces was started in 1991 by several individuals who recognized that the heavily grazed oak woodlands and savannas of the City’s 2,700 acres of open space had little natural oak regeneration. With the approval of the City and a startup grant from the California Native Plant Society, a group of motivated folks began collecting acorns, planting them, and maintaining and watering the resulting seedlings. Much of the planting has been done in the 725 acres of open space that have been withdrawn from grazing. Shortly after initiation, the Project became an activity of the all-volunteer, nonprofit Walnut Creek Open Space Foundation, whose mission is to support and enhance the City’s open spaces. The Foundation now funds the Project. The City of Walnut Creek provides storage space for Project-related equipment and materials.

We began our activities using the planting program published by the California Oak Foundation. We then began the learning experience that continues to lead to refinements in our methods. In brief, we collect acorns in September and store them in open, 1-quart plastic bags in a refrigerator until rain moistens the soil at planting sites to a depth of 8 to 10 inches.

In early November, we construct 2-ft high by 6-inch-diameter screen cylinders from 100-ft rolls of 24-gauge hardware cloth and recondition recovered cylinders from previous unsuccessful plantings. We plant our acorns in the cylinders to protect them from ground squirrels, other rodents, and insects.

Late November through mid-January is our usual planting period. Our planting system involves removing weeds and grass from 3 square feet, digging an 8-inch-deep hole, placing the screen cylinder in the hole, and refilling to 1 inch from the surface. We then place 3 acorns inside the screen, points toward the center, and cover the acorns to about 1/2 to 1 inch above the general soil level. Next we place a 3-ft2, perforated, plastic “mulch mat” around the cylinder, covering the cleared area in order to suppress the competitive weeds and grass.

We use four staples in the corners of the mat to hold it in place. An aluminum ID tag and data sheet complete the planting. We place a 3- ft survey flag in the top of the cylinder to locate the planting after the grass grows tall.

In April, we weed inside the screen cylinders and install 4-ft Tubex treeshelters on successful sites, leaving the screen cylinders in place. We’ve found that shorter treeshelters don’t protect the saplings from deer browsing and taller shelters seem to suppress top growth in Walnut Creek’s fairly-low-rainfall environment. We stabilize the treeshelters with a 5-ft by 3/8-inch rebar post. A data sheet completes the spring maintenance activity. Treessentials [(800) 248- 8239] is our supplier for treeshelters, mulch mats, and staples.

From May through September we water every 4 weeks for the first year and in some cases for 2 years following planting. We have no piped-irrigation system so we truck plastic jugs of water to locations near the plantings. Volunteers carry the jugs to the plantings and place about 2 quarts in each treeshelter. The Project has 18 to 20 activity dates each year, nearly all on Saturday mornings. The Project plants 225 to 300 sites per year. About 75% of the planted sites will contain at least one seedling. At the end of the first growing season, about 6,000 seedlings remain. Five years after planting, about 1/3 of planted sites contain saplings. We have used a number of methods of planting and maintenance over the years—this experience has helped us develop regeneration methods that others may find useful. We welcome visitors to our planting areas and look forward to suggestions that we can adapt to improve our efforts.

Ralph Kraetsch Walnut Creek Open Space Foundation 88 Karen Lane Walnut Creek, CA 94598, (925) 933-5732, ralphkra@netvista.net

prepared and edited by Adina Merenlender and Emily Heaton