In the early 1800s, not long after Spanish explorer Gaspar de Portola first traveled through the wilderness of Southern California, native habitats began to give way to crops and non-native grasses planted for grazing as ranches dominated the landscape. For nearly 200 years, cattle, sheep and other livestock roamed the hills and were herded through the canyons. Today, Irvine Ranch Conservancy scientists are working to restore the land to a similar state to what it looked like when Portola first set foot in Orange County, with a rusted corral in Bee Flat Canyon serving as link between past and future.
Bee Flat Canyon ranges from Limestone Meadow up to Loma Ridge near Santiago Canyon Road in the foothills of the Santa Ana Mountains. It is a nearly 300-acre area that has been selected as a high priority restoration zone for its substantial need for weed control and its ecological value and strong potential for success. While many different habitat types are being restored in the canyon, the Conservancy's restoration project of Coast Live Oak (Quercus agrifolia) may be one of the most visible projects within the Irvine Ranch Natural Landmarks.
"In past oak habitat restorations, providing sufficient irrigation while protecting seedlings from rodents has been a big challenge," says Lars Higdon, Habitat Restoration Project Manager for the Conservancy. "What we learn from this project will help us be more efficient and successful with all our oak plantings throughout the Irvine Ranch Natural Landmarks."
One key to this project? It’s actually found in equipment from the old rusted corral. More specifically, the source of running water that was used for crops and cattle for over one hundred years is now funneled through irrigation lines to half of the trees in the trial area. It is rare for a water source to be available to support habitat restoration far out on the wildlands, so Conservancy scientists and volunteers often need to bring in water to give new plants a boost as they get established. Having a handy water source provides an easy method for testing the importance of giving trees supplemental water. Every other row of trees is irrigated at its roots, offering a critically important comparison between those young trees and others that rely on rainfall alone.
The project is set up using four different treatment methods, and every possible combination of those individual methods – a total of 8 treatment variations. In addition to watering, the treatments include buried hardware cloth to deter rodents, weed matting to control weeds and retain soil moisture, and a "control" of no treatment. The treatment methods are replicated 10 times in the main planting area, and the entire design of 80 trees is duplicated on both tilled soil and compacted soil to determine if the concrete-like compacted soil of Bee Flat is having an overwhelming effect on tree growth. The results of these treatment combinations will provide essential information to help managers determine the most efficient and cost effective method for large-scale restoration of oak woodland habitats.
The Bee Flat Canyon restoration project began in 2011, and is funded by a grant from the Orange County Transportation Authority (OCTA) Measure M Freeway Mitigation and Resource Protection Program. The target timeframe of the entire project is five years, and restoration trials like this are an investment that help the Conservancy and OCTA meet their goals. The goal of these habitat restoration projects is not 100% native plants, but rather restoration of whole native landscapes to a level that sustains native wildlife and biodiversity and provides resilience in the face of wildfire, drought and other disturbances. That is why the Bee Flat project covers more than 300 acres and other Conservancy restoration projects also cover large acreages.
Shady oak woodlands are both important to wildlife and beloved by visitors to Limestone Canyon. For the next several years, hikers, bikers and equestrians will be able to see the Coastal Live Oak Establishment Project develop with each trip down the Limestone Canyon Trail. Additional restoration sites within Bee Flat Canyon can be seen from Sand Trap and Loma Ridge Trails, including coastal sage scrub and grassland habitats. And decades from now - with the information learned from this and other projects and lots of hard work - visitors to Limestone Canyon will be able to see these woodlands the way they were centuries ago.
In November and December, the public can participate in stewardship activities in these areas, to help the restoration work. Visit www.LetsGoOutside.org/activities for more information on stewardship opportunities.