Near Record-Rainfall Leads to Increased Habitat Restoration on the Irvine Ranch Natural Landmarks
After 5 years of extreme drought, Irvine Ranch Conservancy adapts to the recent rainy season through restoration of the open spaces.
The Irvine Ranch Natural Landmarks are home to thousands of acres of thriving native shrubland, woodland, and riparian communities, functioning as important habitat for the region's wildlife and as natural landscapes for visitors to experience and enjoy. Among the healthy environment lies degraded areas altered by years of cattle ranching and successive wildfires, and stressed by invasive plants and animals. OC Parks, City of Irvine and City of Newport Beach, and
major funding partners including the Orange County Transportation Authority, OC Waste and Recycling, OC Parks, City of Irvine and City of Newport Beach have worked with Irvine Ranch Conservancy over the past decade to help restore the land back to its natural setting.
?The Conservancy uses innovative techniques including native plant propagation and seeding, natural regeneration approaches, and targeted weed control on a large-or "landscape-scale"-to
increase the area of healthy native habitat. The resulting biologically rich habitat is more resilient to wildfires, invasive species, and climate change. Over the past five years, extreme drought conditions created challenges at some sites. Native seeds struggled to germinate while nonnative drought-tolerate plants excelled, such as the Russian thistle, commonly known as the tumbleweed plant.
"In normal rain years, our native grasses do well, but during the drought, we had Russian thistle come in and really establish itself," said Matt Major, Project Manager at West Loma Ridge-an expansive area split by the 241 toll road inundated with non-native grasses, black mustard, and now, Russian thistle.
Similar issues cropped up at Bee Flat Canyon, a near-300-acre expanse within Limestone Canyon that includes projects to restore oak woodland habitat through systematic plantings of native coast live oak seedlings, restoring annual grasslands, and improving coastal sage scrub habitats.
"During recent drought years, oaks were very stressed, and often did not produce viable acorns, which made oak woodland restoration a challenge," said Project Manager Robert Freese, PhD.
But now, the rain has come. Native plant and grasses that have long been dealing with miniscule rain amounts are utilizing the much-needed precipitation to grow and establish themselves across the landscape. That's left restoration sites looking much healthier and diverse than even the project managers could have hoped. "Some sites that were really struggling the past few years have come to life, and have more plant diversity than we thought," Freese said.
At Agua Chinon-a 1,200-acre canyonland within the San Diego Creek Watershed and a starting point for the famed hike to The Sinks in OC Parks' Limestone Canyon Nature Preserve-the reintroduction of elderberry, mulefat, and coast live oaks reestablished a riparian habitat.
"This year at Agua Chinon, we are seeing a great mix of native wildflowers, trees, shrubs that have been absent for many years," Freese said.
Native plants are not the only species benefitting from the rain. Nonnative invasive species including black mustard, castor bean, tree tobacco and more are benefitting from the extra rain, growing tall and fast, outcompeting and often shading out the native plant species in the process. The Conservancy employs a wide range of weed abatement efforts depending on the specific species which include scheduled mowing, hand pulls, and other tactics. But getting crews to the sites for weed abatement have proved challenging this past winter, as the dirt access roads can often become unsafe during rainy periods.
At Loma Ridge, Matt Major sees a challenging spring ahead. "When it rains like it has this year, it's tough because the weeds do really well, and we only have a short amount of time to get to them before they go to seed," Matt Major said. "We've got to put our effort now into getting as much of the plants cut down and removed before that happens, so they can't establish themselves next year. It's a tough battle, but it's worth it to fight for this land, and to get the natural plant communities and wildlife back in this area to create a healthy and functioning ecosystem."
There are hundreds of acres of habitat restoration projects currently underway across the Irvine Ranch Natural Landmarks. Many different landowners and partner groups perform habitat
restoration projects, and there are many opportunities for the public to get involved. On behalf of landowners such as OC Parks, City of Irvine and City of Newport Beach, as well as agencies such as Orange County Transportation Authority, Irvine Ranch Conservancy currently manages nearly 250 acres of active habitat restoration, ranging in intensity from sites that need two years of site preparation, seeding, transplanting and site maintenance to sites with some existing native vegetation that just need weed control.
To learn more about these restoration efforts, or to get involved and volunteer in stewardship activities on the land, visit LetsGoOutside.org.