Habitat Restoration at Big Oak Canyon
Earthroots Field School is committed to restoring and protecting the diverse native ecosystems at Big Oak Canyon, our 39-acre educational and ecological preserve in Silverado Canyon. This land serves as both a living classroom and a sanctuary for native plants, wildlife and people learning to live in balance with nature.
Our Habitat Restoration Program focuses on repairing ecological damage that occurs when invasive plants displace native species, reducing the ability of the landscape to support local food webs and wildlife.
Why Restoration is Important
Big Oak Canyon sits at the confluence of several key habitats: oak woodland, riparian corridor, and coastal sage scrub. These ecosystems support over hundreds of wildlife and native plants, many of which are now rare in Orange County.
Through community led-stewardship and science-based restoration, Earthroots is nurturing the canyon’s ability to thrive by restoring its native plants and protecting centuries-old Coast Live Oaks.
🌱 English Ivy Removal Project
The Threat: English ivy (Hedra helix), an aggressive non-native vine, was introduced decades ago as an ornamental ground cover. Over time, it has escaped cultivation and formed thick mats that smother native vegetation, climb oak trunks, and disrupt soil moisture balance.
Our Response: Since 2013, Earthroots has led a relaxed English Ivy removal campaign at Big Oak Canyon, using hand tools and volunteer crews. Despite our efforts, the ivy would grow back quicker than could be maintained each year. In 2024 and 2025, we were able to hire experienced crews and establish a more systemic approach to remove ivy by the root in high-priority riparian zones Thanks to the generous financial support of the Warne Family Fund and the TPC Foundation. Removing ivy by the roots prevents regrowth and allowing diverse native understory species to regrow.
This map shows the ivy removal project site as of September 2025:
Next steps:
- Monitor areas where ivy has been removed, assess and remove new ivy growth, and continue to remove ivy from new areas.
- Plant and tend native species in the ivy removal areas using a diverse plant palette including juncus, sedges, California fuchsia, mugwort, lupine, deerweed and more.
- Conduct amphibian survey in the riparian zone.
- Design and build amphibian tunnels to decrease mortality of newts crossing the main road during rain events.
🌳 Goldspotted Oak Borer (GSOB) Invasion
The Threat: The invasive Goldspotted Oak Borer (Agrilus auroguttatus) has caused widespread oak decline across Southern California. In 2024, Earthroots detected a significant infestation at Big Oak Canyon, threatening centuries-old Coast Live Oaks that anchor this ecosystem.
Our Response: Guided by Shane Brown, Earthroots Lead Land Steward, and with the support of Cal Fire in 2024, 164 oaks were assessed. Conventional and non-toxic treatments were tested, including a limewash experiment that showed early promises. In 2025, with support from the Warne Family Fund for Endangered Species, we advanced this work by developing a clay-plaster treatment that successfully blocked adult beetle emergence, encouraging our pesticides-free GSOB management. There were no new oak deaths in 2025.
These maps track our experiments with the Goldspotted Oak Borer.
Image: Shane Brown
Next Steps:
- Continue monitoring, collecting data, and treating Coast Live oak trees with earthen mixture.
- Continue documenting occurrences of parasitic wasps and woodpeckers that prey on Goldspotted Oak Borer.
- Continue engaging the community and college interns in service work to improve the health of the forest. We invite you to join us at an upcoming Habitat Restoration Volunteer Day!
Image: Shane Brown 2024
Biodiversity at Big Oak Canyon
In 2025, Laguna Canyon Foundation staff and Shane Brown conducted a biological survey that identified 62 plant and animal species of special concern that could benefit from this restoration project.
Plants
The California Rare Plant Rank (CRPR) describes plant rarity in California using a tiered system developed by the California Native Plant Society (CNPS) to guide conservation. You will see this ranking used below. These ranks help prioritize species for protection under the California Endangered Species Act (CESA) and are critical for environmental review.
| 1A | Presumed extirpated or extinct because they have not been seen or collected in the wild in California for many years. |
| 1B | Rare throughout their range with the majority of them endemic to California. |
| 2A | Presumed extirpated because they have not been observed or documented in California for many years. |
| 2B | Except for being common beyond the boundaries of California, these plants would have been ranked 1B. |
| 3 | Plants for which we lack the necessary information to assign them to one of the other ranks or to reject them |
| 4 | Of limited distribution or infrequent throughout a broader area in California, and their status should be monitored regularly |
| 0.1 | Seriously threatened in California (over 80% of occurrences threatened / high degree and immediacy of threat). |
| 0.2 | Moderately threatened in California (20 – 80% occurrences threatened moderate degree and immediacy of threat. |
| 0.3 | Not very threatened in California (less than 20% of occurrences threatened / low degree and immediacy of threat or no current threats known). |
Source: California Rare Plant Ranks: California Native Plant Society (CNPS). California Native Plant Society. (2022, May 23). California Rare Plant Ranks
Observed Plants at Big Oak Canyon
- Cleveland’s Bush Monkeyflower Diplacus clevelandii – 4.2
- Coulter’s Matilija Poppy Romneya coulteri – 4.2
- Fish’s Milkwort Polygala cornuta var. fishiae / Rhinotropis cornuta var. fishiae – 4.3
- Humboldt Lily Lilium humboldtii / Lilium humboldtii ssp. ocellatum – 4.2
- Intermediate Mariposa Lily Calochortus weedii var. intermedius – 1B.2
Image: Shane Brown, June 2025
Involved Plants*
- Chaparral Nolina Nolina cismontana – 1B.2
- Hall’s Monardella Monardella macrantha ssp. hallii – 1B.3
- Heart-Leaved Pitcher Sage Lepechinia cardiophylla – 1B.2
- Intermediate Monardella Monardella hypoleuca ssp. intermedia – 1B.3
- Narrow-Petaled Rein Orchid Piperia leptopetala – 4.3
- Ocellated Humboldt Lily Lilium humboldtii ssp. ocellatum – 4.2
- Palomar Monkeyflower Erythranthe diffusa – 4.3
- Paniculate Tarplant Deinandra paniculata – 4.2
- Robinson’s Pepper-Grass Lepidium virginicum var. robinsonii – 4.3
- Salt Spring Checkerbloom Sidalcea neomexicana – 2B.2
- San Miguel Savory Clinopodium chandleri – 1B.2
- Santa Monica Dudleya Dudleya cymosa ssp. ovatifolia – Threatened; 1B.1
- Santiago Canyon Dudleya Dudleya chasmophyta – 1B.1
- Santiago Peak Phacelia Phacelia keckii – 1B.3
- Small-Flowered Morning-Glory Convolvulus simulans – 4.2
- Southern California Black Walnut Juglans californica – 4.2
- Sticky Dudleya Dudleya viscida – 1B.2
- Summer Holly Comarostaphylis diversifolia ssp. diversifolia – 1B.2
- Tecate Cypress Hesperocyparis forbesii – 1B.1
State and Federally Listed Endangered and Threatened Animals of California
California Natural Diversity Database (CNDDB). October 2025. State and Federally Listed Endangered and Threatened Animals of California.
Wildlife populations are categorized based on occurrence by the California Department of Fish and Wildlife.
Animals
Description of status levels for protected wildlife in California based on population size and location occurrence.
| Species of Special Concern | Uncommon or rare species that are threatened by further population decline. |
| Threatened | A native species not currently endangered but likely to become so in the foreseeable future without special protection. |
| Endangered | A native species in serious danger of extinction in all or a significant portion of its range. |
| Waitlisted | In the review process to determine if species will be added as threatened or endangered |
| Fully Protected | California’s highest protection for species facing extinction |
Source: California Natural Diversity Database (CNDDB). October 2025. State and Federally Listed Endangered and Threatened Animals of California. California Department of Fish and Wildlife. Sacramento, CA. https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=109405&inline
Observed Wildlife at Big Oak Canyon
- American Badger Taxidea taxus – Species of Special Concern
- California Newt Taricha torosa – Species of Special Concern
- Long Eared Owl Asio otus – Species of Special Concern
- Mountain Lion Puma concolor – Species of Special Concern
- Red-Diamond Rattlesnake Crotalus ruber – Species of Special Concern
- Yellow Warbler Setophaga petechia – Species of Special Concern
Involved Wildlife at Big Oak Canyon*
- Arroyo Chub Gila orcuttii – Species of Special Concern
- Arroyo Toad Anaxyrus californicus – Endangered; Species of Special Concern
- Bell’s Sparrow Artemisiospiza belli belli – Waitlisted
- California Spotted Owl Strix occidentalis occidentalis – Proposed Endangered/Threatened; Species of Special Concern
- Coast Horned Lizard Phrynosoma blainvillii – Species of Special Concern
- Coast Patch-Nosed Snake Salvadora hexalepis virgultea – Species of Special Concern
- Coastal Cactus Wren Campylorhynchus brunneicapillus sandiegensis – Species of Special Concern
- Coastal California Gnatcatcher Polioptila californica californica – Threatened; Species of Special Concern
- Coastal Whiptail Aspidoscelis tigris stejnegeri – Species of Special Concern
- Cooper’s Hawk Accipiter cooperii – Waitlisted
- Crotch’s Bumble Bee Bombus crotchii – Special Status
- Golden Eagle Aquila chrysaetos – Fully Protected
- Grasshopper Sparrow Ammodramus savannarum – Species of Special Concern
- Loggerhead Shrike Lanius ludovicianus – Species of Special Concern
- Northern Harrier Circus hudsonius – Species of Special Concern
- Orange-Throated Whiptail Aspidoscelis hyperythra – Waitlisted
- Pallid Bat Antrozous pallidus – Species of Special Concern
- San Diego Banded Gecko Coleonyx variegatus abbotti – Species of Special Concern
- San Diego Desert Woodrat Neotoma lepida intermedia – Species of Special Concern
- Santa Ana Speckled Dace Rhinichthys gabrielino – Proposed Threatened; Species of Special Concern
- Santa Ana Sucker Catostomus santaanae – Threatened
- Sharp-Shinned Hawk Accipiter striatus – Waitlisted
- Southern California Rufous-Crowned Sparrow Aimophila ruficeps canescens – Waitlisted
- Southwestern Pond Turtle Actinemys pallida – Proposed Threatened; Species of Special Concern
- Steelhead – Southern California DPS Oncorhynchus mykiss irideus – Endangered
- Stephens’ Kangaroo Rat Dipodomys stephensi – Threatened
- Summer Tanager Piranga rubra – Species of Special Concern
- Two-Striped Gartersnake Thamnophis hammondii – Species of Special Concern
- Western Mastiff Bat Eumops perotis californicus – Species of Special Concern
- Western Spadefoot Spea hammondii – Proposed Threatened; Species of Special Concern
- White-Tailed Kite Elanus leucurus – Fully Protected
- Yellow-Breasted Chat Icteria virens – Species of Special Concern
* Involved = Potential special status species to occur at Big Oak Canyon
Gratitude to Our Financial Partners
Earthroots has worked for years to restore the native habitats of Big Oak Canyon. Thanks to the generous financial support of the Warne Family Fund and the TPC Foundation, 2025 marked a year of remarkable progress in protecting oak woodlands, removing ivy, and nurturing biodiversity across the canyon. We are deeply grateful for their partnership.
Goals for the Future
In 2026 and beyond, Earthroots will continue restoring Big Oak Canyon by expanding English ivy removal, reestablishing native plants, and protecting Coast Live Oaks using non-toxic treatments, We will deepen biological surveys with a herpetologist to better understand aquatic and riparian species, while maintaining ongoing tree monitoring and habitat assessment. Launching a college internship program will engage emerging restoration practitioners in data collection, planting, and monitoring efforts. These combined actions will strengthen biodiversity, habitat resilience, and community stewardship for the canyon’s long term health. With additional secured funding, we will implement wildlife tunnels for newts and other amphibians to reduce mortality crossing the roads. This project would include amphibian fencing and grate-covered in-ground tunnels through the main road, creating safe passageways from the lower to the upper riparian zone.
