Finding an Ecological Niche: Selected Foothill Woodland and Chaparral Species, Part 1 of 3: The Blue Oak
By Laura Lukes, UC Master Gardener of Butte County, February 22, 2019
[Note: Blue oak (Quercus douglasii), gray pine (Pinus sabiniana), and buckeye (Aesculus californica) are three species that thrive in rugged local foothill woodland and chaparral habitat. Today and in the following weeks, this series will look at these species and the adaptive strategies they have evolved over time to thrive in their challenging environment.]
What drives the evolutionary journey of the flora and fauna that populate our globe?
Some species cooperate by sharing resources. For example, in Tortuguero, a tiny strip of beach along the northeastern shoulder of Costa Rica, four separate species of sea turtle lay their eggs each year. They migrate to the beach at different times, ranging from early March to October, and feed on different resources. Millions of turtles, and untold numbers of their babies, have shared the same tiny piece of real estate for eons.
Here in our own backyard, there are species that have evolved to exploit ecological niches that very few others claim. These are the various oaks, conifers, and woody shrubs that populate the foothill woodland and chaparral zone of the Western Sierra Nevada and Coast Range mountains. A dominant species in this environmental nook is the blue oak (Quercus douglasii). According to Andrew Conlin, Soil Scientist with the Natural Resources Conservation Service (NRCS), “the presence of blue oak woodlands indicates really rough growing conditions: shallow, tough soils” as opposed to the rich loamy soils of the valley, which are preferred by valley oaks.
Quercus douglasii also goes by a number of other common names, including white oak, mountain oak, mountain white oak, and iron oak. But it acquired its most familiar and descriptive common name from the same person from whom its Latin binomial (scientific name) is derived. In 1831 David Douglas, a Scottish botanist, christened it the blue oak for the bluish cast of its deeply lobed leaves. (A digression: Douglas, for whom the Douglas-fir and hundreds of other western plants are named, lived from 1799 to 1834. He made three trips to the American Northwest between 1823 and 1831, encountering the blue oak on his last trip while traveling from the Columbia River in Oregon to San Francisco. He died under curious circumstances, apparently after falling into a bull trap while climbing Mauna Kea in Hawai'i.)
Blue oaks are native to California's foothills, South Coast Range, North Coast Range and San Francisco Bay Area, forming a botanical loop around the Central Valley. Depending on the source consulted, these trees average between 30 and 80 feet tall. But all sources agree that the blue oak is the most drought tolerant of all the deciduous oaks in the state.
Surviving Drought and Fire:
Adaptations to survive the long, hot, dry summers and sparse winter rains of our Mediterranean climate include thick leaves with a bluish-green color. According to the US Department of Agriculture (USDA), blue-gray-green leaf color reduces heat absorption. During severely hot and dry years, blue oaks will sometimes shed their leaves and go dormant to conserve energy, allowing these tough little oaks to survive temperatures above 100° F for several weeks at a time. Like many plants growing in marginal soils, blue oaks are slow growers, usually increasing only a few inches each year.
Although blue oaks can tolerate fast-burning grass fires, they have less success in surviving hotter brush fires, according to University of California Department of Agriculture and Natural Resources (UCANR). If a tree does survive a fire event, it can reproduce both through seeds and by sprouting from burnt stumps. Blue oaks can produce sprouts after a low- to moderate-severity surface fire, and younger trees have the edge on older trees for fire survival odds. On younger trees, the light-colored bark (hence “white oak”) is thick and helps reduce fire damage, the USDA notes, whereas the bark of mature blue oaks is thin and will flake off as the trees age, making older blue oaks less insulated against fire. After a fire, blue oaks can also re-establish from acorns that have dropped from surviving parent trees and/or been dispersed by animals, among other possibilities.
USDA research also reveals that the blue oak's post-fire recovery is likely aided by the fact that it withstands extreme drought by dropping leaves under water stress and producing a flush of new leaves when wet weather returns. In fact, in wet years, crown-scorched blue oaks may produce a flush of new leaves soon after fire.
Native American Uses:
All parts of the blue oak were woven deeply into the culture and survival of California's native peoples. It was one of more than a dozen oak species whose acorns contributed a major source of dietary nutrients and calories. Because of their superior flavor, blue oak acorns were among the most commonly gathered.
A Plant Guide published by the Natural Resources Conservation Service (NRCS) provides an exhaustive list of the ways California Native Americans used blue oak wood, bark, and acorns, including as “medicine, dyes, utensils, games, toys, and construction materials.” Locally, the Maidu used oak shoots to frame cradleboards and oak posts to construct shelter, and the Yana used an oak paddle in cooking. Traps for birds were baited with acorns, and split acorns became dice for gambling.
Besides providing physical sustenance to native peoples, I imagine that the peaceful beauty of blue oak woodlands fed their souls. Twisted, dwarfed blue oak silhouettes are a classic component of the California landscape. These trees are prime examples of successful adaptation to truly demanding habitat and climate conditions.
Sources and further information:
UCANR: Oak Woodland Management: Blue Oak
NRCS:BLUE OAK: Quercus douglasii Hook. & Arn.
Rising From the Ashes
Master Gardeners are taking note of the vegetation emerging on property destroyed by the Camp Fire. On Fay Crociani's Upper Paradise lot, native salvia reappeared in early January, sprouting from roots of plants that had burned to the ground. A potted erodium (Alpine geranium) also showed leaves in January, followed in February by green leaves emerging from desiccated black iris rhizomes. More irises, planted in plastic pots, survived the fire even though the plastic melted around them, and other plants and leaves continue to rise from the scorched ground. Fay encourages folks to watch and see what comes up before totally digging up an area. She says “there is real magic and joy in my heart when I spot new growth. I know hundreds of plants will never come back, but many, many will if we have the patience to wait.”
/h2>- Author: Hannah Bird
HREC and Post-Fire Research Opportunities
What is HREC?
The UC Hopland Research & Extension Center (HREC) is a multi-disciplinary research and education facility in Mendocino County located in the foothills of the Coast Range about two hours north of Berkeley. As part of the UC system for over 65 years, we are stewards of more than 5,300 acres of oak woodland, grassland, chaparral, and riparian environments. Elevation at the center ranges from 500 ft to 3,000 ft. HREC currently maintains a research flock of about 500 breeding ewes that have been the subjects of numerous studies on ranching practices, range management, livestock nutrition, wool production and breeding. Field experiments and demonstrations conducted here since 1951 have led to more than 1,500 publications in animal science, entomology, plant ecology, public health, watershed management, and wildlife biology. Our website is hrec.ucanr.edu.
The River Fire
As part of the Mendocino Complex fire, the River Fire burned through HREC on the evening of July 27 and into July 28. Approximately 3,000 acres of our center burned in this fire. Due to the concentrated efforts of Center staff and Cal Fire crews, all of our employees, residents, sheep, livestock dogs, offices and residences were saved. Below please find the burn map of our property. All of the black area to the north was burned and the dark red patches were areas of vegetation that remained unburned. The fire intensity varied greatly as did oak survival. You will see two smaller burned areas in the southern part of the property that were prescribed burns performed in June of this year.
Research Opportunities
While this was a blow to current research, pastures, and water infrastructure, we also see this as a wonderful opportunity. Due to extensive historical data sets and ongoing research projects, coupled with a variety of grazed and ungrazed pastures, and prescribed burn plots for comparison with wildfire, there is enormous potential for pre- and post-fire studies in the fields of:
- Watersheds and hydrology; fire science; plant science; soil science; entomology and parasitology; wildlife and wildlife ecology; rangeland management; grazing practices as fire suppression…..
To support this research, HREC offers:
- A well maintained network of roads that accesses almost all parts of the property, vehicles to use.
- A fully equipped shop staffed by employees skilled in fabrication and repair of research equipment
o Electrical, wood working, welding and metal fabrication, mechanical
- Skilled staff trained in field work techniques, with long histories of successful research support
- Fiber optic internet with Wi-Fi access throughout headquarters, strong cell service in most areas
- A vault of raw data, photos, and final papers from research conducted at HREC.
- Warehouses for storing equipment, a variety of accommodations from dorms to private houses
- Wet and dry lab space (undergoing renovation during fall 2018, available spring 2019)
- Lysimeter with available watering system, electrical connections, and fiber optic access point
- A research flock of sheep consisting of just under 500 breeding ewes, with all needed facilities and RFID tracking
- Fenced pastures and biological reserve areas for different treatment plots and controls
- A fully equipped conference facility with A/V equipment and fiber optic connections
Next Steps
- Zoom meeting on September 7th, 10am. More in depth information, Q&A.
- Field day on October 19th, 10am-5pm. Presentations, brainstorming, Q&A, site tours, available accommodations
- To register for either event follow this link: http://ucanr.edu/survey/survey.cfm?surveynumber=25451
Contact: HREC Interim Director John Bailey, jtbailey@ucanr.edu, (707) 744-1424 x 112
- Author: Sabrina L. Drill
Ventura County residents looking for information about Thomas Fire Recovery will want to check http://venturacountyrecovers.org/community-meetings/ for the very latest information from county, state, and federal disaster relief agencies. In Santa Barbara, residents will want to check here - https://www.countyofsb.org/fire-recovery.sbc
The agriculture community will be interested in a UCCE hosted workshop on fire and frost damage and preparation January 10th at the Agriculture Museum in Santa Paula - http://ucanr.edu/sites/SAFELandscapes/?calitem=396547&g=29423
If you are looking for information about or volunteer opportunities to help with the recovery of natural areas, however, there are a few events coming up:
Ventura Land Trust will be hosting a volunteer opportunity for Martin Luther King Jr. Day January 15th at their Big Rock Preserve, http://www.venturalandtrust.org/mlk_20180115, and will also be hosting a lecture by my colleague Dr. Sean Anderson from CSU Channel Islands January 17th at 7:00 PM at Poinsettia Pavilion - http://www.venturalandtrust.org/lecture_thomas_fire.
I'll be speaking about fire recovery, invasive species, and erosion issues at the Santa Clara River Watershed Council meeting January 24th, 9-11 am at the United Water Conservation District, and February 24th at the Casitias Water District public meeting - more soon!
February 17th the Ojai Valley Land Conservancy's Plant Walk will include a talk by folks from the California Chaparral Institute - https://www.facebook.com/events/142471386462631/
- Author: Jeannette Warnert
Reposted from the UCANR News Blog
Northern California's Rocky Fire is roaring through shrublands that have no previous recorded history of wildfires, reported Kirk Siegler on All Things Considered. It has already burned 65,000 acres and is 12 percent contained, according to CalFire's Incident Report.
The area has been protected from fire for decades, primed for the type of catastrophic blaze California officials have been predicting.
Siegler spoke to UC Agriculture and Natural Resources Cooperative Extension wildland and forestry advisor Greg Giusti.
"We've got miles and miles of contiguous chaparral vegetation and literally there are no breaks in the vegetation," Giusti said. "It's extremely steep and, in many cases, it's a roadless area."
Four years of drought has left the vegetation bone dry.
'When these fires get to an intensity we've seen, because of the fuel loading, because of fire suppression for the last 50 or 60 years, it allows the plant communities to get so dense, so thick and so expansive that, once a fire starts, it's beyond the capabilities of human control," Guisti said.