California’s native oaks have always evoked the feeling of “home” for me, even though I spent my first quarter-century well east of the Sierra Nevada. From afar, I appreciate the muscular, sculptural beauty of coast live oaks. Up close, I love the multitude of birds and other critters that are drawn to the trees.
“If we had to pick a ‘super species’ for California, oaks would be it,” said Liv O’Keeffe, senior director of communications and engagement for the California Native Plant Society.
Having native oaks as street trees or in your yard creates “a sense of place,” according to Andrea Williams, director of plant science at CNPS. The presence of these iconic trees affects people even “on a subconscious level,” she said.
Planting live oaks
There are many reasons for planting an oak.
- Beauty. Valley oaks, left unpruned, have long branches reaching almost to the ground. Even in winter, without leaves, the galls and the “architecture of the branches” makes them stand out, Williams said. Galls, also called oak apples, occur when gall wasps lay eggs on any part of the tree. The tree reacts by forming these growths, which do not harm the tree.
- Habitat value. Native oaks are like “a supermarket for birds (and other wildlife) to forage in,” Williams said. Birds need native plants that host the succulent caterpillars they need to raise their young. She grew up in Los Altos and remembers “all the acorn woodpeckers and their laughing calls and clownish look” in the oaks.
- Sense of place. Many of the trees grown in California come from other parts of the world. But native oaks are California’s iconic tree. Los Altos already has some oaks planted as street trees, Williams said. If you have a small yard, planting an oak as a street tree is “a great way to get an oak” in your neighborhood, she added.
- Climate adaptation. Native oaks thrive in California’s summer-dry climate. Seedlings are best planted before the winter rains have ended, and they will need occasional water before the next rainy season. But once established, native oaks do best without irrigation in the warmer months.
- Carbon sequestration. A key element in reducing climate disruption is planting trees, which take carbon dioxide from the air. Big oaks are great carbon sinks!
- Shade. When I was helping to vet gardens for a native plant tour, the simple, serene garden where I wanted to spend the entire day had a bench in a grove of coast live oaks.
- Reduced energy costs. Big oak trees can buffer winds and reduce swings in temperature, as well as shade buildings from summer sun.
- Locally appropriate. Acorns collected from a local population of native oaks will be locally and genetically appropriate to your location, Williams said. They can adapt better to local conditions.
- Ecological services. Like other trees, oaks clean and recharge groundwater, prevent soil erosion by holding soil in place with their root systems, filter particulates from the air and buffer noise pollution.
- Fire adaptation. Oaks are tough and less flammable than other trees. They also often resprout after wildfires.
- Free trees! The Re-Oak California initiative from CNPS is offering local residents coast live oak and valley oak saplings grown from acorns collected from locations in the Los Altos and Mountain View area. Launched in response to the Wine Country fires that devastated acres of habitat in 2017, Re-Oak California has distributed approximately 6,000 trees and expanded statewide. Acorns collected from local populations are grown at a nursery in Southern California.