Although redwoods are certainly beloved trees and Palo Alto was named after El Palo Alto, a tree at a campsite of the Portola Expedition Party of 1769, the city is too far inland and too dry to support redwoods without copious amounts of water, City Managing Arborist Dave Dockter said.
That's why the trees have done so poorly in the drought. It's also why, when stressed, they have become susceptible to diseases and, in some cases, have become hazardous.
Many of Palo Alto's street and garden trees originated from other parts of the country. When people relocated to California, they planted some of the trees they knew, he said.
"These trees last maybe 50 years," Dockter said, noting that those trees, planted outside of their natural habitats, have come to the end of their lifespans.
As the city removes and replaces mature trees, it is getting away from some of the old standards. Liquidambar, a beautiful fall street tree, is being replaced by other long-lived attractive species, and magnolias, native to the southeast, are being replaced with varieties that are better suited to grow locally. Canopy, the Palo Alto tree nonprofit, is encouraging the plantings of native oaks such as the coast live oak and the valley oak, which require less water and do well in local soils, Executive Director Catherine Martineau said.
The organization's Canopy Tree Library lists hundreds of trees with information about care, height, water and other requirements to help choose the right tree.
Michael Hawkins, Canopy program director, advised, "Getting trees off to a good start is key in making sure they thrive and have a greater than average lifespan."
Dockter has provided a list, below, of his top picks for street trees that will succeed locally and a list of those that will likely not thrive.
1. Chinese pistache
2. Forest green oak
3. Cork oak
4. Frontier Elm
5. October glory maple
2. Black locust
4. Silver maple
5. Big conifers in general