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Thirsty times

Tree experts weigh in on saving trees while remaining water-conscious during drought

At its inception, Palo Alto was named after a 110-foot tall, over 1,000-years-old coast redwood tree called "El Palo Alto," which loosely translates to "tall tree." Today, in the midst of California's drought, city staff and tree experts are encouraging residents to go back to their roots and care for these trees from which the city gets its name.

More than two-thirds of the city's urban forest is situated on private property, according to Michael Hawkins, a certified arborist and program director of environmental nonprofit Canopy.

"(This) is why we encourage people to plant (and care for) new trees, which would replenish the trees we would lose from the drought," he said.

Two of the main mistakes residents are making with their trees are overwatering or simply not watering at all, he said. Mature trees only need to be watered once a month or every month, according to Hawkins. Younger trees require watering weekly or biweekly, for at least the first three to five years. After which, they can be placed on a monthly watering cycle.

The worst tree-watering method, Hawkins said, is sprinklers because the water will likely evaporate before the tree has a chance to absorb it, especially during warmer temperatures. He recommends running drip emitters for more mature trees, specifically the Netafim brand, for about 90 minutes. They should be placed around the ring of the tree at the drip line where most roots are located. If residents don't want to spend money on drip emitters, Hawkins recommends soaker hoses.

For younger trees, Hawkins said to water the tree by holding a large water bucket with holes drilled in the bottom over it. The holes help regulate flow and prevent water running into the streets.

As a last resort, if sprinklers must be used, they should run in early mornings or evenings and should be set to run only 30 minutes at a time, he said.

Depending on the density of the soil, trees can be watered up to once a week according to Ruben Green, president and consulting arborist at Evergreen Arborist Consultants.

"Water goes right to the root system for sandy soil. Heavy soil or expansive soil will go straight to the street," he said.

He recommends taking a sample and crushing it in between fingers. The heavier soil is very similar to clay and can likely form a solid shape. Sandier or loamy soil, Green said, tends to fall apart and requires more frequent watering because the water passes through the soil much quicker than dense soil.

If there is any silver lining to the drought, Green believes residents are not overwatering their trees, which reduces the decay and diseases among them.

Green recommends not watering plants or bushes and reducing the amount of annual flowers.

"If it dies, it will be easy to replace," he said. "The trees take decades and decades to replace."

Trees are not one size fits all, Green adds. Residents who are looking to plant trees should consider how the tree will evolve during the next few decades.

"It has to be the right tree for the right place," he said.

Green and Hawkins recommend planting trees such as the Chinese elm, silver linden and coast live oaks, and avoiding magnolia trees and Monterey pine. Coincidentally, the southern magnolia is the most common tree along Palo Alto's streets. The next most common tree is the liquidambar.

According to Susan Rosenberg, a Canopy founder, every summer, Canopy staff and volunteers visit trees that have been planted by the city during the past five years and leave fliers for homeowners about tree care. She encourages residents who have questions about caring for these trees and their own to submit questions to Canopy's Tree Hotline.

Despite the drought, trees are worth the water investment, Hawkins said.

"Everyone has been really focused on preserving water and a lot of trees have been suffering as a result," he said. "It's important that we don't lose them as assets."


Muna Sadek is an editorial intern at the Palo Alto Weekly.

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1 person likes this
Posted by David
a resident of Another Palo Alto neighborhood
on Oct 16, 2015 at 10:45 am

Plant native trees rather than showy non native trees (IE: chinese elm) that take regular water applications to survive.

Like this comment
Posted by SuperD
a resident of Community Center
on Oct 16, 2015 at 12:27 pm

Actually, plant both native and non-native trees. Check out Canopy's tree library to find trees that are drought resilient and don't have excessive water needs. Native trees aren't the only ones that fit into this category. Species diversity is a good thing if you want to ensure a fuller canopy. Diseases can wipe out all the street trees if they are only one variety - e.g. Dutch Elm Disease, SOD, etc.

2 people like this
Posted by Jane
a resident of College Terrace
on Oct 16, 2015 at 1:43 pm

Non-native trees may not provide food for birds. Even some non-natives with berries (e.g. cotoneaster) make the birds "drunk" and likely end up being killed by a cat, or give them diarrhea so they feel full but get no nutrition.

1 person likes this
Posted by SuperD
a resident of Community Center
on Oct 16, 2015 at 4:43 pm

Jane, those are valid concerns. But many non-native trees will provide appropriate habitat and food for birds so one can't make a wholesale generalization. It's really a matter of doing research and planting the right tree in the right place.

10 people like this
Posted by Sequoias
a resident of Another Palo Alto neighborhood
on Oct 16, 2015 at 5:24 pm

My brother's best friend is a ranger at Sequoia Nat'l Park. He says they will soon be putting in drip irrigation for the giant sequoias that have been weakened by the drought. They have had neither enough fog ( they absorb water through the flat needles ) nor rain in so long that they will soon be too weak to use their capillary action to get water to the foliage at the top.
Most of these trees are over 1000 years old, and will die otherwise.

2 people like this
Posted by Roger Overnaut
a resident of Evergreen Park
on Oct 16, 2015 at 5:44 pm

"Plant native trees rather than showy non native trees (IE: chinese elm) that take regular water applications to survive."

Chinese elms are actually very well suited to dry climes. You'll find them and their siberian elm cousins thriving unattended all over the southwestern deserts. Being deciduous, they are less prone to the storm winds of our winters.

Among the worst trees for our climate are the most popular street trees that the city planted decades ago: magnolias and camphors.

4 people like this
Posted by Paly Grad
a resident of Leland Manor/Garland Drive
on Oct 16, 2015 at 7:18 pm

A few of the redwood trees between the Art Center and the Rinconada Library look like they would benefit from some more water!

2 people like this
Posted by senor blogger
a resident of Palo Verde
on Oct 17, 2015 at 10:27 am

So, if the city owns and trims the tree ( as it is on my street) then will the City replant/replace a dead tree and maintain ownership?

3 people like this
Posted by Oldbasse
a resident of Midtown
on Oct 17, 2015 at 11:31 am

To resolve or mitigate the "urban forest" controversies fresh City initiatives are needed. A useful, initial step might be the preparation, publication and distribution of a brief "white paper," that objectively identifies and profiles the top 6-8 concerns associated with Palo Alto's "Tree City USA" policies.
The white paper might also address the desirability and feasibility of new or strengthened City ordinances with regard to terms such as "hazard," "nuisance" and "encroachment" as well as tree licensing, fees and fines.
It would be enlightening to see some data on private and public tree ownership by various classifications, segments and types. Dollar amounts in this realm must probably be relegated to "best guesstimates" status. The total, annual sum for private and public tree ownership, maintenance and liability, seen over the past and projected 5-year periods, must at least be in the $10-20MM range.

2 people like this
Posted by Rickey
a resident of another community
on Oct 30, 2015 at 1:15 am

[Post removed.]

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