Ask the PAC: How Petaluma is caring for trees during drought

As the region still copes with the threat of ongoing drought, city officials are making sure they continue to keep Petaluma’s trees from becoming parched.|

After California experienced the second driest year since the late 1800s, many residents may wonder what the future holds for the surrounding canopy, and how even the most prominent of trees can maintain a healthy lifespan without significant yearly rainfall.

Petaluma currently is home to roughly 100,000 trees in total, with more than 100 considered historic trees throughout more than 20 public sites. Such heritage trees, including the California live oak, the giant sequoia and more, are at locations ranging from the west side's Oak Hill Park and on the Petaluma Historical Library and Museum property on 4th Street. Other trees are dispersed throughout other city parks and beyond.

But on a quest to conserve water, even after atmospheric river events in the early fall months, city officials must keep the town’s precious native habitat in mind.

Question: How has the drought affected Petaluma trees and how does the City upkeep their health?

Answer: Fortunately, Petaluma has not lost any trees due to the drought this year, according to the Parks and Recreation department. And as the region still copes with the threat of ongoing drought, city officials are making sure they continue to keep Petaluma’s trees from becoming parched.

“As soon as we knew the drought measures were going into place, we went ahead and started hand-watering plants, said Cindy Chong, Parks and Facilities Maintenance Manager. “So we continued to water our trees just off the irrigation system.”

Workers with the parks and facilities department are using what is called a “water buffalo,” which is a mobile watering tank that is hauled around town to spray the trees down individually. One tank can generally store between 200 and 5,000 gallons of water.

“We also do have this device that (helps us) go into the ground deeper and we inject water closer to the root systems,” Chong said in a Tuesday phone interview. “If you just water on top, it’ll evaporate before it actually reaches the tree.”

Chong said that depending on how dry a tree is, it’s important that trees receive at least five gallons of water at least twice per week, especially when they are young.

Although no trees were completely lost due to drought this year, many did show signs of severe stress, which indicates there’s plenty of work still to do citywide, Chong said.

“If we have to continue with the drought, we’ve got our plan in place,” Chong said. “As long as we don’t have to go into severe reductions like 60% water use reduction. But if we’re at the same level we’re at now, we’ll continue to make sure the trees get watered.”

Another major way to keep trees growing strong is to cover the surface above their roots with layers of mulch. Chong said that mulching helps hold in moisture and keeps water from evaporating.

Chong also warned residents that, when caring for trees on their own property, it’s crucial to keep in mind that different trees take in and use water differently.

“(For example,) redwood trees - they take in water during the rainy season and they hold that in their root systems and it nourishes them through the dry months,” Chong said. “So what we’re trying to do is to give them enough water so they sustain and they don’t go into states of shock.”

Chong said some of the city’s oldest native trees, many of which are dispersed in parks like Oak Hill, Prince and McNear, play a major role in the surrounding biodiversity. Tree cover is especially important in drought as shading can prevent evaporation from reservoirs and soil, saving water for drinking and agriculture in the long run.

“I tell everybody that I’m doing my rain dance every day and I’m not that powerful, but I keep trying,” Chong said. “If you lose a 300-year-old oak tree, it takes you 300 years to get it where it’s at. So the plan is to make sure we are good stewards of our trees and our city properties.”

Amelia Parreira is a staff writer for the Argus-Courier. She can be reached at amelia.parreira@arguscourier.com or 707-521-5208.

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