Drought increases worry about Nevada County’s native trees
Special to the Sun
GRASS VALLEY, Calif. — As the historic drought plaguing California continues, many communities have found it necessary to drastically cut back on water consumption.
Though well-meaning, reduced water usage could have a negative impact on trees in the area.
In California alone, 12 million trees died in the past year due to lack of water, according to the U.S. Forest Service.
Though the majority of those trees were outside of urban areas, the worry is that the mandated water reductions being imposed in many California cities could cause more trees to die out.
Penn Valley resident Kent Treiber, for one, was concerned enough about the large number of native oaks around his neighborhood going brown to reach out to an arborist for answers.
“If I have such an oak on my property, should I give it a deep watering, leave it alone, or what?” he wrote to The Union. “If trees are dying and water could save them, it seems foolish to save water but drastically increase future fire danger.”
Zeno Acton, owner of Acton Arboriculture, says that many of our native trees are accustomed to drought conditions.
“If you look at the climate’s history, I think it’s a very significant drought,” said Acton. “But it’s important to remember our native trees can survive with basically no water from May until November. It’s the climate we live in. We have a drought every year.
“Everyone talks about, ‘Oh, we’re in a drought,’ he added. “Yeah, we have reduced available water and that sort of thing. And there’s reduced water in the soil going earlier in the springtime. But we have a drought for our native trees every year. So they are more or less acclimated to that.”
Arborist Tim Murphy, better known as “Tim the Tree Man,” says that he’s observed a higher rate of tree mortality recently, but recommends a wait-and-see approach. Many of the browning deciduous trees, like oak, are likely shutting down for the winter due to a lack of resources before coming back next year, he says.
As for non-native species, the situation could be more dire if you decide to stop watering, Acton says.
“We’re seeing a lot of people trying to conserve on water or (who) are shutting their water off entirely. That has big-time, long-term repercussions for planted shade trees,” he said. “If the trees become acclimated to regular irrigation and establish their root system in the upper soil, and then you cut them off cold turkey or heavily reduce water, you often see decline and for many species this means they won’t recover or have a hard time recovering. Diseases move in and that sort of thing.”
Bark beetles also pose a significant threat, as drought-stressed trees have a much harder time fending off their attacks. Acton says his company is seeing heavy attacks from Western pine beetles and other insects, as the trees don’t have an adequate sap flow to push beetles out. Ponderosa pines and sugar pines are also frequent targets.
As the trees dry out and succumb to insect infestation and disease, they become brittle and branch failure becomes a concern.
If a tree is not taken down in a timely matter, it could fall and cause major damage.
A strong El Nino system, such the one predicted by many for this winter, could also cause distressed trees to collapse, posing a danger.
The solution, Acton says, is to make sure the parched trees are well-hydrated.
“It’s really recommended that if you’re going to cut back, that you still deeply irrigate your shade trees. Mulching is another good way to help conserve water. You have to check soil conditions — that’s the only way to know,” he said.
Spencer Kellar is a freelance writer for The Union newspaper in Grass Valley and Nevada City; he can be contacted at firstname.lastname@example.org. The Associated Press contributed to this story.