Of all the living plant material most affected by prolonged, extraordinary drought, trees are among the most vulnerable. The historic parched condition that hit Texas so hard, beginning in 2010 and continuing unabated until sometime last year, killed approximately 307 million trees.
Most of the trees that died were in rural areas or forests, but six million of them had graced city parks, lined urban streets, and brought shade to people’s yards.
Even though the Texas drought is officially over, trees are still dying there. The trees that did survive will be stressed for years to come, long after soil moisture returns. “Those figures were based on an assessment we did in 2012,” said Paul Johnson, urban and community forestry program coordinator for the Texas A&M Forest Service in Austin.
Drought killed the fine feeder roots used to take up water and nutrients. Until those feeder roots are fully replaced, the trees won’t be able to support their full complement of leaves.
In the West, the toll is also steep.
A triple whammy of drought, high heat and an exploding pine bark beetle population are estimated to have killed 26 million trees in the Sierra Nevada area in just the eight-month period from October, 2015 to June, 2016. The total loss of trees since 2010 is 66 million, and that number is expected to rise.
Trees devastated by drought are more vulnerable to the onslaught of insects and disease. Pine bark beetles are always present, but adequately hydrated trees can fend off attacks by drowning the bugs in excreted sap, or pitch. But dried-up trees can’t produce enough of it to fight against the insects’ onslaught, and their numbers can multiply exponentially, which they have.
So what’s a landscape contractor to do when a prolonged extraordinary drought threatens his clients’ treasured trees? Charlie Carr owns Texas Tree and Landscape in Wichita Falls, Texas, one of the areas in the state that was hardest hit by the drought. At one point, watering restrictions reached Stage 5: no outdoor irrigation allowed, period—not even drip.
He had to improvise in order to keep his clients’ landscapes, and his business, from drying up completely. “When you’re in business for yourself, that wheel has to keep turning at all costs,” he said. “So we bought some land, started drilling wells, and got into the water hauling business.”
Soon, Carr was hauling 20,000 gallons a day, every day, to his more well-heeled customers who could afford to pay for it. They couldn’t afford not to. As he said, “When you have a landscape that’s worth $50,000 to $75,000, you really want to keep it alive.” Some of those landscapes required 300 to 400 gallons of water per week.
A number of his clients of more modest means, average homeowners, also purchased water. For them, he had yet another ‘improvised’ solution. He rigged up simple downspout-to-rain-barrel systems to collect what little precipitation there was, and fed it through their sprinklers. This was better than nothing.
He also unloaded dump trucks full of mulch onto people’s lawns. The mulch worked as an insulator, keeping moisture from evaporating so quickly.
While smothering lawns with bark chips killed the grass, it kept the trees alive. Carr, who is also a certified arborist, told his clients their grass will grow back, but not their 100-year old oaks.
Johnson said, while that’s what a tree needs to thrive, it can survive on far less. “In a situation like the one in Wichita Falls, where no irrigation was allowed, I would encourage people to put a bucket in the tub or shower, and put it out for their tree,” he said.
The area around Reno, Nevada, is undergoing significant drought right now. “You can’t take a tree that’s been in a lawn for its lifetime, that is used to getting all that water, then just rip out the lawn and put a couple of emitters by it,” said Rick Clark, owner and president of Omega Environmental Solutions, a Reno company that specializes in sustainable landscape design and installation.
He prefers, instead, to install subsurface drip irrigation, looped around a tree’s dripline, and preserving at least some of the turf.
Of course, a complete ban on irrigation is an extreme measure, done in only the most extreme circumstances.
Yes—a client could put a bucket in his shower and reclaim the water, then pour it on his trees’ roots. Or, his landscape/irrigation contractor could install a simple rainwater recapture system, as Carr did, and/or an equally simple, inexpensive laundry-to-landscape graywater apparatus.
Trees are the most valuable part of any landscape. When faced with drought, while we’re working hard to preserve all the growing things, we need to keep these beautiful shade producers top of mind.