As wildfires burn across the West, many are casting a wary eye toward sun-scorched trees right here.
Vancouver’s urban forester, Charles Ray, said he has been answering worried calls from homeowners ever since last month’s record heat.
“The heat dome in June was unprecedented, on the heels of the driest spring on record,” Ray said. “I don’t think we know all the impacts on trees because we really haven’t experienced it before.”
Michael Laster is among those who have noticed trees that look distressed and dead, with desiccated needles cascading down every time the wind gusts.
Don’t Plant
Charles Ray, Vancouver’s urban forester, no longer recommends these trees for planting in the city due to the changing climate:
• Western hemlocks
• Western red cedars
• Katsura trees
• Stewartia trees
• Birches (other than river birch)
“It is especially noticeable on the western sides of evergreen trees, where the needles have turned brown. Many deciduous trees also show wilted, dried and falling leaves,” said Laster, a Felida resident and Vancouver’s fire code officer.
Although his expertise is in fire-suppressing sprinkler systems, Laster said he’s getting terribly worried about heat waves, wildfires and the future of local trees.
“I think the concept that climate change is not happening is foolish. It’s obvious that it is. Our temperatures hit an all-time high, three days in a row. After three days, we see damage to the trees — not just a few of them but all of them,” Laster said. “And dead trees tend to burn more than live trees do.”
Changing landscape
Climate change is shifting the zones where different trees thrive. The official Washington state tree is the western hemlock, Ray said, but he rarely recommends planting those in the city anymore. The same is true of the western red cedar.
“It’s heartbreaking because this is the Pacific Northwest. People love it here because we’re the Evergreen State and we have all these big native conifers,” Ray said. “But the cedar and the hemlock are not doing well in many areas.”
“What Vancouver needs now,” Ray said, “is shade trees.”
“They are becoming more important as our summers are getting longer and hotter and drier. They help cool the heat-island effect in cities,” he said. “Any time you go to a park, you’re looking for the shade trees.”
Doug firs and western white pines are still doing well in the city, but people are sometimes reluctant to plant them because they grow so tall and imposing. That’s nothing to worry about as long as they’re planted in the right place, Ray said.
Informed tree selection and placement has never been more important, Ray said. For detailed information on choosing and planting appropriate trees for streets and yards, visit www.cityofvancouver.us/publicworks/page/treesources or call or call 360-487-8308.
“The research is saying that communities need to look at changing their tree palettes,” Ray said. “We need to look at what’s doing well in southern zones, because those conditions will be gradually moving north over time.”
Deep watering
When homeowners call Ray in a panic about their trees, whether old favorites or new plantings, he tells them, “Stay calm. It might not be as bad as it seems.”
The first thing to do is reach for your garden hose.
“What’s happening is water stress. Just as people need to stay hydrated — we sweat and we have to replenish — trees give off water through their leaves throughout the day. Their reserves can get depleted and they don’t have enough water to replenish,” he said. “Though the plants are scorched, though needles and leaves are browning, the stems and branches might not have had a complete die-back. … New buds might break out next season.”
To help that happen, water the tree properly and faithfully.
“Give it a season of good tree care and deep watering,” Ray said.
Young trees need 10 to 15 gallons a week for their first three summers, he said. Mature trees appreciate extra water during summers too. Each time you water, give the tree 10 gallons of water for every inch of trunk diameter. (To calculate tree diameter, measure the tree circumference at chest height and then divide by pi, or 3.14.)
Don’t use a sprinkler, Ray emphasized. Sprinklers soak only the top 4 inches or so — great for grass, but not for trees.
Instead, set a garden hose at the base of a tree and let it trickle for a good 15 minutes or longer, Ray said. That lets the water run deep, and encourages the tree roots to go deep after it. Deep roots are healthy roots, Ray said. Shallow root systems leave a tree prone to instability and damage. If you don’t have a garden hose, punch small holes in a 5-gallon bucket, fill the bucket with water and set it out to dribble.
Don’t do any watering during warm, sunny daytime, Ray said, because that water will tend to evaporate instead of soaking in. Watering when it’s cool, like early morning or evening, is best. If you water at night, avoid getting tree leaves damp, which can lead to mildew and leaf diseases like black spot fungus.
Add a layer of mulch to the area to hold down moisture, regulate temperature and add nutrients, Ray said. According to the Vancouver Urban Forestry website, “Bark chips make good mulch, using the 3-3-3 rule: 3 inches of mulch in a 3-foot ring with a 3-inch space around the tree trunk.”
Finally, Ray always recommends that property owners develop an ongoing relationship with a trusted arborist who is a member of the International Society of Arboriculture, he said. (Visit www.isa-arbor.com to find one.) It’s no different than having a regular auto mechanic, Ray said. You don’t want to wait for an emergency to start hunting for help.
Unfortunately, he added, most arborists are pretty backed up right now.
