Vancouver is in the throes of another hot, dry summer and, along with residents, the city’s trees are feeling the heat.
“It’s not just the first year of it so the trees that were somewhat perhaps stressed from the previous years the impact is harder on them,” said Amit Gandha, a City of Vancouver arborist.
He added that the trees that are in the city’s commercial areas, or along main arterial routes, are more prone to the stresses of a long, dry summer.
“It’s really the whole heat island effect,” Gandha said.
Those trees that are surrounded by concrete, asphalt and buildings absorb heat from the sun all day long but then when the sun goes down they also take in all the heat released by the surroundings.
“It’s just a constant process so those trees definitely… get more stresses because of that,” he said. “There is less of that on the side streets where the residential properties are. There are just more boulevards, more grass, more yards and all that so they’re doing a bit better.”
So far, 2018 is ranking as the sixth driest summer in the city since 1937. Since June, Vancouver has recorded 51 millimetres of rain. The wettest summer on record was in 1991 when we got 257.2 mm of precipitation. The driest was in 1951 when the city recorded just 26.4 mm of rain.
While the amount of precipitation varies from year to year, overall the amount of summer precipitation appears to the on the decline since 1991.
“This can happen one summer and it can happen another summer, but if it keeps happening it’s going to weaken more and more trees, it’s especially the smaller trees that suffer because they don’t have extensive root systems,” said Rob Guy, a professor at UBC’s faculty of forestry.
“I don’t think it’s quite as bad this year but it’s still bad,” he said, “and it’s not so much the heat, it’s the lack of rain.”
Trees that are distressed because of the lack of rain will often start turning brown and dropping their leaves earlier than usual, but it’s not necessarily a sign that a tree is dying.
“It’s more of a preventative measure for the tree so it doesn’t lose more moisture,” Gandha said. “It’s a sign that it’s hot and all that but sometimes it’s not really that big of a concern. It will be fine it’s just doing its own thing to survive.”
Guy echoed those sentiments.
“Some trees look pretty bad,” he said. “I’m always amazed at how bad the red maples look, they look awful, but then they seem to recover and come back the next year.”
Gandha said residents that are concerned about the health of a tree can report it through 311.
“We can go out and do an inspection of the tree and find out if it’s something to be concerned about or not and go from there,” he said.
Residents can help by watering nearby trees. While city crews are out watering trees around the city during warmer months, they tend to focus on trees that were planted over the last two years since those need the most attention while root systems are established.
Be a tree guardian this Summer! Water street trees if you see signs of stress like wilting leaves, or early leaf drop. Tips for tree care: https://t.co/Rh0BX7NdJX #ThirstyTrees pic.twitter.com/ZhvDdSrq5S— Vancouver Park Board (@ParkBoard) August 19, 2018
“We definitely appreciate any homeowner or business owner that wants to water the trees,” Gandha said. “We welcome it, especially at this time of year with what the trees are going through. We would totally just advocate for people to water trees.”
There has been a push to plant more trees around the city in recent years with council setting a goal of planting 150,000 new trees by 2020. In May, the city marked the planting of more than 105,000 trees.
Gandha said that the current trend towards hotter, dryer summers is taken into consideration when choosing trees to plant around the city.
“As far as the trees that we select to go throughout the city we definitely consider what the climate’s like and what we’re moving towards, so those are definitely factors that are used to select species,” he said.