Boise sought to add 100,000 trees by 2030. It may be lucky just to keep today’s canopy
Boise had planned on planting 100,000 trees in the city by 2030 — but nearly two years in, that goal is less than 3% complete. Now, after a summer of record heat and pervasive drought, planting that many trees has gotten a little more complicated.
The “City of Trees Challenge,” started in 2020, seeks to plant the 100,000 trees as well as 300,000 seedlings in nearby forest lands, to replace trees lost to wildfires.
The aim is to increase Boise’s beloved tree canopy, which can lead to better water retention, more habitat for urban wildlife and less carbon dioxide in the air.
The city, though, remains far off from reaching its goal. So far, nearly 3,000 have been planted, according to the City of Trees Challenge website.
Boise Council President Elaine Clegg, who spearheaded the campaign, said she expected to get off to a slow start the first couple of years, a challenge made worse by the COVID-19 pandemic.
COVID-19 made it more difficult to inform citizens about the initiative and how they could register trees on the website, Clegg said. Figuring out how to supply all the trees necessary has also proven difficult.
She said the current number is not a concern — for now.
“If we can’t pick up the pace, it will become more of a concern,” she said.
And with drought and higher temperatures becoming more prevalent in the U.S. West, some say the city will be lucky to preserve the canopy it already has.
Trees stressed after record-breaking heat
Boise had a record-hot summer in 2021, which saw nine consecutive days above 100 degrees in July, part of a heatwave that torched large swaths of the Pacific Northwest. All of Idaho is also in drought, according to the U.S. Drought Monitor, with much of Ada County classified as being in “severe drought.”
Scientists have said much of the West may enter a period of “megadrought” caused by climate change, marked by high temperatures and more frequent periods of drought.
Boise’s changing climate is making it harder for younger trees to survive its high desert environment, leaving fewer to replace older trees that die or are removed, according to multiple arborists.
James Glenn, owner and arborist at A Cut Above Tree Service in Star, said he’s concerned by the number of mature trees Boise is losing to new developments and the lack of success younger ones are having at replacing them.
A Treasure Valley native, Glenn said he’s seen the problem worsen over the decades. He said making sure younger trees succeed in their environment is key to keeping the canopy healthy; if that doesn’t happen, the whole of Boise could resemble the Foothills.
“We go back to the desert that we were 250 years ago,” Glenn said.
Sean McInerney, owner of Boise Tree, said his company is seeing more fatalities among urban trees than in the previous five years. Drier conditions have left many trees susceptible to disease and infestation by insects such as the lilac ash borer, which can cause severe damage.
“Older guys like me who have been working with trees for a long time, we see it,” McInerney said. “There’s no doubt in my mind that climate change and adverse climate change is affecting our trees.”
Younger trees already have a hard time surviving in a difficult urban climate; those in downtown Boise typically last only about seven years, City Forester Michael Andrews said.
“The heat was bad on a lot of those younger trees if you did not have somebody paying attention and watering it consistently,” Andrews said.
Andrews said he’s also seeing more insect infestations, which he said are due to warmer winters. Cold winters typically reduce the population of pests. He said he’s seen an increase in aphids and elm leafminers, which rarely kill trees, but turn their leaves an unappealing brown color.
Arborists: Where and what kind of tree you plant matters
Arborists say there is a way to help the canopy withstand drier conditions. The key is to adapt and be smarter about how and where trees are planted.
One part of the challenge is helping Boiseans make sure they plant the right tree. Those wishing to plant trees in their yard can contact the city for information on what trees will grow best in their area and register planted trees as part of the challenge.
Glenn said he sees many seedlings fail to mature because they’re in the wrong place, a problem that can lead to major expenses for property owners due to drainage or fungi.
“It’s a problem I’ve seen my entire life,” he said. “It comes down to a lack of education within the general public.”
Those wanting to plant trees can select ones that are more drought-resistant, Andrews said, which can help them survive into maturity. He said the ginkgo tree, which is sturdy and more resistant to pests and disease than other types, is a good selection.
The challenge’s website also includes a map of trees planted during the challenge thus far. Lance Davisson, president of the Treasure Valley Canopy Network, said the challenge doesn’t yet track the current status of trees planted but hopes to in the future.
Andrews said trees managed by the city, which encompass about 25% of the total canopy, have remained mostly healthy thanks to a consistent supply of water. On private lands, though, it can be a different story, since people don’t always know the best way to care for saplings.
But the total health of the canopy remains unknown. The city last completed a survey of its canopy in 2013, although funding has been collected to conduct a new survey in 2022, Clegg said.
Most arborists interviewed agreed: The canopy as a whole appears healthy, but it still has vulnerabilities, which could become exacerbated as Idaho becomes hotter and drier.
Clegg said the goal will still be to increase the canopy’s size from 16% to 23%.
“Even with climate change, I don’t think that’s an unrealistic goal,” she said.
This story was originally published September 29, 2021 at 4:00 AM.
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