This article originally appeared in News Nexus Media.
After a series of winter storms hit California this winter, thousands of trees across the state lost traction and collapsed on power lines, homes and highways. Sacramento one lost over 1000 trees in less than a week. Years of drought, pests and extreme weather have put the city’s trees in trouble.
The US Forest Service estimates that cities are losing some of their 36 million trees is destroyed each year by development, disease and, increasingly, climate stressors such as drought. In a recent study published in NatureThe researchers found that more than half of the city’s trees in 164 cities around the world were already exposed to temperatures and rainfall that were beyond their survival limits.
“So many of the trees we relied on so heavily are now losing popularity due to climate change,” says Nathan Flack, urban forest manager for the city of Santa Barbara. Conifers such as pines and coastal redwoods, which once grew widely along the coast, are dying en masse, he said. “Intensity of heating [and] longer periods [without] The rains are really forcing us urban forestry managers to rethink what good street trees are.”
Read more: 20 things you didn’t know about trees
What types of trees?
Trees help keep the area cool, absorb rainwater and clean the air from pollution. But in order for them to perform these critical functions, they need to survive in the same conditions. For many cities, this means rethinking what types of plants to plant.
Flack says he’s looking for trees that typically grow further east, like paloverde, which do better in warmer, third conditions. “Trees that survive in the desert will do us much more good here,” he says.
In Sacramento, species like the “Bubba” desert willow are replacing redwoods, says Jessica Sanders, executive director of the Sacramento Tree Foundation. “It’s sad because it’s an iconic tree,” says Sanders, “but it’s not really suited to the climate of the Sacramento region at the moment.”
Not only California cities rethinking their awnings.
In Harrisonburg, Virginia, authorities bring willow, oak and eucalyptus from the coast, trees that are more heat tolerant than many native species. In Seattle, they are planting more Pacific madrone and garry oaks, which had a better chance of surviving the hotter three summers.
In Detroit, which was once known as “Tree City” because of its extensive canopy, officials plant hardy trees such as eastern redbud, American witch hazel, and white oak that can withstand extreme heat and flooding.
Variety of trees
The city is also expanding species diversity to fight disease, aiming to prevent any single species from making up more than 10 percent of the city’s overhang. Detroit lost much of its canopy between the 1950s and 1990s due to Dutch elm disease and an invasive beetle called the emerald ash borer.
Today, nearly 40 percent of the remaining trees are considered “low quality,” says Jenny Shockling, senior urban forestry manager in Detroit for the nonprofit American Forests. “[They] consist of species that are prone to disease and storms, damage property and infrastructure, and dump large amounts of debris.”
Forest cover and climate change
Preserving urban tree cover could mean the difference between life and death on a hot planet. extreme heat kills approximately 12,000 people annually already in the USA; experts say the figure could reach 100,000 by the end of the century. A study published lancet found in January that increasing a city’s tree cover by 30 percent could cut heat-related deaths by a third.
Poorer areas with large non-white populations tend to have less forest cover and can be up to 20 degrees warmer than richer (and greener) areas. in accordance with several studies. “A tree map in any city in America, it’s a map of income and a map of race,” says Jud Daly, president and CEO of nonprofit American Forests.
Cities may see some relief soon. The Inflation Reduction Act passed last year includes $1.5 billion for the Forest Service’s Urban and Community Forestry Program, which is a fivefold increase in the program’s annual budget.
According to experts like Daley, the funding has the potential to transform urban canopies. But as Flack and other arborists across the country turn to new species to fill their streets, they face a new challenge: supply.
Read more: What makes a tree a tree?
“Now there are bottlenecks in the traditional nursery supply line,” Schokling says. “Growers tend to favor certain species because they do well in the nursery or grow fast, but that doesn’t necessarily say something about the diversity standards we’re trying to meet.”
American Forests is partnering with the US Forest Service to invest in and develop nurseries across the country to improve the supply chain. “Nurseries need some assurance that what they grow will have a market value, and we have confidence that what we are going to buy will have a stock,” Schokling says.
According to David Teuschler, chief horticulturist at Devil Mountain, one of California’s largest nurseries, this large-scale investment will be critical to renovating the look of the city’s canopies.
Even California’s native trees, like coastal live oak, are battling the state’s drought, Teuschler said. He would like to invest more in trees like Mesa Oak or Silver Oak for sale in Northern California, and Hammer Marsh or Salt Gum for sale in Southern California, but it can take years to grow the trees to marketable size and then he will only limited time to sell these seedlings. Unsold trees are usually composted, burned or otherwise destroyed.
He needs to know that he will have clients who have a clear vision of the future.
“You have to remember that there are a lot of old-school people who want to plant redwoods,” he says. “You want to be a nursery for these drought-adapted species, but if you can’t sell them, it’s a waste of time.”
One of Devil Mountain’s longtime clients is California arborist Dave Muffley, who stocks all of his projects with drought tolerant species.
Trees to combat drought
Muffley first began looking for drought-tolerant trees 15 years ago when he was leading a project to plant 1,000 trees along a two-mile stretch of highway through East Palo Alto. He wanted evergreens to prevent freeway pollution from reaching the low-income population on the other side, and drought-tolerant varieties, but most of the state’s nurseries had few options.
Muffley began to scour the southwest for acorns of the hardier oaks; There are more than 500 oak species around the world that can reproduce and create viable hybrids, Muffley says.
With Teuschler’s help, his projects, including the 9,000-tree mega-project around the Apple campus, have served as proof-of-concept cities as they work to build climate-resilient tree canopies.
By channeling federal funding to nurseries like Devil Mountain, Muffley says such a holistic system can be replicated across the country to meet each region’s unique needs.
“The truth is, we don’t grow enough trees in the US to spend the money the government has just allocated,” Muffley says. “So now it’s time to build the arsenal of ecology, and the production lines are the new nurseries that will need to be built to grow the trees.”
