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The unfinished subdivision in north Natomas looks just like any other, propped up along the banks of a man-made lake. But one strip of land here may be key to the livelihood of Sacramento’s urban forest, a place where scientists are growing the trees of the future.
A group of researchers are wagering on 12 tree species planted near the lake to see if they can withstand the effects of a changing climate. In the future, Sacramento is expected to experience an increasing number of hot and dry days that could unleash a new rash of pests and diseases — both threats to urban trees.
The researchers from the U.S. Forest Service and the UC Cooperative Extension looked to places with harsher terrain than California’s inland valleys as a template for the future: Australia, west Texas and Oklahoma. In Sacramento, they have planted trees at three other sites and a control group on the campus of UC Davis.
Urban forester Kevin Hocker stopped at Fisherman’s Lake on a weekday in July to survey the small Canby oak, a tree native to Mexico with leathery, emerald-colored leaves that can sprout as tall as 50 feet. The oak grows fast and upright and tolerates extreme heat.
“We’re giving it a shot and so far it looks great,” Hocker said. “It’s actually a pretty promising tree.”
Hocker and others are working to make sure Sacramento remains a city of trees. The urban canopy is a source of pride, and a respite to the scorching summer heat. Scattered over about 100 square miles of the city limits, trees blanket more than 20 percent of the area, placing Sacramento among the most tree-friendly urban environments in the world.
But perils lie ahead. As the world’s climate heats up, as the city’s majestic elms and ash trees enter old age, as urban development brings more construction, and as invasive critters and disease creep northward toward the city, scientists and urban planners are worried.
Can the city maintain the majestic canopy that arches high over houses in neighborhoods like East Sacramento and Land Park, or will it have to settle for smaller more sustainable trees that merely reach 30 or 40 feet high? Will new urban development adequately replace the trees they tear out for new apartments?
Many in the city are planning for decades to come, acknowledging that the quality of life in Sacramento could hinge on how well it protects and replants the tree canopy. Researchers don’t know which trees will thrive in the future so the experiment is designed to get a running start.
As Hocker walked down the path at Fisherman’s Lake for about 30 feet, each tree’s condition appeared to be hit or miss. But they have only been in the ground for five years.
“How they’re doing today is not necessarily the end-all-be-all of everything,” Hocker said. “We want to see how they’re going to do over the course of 30 years.”
TREES OF THE FUTURE
Since the city’s founding in 1850, trees have been necessary for the population’s survival, shielding the area from deadly heat and soaking up rain. They also became a status symbol as people adopted European species in areas like Land Park that now provide a spectacular canopy over the neighborhood.
Newspapers such as the Sacramento Bee were influential boosters for tree planting and preservation. C.K. McClatchy was inspired, in part, during a trip to Paris in 1911.
Before him, his father James McClatchy urged residents to wait before cutting down native cottonwoods, whose drippings had become a nuisance, until newly-planted trees became of size.
“In a few years, when the thousands of trees that are being planted have grown to a respectable size, our city will almost appear a forest,” James McClatchy wrote in The Bee in 1857, “and the intense heat of the summer will be much less felt than either in the past or present.”
BEHIND OUR REPORTING
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Why we reported this story
In a region known for its spectacular canopy and variety of trees, as well as its close association with the natural environment, we want to explore how trees play an role in protecting Sacramento from heat, pollution and urban blight.
As older trees die off, and as the climate heats up, what will our tree canopy look like in decades to come? How has rapid development changed the look and feel of the city? What are the best trees to plant to withstand changes in the climate?
This is another in a series of stories that we hope will allow people to think more deeply about one of Sacramento’s crowning achievements.
What is the Tipping Point series?
This story is part of The Bee’s Tipping Point project examining the profound changes taking place in Sacramento. A team of Tipping Point reporters has been looking at housing development, culture and quality of life issues in the capital city.
Elms were planted starting in the late 1800s because they were a sign of wealth on the east coast. In the 1930s, London planes began dominating street corners in places like Land Park, a neighborhood that still boasts a dense canopy.
On paper, these selections appeared problem-free. What’s often unknown are the different diseases, pests and other dangers that can alter a trees’ fate.
Sacramento saw this firsthand with the slow creep of Dutch elm disease. It started in the 1970s, sickening elms on the east coast. The diseases’ slow crawl across the U.S. has been lethal, wiping out hundreds of thousands of trees.
Modesto ashes were favored for a time in Arden Park and other areas but it has been ravaged by at least two diseases and the emerald ash borer.
A formidable new threat has emerged in Southern California, a non-native beetle called the shot hole borer. It thrives near riversides and likes to live in sycamores like the city’s London planes, which account for an estimated quarter of the city tree population.
If the beetle arrived in Northern California it could be a death sentence.
But the study isn’t about finding one or two, or even 12 super trees. And it’s not designed to be a one-to-one replacement for the London plane or another faltering species. Scientists hope it will add to the broad range of trees already present, strengthening the larger canopy in the process.
Like with the elms and ash trees before, Hocker said nature has a way of opposing these efforts. Then the search for solutions starts again.
CLIMATE CHANGE, PESTS AND DISEASE
The specter of losing a large number of London planes in Sacramento is yet to be seen. But the challenge could come at the worst moment.
Shade trees are one of the few investments that yield several benefits for large urban cities. They help reduce the amount of particle pollution in the air, minimize stormwater runoff and mitigate high temperatures on streets and sidewalks.
Climatologists predict the number of dangerous summer heat days, on average, will nearly triple by 2055 in Sacramento, a dire projection the Natural Resources Defense Council said applies to many large cities nationwide. As a result, the number of otherwise preventable deaths in the city from excessive heat exposure could increase seven-fold, according to the NRDC report.
There’s growing urgency in some parts of the world to prepare for a hotter future. The city of Paris, for example, announced this summer that it wants to plant a number of “mini forests” to improve air quality in the French capital.
Is that the answer? Should there be more trees in a city with so much seeming abundance?
An MIT study of street-level tree visibility ranked Sacramento higher than places like Seattle, Los Angeles and Amsterdam. Yet some like Karen Jacques, a member of the advocacy group Trees for Sacramento, is doubtful it will be enough in the coming years.
“What a lot of us have been experiencing as community residents that care about trees is we’re going in the opposite direction,” Jacques said. “We keep losing trees. They’re taken out for different things.”
A city-funded canopy assessment concluded the amount of tree cover could potentially double from its current density to cover approximately 45 percent of the area. That’s more of a moonshot goal, though, that’s possible only if the city decided to plant trees to the exclusion of new housing, businesses, roads and parks.
A stakeholder group recommended 35 percent. But it’s unclear how aggressive Sacramento will be until the City Council adopts the new urban forest master plan, which will guide long-term decisions for decades.
INFILL DEVELOPMENT: ANOTHER MENACE?
Although lately, the city has been dealing with an unintended consequence of the development boom underway in Midtown and surrounding areas.
Sacramento emerged as one of the state’s leaders for streamlining development fees to encourage housing construction, particularly in the central core. The city created more housing units last year than any city in Northern California, nearly 2,400, according to data obtained from the Department of Finance. Close to one-third were for multi-family structures.
“Many of our (challenges) are social or cultural as we begin to densify the housing in downtown Sacramento and office buildings,” said Ray Tretheway, executive director of the Sacramento Tree Foundation. “Often times, in the fight for real estate the tree comes out on the raw end of it.”
Advocates and experts said several trees have been removed to make space for some of the soaring luxury apartments and office buildings. The new construction is often crammed onto vacant land or lots previously occupied by a smaller building.
Tree preservationists say the cultural shift away from protecting existing trees to a policy of substitution has come at the expense of the tree canopy. When large trees limit space, advocates say, on more and more occasions they are deemed expendable by developers.
Francesca Reitano, a resident of Elmhurst, saw this familiar scenario play out for the construction of the GIO Apartment building on Stockton Boulevard and T Street. A number of street trees were sacrificed in the process.
Reitano has come to see the push for infill development as a mixed blessing.
“Every time you build a project, trees come down,” Reitano said. “We need the density; there’s no way around it but we’re going to lose tree canopy because of it.”
There are no trees surrounding the apartment building yet but a project manager, when reached, said there are plans to install enough to substitute and expand on what was lost. He said the land was all but paved over where a two-story office building once stood but in time there will be more trees and coverage than before.
The larger issue with the cut down and replace rationale is once a large tree is lost it’s not always possible to substitute it with another large tree, said Erika Teach, a local ecologist with the U.S. Forest Service and the Davey Tree Expert Company.
Many elm trees, for example, were planted before there was modern infrastructure, allowing them to grow roots and everything was built around them. Teach said it’s not always an issue of size but acknowledges shade is being lost when elms are replaced with medium-sized trees.
“We’re not going to get that arching canopy over the streets with Chinese pistache trees,” Teach said. “But the planting wells and the infrastructure that’s there only allows for Chinese pistache trees.”
CUT DOWN AND REPLACE
The city pools money into a replanting fund from developers who pay replacement, or “in-lieu fees,” if a project is landlocked. Builders are obligated to pay $325 for every inch of trunk diameter that is not replaced.
Now in its second full year, city officials said the fund allows them to plant in places that aren’t limited by space. As of the beginning of August, the account balance totaled more than $600,000, according to city data provided to The Bee
“That in-lieu fee has done more to protect trees than anything else,” Hocker said. “In the past, the developer would find a way to get the ‘no’ turned into a ‘yes’ and not replace it at all.”
It’s not always a win-win in the eyes of everyone.
Debra van Hulsteyn, who lives on I Street, remembers when people looked down on living in Midtown. The ongoing renewal as been remarkable to see. She’s noticed other things, too. Like how the buildings have moved closer to the curb. And some of the architecture — by design — curtails the space available for large trees.
Consider the Golden 1 Center, for example, which has a design that sweeps out over the curb in some places, she said. How is a tree supposed to grow beneath that?
“I think that (building) is going to set the stage for what some people think downtown needs to look like,” van Hulsteyn said. “So trees are kind of going by the wayside.”
Trees for Sacramento recently convinced an architect to change a condominium’s design on I Street that would have eliminated a large black walnut tree. That outcome happens less than activists would like.
Another notable case was the City Council decision to remove 51 trees from around the city-run Sacramento Convention Center Complex last year. The building is undergoing a multi-million dollar expansion that would include a sleek new facade that also sweeps out over the curb.
The decision left the area with fewer trees and noticeably less canopy cover. During the meeting, activists raised points about climate change. A majority of the City Council was not deterred. They agreed instead to pay $150,000 into the replanting fund and cut the trees down.
“(It’s either) we’re a city that’s trying hard to address climate action or we’re not,” said Councilwoman Angelique Ashby, the only dissenting vote. “I want to be a part of the solution.”
A ‘MENU’ OF TREES
It’s easy to forget that Sacramento was once called the city of the plains because of its flat surroundings. Accumulating the dense canopy enjoyed today didn’t happen by mistake.
Trees were necessary.
“Everybody said ‘wow, it’s hot around here’ and they started planting trees more and more until we became the city of trees,” Hocker said. “And now everybody just takes it for granted that we have trees everywhere.”
Although locals have always debated and fought over trees, climate change raises the stakes. There are some, like the researchers and activists and planners, who are focused on the future.
It’s especially clear at Fisherman’s Lake on the outskirts of the city where neighborhoods are still unfolding onto desolate plains. No placard or sign announces the importance of the gangly trees standing opposite the homes in North Natomas.
They chose the spot because it resembled a natural environment, and in real-world fashion, a disease-resistant Elm was recently damaged. The tree, standing in the glare of a sizzling July sun, appeared scraggly and bruised. Others like it were faring well.
Hocker largely decides what happens to the city’s trees; what to plant and how many; where to plant; and if an aging tree needs to come down.
The most desired tree has notably been the London plane, a species often described as an “urban warrior” because of its resilience. But many worry it has been overplanted.
The potential arrival of the shot hole borer — if it makes it this far north — combined with climate impacts could be the tipping point for the sycamores. That’s one of the other reasons the experimental tree plots are of great interest.
He said the solution to outmaneuvering the climate, ravenous bugs and ever-changing diseases is diversity. Only a wide variety will lead to a more sustainable urban forest.
“A lot of diseases and problems are specific to one species of trees so you want to mix it up as much as possible,” Hocker said.
Many cities are limited to 10 species. Not in Sacramento.
“Our current inventory in the city boasts well over 200 individual species of trees so we have quite a big menu to choose from,” Hocker said. “But we want the menu to be even bigger. We want to have as many choices as we can.”
This story is part of Tipping Point, our new project focused on telling the stories of the Sacramento region’s evolution. Read more of our Tipping Point stories here.