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Trees gain ally: Science and Technology

Marc Lefkowitz  |  11/02/17 @ 11:00am  |  Posted in Vibrant cities, Transform, Plants & animals

“Urban Forests” author Jill Jonnes offered Cleveland an invaluable lesson on how the city earned, and then lost, its moniker ‘the Forest City.’

Speaking at Levin College of Urban Affairs yesterday, Jonnes harkened back to John Davey, the 19th century arborist from Kent, Ohio whose book “The Tree Doctor” inspired today’s 8,000-employee Kent-headquartered tree service company, Davey Tree.

In a chapter in his book called ‘Cleveland’s calamity’ Davey explains how the city was having rotten luck planting oaks and maples at the turn of the last century. “They die from thirst because of the barren, sandy soils,” he wrote.

<br />Science and tech have shown how much street trees add to property value and perform valuable ecological services like cleaning the air and reducing flooding.

It speaks volumes about the difficulty, but also the value, of an urban forest that Cleveland lost 97,000 acres of trees since the 1940s. The blame falls mainly with pests like the long horned beetle which devastated the giant chestnut trees, and Dutch elm disease, and emerald ash borer, which made their way into the U.S. because of our global economy.

“Cleveland is not alone,” Jonnes said. “The norm is, American cities are experiencing deadly (pests and diseases).”

While the 20th century may be remembered for the loss of giant trees forming shade canopy over streets, panelists at the Levin College spoke of the forces at work to bring urban forests back.

The new hope is in technology and a groundswell of support for protecting natural resources in cities. That it could inspire a new Davey-like 21st century moment of planting trees. Thousands of them are needed to make up for the missing nature in cities, where the majority of Americans live and get to experience nature firsthand.

Unfortunately, public policy wasn’t very sophisticated in the 20th century, meaning, tree lawns were planted as “mono crops” with one type of tree. Pests could and did lay waste to street trees. Less shade means hotter and drier conditions which have been a public health and environmental concern.

“Hundred foot arches of elm and chestnut trees made everything seem reverent,” Jonnes said. “When they came down, the severity of things like utility lines and cracks in the pavement which was no longer bathed in shade was noticeable.”

The felling of the giant trees by pests was made worse by poor planning: A lack of tree ordinances mean cities have no protections when a utility company rolls up with truck and chain saws to replace aging power infrastructure.

Science provided a powerful tool for cities in negotiating with utilities, and in seeking funds from taxpayers and bond buyers for re-greening the now exposed streets, homes, sidewalks. Quantifying how much protection they provide.

Enter the age of the data-driven tree plan

There’s a deep history that led to headline grabbing moments like New York City’s Million Tree Plan which in 2007 wowed former Mayor Michael Bloomberg into doubling the city’s tree budget. An extensive, high resolution survey of trees produced maps that showed the worst affected areas in the city.

Trees got a new swagger from the likes of Andy Lipkis, a “tree evangelist” in the 1980s who formed Tree People and led the first Million Trees campaign in Los Angeles before the 1988 Olympics, Jonnes recalled. Then, there was former Chicago Mayor Richard Daley who hired renowned arborist, Rowan Roundtree, to survey trees and map the worst hit areas by political ward.

Roundtree and the likes of Dr. David Nowak of the USDA Forest Service are credited with bringing new scientific methods to quantify the “ecological services” that trees provide. They conceived of the method and then tested how much trees absorb in storm water, how much beneficial shade, wind protection, animal habitat and other “services” that trees provide. Others then ascribed dollar figures to these services. This in turn led to the shift in thinking of trees from passive costs to our modern approach to trees as part of a city’s “green infrastructure.”

Green infrastructure then has a real dollar value, provides hundreds of years of civil service, and as such should not be treated as weeds, as Davey wrote, by cities or power companies.

“The idea is, how trees influence sewer rates as green infrastructure,” Jonnes commented. Trees also produce health and social benefit. For example, in Baltimore, an urban tree planting initiative had a calming effect on a rash of violent crime.

Science and technology has been a boon to the urban reforestation efforts. New, hardier tree hybridization techniques have re-introduced the elm and chestnut tree to cities. Modern medicine has quantified the lower levels of stress inducing chemical in humans known as cortisol as a result of living near trees.

It led the Cuyahoga County Planning Department in 2014 to produce a countywide tree canopy assessment using Geographic Information System (GIS) software and high resolution imaging. Which in turn inspired City of Cleveland in 2015 to create the Cleveland Tree Plan and set in motion a return to the Forest City a canopy that today covers only 19% of the ground with shade to 30% by 2030 (50,000 trees are being planted by 2020. The varieties will be selected to withstand climate change, said Office of Sustainability’s Dr. Cathi Lehn).

Running parallel, Jacqueline Gillon, Community Engagement Specialist with Western Reserve Land Conservancy’s Thriving Communities program, commented that vacant land is “the perfect opportunity” to plant trees — which is what they are doing with the assistance of St. Luke’s Foundation in the Woodland and Buckeye areas on the east side of Cleveland.

Technology has also enabled the tree enthusiast to become citizen scientist. The Nature Conservancy, the Forestry Service and Davey have developed mobile apps like iTree that allow individuals to measure neighborhood-scale, or their own property (even down to a single tree!) ecological services like carbon sequestration and community benefits of shade trees.

After all, Jonnes said, to plant a tree that will be enjoyed by future generations doesn’t preclude this generation from feeling the benefit of that tree.

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