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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

© Erik Petersen

Healthy and colorful street trees help define the character of Shorewood Hills. © Corey George
© Corey George

August 2006

A green workforce

At the root of Wisconsin's economy

Healthy trees for healthy cities | Edible urban forests
Parking lots | Social benefits
Quality of life | No price tag on preservation
Enhancing productivity | Wisconsin Champion Trees

Trees support the state's economy by creating jobs. A recent Wisconsin green industry survey showed that trees attract business and people to an area, in turn, increasing the tax base.


The "green industry" describes businesses that produce, install and maintain flowers, shrubs and trees as well as items related to their maintenance. The Wisconsin Green Industry Economic Impact Survey, completed in 2004, indicates that the green industry has a $2.7 billion impact on the state's economy annually. Total retail sales of lawn and garden supplies increased 49 percent from 1997 to 2003.

The Wisconsin green industry includes over 4,700 businesses employing over 43,000 workers. The Wisconsin Green Industry Federation contracted with the Wisconsin Agricultural Statistics Service to develop and perform the survey.

"What we found is that gardening is growing as a hobby and people are more and more valuing green space," says Brian Swingle, executive director of the Wisconsin Green Industry Federation. "People are landscaping, adding water features and they like the tranquility that plants and trees add to their homes."

Swingle says there is a consistent eight percent growth in the green industry. "It's evidence that people are paying more attention to the environment," he says.

Healthy trees for healthy cities

Trees are important working components of community infrastructure, just like streets, sewers, public buildings and recreational facilities. A healthy tree canopy functions as "green infrastructure" reducing the need and expense to manage air quality and waste. The major difference is that trees increase in value over time. Trees need care to survive, but the longer they live, the more benefits they provide. Trees are utilities that pay us back for this care by:

  • conserving energy by shading buildings and paved surfaces;
  • extending the useful life of asphalt pavement;
  • reducing and filtering airborne pollutants;
  • removing atmospheric carbon dioxide, the major "greenhouse" gas;
  • reducing stormwater runoff and noise pollution;
  • filtering and reducing surface and ground water pollution; and
  • providing wildlife habitat

A study of Chicago's urban forest found that increasing tree cover by 10 percent (three additional trees per building) would reduce total heating and cooling energy use by up to 10 percent. At a national level, researchers estimate that planting three additional trees per building could cut more than $2 billion in energy costs.

A reduction in energy demand reduces fossil fuel consumption by power plants to generate energy, resulting in additional energy savings and improved air quality. Trees further improve air quality as leaves filter and remove dust and other particulates. Leaves also absorb carbon dioxide, the major greenhouse gas, and give off oxygen. A single tree stores on average 13 pounds of carbon annually. One acre of trees generates enough oxygen each day for 18 people.

"We can't imagine a Beloit without its trees." – Bruce Slagoski, terrace operations supervisor for the City of Beloit.

Trees soften the glare and hard lines of built-up city streets and they screen buildings, making houses both more attractive and private. The shade from street trees can also help offset pavement costs by protecting asphalt from UV radiation. Streets with little or no shade need to be repaved twice as often as those with tree cover.

Enhancing productivity
Employees at the Teton Wood office building in Madison can connect with nature with a lush view of trees from their windows. © Jeff Roe

According to research by Rachel Kaplan, University of Michigan, workers who had a view of nature from their desks were less frustrated, more enthusiastic and reported higher life satisfaction when compared to workers who couldn't see a view of nature from their desks.

Other studies have shown that trees help workers focus and stay focused. A view of trees can boost worker wellness. Kaplan found that workers without a view of nature from their desks reported 23 percent more instances of illness.

Trees also reduce noise pollution. Concrete and asphalt echo noise, while trees absorb and reduce it. Trees can act as sound barriers and create gentle and natural noise amidst the often harsh city sounds.

Healthy community trees intercept, slow and store water, helping to control erosion and flooding, and limiting water runoff that can lead to sewer overflows. Leaf and branch surfaces intercept and store rainfall, reducing runoff volume. Roots increase the rate at which rainfall infiltrates soil and tree canopies reduce soil erosion by softening the impact of raindrops on the soil surface.

A U.S. Forest Service study of Midwestern trees found that a typical 20-year-old hackberry intercepts 1,394 gallons of rainfall per year. After 40 years, this figure increases to 5,387 gallons per year, nearly enough to fill a milk tanker.

"Each generation takes the earth as trustees. We ought to bequeath to posterity as many forests and orchards as we have exhausted and consumed."
– J. Sterling Morton, founder of Arbor Day

Rain gardens and vegetated swales bring native plants into the landscape. Rather than using curb and gutter to channel runoff into storm sewers, where there is no chance to mitigate its quality or quantity, runoff is filtered through swales planted with native vegetation. Vegetated swales remove sediment, nutrients and other contaminants, increase infiltration and add beauty.

Leaves in fall are often viewed as an environmental problem, but can provide an opportunity to mulch trees and shrub beds for free, eliminating leaf pickup costs and the nutrient flush from piled leaves on the street. The easiest way to dispose of leaves is to simply mow them into the turf.

Edible urban forests

Troy Gardens on Madison's North Side, is not only feeding a community's need for trees, but is putting something on the table.

Steve Ziegler, a Madison landscape architect, was the lead designer for the 31-acre urban agricultural center and natural area, which was once an overgrown state-owned vacant lot. Ziegler believes interaction with the landscape is an important way for people to connect to their environment. That's why Troy Gardens today provides family garden plots, a maple forest, tallgrass prairie, an interpretive trail, and fruit and nut trees.

"There are the obvious environmental benefits, but trees also bring stability to an environment and growth as they are living and thriving," Ziegler says.

In this case, Troy Gardens and the surrounding woodland are providing people with apples, pears, plums – 18 kinds of fruit trees. Add to that berry patches, nuts and currant bushes. There are also edible foods for wildlife – an urban buffet with lots of environmental benefit.

Parking lots

© Cindy Casey

Parking lots occupy about 20 to 30 percent of the land surface in most downtowns. But they don't have to be eyesores or steaming masses of asphalt under the summer sun. Incorporating trees and other vegetation into parking lot design provides shade, cools the air, lessens runoff, muffles noise, controls speed and directs traffic, provides reference points for entrances and exits and helps people locate their cars. According to the Journal of Arboriculture, trees reduce asphalt temperatures by as much as 36 degrees and car interior cabin temperatures by over 47 degrees. By shading parked cars, trees reduce emissions caused by the evaporation of fuel from gas tanks and smog-producing compounds from hosing and vinyl car parts.

"Trees don't take a break," says State Urban Forester Dick Rideout. "They are on the job every day and all day improving the environment and quality of life."

"The best friend on earth of man is the tree. When we use the tree respectfully and economically, we have one of the greatest resources on earth." – Frank Lloyd Wright

Strategic tree planting can be incorporated into state implementation plans to help meet air quality standards set by the Environmental Protection Agency. Due to new ozone standards, many urban sites are designated as non-attainment areas for ozone clean air standards and are required to reach attainment typically by 2007-2010.

Trees attract wildlife to the area. Certain trees provide food, shelter and resting areas to migrating and wintering birds. Urban forests are especially important stopovers for migratory birds such as Tennessee warblers and red-eyed vireos, says Owen Boyle, DNR ecologist in the Bureau of Endangered Resources. Tree height is likely the first characteristic that migrants use to choose stopover sites. Insects in the urban forest canopy are a primary food source for most long-distance migrants.

American Forests, a nonprofit conservation organization, advocates that every community set a tree canopy goal to ensure that their valuable green infrastructure is maintained at working thresholds, even as the community continues to develop. American Forests offers some general goal guidelines based on climate conditions and zone categories.

After identifying what their tree canopy cover is, a community can then set its goals to include an annual work plan to help meet environmental and quality-of-life goals, including federal and local clean air and water standards.

Once a specific goal is determined, the local government can pursue that goal using policies, procedures and budget.

Social benefits

So, when was the last time you were bird watching? Climbed a tree? Spent the night in a tree house? Jumped into a giant crunchy colorful pile of leaves? Children discover early on that they are at home with trees.

And as adults, some still admit to taking detours to stroll in a shaded park. Others feel a sense of despair when a neighbor cuts down a wonderful tree. Some search longer than necessary just to find a parking spot in the shade. Others savor the lazy Sunday afternoons in the hammock under a tree.

"Every mayor talks about quality of life for his or her community. In Stevens Point, urban forestry is very important to our quality of life." – Gary Wescott, mayor

"The simple act of planting trees provides opportunities to connect residents with nature and each other," says Dr. Greg McPherson, director of the USDA Center for Urban Forest Research. "Neighborhood tree plantings and stewardship projects stimulate investment by local citizens, business and government in the betterment of their communities."

DNR Southeast Region Urban Forestry Coordinator Kim Sebastian says, "People don't always make the connection about why they were drawn to live close to the park or why they feel comfortable in their neighborhood, but maybe it is because of the trees."

An Illinois study documented the calming effect of trees and their value for stability and neighborhood crime reduction in the inner city. The study by University of Illinois researchers Frances E. Kuo and William C. Sullivan explored how well residents of the Chicago Robert Taylor Housing Project were doing in their daily lives based upon the amount of contact they had with trees.

Friends enjoy playtime on the shaded swings of Joannes Park in Green Bay. © Tracy Salisbury

Kuo and Sullivan found that trees are a canopy against crime. Trees have the potential to reduce social service budgets, decrease police calls for domestic violence, strengthen urban communities and decrease the incidence of child abuse. Buildings with high levels of greenery had 52 percent fewer total crimes than apartment buildings with little or no greenery. Residents of buildings with more vegetation knew their neighbors better because they were more apt to come outside. Based on study findings, the city of Chicago spent $10 million to plant 20,000 trees as a means of social change.

In another study, University of Illinois researchers Andrea Faber Taylor, Frances Kuo and William Sullivan found that when children with attention deficit disorder played outside in a green environment they were better able to concentrate and complete simple tasks. Another study showed that girls with a view of nature at home scored higher on tests of self-discipline compared to girls with views of manmade settings.

Scientists at the USDA Forest Service in Chicago believe that people make a psychological tie to trees because trees help us reflect on life changes as we observe the changing seasons, tree growth and death.

Research also has provided evidence that the overall hospital environment has an important impact on recovery time. Roger Ulrich, Texas A&M University, found that patients with vibrant surroundings such as flowers and an outside view, recovered three-quarters of a day faster, and needed fewer painkillers than those with dull surroundings. Patients also responded by having slower heartbeats, lower blood pressure and more relaxed brain wave patterns than people who view urban scenes without vegetation.

An article in the February/March 2005 issue of National Wildlife ("Take two hikes and call me in the morning") cites a study that found a group of breast cancer patients who spent 30 minutes watching birds or strolling in a park three times a week had increased attention span and significant gains in quality of life ratings, compared to those who did not take these actions.

Quality of life

Less crime. More shopping. Healthier and happier workplaces. A clean and more comfortable environment. A place to play hide-and-seek. Trees are key.

A drive through Stevens Point (pop. 25,000) has earned the city comparisons from other convention and visitors bureaus to driving through a gigantic park.

"Every mayor talks about quality of life for his or her community," says Stevens Point Mayor Gary Wescott. "In Stevens Point, urban forestry is very important to our quality of life."

In fact, after the onslaught of Dutch elm disease, the community embraced an urban forestry program and has built on it ever since. Stevens Point has a full-time forester, Todd Ernster, and embraces the forestry department's use of the city's website (City of Stevens Point) to provide information to citizens regarding gypsy moth, emerald ash borer, home construction and trees, proper pruning, the city's tree ordinance, general services of the forestry department and a picture of the forestry crew for residents to recognize when they see them working with community trees.

"To exist as a nation, to prosper as a state, and to live as a people, we must have trees." – Theodore Roosevelt

The newest addition to the website is the "Right Tree, Right Place," which gives examples of small trees appropriate for planting under overhead utility lines and explains where these plants can be viewed. This project was carried out in cooperation with UW-Stevens Point and Wisconsin Public Service.

"Having UW-Stevens Point, an undergraduate natural resource college, in our community helps in the overall appreciation of the environment," Wescott says. "I don't think it takes as much convincing [here] as maybe in some communities of the benefits of trees."

No price tag on preservation

It's tough to put a price tag on trees treasured for what they mean to the heart. How do you put a price on a tree planted by a parent for a child? Or a tree that stood at a crossroads where Civil War soldiers marched? Preserving some trees may be as important to communities as preserving historic buildings. Here are two stories: the Forest Home Cemetery and the Dunbar Oak.

In the late 1800s the Forest Home Cemetery was considered Milwaukee's first park. Today, the South Side cemetery has over 148 types of trees with new trees planted each year to shade Milwaukee mayors and Wisconsin governors laid to rest there.

Some people visit the cemetery to see the famous "Beer Baron" corner where the Blatz, Schlitz and Pabst families have plots overlooking each other, but Paul Haubrich, president of the Forest Home Preservation Association, says many people also seek serenity under the towering trees. Of the more than 2,500 trees in the cemetery, some are more than 100 years old. The cemetery offers a self-guided tour to see trees in their early stages of development.

"I'm often telling people to save themselves some money and instead of driving north to see the trees in the fall, to come to Forest Home and see our trees," Haubrich says.

David Liska, Waukesha's city forester, says no other tree in the city is more loved than the legendary Dunbar Oak.

Suffering from diabetes, Civil War veteran Col. Richard Dunbar stopped to rest against a large white oak while traveling in Waukesha County in 1868. During that visit he drank water from a nearby spring and he came to believe the spring water had healing properties and declared himself cured. As news of Dunbar's "miracle" spread, Waukesha's tourist and resort industries flourished. Dunbar called the spring "Bethesda" which signifies mercy.

In 1991, the mighty Dunbar Oak fell during a windstorm. Several shoots were carefully cut and nurtured at a Menomonee Falls tree nursery. In May 2004, in celebration of Waukesha's 25th anniversary as a Tree City USA and Wisconsin's forestry centennial year, a clone was planted at the site where the Dunbar Oak had grown.

Wisconsin Champion Trees
Richard Rideout, DNR urban forestry program coordinator, measures a walnut tree in Wyalusing State Park. © Paul Pingrey

Everybody likes a huge, old tree. The largest specimen of a particular tree species is called a "champion." There is a national registry, a state registry and even some communities who keep local registries of champion trees. The Wisconsin Champion Tree Program identifies and recognizes these large trees and is a great way to encourage appreciation of your community's urban forest. A local champion tree contest puts people in touch with the community's oldest residents" and is always good for media coverage. You might even find a new state or national champion!

The official registry of Wisconsin's largest trees is maintained by the Department of Natural Resources. Information on the location, dimensions and rank of these champions, representing over 270 tree species and cultivars, totals over 2,200 records. The registry is available at Wisconsin's Champion Trees. How to measure and nominate new champions and links to other useful information are there as well.