The nation’s forests save more than 850 lives each year, according to a new report from the U.S. Forest Service.
Image courtesy craigcloutier/Flickr
In a study that will be published in the October issue of Environmental Pollution, scientists with the U.S. Forest Service have determined the magnitude and economic value of the effects trees have on air quality and human health. While we have long known that trees remove pollutants from the air, this study shows that in 2010, trees in the conterminous United States removed 17.4 million tons of pollution, with a human health value of $6.8 billion.
In addition to saving more than 850 lives, these trees reduced more than 670,000 incidences of acute respiratory symptoms and 430,000 incidences of asthma exacerbation. Trees also saved 200,000 lost days of school.
Image courtesy pavlinajane/Flickr
A forest’s pollution removal rates can be affected by pollution concentrations, tree cover, weather conditions, length of growing season and other environmental stressors. In general, scientists found that while trees’ pollution removal was greater in rural areas, the economic value of this pollution removal was greater in urban areas. In other words, because of their proximity to people, trees in urban areas have a greater impact on human health.
“More than 80 percent of Americans live in urban areas containing over 100 million acres of trees and forests,” said Michael T. Rains, director of the Forest Service’s Northern Research Station in a media release. “This research clearly illustrates that America’s urban forests are critical capital investments [that are] helping produce clean air and water [and] reduce energy costs and making cities more livable. Simply put, our urban forests improve people’s lives.”
The Chesapeake Bay Program has set a goal to expand urban tree canopy by 2,400 acres by 2025. Indeed, trees can improve air quality, water quality and habitat in ways not discussed in this study. Trees near buildings, for instance, lower energy use. Trees along rivers and streams reduce the amount of nutrients entering local waterways. And trees provide food, shelter, nesting sites and safe migration paths for critters in the water and on land.
“Urban tree planting is part of the Watershed Improvement Plan for six Bay jurisdictions,” said U.S. Forest Service Chesapeake Liaison Sally Claggett. “To reach water quality goals, these jurisdictions are targeting nearly 20,000 acres of new tree canopy by 2025—so the goal of 2,400 acres may be reached early. Partners are planning an Urban Forestry Summit in fall 2014 to help make that happen.”
For close to 50 years, Nick Carter has owned 33 acres on Maryland’s Eastern Shore. Aside from a house, a few sheds and a trail or two, much of this land has returned to its natural state: former farm fields have become bogs, wetlands and forests, pushed along by natural growth and Carter’s deep-seated desire to create healthy habitat and clean water.
Carter’s property runs next to the Choptank River, which flows into the Chesapeake Bay. Close to one-third of the Choptank watershed is forested, covered with the tree-and-shrub-filled habitat considered the most beneficial land use for the Bay. Forests absorb airborne pollutants, keep nutrients and sediment from entering our rivers and streams, and provide food, shelter and safe migration paths for wildlife. It is for these reasons that Carter has allowed forests to dominate his land.
“I’d like to see this little bit of property go back to old growth,” Carter said, referring to a type of forest that has evaded unnatural changes for a century or two. Carter and his wife purchased their property when he finished graduate school in 1966. For 35 years, Carter worked as a fish biologist with the Maryland Department of Natural Resources (DNR). Now, he offers informal tours to naturalists, native plant societies and school groups, carrying along a walking stick that effectively points out the things visitors might not notice.
Take the plants, for example. There are 250 species on Carter’s property, and in one two-hour walk it seems he can point out most of them. There are spring ephemera like jack-in-the-pulpit and pink lady’s slipper, the latter of which has a relationship with underground fungi that make them almost impossible to transplant. There are cinnamon ferns and sphagnum moss in a bog that Carter is particularly proud of because he created it with the simple act of laying down a few logs to form a makeshift dam. And there are the pine and oak trees that dominate the upland woods, including the willow oak whose acorns are so small that blue jays can pick them up and carry them in their beaks.
Then there are the reptiles and amphibians. Carter has counted 30 species of these, from the tree and wood frogs that favor damp habitat to the broad-headed skink and Eastern fence lizard that like forests with abundant leaf litter. Leaves that litter the ground conserve water, recycle nutrients and offer shelter to small critters. Its presence on Carter’s land can be felt as soon as you step from the hard pavement of Draper’s Mill Road to the soft, spongy forest floor.
Carter’s woods are home to charismatic fauna, too, including 30 species of mammals and 85 species of birds. Because so much of the property is forested, it serves as suitable habitat for “forest interior dwelling” birds, or those birds that need the moderate temperatures and light levels found deep within the woods. Carter has spotted pine warblers, prothonotary warblers and ovenbirds, but on our walk we spotted a bird that was much bigger and a little less particular about its habitat: a female wild turkey on her nest in a grove of skunk cabbage.
These critters flourish here because Carter has done so little to disrupt the natural processes of the world around him, aside from building the dam that led to the bog and managing some invasive species. While Maryland’s white-tailed deer often chew up low-growing plants, changing the structure of area forests, Carter’s dogs have warded them off with their loud howls. And when invasive plants like autumn olive, oriental bittersweet, English ivy and bush honeysuckle start to grow, Carter steps in to exert control. “Some I spray, some I cut, some I pull,” he said.
The changes that have taken place on Carter’s land present a classic case of succession: disturbed ground is replaced by shrubs, shrubs are replaced by pines and pines are replaced by hardwoods. In other words, this land works “the way it ought to work,” Carter said. And it reminds us of the habitats the Maintain Healthy Watersheds Goal Implementation Team is working to preserve in order to demonstrate the challenge of protecting streams.
Carter’s work to bring people onto his property could help further this goal, as he shares knowledge that can inform and inspire his visitors. “Here’s a little piece of land on which I can make all the rules,” Carter said. “Here, I can make this land good for the Bay and its rivers. And I can show people what’s good for the Bay and its rivers.”
To view more photos, visit the Chesapeake Bay Program Flickr page.
Images by Steve Droter and Jenna Valente. Captions by Catherine Krikstan.
Clean air, clean water and healthy communities: the benefits of forests are vast. But as populations rise and development pressure expands, forests across the Chesapeake Bay watershed are fragmented and cut down.
In an effort to slow the loss of Chesapeake forests, the U.S. Forest Service has released a restoration strategy that outlines how officials and individuals alike can improve the environment and their communities by planting and caring for native trees.
According to the strategy, which has been endorsed by each of the watershed's seven State Foresters, expanding forest cover is critical to improving our air and water, restoring wildlife habitat, sequestering carbon and curbing home energy use.
To ensure we get the most “bang” for our tree-planting buck, the strategy targets restoration efforts toward those places in which forests would provide the greatest benefits, from wildlife corridors along streams and rivers to towns, cities and farms.
Trees along the edges of streams and rivers—called a riparian forest buffer—can keep nutrients and sediment out of our waters and nurture critters with vital habitat and food to eat. Trees in towns and cities—called an urban tree canopy—can clean and cool the air, protect drinking water and boost property values, improving the well-being of an entire neighborhood at a low cost. And trees on farms—in the form of wind breaks, forest buffers or large stands of trees—can protect crops, livestock and local wildlife while providing a farmer with a new form of sustainable income.
Other areas targeted for forest restoration include abandoned mine lands in headwater states and contaminated sites where certain tree species could remove toxic metals from the soil.
Learn more about the Chesapeake Forest Restoration Strategy.
Sometimes, even a single tree can make a difference. And it helps when that tree is a big one.
For six seasons, Baltimore County has held a Big Trees sale in an effort to put big, native trees in Maryland backyards. Since its inception in 2009, the program has sold more than 750 trees to Maryland residents, augmenting the state’s existing forests and moving Baltimore County closer to its pollution reduction goals.
Big trees are integral to the health of the Chesapeake Bay. Forests clean polluted air and water and offer food, shelter and rest stops to a range of wildlife.
But big trees can be hard to find. To provide homeowners with the native trees that have high habitat value and the heft that is needed to trap polluted runoff, species like pin oak, sugar maple and pitch pine are grown in a Middle River, Md., reforestation nursery. The one-acre nursery, managed by Baltimore County’s Department of Environmental Protection and Sustainability (EPS), began as a staging ground for large-scale plantings but soon expanded to meet a noticeable residential need.
“We used to give incentives to homeowners to buy large trees at retail nurseries,” said Katie Beechem, Environmental Projects Worker with the EPS Forest Sustainability Program. “But we found that homeowners were buying smaller species—flowering dogwood, crape myrtle—that didn’t achieve the same benefits…that large native trees like oaks and maples and river birch can provide. We were able to fill this big tree niche.”
Emails, signs and word-of-mouth spread news of the sale to homeowners. Some travel from the next town over, while others come from as far as Gettysburg, Pa., to walk among rows of seedlings in black plastic pots.
Staff like Jon-Michael Moore, who supervises the Baltimore County Community Reforestation Program, help residents choose a tree based on growth rate and root pattern, soil drainage and sunlight, and even “urban tolerance”—a tree’s resistance to air pollution, drought, heat, soil compaction and road salt.
One Maryland resident picked up 15 trees to line a fence and replace a few that had fallen. Another purchased two trees to soak up stormwater in his one-acre space. And another chose a chestnut oak simply because she had one when she was a kid.
Out of the 12 tree species that are up for sale, oaks remain the favorite.
Whether red, black, white or pin, oaks are often celebrated as the best big tree. Oaks thrive in a range of soils, drop acorns that feed squirrels, woodpeckers and raccoons and create a home for thousands of insects.
Discussing the oak, Moore mentions University of Delaware professor Doug Tallamy. The entomologist once wrote that a single oak tree can support more than 500 species of caterpillars, which will in turn feed countless insect-loving animals.
But can one big tree make a difference for the Bay? Moore nodded: “Every little bit helps.”
The above 1913 photograph depicts rows of American lindens planted along Washington D.C.’s Massachusetts Avenue, west of Dupont Circle. The “double rows” of trees were planted in the 1880s, but many disappeared as the street was developed, new embassies were built, and utility lines installed. As a street that has historically been an international relations hub (it is home to major embassies), the loss of trees along Massachusetts Avenue seemed to represent the worldwide preference of commercialism over nature.
(Image courtesy Restore Mass Ave/Washingtoniana MLK Library)
Today, the climate has shifted, and politicians jump at the chance to get their photo taken in front of a newly planted tree; but long before the diplomats grabbed their shovels (and press staff), Deborah Shapley was walking up and down Massachusetts Avenue, knocking on her neighbors’ doors, and asking them how far their hoses could stretch to water parched trees in the sidewalk.
Washington’s D.C.'s Department of Transportation's Urban Forestry Administration has taken the important step of planting trees along streets throughout the city, but it did not have the resources to water them. For young trees, lack of water lowers their chances of survival in Washington’s hot summers. Instead of complaining, Deborah encouraged her neighbors to take on the responsibility of watering their nearest city sidewalk tree as if it were their own.
“I started Restore Mass.Ave to be a model of how to get local property owners excited about taking care of the city trees near them.”
But convincing property owners to take care of a tree that isn’t technically in their yard is not so easy.
“People tend not to care about the landscape that is more than a house or two away,” explains Deborah. “So the cry for them to take care of trees beyond a certain distance, that’s just not practical to them.”
But since Deborah began Restore Mass Ave in 2007, more and more residents and embassies along the street have come to understand that these trees are dually beautifying their community and helping to absorb stormwater runoff.
(Image courtesy Restore Mass Ave)
In addition to caring for the 100 sidewalk trees installed by the city, Restore Mass has worked with Casey Trees to plant 125 new trees since 2007. Most of the 225 total trees are large shade trees, which absorb stormwater and lessen pressure on the neighborhood's combined sewer system.
Like most of downtown Washington D.C., Massachusetts Avenue has a combined sewer system (css), which collects water from both stormwater runoff and household’s sanitary sewage. The CSS conveys this to treatment plants to be cleaned before it flows into the Chesapeake Bay.
But during heavy rain events, the combined sewer system often overflows; the stormwater and sanitary wastes flow directly into the Anacostia or Potomac River. This can cause an excess of bacteria and other pollutants in Washington D.C.’s tributaries, rivers and the Chesapeake Bay.
While it is always important to find ways to decrease the amount of stormwater runoff flowing into storm drains, it is particularly crucial in neighborhoods with combined sewer overflows (roughly one-third of the District of Columbia).
“The city is under requirements from the EPA to rebuild the underground tunnels and pipes” associated with the combined overflow system, explains Deborah. “They’re only able to do a certain amount per year of underground infrastructure. But large trees naturally conduct precipitation down into the soil and lowers the burden the underground pipes.”’
Stormwater will instead be absorbed by trees, and help to recharge the groundwater so more plants can grow.
“If you have a continuous line of shade trees alongside of a gutter, less water flows into that storm drain, and less water is barreling around in the tunnels of the combined stormwater system,” Deborah says.
While trees help to absorb stormwater during rain events, they do need to be watered when it is not raining. Droughts and heat waves make it difficult for young trees to survive on their own. Luckily, Restore Mass Ave’s volunteers, known as “Treekeepers,” make sure care is given to every sidewalk tree.
Since roughly one-third of Mass Ave properties are foreign-owned, the organization works with embassies to plant trees on their grounds.
While it was once typical for embassies’ groundskeepers to maintain flowers the colors of the nations’ flags, it is now popular for embassies to also maintain the surrounding trees. Governments relate the activity to their climate change agendas. Groundskeepers become, in effect, "Treekeepers."
“They have a sense of ownership that they didn’t have before,” says Deborah. “When you give people who care for plants the chance to grow nearby sidewalk trees, they are delighted.”
As Restore Mass Ave encourages private homeowners and embassy staffs to care for trees in public space, the sense of shared community and stewardship multiplies.
“As in many neighborhoods, we found that the embassies don’t often talk to each other, but when you point out the common trees, and you engage all the staff, it becomes their common garden,” explains Deborah.
While Restore Mass Ave may have found a way to create a sense of an international environmental stewardship, Deborah, founder and president of the all-volunteer organization, concedes that the nonprofit would like to expand its influence, but not its area.
“The idea is to not take over a bigger and bigger area, but to get other people to start their own groups, such as Restore Georgia Avenue or Restore Connecticut Avenue. Only as more people here understand the importance and fun of growing trees, will DC become the ‘City of Trees’ as it was known a century ago."
(Image courtesy Restore Mass Ave)
For more information on how you can get involved with Restore Mass Ave or start your own “Restore” on your street, visit the Restore Mass Ave Volunteer page.
Restore Mass Ave is trying to spread the word, via their Tree Care Blog (http://blog.restoremassave.org) and their Facebook and Twitter (#restoremassave).