Proof Positive: Fewer Trees Mean Higher Temps

In the back of our rock garden, shaded on three sides by arborvitae and neighboring trees, stands a chest-high, white, capped PVC tube with holes drilled along its sides. Beneath the tube is a wooden stake; attached to the stake are two small climate sensors, one at the top and one at the bottom.

Every day for several months, now, the sensors have been silently recording temperature changes and related data from our garden. Occasionally, a group of graduate and undergraduate students from Clark University’s Geography Department, which owns the equipment, come by to download the data onto a laptop. We chat, they pet our aging golden retriever, who is most curious about any visitors, and then go on their way.

That data, as well as similar information collected from a handful of other sensors placed around Worcester in a variety of spaces with varying tree canopy, have formed the basis of a study this summer about how tree cover affects land surface temperature.

A Ten-degree Drop in Temp Where Trees are Present

The findings, presented on August 1 by undergraduates participating in Clark’s Human-Environment Regional Observatory (HERO) project, are significant: Trees reduce temperature near the ground by between 4 and 10 degrees Fahrenheit.

No surprise for anyone who seeks shelter under a tree on a hot summer’s day. But well worth quantifying and analyzing, given the significant number of trees lost to the Asian Longhorned Beetle infestation here—nearly 32,000 since the eradication effort began in 2008.

About 22,000 trees have been replanted, since, but more trees, still, have been lost to other, human-driven factors. According to a May 21, 2013 op-ed piece by Clark Geography faculty Deborah Martin and John Rogan, between 2008 and 2010, the city lost another 30,000-plus trees to urban development.

Without Tree Cover, Hotter Temps and Higher Energy Bills

To better understand the temperature impact of deforestation and replanting, the HERO student team analyzed satellite images of land surface temperature in Worcester. They compared two periods: 2007-2010, when most of the ALB-infested and at-risk trees were removed, and 2010-2012, when replanting efforts intensified.

The results are striking. In the Burncoat-Greendale neighborhoods that were hardest hit by the beetle, land surface temperatures increased by nearly 2 degrees to a whopping 16 degrees Fahrenheit after trees were removed (1-9 degrees Celcius).

By contrast, during the replanting phase, land surface temperatures began to slip slightly, by nearly a degree Fahrenheit. Given that new plantings are still saplings, it will be decades before neighbors can once again enjoy the cooling comfort of trees on a hot summer’s day.

Hotter temperatures translate into higher energy bills. Researchers from the University of Massachusetts-Amherst found that the presence of trees saved $85 in cooling costs for the average Burncoat resident.

Shared Losses and a Sense of Sacrifice

For now, until the new trees grow taller, higher energy costs will be the norm for neighborhoods stripped of their old, shady tree canopy—just one impact profoundly felt by residents of the affected areas.

Those impacts were the focus of a second team of HERO students, who conducted and analyzed dozens of interviews with residents, government officials and other policy makers to define how tree loss has affected the community’s sense of place.

Even as neighbors grieved the changed landscape, higher energy bills, lowered property values, lack of comforting shade and less attractive views, many of the stakeholders interviewed agreed that the crisis had some unexpected benefits: improved communications between government officials and citizens, increased funding to replant an aging urban forest, and a stronger sense of neighborhood commitment and environmental awareness.

Admirably, residents in the most affected neighborhoods also recognized that their sacrifice of infested trees most likely saved the city, region, and—we hope—the great northern maple forests from ALB devastation.

The HERO students’ presentation concluded a summer of research and the second year of a three-year National Science Foundation grant, headed by Associate Professors Martin and Rogan. The undergraduate teams included students from Clark and around the country.

The students are heading home, now, for a few weeks of well-deserved rest until the fall semester begins. I weeded the back of my rock garden, to make it easier for the next group to download data. Until they return, the sensors continue to silently record temperature changes in my little, tree-shaded corner of the world.

Evelyn Herwitz is the author of  Trees at Risk: Reclaiming an Urban Forest and blogs about ALB prevention and tree stewardship at She predicted the 2008 Asian Longhorned Beetle infestation of Worcester, Mass., in her book, published by Chandler House Press in 2001.

Arbor Day Reminder: Protect Our Urban Forests

spring_trees_cropIt’s been one long, cold spring so far here in Worcester, but the trees are finally in bloom. The Norway and sugar maples that line so many miles of our city’s streets are bursting with pale green flowers. Cylindrical Callery pears shyly show their snowy petals. A few magnolias offer cream and purple blooms to the sky.

It’s an appropriate welcome for Arbor Day, marked in Massachusetts and in most states on the last Friday of April.

Proposed in 1872 by Nebraska newspaper journalist and editor J. Sterling Morton as a way to promote tree planting to create wind breaks, shade, fuel and building materials for the vast Nebraska Territory, Arbor Day soon caught on across the U.S. By 1885, it had become a legal holiday in Nebraska—the same year that Massachusetts first observed the tree planting celebration.

Worcester’s First Arbor Day Shadowed by Deforestation

Worcester marked the Commonwealth’s first Arbor Day on April 30, 1885, by planting nearly 500 trees, thanks largely to the efforts of the Worcester Grange: 413 shade trees (mostly maples), and 80 fruit trees and ornamentals, to be precise.

Standing on a stage bedecked with flowers and potted plants in Horticultural Hall, before a canvas inscribed “Our first Arbor Day—may it take as firm and lasting a hold on the hearts of the people as the trees take root in the soil,” State Grange Master James Draper urged an enthusiastic audience to plant trees. Draper’s concerns about dwindling timber resources and deforestation around Worcester were echoed by Stephen Salisbury III, a member of the city’s Parks Commission.

“It is a matter of common knowledge . . . that the timberlands of the country were disappearing,” reported the next day’s Worcester Daily Spy. “Something more than Arbor Day was needed to prevent utter desolation in New England. Those who participated in its observance, however, would always be honored and their service would be appreciated.”

19th Century Forests Depleted by Centuries of Waste

Deforestation in Massachusetts—the result of centuries of wasteful timber harvesting for fuel, potash and building materials, as well as clear cutting for farmland—had become a serious problem by the mid-19th century. Writing in 1846, botanist George B. Emerson warned that the Commonwealth’s wood-based industries, such as ship building and furniture manufacturing, had so depleted native forests that the state was rapidly becoming depending on timber imported from Maine and New York.

In Massachusetts, deforestation peaked about 1860, when roughly two-thirds of the state was open land, compared to one-tenth in 1800; many Central Massachusetts hill towns had cleared more than 75 percent of upland area by midcentury.

Arbor Day was one step in a long process of reversing that trend. Today, Massachusetts in one of the most forested states in the U.S., with nearly 71 percent tree cover, compared to a national average of 34 percent. According to David Nowak of the U.S. Forest Service, there are about 273 million trees in Massachusetts, moderating climate, stabilizing soil, controlling storm run-off, improving air quality, sheltering animals and beautifying our world.

Urban Tree Canopy Threatened by Development

But that green canopy is once again in jeopardy. Here as throughout the country, development is chipping away at urban forests, replacing trees with buildings and impervious surfaces, such as roads and parking lots.

Nationally, according to Nowak, 17 out of 20 major cities have experienced a significant decline in tree cover during the first decade of the new millennium. On average, we’re losing 4 million trees annually.

It’s a trend we ignore at our peril. Just as deforestation surrounding Worcester in the mid-19th century caused observable changes in climate and growing conditions, so a loss of trees as we continue to expand cities and suburbs will degrade our natural environment.

This past year, Worcester intensified planting to help offset the many trees lost to the Asian Longhorned Beetle infestation. Our streets are lined with young saplings, still taking root after the cold, harsh winter. It will be decades before they shade streets like their aging sylvan neighbors. On this Arbor Day, our 128th, their future, and our city’s, is in our hands.

Evelyn Herwitz is the author of  Trees at Risk: Reclaiming an Urban Forest and blogs about ALB prevention and tree stewardship at She predicted the 2008 Asian Longhorned Beetle infestation of Worcester, Mass., in her book, published by Chandler House Press in 2001.

End in Sight for Worcester’s Beetle Battle

USDA's Clint McFarland inspects trees infested with the Asian longhorned beetle, From "Bugged: The Race to Eradicate the Asian Longhorned Beetle" 20120, photo by Stavros BasisOnly 13 Asian Longhorned Beetles were caught within the Greater Worcester quarantine area during all of 2012. That’s significant progress in the four-and-a-half-year fight to eradicate the black-and-white spotted insect that has gnawed its way through tens of thousands of trees in the city and surrounding towns, feasting on maples and other hardwoods over the past decade-plus.

According to Clint McFarland, director of the USDA’s Animal and Plant Health Inspection Service (APHIS) in Worcester, his team has found pockets of ALB infestations in Shrewsbury, Holden, West Boylston, Boylston and Worcester over the past year, but all have been or are in process of being contained.

The key is finding infestations before the mature beetles emerge from host trees. It takes one to two years for the beetles to develop inside the host. If the infected trees can be discovered and removed during that window, the beetle larvae are destroyed.

Lazy Beetles Help APHIS Eradication Effort

And if the beetles emerge, chewing quarter-sized holes through branches and trunks to venture outside? You need to catch them early, before they mate and lay eggs in new host trees. Fortunately, when the mature beetles first climb out of their trees, they don’t travel far.

“The beetles are lackadaisical,” says McFarland. “They would rather walk from one tree to the next than fly. And they tend to return to their home tree.”

The fact that the beetles are coach potatoes has given the USDA a significant edge in the eradication fight. In 2010, for example, when an infestation was discovered in six trees on the grounds of Faulkner Hospital, across from the Arnold Arboretum in Jamaica Plain, McFarland says they found two holes in trees where beetles had emerged. Soon after, they caught the two ALB culprits wandering nearby. The infected trees were destroyed, the site has been monitored since, and he believes that pocket has been contained.

APHIS has surveyed more than 3 million potential host trees within the 110 square miles of the Greater Worcester quarantine zone since McFarland’s team went into action in 2008, and removed about 31,000, mostly in the heavily infected Burncoat neighborhood. That represents about one percent of the surveyed urban forest. Many of those trees have since been replaced with diverse, beetle-resistant saplings.

Pockets of Beetle Infestations Still Remain

Still, the process has been and continues to be a painful one for neighborhoods where trees need to be cut down to halt the beetle’s advance. McFarland says many trees on a 14-acre plot of town land in Shrewsbury near Ireta Road were heavily infested, requiring “complete host removal” with town permission, angering neighbors who have lost their privacy screen. Though the land will be replanted with saplings, it will be years before the landscape regains its lush tree canopy.

McFarland says the goal, whenever an infested pocket is discovered, is to limit the number of trees that must be removed and continue to monitor the site for indications that the beetles have spread. Infected sites are surveyed three times over a period of years to ensure eradication has been successful.

Imidacloprid, the same insecticide found in flea collars and used to treat lawn grubs, has been employed to inoculate endangered trees near an infestation, but only with landowner permission, and with careful monitoring of possible risks to groundwater and soil quality. McFarland says the insecticide is very effective in killing ALB larvae, but the treatment only lasts for a year.

It will take at least another two years of surveillance to find what McFarland expects will be the last infected trees in Greater Worcester, and another decade to be sure the beetles are gone for good.

Infected Firewood Presents Greatest Risk

In the meantime, he says the biggest risk of another outbreak is “human movement”—in particular, when people take firewood that contains beetle larvae outside the quarantine zone. If the wood is infected and left to cure for a year or more, the mature beetles can emerge and start a new infestation in live trees nearby.

“People are trying to be chivalrous. They leave their unused firewood at a campsite for the next person,” he says. “That scares me because it increases the chances of the ALB’s spread.”

The potential consequences of an ALB infestation in the great northern hardwood forests of Vermont, New Hampshire and Maine would be so dire—sugar maples are a beetle favorite—that all three states have enacted programs to confiscate any firewood that people bring across borders and exchange it for “clean” cords.

In Massachusetts, McFarland says, the Department of Conservation and Recreation won’t allow any firewood to be brought into state camp grounds and provides safe firewood, instead. “We need to buy local, burn local,” he says.

Of all the communities that have been devastated by the ALB—in Illinois, New York, New Jersey, Massachusetts and now, Ohio—Worcester has the dubious distinction of having the densest infestation for the number of trees here.

New Jersey is on track to declare eradication soon, marking the successful end of their ALB fight that began in 2002. McFarland looks forward to the day when Worcester can hold its own ALB eradication ceremony.

Until then, the watchwords are continued vigilance and citizen awareness. The Asian Longhorned Beetle may be a lazy bug. But we can’t afford to be, too.

Photo Credit: Image of Clint McFarland by Stavros Basis, from Bugged: The Race to Eradicate the Asian Longhorned Beetle by Producer/Director Emily V. Driscoll

Evelyn Herwitz is the author of  Trees at Risk: Reclaiming an Urban Forest and blogs about ALB prevention and tree stewardship at She predicted the 2008 Asian Longhorned Beetle infestation of Worcester, Mass., in her book, published by Chandler House Press in 2001.

How Trees Make Our City Livable: Interview on WICN’s “Business Beat”

Thanks to Steve D’Agostino, host of The Business Beat on WICN 90.5FM, I recently joined with Peggy Middaugh, Executive Director of the Worcester Tree Initiative for a half-hour conversation about the importance of Worcester’s urban forest.

Our talk ranged from who planted the first trees in Worcester to why trees are so important to the urban environment, from the Asian Longhorned Beetle infestation and the newest threat, the Emerald Ash Borer, to Worcester’s model public-private partnership to replant the city’s urban forest.

The half-hour program aired Sunday night, February 3, 2013. Enjoy the podcast!

Evelyn Herwitz is the author of  Trees at Risk: Reclaiming an Urban Forest and blogs about ALB prevention and tree stewardship at She predicted the 2008 Asian Longhorned Beetle infestation of Worcester, Mass., in her book, published by Chandler House Press in 2001.

With Beetles in Decline, Worcester Gets $3 Million for More Trees

As hors d’oeuvres circulated amidst tree advocates, environmentalists, politicians, government officials and staff, as TV reporters staged interviews and photographers clicked shots, you could hardly hear the person next to you above the excited chatter at Green Hill Park’s Grill on the Hill last night.

The reason? Worcester will benefit from $3 million in state funding over the next two years, a boost for ongoing efforts to replant tens of thousands of trees lost to the Asian Longhorned Beetle within the city and surrounding towns.

Lt. Gov. Tim Murray made the official announcement at the festive celebration, which marked the Worcester Tree Initiative’s (WTI) progress since January 2009 toward planting 30,000 new trees by the end of 2014. To date, the public-private partnership, which coordinates efforts by the Massachusetts Department of Conservation and Recreation, the U.S. Department of Agriculture and many local non-profits, private businesses and citizens, has planted about 23,000 public and private trees in Worcester and neighboring towns affected by the blight.

ALB Crisis a “Call to Action” to Save Worcester’s Urban Forest

Flanked by Congressman Jim McGovern and a coterie of local and state officials, Murray said the ALB crisis had served as “a call to action” to restore Worcester’s aging urban forest. He thanked McGovern for partnering with him to create the WTI and for helping the city acquire an additional $5 million in federal stimulus money over the past two years to boost replanting efforts.

Adding to the evening’s good cheer, the Walmart Foundation, which had previously donated $150,000 to local tree replanting efforts, presented a $50,000 check to the WTI. Local officials also credited CSX Corp.’s Trees for Tracks program for helping to support reforestation work.

Only 13 Beetles Found in 2012

The funding couldn’t arrive at a better time—with the beetles on their way out. According to Clint McFarland, who has been managing ALB eradication efforts for the USDA since the infestation was discovered in 2008, only 13 beetles were caught this past year via their extensive trapping and reporting program. That’s a dramatic decrease from five years ago, when McFarland said they first found “thousands of beetles” in Worcester—indicative of a vast infestation that probably began in the 1990s.

With improved detection methods, including the use of specially trained dogs that can sniff out the scent of ALB excrement, and more efficient beetle traps, McFarland said eradication specialist are now able to isolate and eliminate any newly discovered pockets of infestation.

So the beetles are no longer the biggest threat to Worcester’s trees, old and new. But there is another challenge looming.

Caring for New Trees is Key

As newly planted saplings sprout throughout the city, with the promise of thousands more plantings over the next two years, Worcester must ensure that the young trees grow and thrive. According to WTI Executive Director Peggy Middaugh, recruiting and training many more citizens and business owners to become tree stewards who will water and watch over their neighborhoods’ public trees is essential.

“Our first tree giveaway was like the running of the brides at Filene’s Basement,” said WTI Co-chair Mary Knittle. “Now that the trees are in the ground and looking good, we need to keep the pressure on.”

Evelyn Herwitz is the author of  Trees at Risk: Reclaiming an Urban Forest and blogs about ALB prevention and tree stewardship at She predicted the 2008 Asian Longhorned Beetle infestation of Worcester, Mass., in her book, published by Chandler House Press in 2001.

What Tree to Plant? These Are Beetle-free

You want to plant a tree, but you want to be sure it won’t be attacked by the Asian longhorned beetle. What’s safe to plant? Take a trip to Worcester’s Green Hill Park this spring to visit the new beetle-resistant arboretum.

A project of the Worcester Garden Club (WGC), the demonstration plantings were made possible by a 2011 national Garden Club of America Founder’s Award for $25,000. The WGC teamed up with the Worcester Tree Initiative, the city Public Works and Parks Department and forestry division, as well as students and faculty from Worcester Technical High School to plant the trees. I joined celebrants on a brisk, windy Arbor Day, April 27, for the groundbreaking ceremony, described in this report by Worcester Channel 3.

Diversity is key to a healthy urban forest, and the new arboretum is a healthy mix of 12 different beetle-resistant species. Here’s the list; consider one of these species for your own tree planting this spring:

  • Serviceberry ‘Autumn Brilliance’  Amelanchier arborea ‘Autumn Brilliance’
  • Corneliancherry Dogwood  Cornus mas
  • Thornless Cockspur Hawthorn   Crataegus crusgalli var. inermis
  • Kousa Dogwwod  Cornus kousa
  • Japanese Tree Lilac   Syringa reticulata
  • Upright European Beech  Fagus sylvatica ‘Dawyck
  • Fastigiate White Pine  Pinus strobus ‘Fastigiata’
  • Upright European Hornbeam  Carpinus betulus ‘Fastigiata’
  • Tupelo  Nyssa sylvatica
  • Thornless Honeylocust ‘Skyline’  Gleditsia triancanthos var. inermis ‘Skyline’
  • Green Pillar Pin Oak  Quercus palustris ‘Green Pillar’
  • Japanese Zelkova  Zelkova serrata

Evelyn Herwitz is the author of  Trees at Risk: Reclaiming an Urban Forest and blogs about ALB prevention and tree stewardship at She predicted the 2008 Asian Longhorned Beetle infestation of Worcester, Mass., in her book, published by Chandler House Press in 2001.