Howland Forest research: A lasting Woodwell legacy

Miles Grant Director of Publications & Media Relations

A one-square-mile plot of Maine’s vast, old-growth woods known as Howland Forest has become the site of one of the world’s longest-running scientific studies of how climate change and trees interact—and Woodwell Climate Research Center researchers have been there from the start.

The research at Howland Forest has highlighted one aspect of the carbon cycle that we don’t fully understand yet—how carbon absorption by trees changes as they grow and age. Previous theory held that trees grew fast and stored a lot of carbon when they were younger, then gradually stored less and less with passing years. But Howland’s trees, many of which are hundreds of years old, are absorbing carbon at rates higher than would have been predicted.

Ancient Giants

In the years since the studies at Howland Forest began, scientists have taken core samples of the trees and have been astounded to find many are hundreds of years old. One randomly selected yellow birch was found to be at least 363 years old.

How have some of these birch, red spruce, and eastern hemlock survived so long over just a thin layer of cool, damp soil? It’s a case of slow and steady winning the race. The oldest trees aren’t the largest—they’ve bided their time under the canopy for decades or centuries, watching white pines grow fast and fall hard. The information stored in their rings— and even in their stumps, which rot very slowly—has been a bounty for years of scientific study. The beginnings of a scientific heritage

In the late 1980s, Drs. George M. Woodwell and Richard A. Houghton recognized the need to measure the exchange of carbon dioxide between land and the atmosphere. The two had been successful in “using measurements of carbon dioxide in air to make what were probably the first appraisals of respiration of a forest,” recalled Dr. Woodwell. “So it was understandable that I was interested in seeing the further development of those measurements, especially simple monitoring of air over time.”

Coincidentally, researchers at the University of Maine in Orono were working on similar issues at Howland Forest, part of a large tract in central Maine owned by the International Paper Company. The company had established an “experimental woods” and was running a project through the University to determine the length of time it would take to regrow a harvested forest. Dr. Woodwell found support for the Center to join with UMaine in measuring the respiration of the forest, and in the fall of 1989, Paul Lefebvre, then a young research assistant, began work at Howland.

A gifted technician, Lefebvre perfected a data logger to record carbon dioxide measurements. Every few months, he made the six-hour drive from Woods Hole to Howland. In the winter, when the bumpy dirt road to the Forest snowed over, Lefebvre would pull a sled carrying a 30-pound computer for an hour to reach the site.

Previous page: Woodwell scientist Kathleen Savage walks along a path in Howland Forest. Above, left: Kathleen Savage’s automated trace gas flux chambers providing data in the wetland at Howland Forest. Above, center: Woodwell scientists atop the instrument tower. Above, right: Shawn Fraver (UMaine), Marcia Macedo, Dave Hollinger (US Forestry Service), Paul Lefebvre, and John Lee (UMaine) touring the mature forest at Howland in September 2019.

“It was a beast. It was the only one we had that was portable at the time. It ran off one floppy disk and saved on the other,” remembered Lefebvre, still a scientist at Woodwell Climate Research Center. UMaine researchers would regularly download the carbon dioxide data and mail the precious disk back to Lefebvre.

“I loved it. I thought it was the most exotic thing in the world that I got to cross country ski in and collect the data off this tower,” said Lefebvre. “Once, I came out of the instrument shed and there were fresh bear tracks across my ski tracks. Not long after that, they forbade me from going out there on skis all by myself. UMaine got a snowmobile so someone could drive me out there and stay with me. It was safer, but I missed skiing.”

Changing with the times In the beginning, Lefebvre’s methods of measuring gases relied on collecting air samples. Today, scientists use eddy covariance, a technique to observe the exchange of gases considered the gold standard not just at Howland Forest but around the world. At the heart of the research site, a narrow 35-meter tower dotted with instruments rises above the forest canopy, relaying data to researchers in real-time.

Management of the Howland Forest project has since passed on to Woodwell Climate bio-geochemist Kathleen Savage, who joined the Center in the late 1990s. Savage and Lefebvre have spent countless hours measuring aspects of the forest and inventing new techniques for monitoring carbon stocks—amidst the moose, black bears, bobcats, and bald eagles that inhabit the forest.

In the early 2000s, an investor interested in logging bought the forest. The coalition’s scientists became concerned about the fate of the research site and contacted the Northeast Wilderness Trust to seek a solution. In 2007, the Trust raised $1 million to purchase the 550 acres of land, which ensured that Howland research would continue and the forest would be permanently protected. Woodwell Climate’s work in Howland Forest continues to this day. The first tower to measure carbon exchange at Howland Forest has turned out to be one of the longest-running research towers in North America. Three more research towers were added, and in 1996 the forest became the first base site for the Department of Energy’s AmeriFlux Network. Howland Forest has been the focus of studies on acid rain, forest ecology, ecosystem modeling, nutrient cycling, and carbon sequestration—all critical components of climate change research.

GIVE

A legacy gift can help Woodwell Climate make an even greater impact in the fight against climate change for generations to come. Bequests, charitable gift annuities, and charitable remainder trusts combine your philanthropic interests with your financial needs and tax-planning strategies. Contact Beth Bagley at ebagley@woodwellclimate.org to learn more.