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N.H. and the acid rain connection

  • This illustration from the 2016 book "Hubbard Brook: The Story of a Forest Ecosystem" reflects the complexity of life in a New Hampshire forest. Courtesy—

  • The Hubbard Brook watershed valley in autum. From the 2016 book "Hubbard Brook: The Story of a Forest Ecosystem." Courtesy photo by J.F. Franklin—

  • A portion of the Hubbard Brook watershed in autumn. From the 2016 book "Hubbard Brook: The Story of a Forest Ecosystem." Courtesy photo by D.C. Buso—

  • Hubbard Brook, from the 2016 book “Hubbard Brook: The Story of a Forest Ecosystem.” Courtesy ofA.G. Muniz

  • An example of some of the monitoring equipment located throughout the Hubbard Brook Experimental Forest. From the 2016 book "Hubbard Brook: The Story of a Forest Ecosystem." Courtesy photo by A.S. Bailey, U.S. Forest Service 


Tuesday, May 24, 2016

Where did the most important scientific research in New Hampshire’s history take place?

That’s a ridiculously broad question with no single answer, of course, but you can make a solid case for a small, dead-end valley off Interstate 93, midway between Plymouth and Lincoln. This is the Hubbard Brook Experimental Forest, roughly 12 square miles of woods and streams that since 1963 has been home to a broad series of long-term experiments, starting right off the bat with work that uncovered acid rain.

“When they took the first water sample in 1963 it was a shock to realize the pH was that low. They realized something was happening that no one had picked up on, and that set off a whole series of studies,” said Richard Holmes, a Dartmouth College biology professor who has co-written a handsome new book about Hubbard Brook Experimental Forest.

A 1972 research paper resulting from that work described how compounds like sulfur oxides and nitrogen oxides, mostly from burning fossil fuels, were altering the chemistry of precipitation, and in the process invented the term “acid rain.” That pushed the issue into the public’s gaze, an important step in making us laymen understand how we are changing the atmosphere on a regional, even global, scale – in other words, it helped pave the way for our slow, grudging acceptance of the reality of climate change.

Not bad for a semi-obscure New Hampshire spot. And not a solitary accomplishment: More than 100 Ph.D. theses have been conducted at Hubbard Brook and more than 1,500 research papers have been published have come out of it, on topics ranging from nitrogen leaching to the life of ground beetles to decay rates of bark to songbirds.

That last topic is Holmes’s field – his research publications have titles like “Non-breeding season habitat quality mediates the strength of density-dependence for a migratory bird” – and he admits to a soft spot for this portion of Hubbard Forest’s focus. It has produced groundbreaking research into the connection between New England’s songbirds and winter conditions farther south, helping explain why the sounds and sights of New Hampshire summers are changing.

“Over time we expanded (research) to the wintering grounds in the Caribbean. More, broader-scale work was done, which no one had done before. Hubbard Brook gave us the start,” Holmes said. “It was a convenient place with a lot of supporting data from the system as a whole.”

“A lot of supporting data from the system as a whole” is a pretty good description of why Hubbard Brook Experimental Forest is so important and why Yale Press has deemed it worthy of this new book.

Hubbard Brook: The Story of a Forest Ecosystem was co-written with former Dartmouth professor Gene Likens, one of the founding fathers of the experimental forest. It’s a cross between an oversized, glossy coffee-table book, with some truly gorgeous photographs, and a textbook for an introductory ecology class, with clear explanations of how and why northern forests work and descriptions of how we have been studying this forest and what has been found. I’m not entirely sure who the audience is, to be honest, but I thought it was great.

“It’s been 50 years of this research project and nobody’s ever tried to do a single overview of the work that’s going on,” Holmes said. “We didn’t want to make it a highly technical synthesis. We wanted it to be fairly accessible to a broader audience.”

The area was bought in 1955 by the United States Forest Service, which realized that to manage forests you have to understand them, and to understand forests you have to run experiments on them. Not just experiments on a few trees but on a whole ecosystem – in this case, a self-contained watershed, where all water flows down to the same place (Hubbard Brook, of course), making plants and animals conjoined in interesting ways.

The USFS still owns and oversees the experimental forest, but it has expanded the research focus greatly, creating a sort of research university without the university.

At any given time there are 20 to 30 principal investigators from research institutions across the country, and sometimes outside, who come with their own grant funding, their own students and post-docs and equipment. Many live for weeks or more at housing around the area, sometimes crashing overnight in some of the USFS buildings if they have to baby-sit an experiment, producing a serendipity of collisions among unconnected fields that can help breed new insight.

“In the summertime, there’s quite a large crowd. There’s an meeting of investigators and groups in July, where they present brief papers on their work during a two-day session. It can have about 150 people,” Holmes said.

There’s even a barn dance. How North Country can you get?

Hubbard Brook Experiment Forest isn’t alone, fortunately. It’s one of a number of the U.S. Forest Service’s long-term experiment research network of similar forests across the country, and there many others outside the network, including the Bartlett Experimental Forest in the middle of the White Mountain National Forest. All of these are valuable because they’re pretty big, but they’re more valuable if they’re pretty old.

“The long-term record is very special. It’s very unusual to have 50 years of climate records and plant growth records and all kinds of detailed work that can provide insight in terms of carbon capture and release and cycling, and so on,” Holmes said.

This is exactly the kind of work that makes it possible to have better climate models, which we desperately need to cope with global warming. Expect to see more of it.

“As climate change issues have grown, there’s been a lot more work at Hubbard Brook on climate issues,” Holmes said. “Research goes where the big questions are.”

(David Brooks can be reached at 369-3313, dbrooks@cmonitor.com or on Twitter @GraniteGeek.)