In a warming world, New England’s trees are storing more carbon

Unprecedented 25-year study traced forest carbon through air, trees, soil, and water



Climate change has increased the productivity of forests, according to a new study that synthesizes hundreds of thousands of carbon observations collected over the last quarter century at the Harvard Forest Long-Term Ecological Research site, one of the most intensively studied forests in the world.

The study, published today in Ecological Monographs, reveals that the rate at which carbon is captured from the atmosphere at Harvard Forest nearly doubled between 1992 and 2015. The scientists attribute much of the increase in storage capacity to the growth of 100-year-old oak trees, still vigorously rebounding from colonial-era land clearing, intensive timber harvest, and the 1938 Hurricane – and bolstered more recently by increasing temperatures and a longer growing season due to climate change. Trees have also been growing faster due to regional increases in precipitation and atmospheric carbon dioxide, while decreases in atmospheric pollutants such as ozone, sulfur, and nitrogen have reduced forest stress.

“It is remarkable that changes in climate and atmospheric chemistry within our own lifetimes have accelerated the rate at which forest are capturing carbon dioxide from the atmosphere,” says Adrien Finzi, Professor of Biology at Boston University and a co-lead author of the study.

The volume of data brought together for the analysis – by two dozen scientists from 11 institutions – is unprecedented, as is the consistency of the results. Carbon measurements taken in air, soil, water, and trees are notoriously difficult to reconcile, in part because of the different timescales on which the processes operate. But when viewed together, a nearly complete carbon budget – one of the holy grails of ecology – emerges, documenting the flow of carbon through the forest in a complex, multi-decadal circuit.

“Our data show that the growth of trees is the engine that drives carbon storage in this forest ecosystem,” says Audrey Barker Plotkin, Senior Ecologist at Harvard Forest and a co-lead author of the study. “Soils contain a lot of the forest’s carbon – about half of the total – but that storage hasn’t changed much in the past quarter-century.”

The trees show no signs of slowing their growth, even as they come into their second century of life. But the scientists note that what we see today may not be the forest’s future. “It’s entirely possible that other forest development processes like tree age may dampen or reverse the pattern we’ve observed,” says Finzi.

The study revealed other seeds of vulnerability resulting from climate change and human activity, such as the spread of invasive insects.

At Harvard Forest, hemlock-dominated forests were accumulating carbon at similar rates to hardwood forests until the arrival of the hemlock woolly adelgid, an invasive insect, in the early 2000s. In 2014, as more trees began to die, the hemlock forest switched from a carbon “sink,” which stores carbon, to a carbon “source,” which releases more carbon dioxide to the atmosphere than it captures.

The research team also points to extreme storms, suburbanization, and the recent relaxation of federal air and water quality standards as pressures that could reverse the gains forests have made.

“Witnessing in real time the rapid decline of our beloved hemlock forest makes the threat of future losses very real,” says Barker Plotkin. “It’s important to recognize the vital service forests are providing now, and to safeguard those into the future.”


From EurekAlert!

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August 4, 2020 10:20 pm

“It is remarkable that changes in climate and atmospheric chemistry within our own lifetimes have accelerated the rate at which forest are capturing carbon dioxide from the atmosphere,

Did he seriously say it was remarkable !! WOW !

Us realists have been pointing that simple fact out for ages.

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Nicholas McGinley
Reply to  fred250
August 5, 2020 3:53 am

He was able to remark on it.
Hence, remarkable.

Reply to  Nicholas McGinley
August 5, 2020 7:34 am

Should be a “like” function, would have “liked” this one.

Paul Johnson
Reply to  Nicholas McGinley
August 5, 2020 1:54 pm

That Harvard allowed him to remark on it is remarkable. Hence my remark.

Dan Sudlik
Reply to  fred250
August 5, 2020 7:30 am

I have a great idea! Let’s cut down tens of thousands of acres or forests to put up windmills and solar panels. (Do I need sarc?)

Joseph Zorzin
Reply to  Dan Sudlik
August 5, 2020 12:27 pm

about 8,000 acres of forest in the TINY state of Massachusetts have been UTTERLY destroyed in the past 5 years to install solar “farms”

The enviros think installing such “farms” will save the planet- TOTALLY ignored the vast destruction. I point it out them almost daily but they are so brainwashed they don’t get it.

Gary Pearse
Reply to  fred250
August 5, 2020 8:33 am

Did anyone notice that the role of increased CO2 in this marvel is subordinated to the global warming contribution rather than putting it front and center. They muddy it further by introducing the non sequitur of the large amount of carbon in the soil, with the ‘afterthought’ that it has remained unchanged over the years. This was done to hopefully have the full reader get an image of the roots sort of having all this carbon available. Also the spectre of this all coming to a stop (the hemlock bugs) and the process reversing, making the forest a huge source of carbon pollution.

I’ve followed the reluctant literature on this from ~2014 after NASA released the story of the Greening of the planet imagery. First, there was silence on this dumbfounding, exciting, ameliorating development. They had to say something, ultimately. Making it a global warming phenomenon, with an .. ahem… CO2 bit part was decided upon, plus adding the ‘spectre’ of even worse carbon emissions from the forest itself.

This treatment is totally disingenuous. The most obvious effected areas were in regions already plenty warm like the Sahel in Africa and arid regions around the world, which are purely increased CO2 plays. The greenhouse growers clearly understood this, having pumped CO2 up to 1000ppm plus to accelerate growth. Don’t be numbed by even the positive articles into receiving the propaganda that they must include.

Joel O'Bryan
August 4, 2020 10:34 pm

FFS, I lived in Massachusetts for 9 years. I cleared out the back 1/2 acre bordering a wetland down to the Assabet River further back. 50 years earlier the entire section of now modern houses it had been part of a farm, but somewhere in between it became a jungle of tree and briar totally hiding the view of the river.
Clearing it out took 5 years of huge burn piles every spring with a burn permit from the town. Then I had to keep it cleared. And just below the top soil was rocks. The kind the farmers stacked everywhere to make rock fences through New England country-side. But it was like a constant battle agains the jungle until the first frost in late September or October.
It is no wonder the farmers of the Early 18th Century said, ” F-this” and literally dropped everything, left New England in massive waves of climate emigration when the frontier opened up and went West to the deep fertile soils of the MidWest to farm there.

Joel O’Bryan
Reply to  Joel O'Bryan
August 4, 2020 11:05 pm

erratta: I meant 19th Century. From about 1830-1850 New England’s farmer were abandoning the rocky NE farms for better land to the midwest. I had Joe Biden Moment on Century #’s versus calendar years.

August 4, 2020 10:34 pm

Ah, climate change, not catastrophic, not anthropogenic, not too cold, not too hot, a wide range of normal, a refreshing and welcome return to science-based reporting.

Scouser in AZ
Reply to  n.n
August 4, 2020 10:57 pm

“At Harvard Forest, hemlock-dominated forests were accumulating carbon at similar rates to hardwood forests until the arrival of the hemlock woolly adelgid, an invasive insect, in the early 2000s. In 2014, as more trees began to die, the hemlock forest switched from a carbon “sink,” which stores carbon, to a carbon “source,” which releases more carbon dioxide to the atmosphere than it captures.”

It sounds like the invasive insects may have more to do with the change of the forest than climate change.

Reply to  Scouser in AZ
August 5, 2020 12:26 am

Hi Scouser AZ, – As you suggest the forest changes significanly involved invasive insect impacts.

With the adelgid hemlock foliar litter fall averaged 129 grams of carbon per square meter in a year. In comparison unaffected hemlock in a woodlot had an average of 173 gr. carbon/ of foliar litter fall.

Subsequently the grams of carbon per square meter in the hemlock soil profile also went down with adelgid infestation. In the top 30 cm of soil it was reduced from an average of 9,195 gr. carbon/ to just an average of 6,495 gr. carbon/sq. mt. where aldegid infested.

Even in the fine roots of the top 15 cm soil there was a reduction of carbon due to aldegids. In those hemlock roots of less than 2 mm diameter that normally amounted to an average of 177 grams of carbon per the comparable aldegid infested hemlocks’ roots biomass only averaged 131 gr. carbon/

David A
Reply to  gringojay
August 5, 2020 4:23 am

Droughts and infestations happen, regardless of CO2 flux.

Trees do better in droughts with more CO2. Forrest recover from droughts and insect infestations faster with more CO2.

John F. Hultquist
Reply to  gringojay
August 5, 2020 11:20 am

(2014) It has been just 6 years since the decrease of Hemlocks.
Next question: What is growing there now, or realistically, what will now grow there?
It may be awhile before a damaged tree dies, and longer still before it falls to open the ground for new species.

… the last quarter century …
An interesting research project. Started in the late 70s or early 1980s.

Joseph Zorzin
Reply to  Scouser in AZ
August 5, 2020 12:32 pm

“It sounds like the invasive insects may have more to do with the change of the forest than climate change.”
Many of the invasive insects get here thanks to “free trade” and the daily vast movement of ships, planes and people across the planet. The tiny change in temperatures isn’t, in my opinion, much of a cause. And, some of this northerly movement of insects might simply be something that has been going on for centuries- but very slowly. There is no fixed set of species anywhere.

I’ve been a forester in Mass. for 47 years so I do know something about this subject.

Mike Dubrasich
August 4, 2020 10:52 pm

The press blurb above is not the actual study report. The Abstract is here:

I don’t know how to access the body of the study report.

In short, the composition of the stand (species, age, density, leaf area, tree vigor, etc.) are the determinants of productivity and carbon capture. Climate change has nothing to do with it. The climate hasn’t changed significantly over the last 25 years.

Healthy vigorous trees at the peak of their growth rates will fix more carbon than dying trees. Beetle-killed stands stop growing and start decaying. Underbrush does not fix as much carbon as healthy trees with full canopies that tower 100 feet or more.

The Abstract states “The increase in mean annual temperature and growing season length alone accounted for ~30% of the increase in productivity.” That is preposterous. Without the report or the data I cannot refute it in detail, but it is an error in analysis — of that I am sure.

In addition, the Harvard Forest is not representative of any other forest anywhere.

Nicholas McGinley
Reply to  Mike Dubrasich
August 5, 2020 4:03 am

The basic premise that the growth rate of trees is a simply function of temperature is obvious malarkey.
If it is hot and dry in the growing season, growth will be slower than average, while mild and moist conditions in the hottest part of the year will lead to increased growth rates, all else being equal in both examples, and compared to average local conditions.
Extremes of temperature and moisture inhibit the growth rates of most types of plants and trees.
Considering that alarmist models postulate global warmening to increase extremes of temperature and precipitation, there is an additional large element of talking out of both sides of their mouth with this particular assertion by them.

The purpose of this particular spin on growth rates of trees would seem to be a further effort to make sure that no positive findings or conclusions can be made of increasing CO2.
It has to be all bad, all the time, to keep the alarmist narrative viable.

Jeremiah Puckett
Reply to  Nicholas McGinley
August 5, 2020 5:31 am

This is nothing new. It was scientifically proven long long ago that the limiting factor in photosynthesis is CO2. Plants and trees are STARVING for more CO2.

Tim Gorman
Reply to  Nicholas McGinley
August 5, 2020 11:39 am

Remember that an increasing “average” temperature can mean that minimum temps are increasing while maximum temperatures are stagnating or falling. This means a longer growing season for the trees as well as for crops.

The models only cover the *average* temp. Average temps cannot say anything about extremes of the temperature envelope, that data is lost when the average is taken. Saying that the temp envelope is seeing higher max temps based solely on the average temperature going up is just plain willful ignorance. A sixth grader taking a math class would understand this mistake in analysis.

Nicholas McGinley
Reply to  Tim Gorman
August 5, 2020 3:06 pm

The number of ways that the temperature can change is huge.
Above/below normal in one part of the year, or at a certain part of each day, which can vary during a single year.
And then these variations in temp can combine with above or below normal precip, which itself can go one way in Spring and the other way in fall.
But as others have noted, the climate has actually changed very little in the specified time period, while CO2 has increased sharply.
CO2, the stuff that all plants need to grow, that is a fraction of one tenth of one percent of the air.
In any case, they have documented trees growing more.
Which comports with zero of the alarmist’s predictions.

But I do not think they made any mistake.
I think they started out with a certain idea in mind…to invent some malarkey that could provide an alternative explanation for faster growling trees besides the obvious one, which is of course CO2 fertilization.
It is going to be hard to pretend that more CO2 is gonna end life on Earth if they have to admit that the biosphere is actually expanding because of it.

August 4, 2020 11:10 pm

More CO2 = More tree and plant growth using CO2 = less free CO2 = Everyone can relax.

Jeremiah Puckett
Reply to  nicholas tesdorf
August 5, 2020 5:32 am

It’s almost like an intelligently designed balancing act.

Jeff Alberts
Reply to  Jeremiah Puckett
August 5, 2020 10:08 am

or not.

August 4, 2020 11:39 pm

The actual research paper’s supplemental data shows that the hemlock & hardwood trees which survived had greater diameters than those which did not. While those survivors were less dense than their counterparts.

This is consistant with how elevated CO2 requires leaves clearing carbon assimilated by sinking it elsewhere in the plant; commonly stems/trunks & roots. While the elevated CO2 propensity toward reduced plant density has been implicated as rendering plants more vulnerable to insect/pest damage.

For those assuming our currently rising C02 exerts linear impact it may be worth detailing what showed up in Hemlock trees. In 2005,2006,2007 & again in 2012 these trees switched back & forth during the winter from being both a carbon source & carbon sink. In those years it sometimes took as little as 21 days & in other years up to 99 days to become “… a consistent net C sink ….”

Yet there was also a contrary carbon allotment despite our currently rising CO2 recorded in 2014 when it took 274 days for those hemlock to go from being a net carbon sink to being a net carbon source . And despite taking so long in time to actually become a carbon source those trees ended up being a net carbon source for the year. Meanwhile the following year 2015 had the same characteristic of ending up a net carbon source, but then it only took 205 days to phase out of being a net carbon sink to become a net carbon source.

Then there were straightforward years where those hemlock just progressively became net carbon sinks as the days went by. In 2009 that took 92 days, in 2010 ’twas 83 days, in 2011 it took 100 days & in 2013 it took 105 days to progress from being a net carbon source into a carbon sink.

Reply to  gringojay
August 5, 2020 8:27 am

The adelgid has some years ago swept thru my central Appalachian area — many hemlocks were k*lled, but not all (further east in the Blue Ridge Mnts the death rate was near 100%), and now the adelgid population is cycling, w/some years practically absent in many areas, then showing up again for a few yrs, then absent again, etc. There aren’t any large, extensive pure stands of hemlocks here, and in areas where many have died, the other species like sugar maples, oaks, hickories, tuliptrees, white pines, etc, simply grow into the opened spaces. Unfortunate of course, but the forest adapts. Presently we also have massive death of ashes from the introduced Emerald ash borer, but again, the adjacent trees simply grow into the opened areas.

August 4, 2020 11:42 pm

A pity that Harvard are not doing a similar exercise on the forest areas being felled and chipped to fuel the Drax power station in the UK.
One big slug of carbon (timber) turned into CO2, and it would be interesting to see how the CO2 capture by the regrowth develops.

August 5, 2020 12:22 am

So I guess that CO2 was not in equilibrium then?

Reply to  lee
August 5, 2020 1:06 am

How can it be because trees are eating it all. Those bstrds.

August 5, 2020 12:39 am

If AGW warming causes increased carbon sequestration by photosynthesis then is AGW self correcting?

Matthew Sykes
August 5, 2020 12:49 am

Doubled, in 30 years? Good god that’s a remarkable response from nature!

I am not surprised though, life is tough, life adapts, life exploits every niche it can.

Dudley Horscroft
August 5, 2020 12:52 am

So Socrates helped by drinking a forest tree?

Reply to  Dudley Horscroft
August 5, 2020 2:17 am

Wrong type of hemlock. I think the poisonous one would be classified as a forb. We have it growing in wet areas in our back yard. It looks like cow parsley but has red blotches on its stem.

Nicholas McGinley
August 5, 2020 3:51 am

“In a warming world, New England’s trees are storing more carbon”

I have an idear for a more explanatory headline:
In a world with more carbon to store, the plants and trees all over the world that have always stored carbon, are storing more carbon!
Film at 11:00.

August 5, 2020 4:32 am

Meanwhile, plans for an 800 MW offshore wind farm of the coast off New England severely threatens the livelihoods of the New England Fishing Industry:

Trump would do well to favour the fishermen and cancel this project.

Bruce Cobb
August 5, 2020 4:33 am

It is remarkable how dumb these “scientists” are becoming. Trees are bouncing back. Duh. They do that. And, they also have more CO2, aka “plant food”, which they happily gobble. Duh. They then leap to their remarkably dumb conclusion that it’s because of “climate change”. Er, no.

August 5, 2020 4:40 am

Doubled CO2 uptake in 25 years? How much longer will the media-political establishment be able to turn a blind eye to dramatic and beneficial CO2 greening?

Right-Handed Shark
August 5, 2020 5:58 am

Do people pay to go to Harvard U?

Bruce Cobb
Reply to  Right-Handed Shark
August 5, 2020 8:36 am

Yes. Remarkable, innit? Even more remarkable that it’s still considered “prestigious”.

Joseph Zorzin
Reply to  Bruce Cobb
August 5, 2020 12:40 pm

The Harvard Forest is a research Institute, owned by, but not really part of the University’s academic body. They bring in PhDs and grad students and post docs from around the world for long term research projects. It is indeed very prestigious in forestry and ecological circles. I live a 10 drive from there and have attended conferences and symposiums there- as a forester here in Mass. with decades of experience. I really like some of their work but not all of it.

Just Jenn
August 5, 2020 6:00 am

So photosynthesis is “storing carbon” now?

Ed Zuiderwijk
August 5, 2020 6:38 am

Eh, what warming climate?

Jeff Alberts
Reply to  Ed Zuiderwijk
August 5, 2020 10:17 am

Well, you’ve got all these big shot institutions presenting fancy graphs with a single line representing the chimera called “global temperature”, a particularly un-physical representation at that.

Some places have warmed (mostly urban area), some have cooled, some have remained relatively static. Averaging them all together is a no-no, but they do it anyway. So they end up with “global warming”.

Tim Gorman
Reply to  Jeff Alberts
August 5, 2020 11:47 am

Once you have taken an average you LOSE all data associated with the temperature envelope. And it is the temperature ENVELOPE that determines climate, not the average temperature. This applies at the local, regional, and global level.

It’s why I continue to advocate from changing from “average global temperature”, which is actually meaningless, to cooling and heating degree-days which calculates the area under the temperature envelope and, therefore, captures far more information concerning the actual climate.

I understand that “average global temperature” is far easier to collect, calculate, and work with but it is still meaningless. Cooling and heating degree days would be far more difficult to work with but would be far more meaningful. Forecasting CDD and HDD two decades into the future would be far more useful in deciding what ameliorative measures might be needed in our building designs and/or zoning plans.

Jeff Alberts
Reply to  Tim Gorman
August 5, 2020 12:15 pm

Tim, it’s meaningless for the single reason that temperature is an intensive property of the point in space and time it was recorded. Averaging intensive properties from disparate locations is the no-no portion of the equation.

Which is why comparing temperatures with a “nearby” station is pointless. Where I live, I’ve seen as much as a 27f difference in temps only 13 miles apart at the same time of day.

August 5, 2020 6:48 am

“recent relaxation of federal air and water quality standards”

This reminds me of various government agencies. It’s common practice in DC that whenever an agency fails to get all of the budget increase that they requested, start whining to the media about how their budget has been cut.

August 5, 2020 7:38 am

Okay, what I learned is there was significant impact from a hurricane in 1938. That will aid in discounting “remarkable” and “unprecedented” claims when the next one makes landfall in that intensely studied and high-existential threat prone region of New England with its high concentration of global warming media consultants.

August 5, 2020 7:39 am

This a serious for real study. TGhen just add to it something on climate change by man and you are home free. Same thing during the Dark Ages, just add to anything your were doing about God and they left you alone.

August 5, 2020 7:54 am

New England’s trees are storing more carbon

Any place where there is “greening”, including plankton in ocean areas, is storing more carbon.

August 5, 2020 8:51 am

Anything to to keep the Harvard undergrads busy while paying tuition.

Joseph Zorzin
Reply to  ResourceGuy
August 5, 2020 12:46 pm

Harvard Forest is not part of Harvard’s academic system- it’s a research institute 100 miles away in the center of Mass. with several thousand acres of forest. No undegrads- mostly post docs.

Loren C. Wilson
August 5, 2020 10:58 am

“It is remarkable that changes in climate and atmospheric chemistry within our own lifetimes have accelerated the rate at which forest are capturing carbon dioxide from the atmosphere,”. No, it would be remarkable if this didn’t happen. My opinion of professors at Boston University just dropped a lot.

August 5, 2020 11:01 am

Who knew these trees were deniers.

August 5, 2020 1:32 pm

It has been 66 years since the last real tree-snapping hurricane passed through this area, as “Carol” in 1954. Prior to that the 1938 hurricane did worse. But before that you have to peer back over a century to find the prior tree-snapper. They are so rare that, just before the 1938 hurricane, some foolish “authority” stated “Hurricanes never hit New England.” They do. They may be rare, but they are natural. And they demolish forests in a way I can’t really imagine, for I’ve never seen it.

I can wander the woods and see evidence of both Carol and the 1938 Hurricane. One rather neat thing is stripes of green moss among the brown pine needles of a forest floor, all striping in the same direction. That is all that is left of rotted tree trunks. At the end of each green stripe is a pile of stones. That is all that is left of the root ball which was torn from the ground.

Another rare event involves an especially warm “Indian Summer” with a stream of air basically coming along a vector from the deserts of Arizona, when our forests ordinarily are drenched by former tropical storms and the first nor’easters of the autumn. The summer dryness extends into autumn, with the falling leaves are crisp and dry, and then some fool ignores Smokey The Bear. Then New England experiences a California fire, and in the past we have been inept at slowing the blazes spread. In 1947 several towns were wiped out, but my favorite tale was told by an old fisherman who was out to sea as the fire roared over Mount Desert Island in Maine. He stated that the fire was so intense that, when it reached the end of the island and you would think it would run out of fuel, it continued on out to sea as a fireball over the water. Yowza!

When you visit Mount Desert Island now you see verdant forests. You’d never believe such a fire could occur, and would be a perfectly natural event, if it happened again.

These young whippersnappers need to study history. Then they may understand no “equation” involving “carbon flow” and “carbon storage” in New England can be called complete until it includes one whopper of a hurricane, and one whopper of a forest fire.

Reply to  Caleb Shaw
August 6, 2020 8:53 am

Caleb says:
The summer dryness extends into autumn, with the falling leaves are crisp and dry, and then some fool ignores Smokey The Bear.

Good to see you post, Caleb. What you describe happened to some areas of West Virginia back in the fall of 1991. Drought since August & extending thru October caused forest-fires — smoke could be smelled for weeks where I was in southwest VA, but finally got put out by a cold rain first couple days of November.

Reply to  Caleb Shaw
August 6, 2020 8:55 am

Mount Desert Island. Now that’s a confused identity.

August 5, 2020 8:18 pm

“increasing temperatures and a longer growing season”.?? I’d wager that in the Harvard Forest any changes, if any in the plus direction, are minuscule at best. More garbage.

August 5, 2020 8:19 pm

“Our data show that the growth of trees is the engine that drives carbon storage in this forest ecosystem,”

Really? Wow! Well I never…..Amazing ”data” you have there!

How did they think an increase in mass was possible in a tree?
And trees don’t ”store” carbon by the way, they use it to make more tree.

Bill Everett
August 8, 2020 12:35 pm

A NASA Earth Observatory internet offering entitled “Satellite Detects Human Contribution To Atmospheric CO2” dated 2014-2016 purported to show a mapping of human induced atmospheric CO2 in the United States and other countries. The U.S. map showed that almost all of the “human induced CO2” occurred in the cold, moist Northeastern and warm rainy Southeastern quadrants of the country. The semi- arid Western half of the U.S. showed little or no presence of human induced CO2. The most pronounced areas of human induced CO2 did not appear at centers of human concentration but rather in those areas of more intense broad leaf vegetation especially forests containing broad leaf trees.

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