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Natural Debate: Do forests grow better with or without our help?: Yale Environment 360 #forestfuels #ecosystem


Kim Chaffee
 

Natural Debate:  Do forests grow better with or without our help?:  Yale Environment 360

All,

This article makes a strong case for letting nature do all the work of reforestation, except perhaps where the soil is very poor.  This just published study found that natural regeneration can capture more carbon more quickly and securely than tree plantations.  No mention of biochar, but adding it to poor soils would certainly speed up regrowth and accelerate carbon storage. 

Kim

Combining the mapping and carbon accumulation data, Cook-Patton estimates that natural forest regrowth could capture in biomass and soils 73 billion tons of carbon between now and 2050. That is equal to around seven years of current industrial emissions, making it “the single largest natural climate solution.”

Nations around the world are pledging to plant billions of trees to grow new forests. But a new study shows that the potential for natural forest regrowth to absorb carbon from the atmosphere and fight climate change is far greater than has previously been estimated.

Here is the abstract from Nature:


Nations around the world are pledging to plant billions of trees to grow new forests. But a new study shows that the potential for natural forest regrowth to absorb carbon from the atmosphere and fight climate change is far greater than has previously been estimated.

When Susan Cook-Patton was doing a post-doc in forest restoration at the Smithsonian Environmental Research Center in Maryland seven years ago, she says she helped plant 20,000 trees along Chesapeake Bay. It was a salutary lesson. “The ones that grew best were mostly ones we didn’t plant,” she remembers. “They just grew naturally on the ground we had set aside for planting. Lots popped up all around. It was a good reminder that nature knows what it is doing.”

What is true for Chesapeake Bay is probably true in many other places, says Cook-Patton, now at The Nature Conservancy. Sometimes, we just need to give nature room to grow back naturally. Her conclusion follows a new global study that finds the potential for natural forest regrowth to absorb atmospheric carbon and fight climate change has been seriously underestimated.

Tree planting is all the rage right now. This year’s World Economic Forum in Davos, Switzerland, called for the world to plant a trillion trees. In one of its few actions to address climate concerns, the U.S. administration — with support from businesses and nonprofits such as American Forests — last month promised to contribute close to a billion of them — 855 million, to be precise — across an estimated 2.8 million acres.

The European Union this year promised 3 billion more trees as part of a Green Deal; and existing worldwide pledges under the 2011 Bonn Challenge and the 2015 Paris Climate Accord set targets to restore more than 850 million acres of forests, mostly through planting. That is an area slightly larger than India, and provides room for roughly a quarter-trillion trees.

The study found that natural regeneration can capture more carbon more quickly and securely than tree plantations.

Planting is widely seen as a vital “nature-based solution” to climate change — a way of moderating climate change in the next three decades as the world works to achieve a zero-carbon economy. But there is pushback.

Nobody condemns trees. But some critics argue that an aggressive drive to achieve planting targets will provide environmental cover for land grabs to blanket hundreds of millions of acres with monoculture plantations of a handful of fast-growing and often non-native commercial species such as acacia, eucalyptus, and pine. Others ask: Why plant at all, when we can often simply leave the land for nearby forests to seed and recolonize? Nature knows what to grow, and does it best.

Cook-Patton’s new study, published in Nature and co-authored by researchers from 17 academic and environmental organizations, says estimates of the rate of carbon accumulation by natural forest regrowth, endorsed last year by the UN’s Intergovernmental Panel on Climate Change, are on average 32 percent too low, a figures that rises to 53 percent for tropical forests.

The study is the most detailed attempt yet to map where forests could grow back naturally, and to assess the potential of those forests to accumulate carbon. “We looked at almost 11,000 measurements of carbon uptake from regrowing forests, measured in around 250 studies around the world,” Cook-Patton told Yale Environment 360.

New vegetation grows amid burnt trees in the Amazon in the state of Para, Brazil.

New vegetation grows amid burnt trees in the Amazon in the state of Para, Brazil. ANTONIO SCORZA/AFP VIA GETTY IMAGES

She found that current carbon accumulation rates vary by a factor of a hundred, depending on climate, soils, altitude, and terrain. This is much greater than previously assessed. “Even within countries there were huge differences.” But overall, besides being better for biodiversity, the study showed, natural regeneration can capture more carbon more quickly and more securely than plantations.

Cook-Patton agrees that as climate change gathers pace in the coming decades, rates of carbon accumulation will change. But while some forests will grow more slowly or even die, others will probably grow faster due to the fertilization effect of more carbon dioxide in the air, an existing phenomenon sometimes called global greening.

The study identified up to 1.67 billion acres that could be set aside to allow trees to regrow. This excludes land under cultivation or built on, along with existing valuable ecosystems such as grasslands and boreal regions, where the warming effects of dark forest canopy outweigh the cooling benefits of carbon take-up.

Combining the mapping and carbon accumulation data, Cook-Patton estimates that natural forest regrowth could capture in biomass and soils 73 billion tons of carbon between now and 2050. That is equal to around seven years of current industrial emissions, making it “the single largest natural climate solution.”

Cook-Patton said the study’s local estimates of carbon accumulation fill an important data gap. Many countries intent on growing forests to store carbon have data for what can be achieved by planting, but lack equivalent data for natural regeneration. “I kept getting emails from people asking me what carbon they would get from [natural] reforesting projects,” she says. “I had to keep saying: ‘It depends.’ Now we have data that allow people to estimate what happens if you put up a fence and let forest regrow.”

Aboveground carbon accumulation rates, in metric tons of carbon per hectare per year, in naturally regrowing forests in forest and savanna biomes.

Aboveground carbon accumulation rates, in metric tons of carbon per hectare per year, in naturally regrowing forests in forest and savanna biomes. COOK-PATTON ET AL., NATURE 2020

The new local estimates also allow comparisons between the potential of natural regrowth and planting. “I think planting has its place, for instance where soils are degraded and trees won’t grow,” she said. “But I do think natural regrowth is hugely under-appreciated.”


The great thing about natural restoration of forests is that it often requires nothing more than human inaction. Nature is constantly at work restoring forests piecemeal and often unseen on the edges of fields, on abandoned pastures, in scrubby bush, and wherever forests lie degraded or former forest land is abandoned.

But because it requires no policy initiatives, investments, or oversight, data on its extent is badly lacking. Satellites such as Landsat are good at identifying deforestation, which is sudden and visible; but the extent of subsequent recovery is slower, harder to spot, and rarely assessed. Headline grabbing statistics on the loss of the world’s forests generally ignore it.

In a rare study, Philip Curtis of the University of Arkansas recently attempted to get around the problem by devising a model that could predict from satellite imagery what had caused the deforestation, and hence the potential for forest recovery. He found that only about a quarter of lost forests are permanently taken over for human activities such as buildings, infrastructure, or farming. The remaining three-quarters suffered from forest fires, shifting cultivation, temporary grazing, or logging, and at least had the potential for natural recovery.

Another study published this year found that such recovery was widespread and rapid even in an epicenter of deforestation such as the Amazon. When Yunxia Wang of the University of Leeds in England analyzed recently-released Brazilian data from the Amazon, she found that 72 percent of the forest being burned by ranchers to create new cattle pasture is not pristine forest, as widely assumed, but is actually recent regrowth. The forest had been cleared, converted to cattle pasture and then abandoned, whereupon the forest returned so fast that it was typically only six years before it was cleared again. Such was the confusion caused by this rapid forest turnover that regular land-use assessments frequently wrongly categorized this new growth as degraded old-growth forest.

“Actively reintroducing native plants will still be a better option in highly degraded sites,” says one scientist.

Wang noted that if Brazil’s President, Jair Bolsonaro, wanted to fulfill a promise made by his predecessor Dilma Rousseff at the 2015 Paris climate summit to restore 30 million acres of forest by 2030, then he need not plant at all. He could just allow regrowth to proceed in the Amazon without further clearing.

Brazil’s other great forest, the Atlantic forest, is already on that path, recovering slowly after more than a century of clearance for coffee and cattle. The government has an Atlantic Forest Restoration Pact that subsidizes landowners to replant, often with trees intended to supply the paper industry. Yet Camila Rezende of the Federal University of Rio de Janeiro says most of the forest regrowth is not from planting but from “spontaneous” regrowth, as forest remnants colonize neighboring abandoned farmland. She estimates that some 6.7 million acres of Atlantic Forest has naturally regenerated in this way since 1996. It now makes up about a tenth of the forest.

Much the same has been happening in Europe, where forest cover is now up to 43 percent, often from naturally recolonizing farmland rather than planting. Italy, for instance, has grown its forest cover by a 2.5 million acres. In the former Communist nations of central Europe, 16 percent of farmland in the Carpathian Mountains was abandoned in the 1990s, much of it reclaimed by the region’s famed beech forests. Across Russia, an area of former farmland about twice the size of Spain has been recolonized by forests. Irina Kurganova of the Russian Academy of Sciences calls this retreat of the plow “the most widespread and abrupt land-use change in the 20th century in the Northern Hemisphere.”

The United States has also seen natural forests regenerate as arable farmland has declined by almost a fifth in the past 30 years. “The entire eastern United States was deforested 200 years ago,” says Karen Holl of the University of California, Santa Cruz. “Much of that has come back without actively planting trees.” According to the U.S. Forest Service, over the past three decades the country’s regrowing forests have soaked up about 11 percent of national greenhouse gas emissions.

A worker plants Sitka spruce saplings at a reforestation project in Doddington, England in 2018.

A worker plants Sitka spruce saplings at a reforestation project in Doddington, England in 2018. DAN KITWOOD/GETTY IMAGES

With nature on the march, a major concern is whether a push for planting might grab land for plantations that natural forests might otherwise recolonize. The result would be less wildlife, less amenity for humans, and often less carbon stored.


Ecologists have traditionally dismissed the ecological gains from natural restoration of what is often called “secondary” forest. Such regrowth is often regarded as ephemeral, rarely sought out by wildlife, and prone to being cleared again. This has led many to regard planting to mimic natural forests as preferable.

Thomas Crowther, co-author of a widely-publicized study last year calling for a “global restoration” of a trillion trees to soak up carbon dioxide, emphasizes that, while nature could do the job in places, “people need to help out by spreading seeds and planting saplings.”

But a reappraisal is going on. J. Leighton Reid, director of Restoration Ecology at Virginia Tech, who recently warned against bias in studies comparing natural regeneration with planting, nonetheless told e360, “Natural regeneration is an excellent restoration strategy for many landscapes, but actively reintroducing native plants will still be a better option in highly degraded sites and in places where invasive species dominate.”

Others make the case that most of the time, natural restoration of secondary forests is a better option than planting. In her book, Second Growth, Robin Chazdon, a forest ecologist formerly at the University of Connecticut, says that secondary forests “continue to be misunderstood, understudied, and unappreciated for what they really are — young self-organizing forest ecosystems that are undergoing construction.”

Yes, she agrees, they are work in progress. But they generally recover “remarkably fast.” Recent research shows that regrowing tropical forests recover 80 percent of their species richness within 20 years, and frequently 100 percent within 50 years. That seems to be better than what human foresters achieve when trying to replant forest ecosystems.

Tree planting can worsen outcomes for everything from the number of bird and insect species to canopy cover.

review of more than 100 tropical forest restoration projects by Renato Crouzeilles of the International Institute for Sustainability in Rio de Janeiro, with Chazdon as a co-author, found that success rates were higher for secondary forests allowed to regenerate naturally than for those subjected to the “active restoration” techniques of foresters. In other words, planting can often worsen outcomes for everything from the number of bird, insect, and plant species, to measures of canopy cover, tree density, and forest structure. Nature knows best.

Now, Cook-Patton has extended the reappraisal to the carbon-accumulating potential of natural forest regeneration. It too may often be superior.

This scientific rethink requires a policy rethink, says Holl. “Business leaders and politicians have jumped on the tree-planting bandwagon, and numerous nonprofit organizations and governments worldwide have started initiatives to plant billions or even trillions of trees for a host of social, ecological, and aesthetic reasons”.

She concedes that on some damaged lands, “we will need to plant trees, but that should be the last option, since it is the most expensive and often is not successful.”

Planting a trillion trees over the next three decades would be a huge logistical challenge. A trillion is a big number. That target would require a thousand new trees in the ground every second, and then for all of them to survive and grow. Once the cost of nurseries, soil preparation, seeding, and thinning are accounted for, says Crouzeilles, it would cost hundreds of billions of dollars. If natural forest growth is cheaper and better, does that make sense?




Albert Bates
 

Thanks for this Kim. It is a key debate at this turning point in human history.

I feel the article low-balls the forest contribution potential, although I find 1.67 billion acres of available land to be a robust number. 73 GtC over 30 years is pitiful and far below what is needed. I described some reasons why standard reforestation understates the potential in The Biochar Solution (2010). Other recent studies have assayed the potential for protecting already-establishing natural regrowth and posted similar sequestration numbers.

I will address this more directly in my video talk at the Sonoma Biochar Forum Oct 13, but to preview the key takeaways: one cannot look at reforestation or afforestation mechanically. The highest performance comes from diverse, mixed-aged, mixed-species forests. Juvenile trees sequester at greater rates than mature trees. Hence what is required is an integrated human ecology of forest peoples who continuously garden their forest, as was the way in many places before about AD 1800.

We know from terra preta and more recent discoveries that biochar is a value proposition for sustaining these sorts of economies. By rotational harvest systems (milpa), and traditional extractive forest crafts, it is possible to produce biochar as a co-product that multiplies the sequestration potential. The carbon cascades Kathleen Draper and I described in Burn (2019) are only the tip of the iceberg for the new carbon economy enterprise possibilities that could be realized well before 2050.

It is not enough for governments to plant large forests. He who plants must cultivate. He who cultivates must harvest. And then replant. All of this needs to carry its own internal incentives in order to scale and sustain.

Albert

On 9/28/20 4:32 PM, Kim Chaffee wrote:
Natural Debate:  Do forests grow better with or without our help?:  Yale Environment 360

All,

This article makes a strong case for letting nature do all the work of reforestation, except perhaps where the soil is very poor.  This just published study found that natural regeneration can capture more carbon more quickly and securely than tree plantations.  No mention of biochar, but adding it to poor soils would certainly speed up regrowth and accelerate carbon storage. 

Kim

Combining the mapping and carbon accumulation data, Cook-Patton estimates that natural forest regrowth could capture in biomass and soils 73 billion tons of carbon between now and 2050. That is equal to around seven years of current industrial emissions, making it “the single largest natural climate solution.”

Nations around the world are pledging to plant billions of trees to grow new forests. But a new study shows that the potential for natural forest regrowth to absorb carbon from the atmosphere and fight climate change is far greater than has previously been estimated.

Here is the abstract from Nature:


Nations around the world are pledging to plant billions of trees to grow new forests. But a new study shows that the potential for natural forest regrowth to absorb carbon from the atmosphere and fight climate change is far greater than has previously been estimated.

When Susan Cook-Patton was doing a post-doc in forest restoration at the Smithsonian Environmental Research Center in Maryland seven years ago, she says she helped plant 20,000 trees along Chesapeake Bay. It was a salutary lesson. “The ones that grew best were mostly ones we didn’t plant,” she remembers. “They just grew naturally on the ground we had set aside for planting. Lots popped up all around. It was a good reminder that nature knows what it is doing.”

What is true for Chesapeake Bay is probably true in many other places, says Cook-Patton, now at The Nature Conservancy. Sometimes, we just need to give nature room to grow back naturally. Her conclusion follows a new global study that finds the potential for natural forest regrowth to absorb atmospheric carbon and fight climate change has been seriously underestimated.

Tree planting is all the rage right now. This year’s World Economic Forum in Davos, Switzerland, called for the world to plant a trillion trees. In one of its few actions to address climate concerns, the U.S. administration — with support from businesses and nonprofits such as American Forests — last month promised to contribute close to a billion of them — 855 million, to be precise — across an estimated 2.8 million acres.

The European Union this year promised 3 billion more trees as part of a Green Deal; and existing worldwide pledges under the 2011 Bonn Challenge and the 2015 Paris Climate Accord set targets to restore more than 850 million acres of forests, mostly through planting. That is an area slightly larger than India, and provides room for roughly a quarter-trillion trees.

The study found that natural regeneration can capture more carbon more quickly and securely than tree plantations.

Planting is widely seen as a vital “nature-based solution” to climate change — a way of moderating climate change in the next three decades as the world works to achieve a zero-carbon economy. But there is pushback.

Nobody condemns trees. But some critics argue that an aggressive drive to achieve planting targets will provide environmental cover for land grabs to blanket hundreds of millions of acres with monoculture plantations of a handful of fast-growing and often non-native commercial species such as acacia, eucalyptus, and pine. Others ask: Why plant at all, when we can often simply leave the land for nearby forests to seed and recolonize? Nature knows what to grow, and does it best.

Cook-Patton’s new study, published in Nature and co-authored by researchers from 17 academic and environmental organizations, says estimates of the rate of carbon accumulation by natural forest regrowth, endorsed last year by the UN’s Intergovernmental Panel on Climate Change, are on average 32 percent too low, a figures that rises to 53 percent for tropical forests.

The study is the most detailed attempt yet to map where forests could grow back naturally, and to assess the potential of those forests to accumulate carbon. “We looked at almost 11,000 measurements of carbon uptake from regrowing forests, measured in around 250 studies around the world,” Cook-Patton told Yale Environment 360.

New vegetation grows amid burnt trees in the
                      Amazon in the state of Para, Brazil.

New vegetation grows amid burnt trees in the Amazon in the state of Para, Brazil. ANTONIO SCORZA/AFP VIA GETTY IMAGES

She found that current carbon accumulation rates vary by a factor of a hundred, depending on climate, soils, altitude, and terrain. This is much greater than previously assessed. “Even within countries there were huge differences.” But overall, besides being better for biodiversity, the study showed, natural regeneration can capture more carbon more quickly and more securely than plantations.

Cook-Patton agrees that as climate change gathers pace in the coming decades, rates of carbon accumulation will change. But while some forests will grow more slowly or even die, others will probably grow faster due to the fertilization effect of more carbon dioxide in the air, an existing phenomenon sometimes called global greening.

The study identified up to 1.67 billion acres that could be set aside to allow trees to regrow. This excludes land under cultivation or built on, along with existing valuable ecosystems such as grasslands and boreal regions, where the warming effects of dark forest canopy outweigh the cooling benefits of carbon take-up.

Combining the mapping and carbon accumulation data, Cook-Patton estimates that natural forest regrowth could capture in biomass and soils 73 billion tons of carbon between now and 2050. That is equal to around seven years of current industrial emissions, making it “the single largest natural climate solution.”

Cook-Patton said the study’s local estimates of carbon accumulation fill an important data gap. Many countries intent on growing forests to store carbon have data for what can be achieved by planting, but lack equivalent data for natural regeneration. “I kept getting emails from people asking me what carbon they would get from [natural] reforesting projects,” she says. “I had to keep saying: ‘It depends.’ Now we have data that allow people to estimate what happens if you put up a fence and let forest regrow.”

Aboveground carbon accumulation rates, in
                      metric tons of carbon per hectare per year, in
                      naturally regrowing forests in forest and savanna
                      biomes.

Aboveground carbon accumulation rates, in metric tons of carbon per hectare per year, in naturally regrowing forests in forest and savanna biomes. COOK-PATTON ET AL., NATURE 2020

The new local estimates also allow comparisons between the potential of natural regrowth and planting. “I think planting has its place, for instance where soils are degraded and trees won’t grow,” she said. “But I do think natural regrowth is hugely under-appreciated.”


The great thing about natural restoration of forests is that it often requires nothing more than human inaction. Nature is constantly at work restoring forests piecemeal and often unseen on the edges of fields, on abandoned pastures, in scrubby bush, and wherever forests lie degraded or former forest land is abandoned.

But because it requires no policy initiatives, investments, or oversight, data on its extent is badly lacking. Satellites such as Landsat are good at identifying deforestation, which is sudden and visible; but the extent of subsequent recovery is slower, harder to spot, and rarely assessed. Headline grabbing statistics on the loss of the world’s forests generally ignore it.

In a rare study, Philip Curtis of the University of Arkansas recently attempted to get around the problem by devising a model that could predict from satellite imagery what had caused the deforestation, and hence the potential for forest recovery. He found that only about a quarter of lost forests are permanently taken over for human activities such as buildings, infrastructure, or farming. The remaining three-quarters suffered from forest fires, shifting cultivation, temporary grazing, or logging, and at least had the potential for natural recovery.

Another study published this year found that such recovery was widespread and rapid even in an epicenter of deforestation such as the Amazon. When Yunxia Wang of the University of Leeds in England analyzed recently-released Brazilian data from the Amazon, she found that 72 percent of the forest being burned by ranchers to create new cattle pasture is not pristine forest, as widely assumed, but is actually recent regrowth. The forest had been cleared, converted to cattle pasture and then abandoned, whereupon the forest returned so fast that it was typically only six years before it was cleared again. Such was the confusion caused by this rapid forest turnover that regular land-use assessments frequently wrongly categorized this new growth as degraded old-growth forest.

“Actively reintroducing native plants will still be a better option in highly degraded sites,” says one scientist.

Wang noted that if Brazil’s President, Jair Bolsonaro, wanted to fulfill a promise made by his predecessor Dilma Rousseff at the 2015 Paris climate summit to restore 30 million acres of forest by 2030, then he need not plant at all. He could just allow regrowth to proceed in the Amazon without further clearing.

Brazil’s other great forest, the Atlantic forest, is already on that path, recovering slowly after more than a century of clearance for coffee and cattle. The government has an Atlantic Forest Restoration Pact that subsidizes landowners to replant, often with trees intended to supply the paper industry. Yet Camila Rezende of the Federal University of Rio de Janeiro says most of the forest regrowth is not from planting but from “spontaneous” regrowth, as forest remnants colonize neighboring abandoned farmland. She estimates that some 6.7 million acres of Atlantic Forest has naturally regenerated in this way since 1996. It now makes up about a tenth of the forest.

Much the same has been happening in Europe, where forest cover is now up to 43 percent, often from naturally recolonizing farmland rather than planting. Italy, for instance, has grown its forest cover by a 2.5 million acres. In the former Communist nations of central Europe, 16 percent of farmland in the Carpathian Mountains was abandoned in the 1990s, much of it reclaimed by the region’s famed beech forests. Across Russia, an area of former farmland about twice the size of Spain has been recolonized by forests. Irina Kurganova of the Russian Academy of Sciences calls this retreat of the plow “the most widespread and abrupt land-use change in the 20th century in the Northern Hemisphere.”

The United States has also seen natural forests regenerate as arable farmland has declined by almost a fifth in the past 30 years. “The entire eastern United States was deforested 200 years ago,” says Karen Holl of the University of California, Santa Cruz. “Much of that has come back without actively planting trees.” According to the U.S. Forest Service, over the past three decades the country’s regrowing forests have soaked up about 11 percent of national greenhouse gas emissions.

A worker plants Sitka spruce saplings at a
                      reforestation project in Doddington, England in
                      2018.

A worker plants Sitka spruce saplings at a reforestation project in Doddington, England in 2018. DAN KITWOOD/GETTY IMAGES

With nature on the march, a major concern is whether a push for planting might grab land for plantations that natural forests might otherwise recolonize. The result would be less wildlife, less amenity for humans, and often less carbon stored.


Ecologists have traditionally dismissed the ecological gains from natural restoration of what is often called “secondary” forest. Such regrowth is often regarded as ephemeral, rarely sought out by wildlife, and prone to being cleared again. This has led many to regard planting to mimic natural forests as preferable.

Thomas Crowther, co-author of a widely-publicized study last year calling for a “global restoration” of a trillion trees to soak up carbon dioxide, emphasizes that, while nature could do the job in places, “people need to help out by spreading seeds and planting saplings.”

But a reappraisal is going on. J. Leighton Reid, director of Restoration Ecology at Virginia Tech, who recently warned against bias in studies comparing natural regeneration with planting, nonetheless told e360, “Natural regeneration is an excellent restoration strategy for many landscapes, but actively reintroducing native plants will still be a better option in highly degraded sites and in places where invasive species dominate.”

Others make the case that most of the time, natural restoration of secondary forests is a better option than planting. In her book, Second Growth, Robin Chazdon, a forest ecologist formerly at the University of Connecticut, says that secondary forests “continue to be misunderstood, understudied, and unappreciated for what they really are — young self-organizing forest ecosystems that are undergoing construction.”

Yes, she agrees, they are work in progress. But they generally recover “remarkably fast.” Recent research shows that regrowing tropical forests recover 80 percent of their species richness within 20 years, and frequently 100 percent within 50 years. That seems to be better than what human foresters achieve when trying to replant forest ecosystems.

Tree planting can worsen outcomes for everything from the number of bird and insect species to canopy cover.

review of more than 100 tropical forest restoration projects by Renato Crouzeilles of the International Institute for Sustainability in Rio de Janeiro, with Chazdon as a co-author, found that success rates were higher for secondary forests allowed to regenerate naturally than for those subjected to the “active restoration” techniques of foresters. In other words, planting can often worsen outcomes for everything from the number of bird, insect, and plant species, to measures of canopy cover, tree density, and forest structure. Nature knows best.

Now, Cook-Patton has extended the reappraisal to the carbon-accumulating potential of natural forest regeneration. It too may often be superior.

This scientific rethink requires a policy rethink, says Holl. “Business leaders and politicians have jumped on the tree-planting bandwagon, and numerous nonprofit organizations and governments worldwide have started initiatives to plant billions or even trillions of trees for a host of social, ecological, and aesthetic reasons”.

She concedes that on some damaged lands, “we will need to plant trees, but that should be the last option, since it is the most expensive and often is not successful.”

Planting a trillion trees over the next three decades would be a huge logistical challenge. A trillion is a big number. That target would require a thousand new trees in the ground every second, and then for all of them to survive and grow. Once the cost of nurseries, soil preparation, seeding, and thinning are accounted for, says Crouzeilles, it would cost hundreds of billions of dollars. If natural forest growth is cheaper and better, does that make sense?




--
BURN: Using Fire to Cool the Earth

Global Village Institute for Appropriate Technology
Summertown TN 38483-0090


ALAN PAGE
 

Hi Albert et al,
I agree with much of what you have said and certainly about what is stated about the process of natural restocking of vacant or harvested land. I would like to add a couple of points:
1) As Albert said what is cultivated must be harvested by someone / something. Nature will do it if people do not and it is not pretty when nature does it (it may not be pretty when a normal logger does the harvesting either but the possibility of making charcoal and turning it into real biochar can go a long way toward cleaning up most situations. While Tom and Kelpie talk about the progress made in their area is certainly has not found any significant place in normal forestry on the east coast.
2) Our experience with seeding from natural sources show that the presence of large trees really makes a lot of difference in what kind of forest will replace the biome that is harvested. Some species make seeds nearly every year others are much less frequent, but when there is a good seed crop there will be hundreds of thousands of new seedlings started in the next few years after the seed release. This process happens regularly so there are frequently millions of seeds from a variety of species every few years and their viability may extend for decades in some cases. Read Gaviotas regarding the regrowing of a forest in a savanna.
We get best regeneration in places where there was significant wheeled traffic - we believe that this is due to the lack of water competition from the side because the traffic has cut the roots of trees on both sides of the path. There are many strange things that happen to add to the success of one species over another over time.
3) No one seems to worry about retaining the rural skill set as the tech revolution is pushed onto our children. I do and I find that there are many parts to the cultivation paradigm that needs to be expanded and each activity must be paid for to allow the participants to have a normal healthy family. It is not okay for foreign volunteers to come in for a few weeks and then go home thinking they have done all that was needed.
4) Our family has helped keep a biochar experiment going in Plainfield, MA that was shown at the 2013 Biochar Symposium at UMASS. The work there has shown that of all the several hundred trees recorded there are two that stand out: they are both small cherry trees that were less than 2" in diameter in 2013. One is now nearly 5 " and is growing 4-7' in height per year and the other is still about 1.5' in diameter and hardly growing in height at all. The trees are less than 75' apart. The slow growing tree is like most of the rest of the forest in that there is too much competition for light, water and space. for much diameter growth to occur. However it is obvious that unless we continue to open up additional area around the fast growing tree it too will slow down and possibly be overtopped by some taller neighbors that are growing in from the sides.  
5) Finally, in our region we are finding that many trees form crotches as storms (wind, and heavy show and Ice) as well as insects or disease may deform the central stem and allow side branches to turn up and take over the height growth. Once that happens generally the wood formed above the crotch is junk. This and the possibility of forming defect free wood with upper branch removal as the tree grows taller can greatly improve the amount of harvestable high quality wood per tree. We expect to be able to remove branches and crotches from the main stem to over 60 feet given the funding to follow individual tree development. 

Alan C. Page, Ph.D., Research Forester - MA License #184
Green Diamond Systems
125 Blue Meadow Road
Belchertown, MA 01007

Phone: 413-323-4401
Cell: 413-883-9642

Sent with ProtonMail Secure Email.

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐

On Monday, September 28, 2020 5:59 PM, Albert Bates <peaksurfer@...> wrote:

Thanks for this Kim. It is a key debate at this turning point in human history.

I feel the article low-balls the forest contribution potential, although I find 1.67 billion acres of available land to be a robust number. 73 GtC over 30 years is pitiful and far below what is needed. I described some reasons why standard reforestation understates the potential in The Biochar Solution (2010). Other recent studies have assayed the potential for protecting already-establishing natural regrowth and posted similar sequestration numbers.

I will address this more directly in my video talk at the Sonoma Biochar Forum Oct 13, but to preview the key takeaways: one cannot look at reforestation or afforestation mechanically. The highest performance comes from diverse, mixed-aged, mixed-species forests. Juvenile trees sequester at greater rates than mature trees. Hence what is required is an integrated human ecology of forest peoples who continuously garden their forest, as was the way in many places before about AD 1800.

We know from terra preta and more recent discoveries that biochar is a value proposition for sustaining these sorts of economies. By rotational harvest systems (milpa), and traditional extractive forest crafts, it is possible to produce biochar as a co-product that multiplies the sequestration potential. The carbon cascades Kathleen Draper and I described in Burn (2019) are only the tip of the iceberg for the new carbon economy enterprise possibilities that could be realized well before 2050.

It is not enough for governments to plant large forests. He who plants must cultivate. He who cultivates must harvest. And then replant. All of this needs to carry its own internal incentives in order to scale and sustain.

Albert

On 9/28/20 4:32 PM, Kim Chaffee wrote:
Natural Debate:  Do forests grow better with or without our help?:  Yale Environment 360

All,

This article makes a strong case for letting nature do all the work of reforestation, except perhaps where the soil is very poor.  This just published study found that natural regeneration can capture more carbon more quickly and securely than tree plantations.  No mention of biochar, but adding it to poor soils would certainly speed up regrowth and accelerate carbon storage. 

Kim

Combining the mapping and carbon accumulation data, Cook-Patton estimates that natural forest regrowth could capture in biomass and soils 73 billion tons of carbon between now and 2050. That is equal to around seven years of current industrial emissions, making it “the single largest natural climate solution.”

Nations around the world are pledging to plant billions of trees to grow new forests. But a new study shows that the potential for natural forest regrowth to absorb carbon from the atmosphere and fight climate change is far greater than has previously been estimated.

Here is the abstract from Nature:


Nations around the world are pledging to plant billions of trees to grow new forests. But a new study shows that the potential for natural forest regrowth to absorb carbon from the atmosphere and fight climate change is far greater than has previously been estimated.

When Susan Cook-Patton was doing a post-doc in forest restoration at the Smithsonian Environmental Research Center in Maryland seven years ago, she says she helped plant 20,000 trees along Chesapeake Bay. It was a salutary lesson. “The ones that grew best were mostly ones we didn’t plant,” she remembers. “They just grew naturally on the ground we had set aside for planting. Lots popped up all around. It was a good reminder that nature knows what it is doing.”

What is true for Chesapeake Bay is probably true in many other places, says Cook-Patton, now at The Nature Conservancy. Sometimes, we just need to give nature room to grow back naturally. Her conclusion follows a new global study that finds the potential for natural forest regrowth to absorb atmospheric carbon and fight climate change has been seriously underestimated.

Tree planting is all the rage right now. This year’s World Economic Forum in Davos, Switzerland, called for the world to plant a trillion trees. In one of its few actions to address climate concerns, the U.S. administration — with support from businesses and nonprofits such as American Forests — last month promised to contribute close to a billion of them — 855 million, to be precise — across an estimated 2.8 million acres.

The European Union this year promised 3 billion more trees as part of a Green Deal; and existing worldwide pledges under the 2011 Bonn Challenge and the 2015 Paris Climate Accord set targets to restore more than 850 million acres of forests, mostly through planting. That is an area slightly larger than India, and provides room for roughly a quarter-trillion trees.

The study found that natural regeneration can capture more carbon more quickly and securely than tree plantations.

Planting is widely seen as a vital “nature-based solution” to climate change — a way of moderating climate change in the next three decades as the world works to achieve a zero-carbon economy. But there is pushback.

Nobody condemns trees. But some critics argue that an aggressive drive to achieve planting targets will provide environmental cover for land grabs to blanket hundreds of millions of acres with monoculture plantations of a handful of fast-growing and often non-native commercial species such as acacia, eucalyptus, and pine. Others ask: Why plant at all, when we can often simply leave the land for nearby forests to seed and recolonize? Nature knows what to grow, and does it best.

Cook-Patton’s new study, published in Nature and co-authored by researchers from 17 academic and environmental organizations, says estimates of the rate of carbon accumulation by natural forest regrowth, endorsed last year by the UN’s Intergovernmental Panel on Climate Change, are on average 32 percent too low, a figures that rises to 53 percent for tropical forests.

The study is the most detailed attempt yet to map where forests could grow back naturally, and to assess the potential of those forests to accumulate carbon. “We looked at almost 11,000 measurements of carbon uptake from regrowing forests, measured in around 250 studies around the world,” Cook-Patton told Yale Environment 360.

New vegetation grows amid burnt trees in the
                      Amazon in the state of Para, Brazil.

New vegetation grows amid burnt trees in the Amazon in the state of Para, Brazil. ANTONIO SCORZA/AFP VIA GETTY IMAGES

She found that current carbon accumulation rates vary by a factor of a hundred, depending on climate, soils, altitude, and terrain. This is much greater than previously assessed. “Even within countries there were huge differences.” But overall, besides being better for biodiversity, the study showed, natural regeneration can capture more carbon more quickly and more securely than plantations.

Cook-Patton agrees that as climate change gathers pace in the coming decades, rates of carbon accumulation will change. But while some forests will grow more slowly or even die, others will probably grow faster due to the fertilization effect of more carbon dioxide in the air, an existing phenomenon sometimes called global greening.

The study identified up to 1.67 billion acres that could be set aside to allow trees to regrow. This excludes land under cultivation or built on, along with existing valuable ecosystems such as grasslands and boreal regions, where the warming effects of dark forest canopy outweigh the cooling benefits of carbon take-up.

Combining the mapping and carbon accumulation data, Cook-Patton estimates that natural forest regrowth could capture in biomass and soils 73 billion tons of carbon between now and 2050. That is equal to around seven years of current industrial emissions, making it “the single largest natural climate solution.”

Cook-Patton said the study’s local estimates of carbon accumulation fill an important data gap. Many countries intent on growing forests to store carbon have data for what can be achieved by planting, but lack equivalent data for natural regeneration. “I kept getting emails from people asking me what carbon they would get from [natural] reforesting projects,” she says. “I had to keep saying: ‘It depends.’ Now we have data that allow people to estimate what happens if you put up a fence and let forest regrow.”

Aboveground carbon accumulation rates, in
                      metric tons of carbon per hectare per year, in
                      naturally regrowing forests in forest and savanna
                      biomes.

Aboveground carbon accumulation rates, in metric tons of carbon per hectare per year, in naturally regrowing forests in forest and savanna biomes. COOK-PATTON ET AL., NATURE 2020

The new local estimates also allow comparisons between the potential of natural regrowth and planting. “I think planting has its place, for instance where soils are degraded and trees won’t grow,” she said. “But I do think natural regrowth is hugely under-appreciated.”



The great thing about natural restoration of forests is that it often requires nothing more than human inaction. Nature is constantly at work restoring forests piecemeal and often unseen on the edges of fields, on abandoned pastures, in scrubby bush, and wherever forests lie degraded or former forest land is abandoned.

But because it requires no policy initiatives, investments, or oversight, data on its extent is badly lacking. Satellites such as Landsat are good at identifying deforestation, which is sudden and visible; but the extent of subsequent recovery is slower, harder to spot, and rarely assessed. Headline grabbing statistics on the loss of the world’s forests generally ignore it.

In a rare study, Philip Curtis of the University of Arkansas recently attempted to get around the problem by devising a model that could predict from satellite imagery what had caused the deforestation, and hence the potential for forest recovery. He found that only about a quarter of lost forests are permanently taken over for human activities such as buildings, infrastructure, or farming. The remaining three-quarters suffered from forest fires, shifting cultivation, temporary grazing, or logging, and at least had the potential for natural recovery.

Another study published this year found that such recovery was widespread and rapid even in an epicenter of deforestation such as the Amazon. When Yunxia Wang of the University of Leeds in England analyzed recently-released Brazilian data from the Amazon, she found that 72 percent of the forest being burned by ranchers to create new cattle pasture is not pristine forest, as widely assumed, but is actually recent regrowth. The forest had been cleared, converted to cattle pasture and then abandoned, whereupon the forest returned so fast that it was typically only six years before it was cleared again. Such was the confusion caused by this rapid forest turnover that regular land-use assessments frequently wrongly categorized this new growth as degraded old-growth forest.

“Actively reintroducing native plants will still be a better option in highly degraded sites,” says one scientist.

Wang noted that if Brazil’s President, Jair Bolsonaro, wanted to fulfill a promise made by his predecessor Dilma Rousseff at the 2015 Paris climate summit to restore 30 million acres of forest by 2030, then he need not plant at all. He could just allow regrowth to proceed in the Amazon without further clearing.

Brazil’s other great forest, the Atlantic forest, is already on that path, recovering slowly after more than a century of clearance for coffee and cattle. The government has an Atlantic Forest Restoration Pact that subsidizes landowners to replant, often with trees intended to supply the paper industry. Yet Camila Rezende of the Federal University of Rio de Janeiro says most of the forest regrowth is not from planting but from “spontaneous” regrowth, as forest remnants colonize neighboring abandoned farmland. She estimates that some 6.7 million acres of Atlantic Forest has naturally regenerated in this way since 1996. It now makes up about a tenth of the forest.

Much the same has been happening in Europe, where forest cover is now up to 43 percent, often from naturally recolonizing farmland rather than planting. Italy, for instance, has grown its forest cover by a 2.5 million acres. In the former Communist nations of central Europe, 16 percent of farmland in the Carpathian Mountains was abandoned in the 1990s, much of it reclaimed by the region’s famed beech forests. Across Russia, an area of former farmland about twice the size of Spain has been recolonized by forests. Irina Kurganova of the Russian Academy of Sciences calls this retreat of the plow “the most widespread and abrupt land-use change in the 20th century in the Northern Hemisphere.”

The United States has also seen natural forests regenerate as arable farmland has declined by almost a fifth in the past 30 years. “The entire eastern United States was deforested 200 years ago,” says Karen Holl of the University of California, Santa Cruz. “Much of that has come back without actively planting trees.” According to the U.S. Forest Service, over the past three decades the country’s regrowing forests have soaked up about 11 percent of national greenhouse gas emissions.

A worker plants Sitka spruce saplings at a
                      reforestation project in Doddington, England in
                      2018.

A worker plants Sitka spruce saplings at a reforestation project in Doddington, England in 2018. DAN KITWOOD/GETTY IMAGES

With nature on the march, a major concern is whether a push for planting might grab land for plantations that natural forests might otherwise recolonize. The result would be less wildlife, less amenity for humans, and often less carbon stored.



Ecologists have traditionally dismissed the ecological gains from natural restoration of what is often called “secondary” forest. Such regrowth is often regarded as ephemeral, rarely sought out by wildlife, and prone to being cleared again. This has led many to regard planting to mimic natural forests as preferable.

Thomas Crowther, co-author of a widely-publicized study last year calling for a “global restoration” of a trillion trees to soak up carbon dioxide, emphasizes that, while nature could do the job in places, “people need to help out by spreading seeds and planting saplings.”

But a reappraisal is going on. J. Leighton Reid, director of Restoration Ecology at Virginia Tech, who recently warned against bias in studies comparing natural regeneration with planting, nonetheless told e360, “Natural regeneration is an excellent restoration strategy for many landscapes, but actively reintroducing native plants will still be a better option in highly degraded sites and in places where invasive species dominate.”

Others make the case that most of the time, natural restoration of secondary forests is a better option than planting. In her book, Second Growth, Robin Chazdon, a forest ecologist formerly at the University of Connecticut, says that secondary forests “continue to be misunderstood, understudied, and unappreciated for what they really are — young self-organizing forest ecosystems that are undergoing construction.”

Yes, she agrees, they are work in progress. But they generally recover “remarkably fast.” Recent research shows that regrowing tropical forests recover 80 percent of their species richness within 20 years, and frequently 100 percent within 50 years. That seems to be better than what human foresters achieve when trying to replant forest ecosystems.

Tree planting can worsen outcomes for everything from the number of bird and insect species to canopy cover.

review of more than 100 tropical forest restoration projects by Renato Crouzeilles of the International Institute for Sustainability in Rio de Janeiro, with Chazdon as a co-author, found that success rates were higher for secondary forests allowed to regenerate naturally than for those subjected to the “active restoration” techniques of foresters. In other words, planting can often worsen outcomes for everything from the number of bird, insect, and plant species, to measures of canopy cover, tree density, and forest structure. Nature knows best.

Now, Cook-Patton has extended the reappraisal to the carbon-accumulating potential of natural forest regeneration. It too may often be superior.

This scientific rethink requires a policy rethink, says Holl. “Business leaders and politicians have jumped on the tree-planting bandwagon, and numerous nonprofit organizations and governments worldwide have started initiatives to plant billions or even trillions of trees for a host of social, ecological, and aesthetic reasons”.

She concedes that on some damaged lands, “we will need to plant trees, but that should be the last option, since it is the most expensive and often is not successful.”

Planting a trillion trees over the next three decades would be a huge logistical challenge. A trillion is a big number. That target would require a thousand new trees in the ground every second, and then for all of them to survive and grow. Once the cost of nurseries, soil preparation, seeding, and thinning are accounted for, says Crouzeilles, it would cost hundreds of billions of dollars. If natural forest growth is cheaper and better, does that make sense?




--
BURN: Using Fire to Cool the Earth

Global Village Institute for Appropriate Technology
Summertown TN 38483-0090


Muriel Strand
 

how can i attend the sonoma biochar forum?

i find no link online… including at https://sonomabiocharinitiative.org

is there a way to redirect all those fearful laid-off right-wing trumper guys to start the kind of widespread forest farming you allude to?

thanks,
Muriel Strand, P.E.

Advertising is a private tax.
- Andre Schiffrin

www.bio-paradigm.blogspot.com/
www.work4sustenance.blogspot.com

On Sep 28, 2020, at 2:59 PM, Albert Bates <peaksurfer@gmail.com> wrote:

Thanks for this Kim. It is a key debate at this turning point in human history.

I feel the article low-balls the forest contribution potential, although I find 1.67 billion acres of available land to be a robust number. 73 GtC over 30 years is pitiful and far below what is needed. I described some reasons why standard reforestation understates the potential in The Biochar Solution (2010). Other recent studies have assayed the potential for protecting already-establishing natural regrowth and posted similar sequestration numbers.

I will address this more directly in my video talk at the Sonoma Biochar Forum Oct 13, but to preview the key takeaways: one cannot look at reforestation or afforestation mechanically. The highest performance comes from diverse, mixed-aged, mixed-species forests. Juvenile trees sequester at greater rates than mature trees. Hence what is required is an integrated human ecology of forest peoples who continuously garden their forest, as was the way in many places before about AD 1800.
We know from terra preta and more recent discoveries that biochar is a value proposition for sustaining these sorts of economies. By rotational harvest systems (milpa), and traditional extractive forest crafts, it is possible to produce biochar as a co-product that multiplies the sequestration potential. The carbon cascades Kathleen Draper and I described in Burn (2019) are only the tip of the iceberg for the new carbon economy enterprise possibilities that could be realized well before 2050.

It is not enough for governments to plant large forests. He who plants must cultivate. He who cultivates must harvest. And then replant. All of this needs to carry its own internal incentives in order to scale and sustain.
Albert
On 9/28/20 4:32 PM, Kim Chaffee wrote:
Natural Debate: Do forests grow better with or without our help?: Yale Environment 360

All,

This article makes a strong case for letting nature do all the work of reforestation, except perhaps where the soil is very poor. This just published study found that natural regeneration can capture more carbon more quickly and securely than tree plantations. No mention of biochar, but adding it to poor soils would certainly speed up regrowth and accelerate carbon storage.

Kim

Combining the mapping and carbon accumulation data, Cook-Patton estimates that natural forest regrowth could capture in biomass and soils 73 billion tons of carbon between now and 2050. That is equal to around seven years of current industrial emissions, making it “the single largest natural climate solution.”

Nations around the world are pledging to plant billions of trees to grow new forests. But a new study shows that the potential for natural forest regrowth to absorb carbon from the atmosphere and fight climate change is far greater than has previously been estimated.

https://e360.yale.edu/features/natural-debate-do-forests-grow-better-with-our-help-or-without

Here is the abstract from Nature:

https://www.nature.com/articles/s41586-020-2686-x

Nations around the world are pledging to plant billions of trees to grow new forests. But a new study shows that the potential for natural forest regrowth to absorb carbon from the atmosphere and fight climate change is far greater than has previously been estimated.
When Susan Cook-Patton was doing a post-doc in forest restoration at the Smithsonian Environmental Research Center in Maryland seven years ago, she says she helped plant 20,000 trees along Chesapeake Bay. It was a salutary lesson. “The ones that grew best were mostly ones we didn’t plant,” she remembers. “They just grew naturally on the ground we had set aside for planting. Lots popped up all around. It was a good reminder that nature knows what it is doing.”

What is true for Chesapeake Bay is probably true in many other places, says Cook-Patton, now at The Nature Conservancy. Sometimes, we just need to give nature room to grow back naturally. Her conclusion follows a new global study that finds the potential for natural forest regrowth to absorb atmospheric carbon and fight climate change has been seriously underestimated.

Tree planting is all the rage right now. This year’s World Economic Forum in Davos, Switzerland, called for the world to plant a trillion trees. In one of its few actions to address climate concerns, the U.S. administration — with support from businesses and nonprofits such as American Forests — last month promised to contribute close to a billion of them — 855 million, to be precise — across an estimated 2.8 million acres.

The European Union this year promised 3 billion more trees as part of a Green Deal; and existing worldwide pledges under the 2011 Bonn Challenge and the 2015 Paris Climate Accord set targets to restore more than 850 million acres of forests, mostly through planting. That is an area slightly larger than India, and provides room for roughly a quarter-trillion trees.

The study found that natural regeneration can capture more carbon more quickly and securely than tree plantations.
Planting is widely seen as a vital “nature-based solution” to climate change — a way of moderating climate change in the next three decades as the world works to achieve a zero-carbon economy. But there is pushback.

Nobody condemns trees. But some critics argue that an aggressive drive to achieve planting targets will provide environmental cover for land grabs to blanket hundreds of millions of acres with monoculture plantations of a handful of fast-growing and often non-native commercial species such as acacia, eucalyptus, and pine. Others ask: Why plant at all, when we can often simply leave the land for nearby forests to seed and recolonize? Nature knows what to grow, and does it best.

Cook-Patton’s new study, published in Nature and co-authored by researchers from 17 academic and environmental organizations, says estimates of the rate of carbon accumulation by natural forest regrowth, endorsed last year by the UN’s Intergovernmental Panel on Climate Change, are on average 32 percent too low, a figures that rises to 53 percent for tropical forests.

The study is the most detailed attempt yet to map where forests could grow back naturally, and to assess the potential of those forests to accumulate carbon. “We looked at almost 11,000 measurements of carbon uptake from regrowing forests, measured in around 250 studies around the world,” Cook-Patton told Yale Environment 360.


New vegetation grows amid burnt trees in the Amazon in the state of Para, Brazil. ANTONIO SCORZA/AFP VIA GETTY IMAGES

She found that current carbon accumulation rates vary by a factor of a hundred, depending on climate, soils, altitude, and terrain. This is much greater than previously assessed. “Even within countries there were huge differences.” But overall, besides being better for biodiversity, the study showed, natural regeneration can capture more carbon more quickly and more securely than plantations.


ALSO ON YALE E360

Will climate change upend projections of future forest growth? Read more.

Cook-Patton agrees that as climate change gathers pace in the coming decades, rates of carbon accumulation will change. But while some forests will grow more slowly or even die, others will probably grow faster due to the fertilization effect of more carbon dioxide in the air, an existing phenomenon sometimes called global greening.

The study identified up to 1.67 billion acres that could be set aside to allow trees to regrow. This excludes land under cultivation or built on, along with existing valuable ecosystems such as grasslands and boreal regions, where the warming effects of dark forest canopy outweigh the cooling benefits of carbon take-up.

Combining the mapping and carbon accumulation data, Cook-Patton estimates that natural forest regrowth could capture in biomass and soils 73 billion tons of carbon between now and 2050. That is equal to around seven years of current industrial emissions, making it “the single largest natural climate solution.”

Cook-Patton said the study’s local estimates of carbon accumulation fill an important data gap. Many countries intent on growing forests to store carbon have data for what can be achieved by planting, but lack equivalent data for natural regeneration. “I kept getting emails from people asking me what carbon they would get from [natural] reforesting projects,” she says. “I had to keep saying: ‘It depends.’ Now we have data that allow people to estimate what happens if you put up a fence and let forest regrow.”


Aboveground carbon accumulation rates, in metric tons of carbon per hectare per year, in naturally regrowing forests in forest and savanna biomes. COOK-PATTON ET AL., NATURE 2020

The new local estimates also allow comparisons between the potential of natural regrowth and planting. “I think planting has its place, for instance where soils are degraded and trees won’t grow,” she said. “But I do think natural regrowth is hugely under-appreciated.”

The great thing about natural restoration of forests is that it often requires nothing more than human inaction. Nature is constantly at work restoring forests piecemeal and often unseen on the edges of fields, on abandoned pastures, in scrubby bush, and wherever forests lie degraded or former forest land is abandoned.

But because it requires no policy initiatives, investments, or oversight, data on its extent is badly lacking. Satellites such as Landsat are good at identifying deforestation, which is sudden and visible; but the extent of subsequent recovery is slower, harder to spot, and rarely assessed. Headline grabbing statistics on the loss of the world’s forests generally ignore it.

In a rare study, Philip Curtis of the University of Arkansas recently attempted to get around the problem by devising a model that could predict from satellite imagery what had caused the deforestation, and hence the potential for forest recovery. He found that only about a quarter of lost forests are permanently taken over for human activities such as buildings, infrastructure, or farming. The remaining three-quarters suffered from forest fires, shifting cultivation, temporary grazing, or logging, and at least had the potential for natural recovery.

Another study published this year found that such recovery was widespread and rapid even in an epicenter of deforestation such as the Amazon. When Yunxia Wang of the University of Leeds in England analyzed recently-released Brazilian data from the Amazon, she found that 72 percent of the forest being burned by ranchers to create new cattle pasture is not pristine forest, as widely assumed, but is actually recent regrowth. The forest had been cleared, converted to cattle pasture and then abandoned, whereupon the forest returned so fast that it was typically only six years before it was cleared again. Such was the confusion caused by this rapid forest turnover that regular land-use assessments frequently wrongly categorized this new growth as degraded old-growth forest.

“Actively reintroducing native plants will still be a better option in highly degraded sites,” says one scientist.
Wang noted that if Brazil’s President, Jair Bolsonaro, wanted to fulfill a promise made by his predecessor Dilma Rousseff at the 2015 Paris climate summit to restore 30 million acres of forest by 2030, then he need not plant at all. He could just allow regrowth to proceed in the Amazon without further clearing.

Brazil’s other great forest, the Atlantic forest, is already on that path, recovering slowly after more than a century of clearance for coffee and cattle. The government has an Atlantic Forest Restoration Pact that subsidizes landowners to replant, often with trees intended to supply the paper industry. Yet Camila Rezende of the Federal University of Rio de Janeiro says most of the forest regrowth is not from planting but from “spontaneous” regrowth, as forest remnants colonize neighboring abandoned farmland. She estimates that some 6.7 million acres of Atlantic Forest has naturally regenerated in this way since 1996. It now makes up about a tenth of the forest.

Much the same has been happening in Europe, where forest cover is now up to 43 percent, often from naturally recolonizing farmland rather than planting. Italy, for instance, has grown its forest cover by a 2.5 million acres. In the former Communist nations of central Europe, 16 percent of farmland in the Carpathian Mountains was abandoned in the 1990s, much of it reclaimed by the region’s famed beech forests. Across Russia, an area of former farmland about twice the size of Spain has been recolonized by forests. Irina Kurganova of the Russian Academy of Sciences calls this retreat of the plow “the most widespread and abrupt land-use change in the 20th century in the Northern Hemisphere.”

The United States has also seen natural forests regenerate as arable farmland has declined by almost a fifth in the past 30 years. “The entire eastern United States was deforested 200 years ago,” says Karen Holl of the University of California, Santa Cruz. “Much of that has come back without actively planting trees.” According to the U.S. Forest Service, over the past three decades the country’s regrowing forests have soaked up about 11 percent of national greenhouse gas emissions.


A worker plants Sitka spruce saplings at a reforestation project in Doddington, England in 2018. DAN KITWOOD/GETTY IMAGES

With nature on the march, a major concern is whether a push for planting might grab land for plantations that natural forests might otherwise recolonize. The result would be less wildlife, less amenity for humans, and often less carbon stored.

Ecologists have traditionally dismissed the ecological gains from natural restoration of what is often called “secondary” forest. Such regrowth is often regarded as ephemeral, rarely sought out by wildlife, and prone to being cleared again. This has led many to regard planting to mimic natural forests as preferable.

Thomas Crowther, co-author of a widely-publicized study last year calling for a “global restoration” of a trillion trees to soak up carbon dioxide, emphasizes that, while nature could do the job in places, “people need to help out by spreading seeds and planting saplings.”

But a reappraisal is going on. J. Leighton Reid, director of Restoration Ecology at Virginia Tech, who recently warned against bias in studies comparing natural regeneration with planting, nonetheless told e360, “Natural regeneration is an excellent restoration strategy for many landscapes, but actively reintroducing native plants will still be a better option in highly degraded sites and in places where invasive species dominate.”

Others make the case that most of the time, natural restoration of secondary forests is a better option than planting. In her book, Second Growth, Robin Chazdon, a forest ecologist formerly at the University of Connecticut, says that secondary forests “continue to be misunderstood, understudied, and unappreciated for what they really are — young self-organizing forest ecosystems that are undergoing construction.”

Yes, she agrees, they are work in progress. But they generally recover “remarkably fast.” Recent research shows that regrowing tropical forests recover 80 percent of their species richness within 20 years, and frequently 100 percent within 50 years. That seems to be better than what human foresters achieve when trying to replant forest ecosystems.

Tree planting can worsen outcomes for everything from the number of bird and insect species to canopy cover.
A review of more than 100 tropical forest restoration projects by Renato Crouzeilles of the International Institute for Sustainability in Rio de Janeiro, with Chazdon as a co-author, found that success rates were higher for secondary forests allowed to regenerate naturally than for those subjected to the “active restoration” techniques of foresters. In other words, planting can often worsen outcomes for everything from the number of bird, insect, and plant species, to measures of canopy cover, tree density, and forest structure. Nature knows best.

Now, Cook-Patton has extended the reappraisal to the carbon-accumulating potential of natural forest regeneration. It too may often be superior.

This scientific rethink requires a policy rethink, says Holl. “Business leaders and politicians have jumped on the tree-planting bandwagon, and numerous nonprofit organizations and governments worldwide have started initiatives to plant billions or even trillions of trees for a host of social, ecological, and aesthetic reasons”.

She concedes that on some damaged lands, “we will need to plant trees, but that should be the last option, since it is the most expensive and often is not successful.”


ALSO ON YALE E360

Why green pledges will not create the natural forests we need. Read more.

Planting a trillion trees over the next three decades would be a huge logistical challenge. A trillion is a big number. That target would require a thousand new trees in the ground every second, and then for all of them to survive and grow. Once the cost of nurseries, soil preparation, seeding, and thinning are accounted for, says Crouzeilles, it would cost hundreds of billions of dollars. If natural forest growth is cheaper and better, does that make sense?


--
BURN: Using Fire to Cool the Earth

Global Village Institute for Appropriate Technology
Summertown TN 38483-0090


ALAN PAGE
 

 Hi Albert et al,
I agree with much of what you have said and certainly about what is stated about the process of natural restocking of vacant or harvested land. I would like to add a couple of points:
1) As Albert said what is cultivated must be harvested by someone / something. Nature will do it if people do not and it is not pretty when nature does it (it may not be pretty when a normal logger does the harvesting either but the possibility of making charcoal and turning it into real biochar can go a long way toward cleaning up most situations. While Tom and Kelpie talk about the progress made in their area of the world, it certainly has not found any significant place in normal forestry on the east coast.
2) Our experience with planting has been that it does work with proper growing space preparation, but that it is not generally needed as seeding from natural sources is more than adequate to restock most situations, Long observation shows that the presence of large trees really makes a lot of difference in what kind of forest will replace the biome that is harvested. Some species make seeds nearly every year others are much less frequent, but when there is a good seed crop there will be hundreds of thousands+ of new seedlings started in the next few years after the seed release. This process happens regularly so there are frequently millions of seeds from a variety of species every few years and their viability may extend for decades in some cases. Read Gaviotas regarding the regrowing of a forest in a savanna.
We get best regeneration in places where there was significant wheeled traffic - we believe that this is due to the lack of water competition from the side because the traffic has cut the roots of trees on both sides of the path. There are many strange things that happen to add to the success of one species over another over time.
3) No one seems to worry about retaining the rural skill set as the tech revolution is pushed onto our children. I do and I find that there are many parts to the cultivation paradigm that needs to be expanded and each activity must be paid for to allow the participants to have a normal healthy family. It is not okay for foreign volunteers to come in for a few weeks and then go home thinking they have done all that was needed. This happened with the CCC planting of the new Quabbin Reservoir fields with 4'x4' planted red pine. Many of these areas are now dying after being left for generations with no thinning.
4) Our family has helped keep a biochar experiment going in Plainfield, MA that was shown at the 2013 Biochar Symposium at UMASS. The work there has shown that of all the several hundred trees recorded there are two that stand out: they are both small cherry trees that were less than 2" in diameter in 2013. One is now nearly 5 " and is growing 4-7' in height per year and the other is still about 1.5' in diameter and hardly growing in height at all. The trees are less than 75' apart. The slow growing tree is like most of the rest of the forest in that there is too much competition for light, water and space. for much diameter growth to occur. However it is obvious that unless we continue to open up additional area around the fast growing tree it too will slow down and possibly be overtopped by some taller neighbors that are growing in from the sides.  
 5) Finally, in our region we are finding that many trees form crotches as storms (wind, and heavy snow and Ice) as well as insects or disease may deform the central stem and allow side branches to turn up and take over the height growth. Once that happens generally the wood formed above the crotch is junk, and the whole tree may die after the crotches break off leaving a tree stem with no foliage. The early removal of crotches and the possibility of forming defect free wood with upper branch removal as the tree grows taller can greatly improve the amount of harvestable high quality wood per tree. We expect to be able to remove branches and crotches from the main stem to over 60 feet given the funding to follow individual tree development. 

Alan C. Page©, Ph.D., Research Forester
Green Diamond Systems©
125 Blue Meadow Road
Belchertown, MA 01007

Phone: 413-323-4401
Cell: 413-883-9642


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‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐

On Monday, September 28, 2020 5:59 PM, Albert Bates <peaksurfer@...> wrote:

Thanks for this Kim. It is a key debate at this turning point in human history.

I feel the article low-balls the forest contribution potential, although I find 1.67 billion acres of available land to be a robust number. 73 GtC over 30 years is pitiful and far below what is needed. I described some reasons why standard reforestation understates the potential in The Biochar Solution (2010). Other recent studies have assayed the potential for protecting already-establishing natural regrowth and posted similar sequestration numbers.

I will address this more directly in my video talk at the Sonoma Biochar Forum Oct 13, but to preview the key takeaways: one cannot look at reforestation or afforestation mechanically. The highest performance comes from diverse, mixed-aged, mixed-species forests. Juvenile trees sequester at greater rates than mature trees. Hence what is required is an integrated human ecology of forest peoples who continuously garden their forest, as was the way in many places before about AD 1800.

We know from terra preta and more recent discoveries that biochar is a value proposition for sustaining these sorts of economies. By rotational harvest systems (milpa), and traditional extractive forest crafts, it is possible to produce biochar as a co-product that multiplies the sequestration potential. The carbon cascades Kathleen Draper and I described in Burn (2019) are only the tip of the iceberg for the new carbon economy enterprise possibilities that could be realized well before 2050.

It is not enough for governments to plant large forests. He who plants must cultivate. He who cultivates must harvest. And then replant. All of this needs to carry its own internal incentives in order to scale and sustain.

Albert

On 9/28/20 4:32 PM, Kim Chaffee wrote:
Natural Debate:  Do forests grow better with or without our help?:  Yale Environment 360

All,

This article makes a strong case for letting nature do all the work of reforestation, except perhaps where the soil is very poor.  This just published study found that natural regeneration can capture more carbon more quickly and securely than tree plantations.  No mention of biochar, but adding it to poor soils would certainly speed up regrowth and accelerate carbon storage. 

Kim

Combining the mapping and carbon accumulation data, Cook-Patton estimates that natural forest regrowth could capture in biomass and soils 73 billion tons of carbon between now and 2050. That is equal to around seven years of current industrial emissions, making it “the single largest natural climate solution.”

Nations around the world are pledging to plant billions of trees to grow new forests. But a new study shows that the potential for natural forest regrowth to absorb carbon from the atmosphere and fight climate change is far greater than has previously been estimated.

Here is the abstract from Nature:


Nations around the world are pledging to plant billions of trees to grow new forests. But a new study shows that the potential for natural forest regrowth to absorb carbon from the atmosphere and fight climate change is far greater than has previously been estimated.

When Susan Cook-Patton was doing a post-doc in forest restoration at the Smithsonian Environmental Research Center in Maryland seven years ago, she says she helped plant 20,000 trees along Chesapeake Bay. It was a salutary lesson. “The ones that grew best were mostly ones we didn’t plant,” she remembers. “They just grew naturally on the ground we had set aside for planting. Lots popped up all around. It was a good reminder that nature knows what it is doing.”

What is true for Chesapeake Bay is probably true in many other places, says Cook-Patton, now at The Nature Conservancy. Sometimes, we just need to give nature room to grow back naturally. Her conclusion follows a new global study that finds the potential for natural forest regrowth to absorb atmospheric carbon and fight climate change has been seriously underestimated.

Tree planting is all the rage right now. This year’s World Economic Forum in Davos, Switzerland, called for the world to plant a trillion trees. In one of its few actions to address climate concerns, the U.S. administration — with support from businesses and nonprofits such as American Forests — last month promised to contribute close to a billion of them — 855 million, to be precise — across an estimated 2.8 million acres.

The European Union this year promised 3 billion more trees as part of a Green Deal; and existing worldwide pledges under the 2011 Bonn Challenge and the 2015 Paris Climate Accord set targets to restore more than 850 million acres of forests, mostly through planting. That is an area slightly larger than India, and provides room for roughly a quarter-trillion trees.

The study found that natural regeneration can capture more carbon more quickly and securely than tree plantations.

Planting is widely seen as a vital “nature-based solution” to climate change — a way of moderating climate change in the next three decades as the world works to achieve a zero-carbon economy. But there is pushback.

Nobody condemns trees. But some critics argue that an aggressive drive to achieve planting targets will provide environmental cover for land grabs to blanket hundreds of millions of acres with monoculture plantations of a handful of fast-growing and often non-native commercial species such as acacia, eucalyptus, and pine. Others ask: Why plant at all, when we can often simply leave the land for nearby forests to seed and recolonize? Nature knows what to grow, and does it best.

Cook-Patton’s new study, published in Nature and co-authored by researchers from 17 academic and environmental organizations, says estimates of the rate of carbon accumulation by natural forest regrowth, endorsed last year by the UN’s Intergovernmental Panel on Climate Change, are on average 32 percent too low, a figures that rises to 53 percent for tropical forests.

The study is the most detailed attempt yet to map where forests could grow back naturally, and to assess the potential of those forests to accumulate carbon. “We looked at almost 11,000 measurements of carbon uptake from regrowing forests, measured in around 250 studies around the world,” Cook-Patton told Yale Environment 360.

New vegetation grows amid burnt trees in the
                      Amazon in the state of Para, Brazil.

New vegetation grows amid burnt trees in the Amazon in the state of Para, Brazil. ANTONIO SCORZA/AFP VIA GETTY IMAGES

She found that current carbon accumulation rates vary by a factor of a hundred, depending on climate, soils, altitude, and terrain. This is much greater than previously assessed. “Even within countries there were huge differences.” But overall, besides being better for biodiversity, the study showed, natural regeneration can capture more carbon more quickly and more securely than plantations.

Cook-Patton agrees that as climate change gathers pace in the coming decades, rates of carbon accumulation will change. But while some forests will grow more slowly or even die, others will probably grow faster due to the fertilization effect of more carbon dioxide in the air, an existing phenomenon sometimes called global greening.

The study identified up to 1.67 billion acres that could be set aside to allow trees to regrow. This excludes land under cultivation or built on, along with existing valuable ecosystems such as grasslands and boreal regions, where the warming effects of dark forest canopy outweigh the cooling benefits of carbon take-up.

Combining the mapping and carbon accumulation data, Cook-Patton estimates that natural forest regrowth could capture in biomass and soils 73 billion tons of carbon between now and 2050. That is equal to around seven years of current industrial emissions, making it “the single largest natural climate solution.”

Cook-Patton said the study’s local estimates of carbon accumulation fill an important data gap. Many countries intent on growing forests to store carbon have data for what can be achieved by planting, but lack equivalent data for natural regeneration. “I kept getting emails from people asking me what carbon they would get from [natural] reforesting projects,” she says. “I had to keep saying: ‘It depends.’ Now we have data that allow people to estimate what happens if you put up a fence and let forest regrow.”

Aboveground carbon accumulation rates, in
                      metric tons of carbon per hectare per year, in
                      naturally regrowing forests in forest and savanna
                      biomes.

Aboveground carbon accumulation rates, in metric tons of carbon per hectare per year, in naturally regrowing forests in forest and savanna biomes. COOK-PATTON ET AL., NATURE 2020

The new local estimates also allow comparisons between the potential of natural regrowth and planting. “I think planting has its place, for instance where soils are degraded and trees won’t grow,” she said. “But I do think natural regrowth is hugely under-appreciated.”



The great thing about natural restoration of forests is that it often requires nothing more than human inaction. Nature is constantly at work restoring forests piecemeal and often unseen on the edges of fields, on abandoned pastures, in scrubby bush, and wherever forests lie degraded or former forest land is abandoned.

But because it requires no policy initiatives, investments, or oversight, data on its extent is badly lacking. Satellites such as Landsat are good at identifying deforestation, which is sudden and visible; but the extent of subsequent recovery is slower, harder to spot, and rarely assessed. Headline grabbing statistics on the loss of the world’s forests generally ignore it.

In a rare study, Philip Curtis of the University of Arkansas recently attempted to get around the problem by devising a model that could predict from satellite imagery what had caused the deforestation, and hence the potential for forest recovery. He found that only about a quarter of lost forests are permanently taken over for human activities such as buildings, infrastructure, or farming. The remaining three-quarters suffered from forest fires, shifting cultivation, temporary grazing, or logging, and at least had the potential for natural recovery.

Another study published this year found that such recovery was widespread and rapid even in an epicenter of deforestation such as the Amazon. When Yunxia Wang of the University of Leeds in England analyzed recently-released Brazilian data from the Amazon, she found that 72 percent of the forest being burned by ranchers to create new cattle pasture is not pristine forest, as widely assumed, but is actually recent regrowth. The forest had been cleared, converted to cattle pasture and then abandoned, whereupon the forest returned so fast that it was typically only six years before it was cleared again. Such was the confusion caused by this rapid forest turnover that regular land-use assessments frequently wrongly categorized this new growth as degraded old-growth forest.

“Actively reintroducing native plants will still be a better option in highly degraded sites,” says one scientist.

Wang noted that if Brazil’s President, Jair Bolsonaro, wanted to fulfill a promise made by his predecessor Dilma Rousseff at the 2015 Paris climate summit to restore 30 million acres of forest by 2030, then he need not plant at all. He could just allow regrowth to proceed in the Amazon without further clearing.

Brazil’s other great forest, the Atlantic forest, is already on that path, recovering slowly after more than a century of clearance for coffee and cattle. The government has an Atlantic Forest Restoration Pact that subsidizes landowners to replant, often with trees intended to supply the paper industry. Yet Camila Rezende of the Federal University of Rio de Janeiro says most of the forest regrowth is not from planting but from “spontaneous” regrowth, as forest remnants colonize neighboring abandoned farmland. She estimates that some 6.7 million acres of Atlantic Forest has naturally regenerated in this way since 1996. It now makes up about a tenth of the forest.

Much the same has been happening in Europe, where forest cover is now up to 43 percent, often from naturally recolonizing farmland rather than planting. Italy, for instance, has grown its forest cover by a 2.5 million acres. In the former Communist nations of central Europe, 16 percent of farmland in the Carpathian Mountains was abandoned in the 1990s, much of it reclaimed by the region’s famed beech forests. Across Russia, an area of former farmland about twice the size of Spain has been recolonized by forests. Irina Kurganova of the Russian Academy of Sciences calls this retreat of the plow “the most widespread and abrupt land-use change in the 20th century in the Northern Hemisphere.”

The United States has also seen natural forests regenerate as arable farmland has declined by almost a fifth in the past 30 years. “The entire eastern United States was deforested 200 years ago,” says Karen Holl of the University of California, Santa Cruz. “Much of that has come back without actively planting trees.” According to the U.S. Forest Service, over the past three decades the country’s regrowing forests have soaked up about 11 percent of national greenhouse gas emissions.

A worker plants Sitka spruce saplings at a
                      reforestation project in Doddington, England in
                      2018.

A worker plants Sitka spruce saplings at a reforestation project in Doddington, England in 2018. DAN KITWOOD/GETTY IMAGES

With nature on the march, a major concern is whether a push for planting might grab land for plantations that natural forests might otherwise recolonize. The result would be less wildlife, less amenity for humans, and often less carbon stored.



Ecologists have traditionally dismissed the ecological gains from natural restoration of what is often called “secondary” forest. Such regrowth is often regarded as ephemeral, rarely sought out by wildlife, and prone to being cleared again. This has led many to regard planting to mimic natural forests as preferable.

Thomas Crowther, co-author of a widely-publicized study last year calling for a “global restoration” of a trillion trees to soak up carbon dioxide, emphasizes that, while nature could do the job in places, “people need to help out by spreading seeds and planting saplings.”

But a reappraisal is going on. J. Leighton Reid, director of Restoration Ecology at Virginia Tech, who recently warned against bias in studies comparing natural regeneration with planting, nonetheless told e360, “Natural regeneration is an excellent restoration strategy for many landscapes, but actively reintroducing native plants will still be a better option in highly degraded sites and in places where invasive species dominate.”

Others make the case that most of the time, natural restoration of secondary forests is a better option than planting. In her book, Second Growth, Robin Chazdon, a forest ecologist formerly at the University of Connecticut, says that secondary forests “continue to be misunderstood, understudied, and unappreciated for what they really are — young self-organizing forest ecosystems that are undergoing construction.”

Yes, she agrees, they are work in progress. But they generally recover “remarkably fast.” Recent research shows that regrowing tropical forests recover 80 percent of their species richness within 20 years, and frequently 100 percent within 50 years. That seems to be better than what human foresters achieve when trying to replant forest ecosystems.

Tree planting can worsen outcomes for everything from the number of bird and insect species to canopy cover.

review of more than 100 tropical forest restoration projects by Renato Crouzeilles of the International Institute for Sustainability in Rio de Janeiro, with Chazdon as a co-author, found that success rates were higher for secondary forests allowed to regenerate naturally than for those subjected to the “active restoration” techniques of foresters. In other words, planting can often worsen outcomes for everything from the number of bird, insect, and plant species, to measures of canopy cover, tree density, and forest structure. Nature knows best.

Now, Cook-Patton has extended the reappraisal to the carbon-accumulating potential of natural forest regeneration. It too may often be superior.

This scientific rethink requires a policy rethink, says Holl. “Business leaders and politicians have jumped on the tree-planting bandwagon, and numerous nonprofit organizations and governments worldwide have started initiatives to plant billions or even trillions of trees for a host of social, ecological, and aesthetic reasons”.

She concedes that on some damaged lands, “we will need to plant trees, but that should be the last option, since it is the most expensive and often is not successful.”

Planting a trillion trees over the next three decades would be a huge logistical challenge. A trillion is a big number. That target would require a thousand new trees in the ground every second, and then for all of them to survive and grow. Once the cost of nurseries, soil preparation, seeding, and thinning are accounted for, says Crouzeilles, it would cost hundreds of billions of dollars. If natural forest growth is cheaper and better, does that make sense?




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BURN: Using Fire to Cool the Earth

Global Village Institute for Appropriate Technology
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