Agroforestry stores less carbon than reforestation, but has many other benefits, study finds

Shade grown coffee. Image courtesy of World Agroforestry/CIFOR-ICRAF.

A recent study in Ecological Solutions and Evidence shows just how complicated and challenging it is to achieve carbon sequestration goals through forest management — but not impossible.

The research evaluates 10 years of a 14-year-long carbon project in Panama run by an Indigenous Emberá community, which collectively owns the land and tried different methods to store carbon by managing its tropical forest, including planting mixed species of native trees, planting single tree monocultures, and agroforestry, which involves growing food or other crops in combination with useful perennial shrubs and trees.

“For us as land stewards, it is important to reforest trees for the well-being of our community and to have carbon credits that we can trade and earn an income, for the well-being of our family,” said Ariosto Guainora, one of the local reforestation project coordinators.

The carbon project started in 2008 when the Smithsonian Tropical Research Institute (STRI) initiated the research with the Emberá community. Over the next three years, they’d contract the community for storage of 3,400 metric tons of carbon, assuming that 80% of trees would survive. But the new study found that, in all, the project has only sequestered about half of the carbon anticipated: the surviving plots are underperforming by 23%, while the overall target has been missed by 46% to date. While this result sounds low, it’s still better than the average for carbon offset project.

Emberá community member Lidia Barrigón discusses the project with McGill University students. Image courtesy of Smithsonian Tropical Research Institute (STRI).

“I would call that a glass half-full moment, with a lot of lessons learned,” said STRI director Joshua Tewksbury. “What this proves is that there are trade-offs in how we value different landscape uses. It probably tells us more about how we might approach large-scale reforestation projects.”

Valentina Robiglio, an expert in forestry with the Center for International Forestry Research and World Agroforestry, who wasn’t affiliated with the study and the project, said the outcomes weren’t surprising, adding the project didn’t adequately estimate the carbon storage, “considering all the different elements.” This is a common problem is the nascent carbon storage market.

Overall, the research found that timber planting, either of mixed or single species, held the best potential for carbon storage, but even that was undercut by fire, a problem worsening in an age of climate change.

“The primary reason the carbon goals fell short was the impact of fire,” said Katia Forgues, who acted as lead author of the paper while earning her master’s degree in biology at McGill University in Canada before becoming co-director of the NGO Sustainable Youth Canada.

Tewksbury said the project was specifically designed as a pilot project where the people could be “allowed to fail” on carbon goals.

“No one put them in a contract saying you can’t fail [otherwise you’re] not going to get paid, right?” he said. “Deliberately, that was not the way this was approached, because we wanted to understand the decisions people made, and the risk profiles that are associated with doing work to protect the planet as you try and have a livelihood on the landscape.”

Burning carbon

Of 20 participants, three converted their land to other uses, while fire impacted two out of every three of the remaining plots, with two losing their plots to flames entirely.

“Fire is deeply connected to the Emberá people’s traditional slash-and-burn agricultural practices, but on many occasions, it spread out of bounds and affected nearby reforestation plots,” Forgues said. “This significantly hindered tree survival and growth, reducing their ability to store carbon. Two-thirds of the plots experienced varying levels of fire damage over the 14 years of the study.”

The community did employ fire breaks, but often the fire would jump over them. In one case, a fire leaped the Pan-American Highway from a neighboring community.

“We do not have firefighter personnel to help us,” Guainora said. “We have to find a way to control the fires ourselves, so that they do not affect our crops or other people’s crops.”

STRI provided funding for fire protection, which paid for fire break construction as well as weed clearance and irrigation during the dry season. But initially this only covered the first seven years of the project. The community has since renegotiated contracts for more fire prevention funding.

“Fire risks extend beyond project boundaries, making broader coordination necessary,” Forgues said. “To effectively address fire threats, collaboration with neighbors, local authorities and nearby communities is essential. Community-led initiatives could work with local authorities to establish systems for liability, and retribution, and improve communication between neighbors to reduce landscape-level risks.”

Other ways to better manage fire, according to Robiglio, is to plant fire-adapted species and build barriers with species “that can maintain humidity.” She said a “mosaic” system can help mitigate fires.

Emberá community member Omaira Casama (right) discusses the project with the McGill University team. Image courtesy of Smithsonian Tropical Research Institute (STRI).

Timber stores more than agroforestry

In the first 10 years, timber plantings stored three times more carbon than agroforestry plots, but part of this was due to different expectations of agroforestry practices at the outset of the project. The initial estimates of carbon sequestration assumed the community would practice agroforestry similar to traditional Emberá agroforests, Forgues said, which depend on large fruit trees.

“In practice however, participants opted for coffee agroforestry, which consists of a high percentage of understory coffee plants (43%) shaded by taller fruit and timber trees, prioritizing the income-generating potential of coffee,” Forgues said. This preponderance of smaller coffee bushes over larger fruit trees “resulted in 40% less carbon storage compared to traditional systems.”

The discrepancy “highlights the importance of thoroughly understanding participants’ motivations,” Forgues added. While she noted that the carbon storage compared pretty well to other coffee agroforestry systems overall, shrubs planted for economic use — including coffee, cacao and achiote, a popular spice — accounted for only 1% of the total carbon sequestration in the community.

Forgues said participants unsurprisingly preferred agroforestry because it provided additional income. Participants also told the researchers that agroforestry allowed them to view the standing trees as permanent, rather than assuming they’d be cut one day, such as those in mixed native or monoculture planting. Robiglio said agroforestry also has the potential to conserve biodiversity and restore soil, if done well.

“Carbon capture was mostly of interest to the carbon buyer. The community’s motivations were much more environmental, cultural and economic,” Forgues said. “Broadly, the community was driven by the desire to increase forest cover and was particularly interested in reintroducing culturally important native species.”

From the community’s perspective, Guainora said agroforestry was also important because it improved soil quality and added to local food supply. In addition to coffee, he said locals also grow corn, rice and bananas.

Achiote grown in an agroforestry system. Image by Ocean Malandra for Mongabay.

Moving forward

New research in Nature Communications shows that only 16% of carbon credit products studied actually achieved any real emissions reductions, highlighting not just the cowboy mentality and corruption in some of these projects, but also the complexity of trying to store carbon in natural ecosystems on a planet housing 8 billion-plus people as it rapidly warms.

“How do you do [large-scale reforestation] in an equitable way?” Tewksbury said. “What does ‘nature positive’ actually, really mean? How much do you consider the equities of the people on the land versus the carbon you put in the ground?”

The Emberá project in Panama did manage to store additional carbon, just not as much as first calculated, and none of it would have happened without the payments from STRI.

“The reforestation project provided participants with a new source of revenue where they could be paid to grow the forest, as opposed to cutting it or renting it out. People were very proud of their reforestation plots and saw them as a legacy for their children,” Forgues said.

Such sentiments show how different expectations can change the ways these programs succeed, and how that success is measured. If looking at just carbon, the program to date has succeeded in only producing around half of the benefits expected. And though this is far better than many other carbon programs, it has also clearly succeeded in other ways, because, as Forgues pointed out, the results show “two possible designs for agroforestry.”

One design is “focused on traditional, diverse plots rich in fruit species that provide food security and higher carbon storage, and another favored by participants that emphasizes the production of coffee as an income-generating crop,” she said. Neither is superior, but both end in different deliverables.

“There isn’t necessarily a better design, but rather a need to deeply understand and align with the diverse motivations of stakeholders — whether they’re prioritizing carbon offsets, biodiversity, livelihoods, or other goals,” Forgues said. “This helps optimize outcomes based on what is most important to those involved.”

The STRI project will run until 2035, but the community has also started a second reforestation project through McGill University. Tewksbury said his organization is interested in further investment, but this will depend on STRI researchers’ prerogatives.

“The future of this project is to maintain the conservation of forests, to have fewer fires, to plant more trees, and at the same time to help us economically,” Guainora said.

As the world looks for ways to better plan and manage carbon projects, this study provides some valuable lessons.

“The lessons learned are much more important than the tons of carbon put in the ground,” Tewksbury said, “particularly because we weren’t establishing those goals against some net-neutral promise.”

Lessons for large-scale reforestation

Although a small research project, the findings can perhaps be applied to large-scale reforestation efforts, which have come under increasing criticism.

Tewksbury said it’s vital for investors to recognize they often lack local knowledge. He noted that most of the groups with enough funding for large-scale reforestation aren’t from the tropics, but are rather in the Western world.

Shade grown cacao. Image by Erik Hoffner for Mongabay.

“There’s a natural tension here, that those that know how to do it best don’t have access to capital, and those that have access to capital don’t know the local context. And that’s not a new problem,” he said, adding that investors may “come in with the best intentions,” but their success depends on “their ability to work closely with local communities.”

Reforestation projects, like many investments, also come with risk, especially from fire. And unlike some investments, they require long time scales to achieve success.

“Payments for these projects should reflect this long-term commitment to ensure success,” Forgues said. “Even as trees grow and become more resilient, threats like fire remain a significant concern and need continuous management to avoid undermining the project’s goals.”

One way to work better with local people, according to Tewksbury, is to set up reforestation projects that allow selective harvesting within an agreed-upon time frame.

“Carbon farming becomes profitable for a lot of landowners in Panama if you’re allowed to selectively harvest in 20 years,” he said. “I think that’s probably the future,” although he acknowledged this makes investors “jittery.”

Tewksbury also said that a time will come when verification of carbon storage in reforestation projects has matured. In other words, if you pay for a ton of carbon, you’re assured sequestration of a ton of carbon.

“We have to get there,” he said. “There’s just no other global marketplace where you don’t have to verify what you’re buying and selling.

---

This article was originally published on Mongabay under the Creative Commons BY NC ND licence. Read the original article.