The surprising downsides to planting trillions of trees

On November 11, 2019, volunteers planted 11 million trees in Turkey as part of a government-backed initiative called Breath for the Future. In one northern city, the tree-planting campaign set the Guinness World Record for the most saplings planted in one hour in a single location: 303,150.

“By planting millions of young trees, the nation is working to foster a new, lush green Turkey,” Turkey’s president, Recep Tayyip Erdoğan, said when he kicked off the project in Ankara.

Less than three months later, up to 90 percent of the saplings were dead, the Guardian reported. The trees were planted at the wrong time and there wasn’t enough rainfall to support the saplings, the head of the country’s agriculture and forestry trade union told the paper.

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In the past two decades, mass tree-planting campaigns like this one have gained popularity as a salve for many of our modern woes, from climate change to the extinction crisis. Companies and billionaires love these kinds of initiatives. So do politicians. Really, what’s not to like about trees? They suck up carbon emissions naturally while providing resources for wildlife and humans — and they’re even nice to look at. It sounds like a win-win-win.

There’s just one problem: These campaigns often don’t work, and sometimes they can even fuel deforestation.

In one recent study in the journal Nature, for example, researchers examined long-term restoration efforts in northern India, a country that has invested huge amounts of money into planting over the last 50 years. The authors found “no evidence” that planting offered substantial climate benefits or supported the livelihoods of local communities.

The study is among the most comprehensive analyses of restoration projects to date, but it’s just one example in a litany of failed campaigns that call into question the value of big tree-planting initiatives. Often, the allure of bold targets obscures the challenges involved in seeing them through, and the underlying forces that destroy ecosystems in the first place.

Instead of focusing on planting huge numbers of trees, experts told Vox, we should focus on growing trees for the long haul, protecting and restoring ecosystems beyond just forests, and empowering the local communities that are best positioned to care for them.

Asim Hafeez/Bloomberg via Getty Images

The push to plant a trillion trees

In the past three decades, the number of tree-planting organizations has skyrocketed, growing nearly threefold in the tropics alone. So have global drives: Today, there are no fewer than three campaigns focused on planting 1 trillion trees, including the World Economic Forum’s (WEF) One Trillion Trees Initiative, which launched in 2020.

It is hard to identify the exact moment when we became obsessed with planting trees. Some scientists point to the 2011 Bonn Challenge, which set an initial goal of restoring 150 million hectares of degraded and deforested land globally by 2020 and 350 million hectares by 2030. Others highlight a highly controversial study that appeared in Science in 2019 and inspired the WEF’s trillion tree campaign.

The authors of the Science paper originally argued that restoring trees is “our most effective climate change solution to date” and said there’s “room” for 900 million hectares (2.2 billion acres) of new trees across the world. Almost 600 media outlets (including Vox) ran stories about the study in 2019, according to Carbon Brief.

While many scientists criticized the paper, the idea behind it — that we can plant our way out of climate change, while simultaneously solving other problems like biodiversity loss — has stuck around. It’s a charming notion that’s much easier for companies or countries to act on, compared with doing the hard work of slashing greenhouse emissions.

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Many tree-planting projects fail

Tree-planting campaigns are typically well-intentioned, but they often fall short of delivering the benefits they promise, from capturing carbon to providing refuge for rare species. “Large-scale tree planting programs have high failure rates,” the authors of one paper, led by environmental researcher Forrest Fleischman, wrote in 2020.

One of the most stunning examples of these failures comes from Fleischman’s research in northern India. If there’s a place where tree-planting projects might work, it’s in the state of Himachal Pradesh, said Fleischman, an associate professor at the University of Minnesota who led the recent Nature study. The state government has a strong track record of delivering services to the public, he said, and has been planting trees since at least 1980.

Courtesy of Forrest Fleischman

An analysis of satellite imagery and interviews with hundreds of households, however, revealed that decades of planting by the government — amounting to hundreds of millions of seedlings — “had almost no impact on forest canopy cover,” Fleischman wrote on Twitter. The researchers also measured a shift in the type of trees within the ecosystem, away from species that locals prefer for firewood and animal fodder. In other words, residents of Himachal Pradesh actually had fewer useful forest resources.

What went wrong? Some of the trees may have died quickly because they were planted in poor-quality habitat, Fleischman suspects. Farm animals could have also destroyed the saplings if they were planted in former grazing lands, he said. “Well-resourced forest restoration programs can fail to achieve their goals,” he added. “We need to be more skeptical of big claims.”

In other parts of the world, tree-planting projects didn’t just fail, but also harmed existing ecosystems or ways of life.

In Mexico, a $3.4 billion tree-planting campaign launched by the government in 2018 actually caused deforestation, as Bloomberg News’ Max de Haldevang reported earlier this year. The program known as Sembrando Vida, or Sowing Life, pays farmers to plant trees on their land, but in some cases, they would clear a chunk of forest before putting seedlings in the ground. One analysis by the World Resources Institute, an environmental group, suggests that it caused almost 73,000 hectares of forest loss in 2019.

In Pakistan, researchers have linked a large, government-backed planting campaign that began in 2014 — known then as the Billion Tree Tsunami — to the erosion of culture and livelihoods of a nomadic group called the Gujjars. Traditionally, Gujjars rent winter pastures from landowners in parts of Pakistan to graze their animals. But through the tree-planting campaign, many of those landowners have replaced grazing land with tree plantations. “Many of the Gujjars have lost access to the private land on which they used to graze their animals in the winter,” Usman Ashraf, a researcher at the University of Helsinki, wrote in a 2018 paper.

Researchers have also blamed large tree-planting efforts in China and Brazil for degrading grassland ecosystems. As I’ve previously reported, grasslands store vast amounts of carbon — most of which is below ground — and provide homes for countless species. Yet these ecosystems are sometimes considered degraded and are targeted for forest restoration campaigns.

“We need to be looking at all of our ecosystems and not just put trees everywhere,” said Karen Holl, a professor of environmental studies and restoration expert at the University of California Santa Cruz.

How to restore forests for the long haul

Solving a problem as vast as climate change or biodiversity loss is never as straightforward as planting lots of trees. People often think, “We’ll just plant trees and call that a restoration project, and we’ll exonerate our carbon sins,” said Robin Chazdon, a forest researcher at the University of the Sunshine Coast. Usually, she said, “that fails.”

Buzzy tree-planting programs tend to obscure the fact that restoration requires a long-term commitment of resources and many years of monitoring. “We should just stop thinking about only tree-planting,” as climate scientist Lalisa Duguma has said. “It has to be tree-growing.” Even fast-growing trees take at least three years to mature, he added, while others can require eight years or more. “If our thinking of growing trees is downgraded to planting trees, we miss that big part of the investment that is required,” Duguma said.

Xinhua/Yang Guanyu via Getty Images

Holl, who has been involved in reviewing projects under the World Economic Forum’s trillion trees program, said she was “shocked” that many proposals called for two years or less of monitoring. “That’s not how long it takes for us to get the carbon or the biodiversity benefits that we want,” she said. (Companies with planting projects under the WEF program must report on progress each year for the duration of their projects, which the companies determine, a WEF spokesperson told Vox. Those reports typically include information on the projects’ social and ecological benefits, the spokesperson said.)

A bigger problem still is that many large planting campaigns don’t account for the underlying social or economic conditions that fuel deforestation in the first place. People may cut down trees to collect firewood or carve out land for their animals. In those cases, putting seedlings in the ground won’t do much to end deforestation. “Planting trees might not be the intervention,” Fleischman said. “The intervention might be giving people a substitute for firewood.”

This problem played out in Brazil after the 2019 fires in the Amazon rainforest. The group of powerful countries known as the G7 responded by offering to pay for restoration — but this offer didn’t address “the core issues of enforcing laws, protecting lands of indigenous people, and providing incentives to landowners to maintain forest cover,” Holl and her co-author wrote in a perspective in Science. The following year, Amazon fires and deforestation both surged. “The simplistic assumption that tree planting can immediately compensate for clearing intact forest is not uncommon,” they wrote.

Ultimately, the only true global solution to restoring ecosystems is to support Indigenous and rural communities, Fleischman said. “Let's look at places and think about how we can improve people's lives,” he said. “The people who need nature are going to vote for nature.”

When planting trees works

To be clear, there are plenty of successful restoration programs — and they’re getting better, said Chazdon, who’s also an adviser for the WEF trillion trees campaign. “There is ample evidence that when restoration is done properly, it works,” she said.

Courtesy of Laurie Hedges/Instituto de Pesquisas Ecológicas

Courtesy of Gabriela Cabral Rezende

Consider the Pontal do Paranapanema, a region in southern Brazil home to vulnerable species like the rare black lion tamarin monkey. Over the last 35 years, a nonprofit called Instituto de Pesquisas Ecológicas has worked with local communities to plant some 2.7 million native trees, as Mongabay’s Liz Kimbrough reports. The trees provide useful products that locals want, such as fruit to eat and wood for building, and a new revenue stream from selling seedlings. At the same time, the new trees create a network of forest corridors that has helped populations of the tamarin recover. In this case, it really does seem to be a win-win-win.

At the center of successful tree-planting campaigns like this are people, said Chazdon, who is compiling examples of effective restoration projects for a new mapping platform called Restor. As it happens, the platform is led by Thomas Crowther, an author of the controversial 2019 study in Science, which helped fuel the forest restoration frenzy.

Even Crowther acknowledges that headlines stemming from the paper — namely, that we should plant a trillion trees — were too simplistic and even misleading. “We messed up the communications so badly,” Crowther told the Guardian earlier this month. “I hate that people keep asking me: where are you going to plant these trillion trees? I’ve never in my life said we should plant a trillion trees.” Crowther and his co-authors even revised the abstract of the Science paper to clarify their claim that tree restoration is “one of” the most effective solutions to fight climate change — not the most important one.

Forests are, of course, good for the planet. And they do absorb loads of greenhouse gases, making them an important bulwark against rising temperatures. But headline-grabbing campaigns focused solely on planting trees can harm both people and ecosystems by focusing more on the goal itself than on the purpose behind it — and distracting us from the hard work of reducing emissions. The tough reality, as Holl puts it, is that “we’re not going to plant our way out of climate change.”

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