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The Conservationists Who Taught Us to Plant Forests

by One Tree Planted ● March 13, 2025 ● 6 min read

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The Green Belt Movement, founded by Wangari Maathai in Kenya in 1977, has grown more than 51 million trees.
Farmer-managed natural regeneration, the method Tony Rinaudo developed in Niger, has restored 5 million hectares and more than 200 million trees.
Theodore Roosevelt protected about 230 million acres of public land as president, including 150 national forests.
The first Earth Day in 1970 drew 20 million Americans, 10 percent of the U.S. population, and the day now mobilizes more than 1 billion people each year.

Conservationists protect and restore forests, wildlife, and the land and water they depend on — and some of the most influential have done it by planting trees.

The Green Belt Movement, which Wangari Maathai founded in Kenya in 1977, has grown more than 51 million trees, and the regeneration method Tony Rinaudo developed in Niger has restored 5 million hectares of land and more than 200 million trees.

Others worked through science, broadcasting, and law. Rachel Carson's Silent Spring helped lead to the U.S. cancellation of DDT in 1972, and Gaylord Nelson's idea for a national teach-in became the first Earth Day in 1970, when 20 million Americans, 10 percent of the U.S. population at the time, took part. Earth Day now mobilizes more than 1 billion people each year.

The conservationists below include forest restorers, scientists, broadcasters, activists, and lawmakers from six continents, and their work spans more than 150 years, from John Muir's thousand-mile walk in 1867 to Greta Thunberg's first school strike in 2018.

Environmental Heroes Who Restored Forests

These conservationists planted, protected, or regenerated forests in Kenya, Brazil, Niger, India, Uganda, and beyond.

1. Wangari Maathai (1940–2011)

The Green Belt Movement that Wangari Maathai founded in Kenya in 1977 grew from her 1976 idea of planting trees with rural communities. By then she had already become the first woman in East and Central Africa to earn a doctorate, and in 2004 she became the first African woman to receive the Nobel Peace Prize. "In the course of history, there comes a time when humanity is called to shift to a new level of consciousness, to reach a higher moral ground," she said in her Nobel lecture. "A time when we have to shed our fear and give hope to each other. That time is now."

2. Chico Mendes (1944–1988)

"At first I thought I was fighting to save rubber trees, then I thought I was fighting to save the Amazon rainforest. Now I realise I am fighting for humanity," Mendes famously said.

Mendes tapped rubber trees alongside his father as a boy in Brazil's Acre state and later led the Xapuri Rural Workers Union, organizing rubber tappers to keep the forest standing. In 1990, Brazil created the Chico Mendes Extractive Reserve near his hometown, and the country's national biodiversity agency now bears his name.

3. Tony Rinaudo

When Australian agronomist Tony Rinaudo arrived in Niger in 1981, the cleared fields around him still held living tree stumps and root systems, which he came to call an "underground forest."

Farmer-managed natural regeneration, the method he developed to let those stumps grow back into trees, has since restored 5 million hectares and more than 200 million trees across Niger. "Trees reduce temperatures, wind speeds and evaporation," Rinaudo told Mongabay. "Thus, restoring tree cover helps communities to adapt to climate change." The work earned him a 2018 Right Livelihood Award and the nickname "forest maker."

4. Jadav Payeng

"When I saw it, I thought even we humans will have to die this way in the heat," Jadav "Molai" Payeng told NPR, recalling the snakes he found dead on a barren sandbar in the Brahmaputra River. "It struck me. In the grief of those dead snakes, I created this forest."

He was 16 when he started planting there in 1979. The forest now covers about 550 hectares and shelters elephants, tigers, rhinos, and deer, and in 2015 India awarded him the Padma Shri.

5. Richard St. Barbe Baker (1889–1982)

Working as a British forestry officer in Kenya in 1922, Richard St. Barbe Baker joined with Chief Josiah Njonjo to found Watu wa Miti, or the Men of the Trees, which continues today as the International Tree Foundation. "Today it is the duty of every thinking being to live and to serve not only his own day and generation, but also generations unborn, by helping restore and maintain the green glory of the forests of the earth," he said.

6. Jane Goodall (1934–2025)

Months after arriving at Gombe, in what is now Tanzania, in 1960, Jane Goodall watched a chimpanzee strip the leaves from a twig and use it to fish termites from their mound, upending the belief that only humans made tools. "Now we must redefine tool, redefine Man, or accept chimpanzees as humans," her mentor, Louis Leakey, famously said in response.

Since 2020, we have worked with the Jane Goodall Institute, which she founded in 1977, to restore 3 million trees in Uganda.

Conservationists Who Changed How the World Sees Nature

These conservationists reached the public through books, television, and protest, and their work changed pesticide rules, environmental law, and how audiences see wildlife.

1. Rachel Carson (1907–1964)

"Can anyone believe it is possible to lay down such a barrage of poison on the surface of the earth without making it unfit for all life?" Carson asked in Silent Spring, her 1962 book that documented the damage caused by synthetic pesticides such as DDT. "They should not be called 'insecticides' but 'biocides.'"

She wrote it after years as editor-in-chief of all U.S. Fish and Wildlife Service publications, and the public concern it stirred helped lead to the Environmental Protection Agency's 1972 cancellation of DDT.

2. Sir David Attenborough

More than seven decades separate Zoo Quest, the BBC series that launched Sir David Attenborough's career in 1954, from Ocean With David Attenborough, the film he released on his 99th birthday in 2025. In between came Life on Earth, watched by upwards of 500 million people, along with The Blue Planet and Our Planet. "Wherever we have given nature the space to recover, it's done so, and, as a result of its recovery, our own lives are improved," he told National Geographic.

3. David Suzuki

For 44 years, Canadian television audiences learned about science and nature from geneticist David Suzuki, who hosted CBC's The Nature of Things from 1979 to 2023. "In the end, that's all that matters is that you try — it's what I think defines our species, that people in the face of challenges, they try to make it better," he told CBC Radio earlier this year. The foundation he cofounded in 1990 led the Blue Dot movement for a right to a healthy environment, which Canada recognized in federal law in 2023.

4. Steve Irwin (1962–2006)

The footage Steve and Terri Irwin shot relocating crocodiles on their 1992 honeymoon became The Crocodile Hunter, and the Queensland reptile park his parents opened became Australia Zoo. "The term 'wildlife warriors' actually originated from my dad," Bindi Irwin told Science Friday. "My dad first created that term. And it has just become our family's motto." The couple founded Wildlife Warriors in 2002, and the family now manages the 330,000-acre Steve Irwin Wildlife Reserve on Cape York.

5. Greta Thunberg

"We are in the beginning of a mass extinction and all you can talk about is money and fairytales of eternal economic growth," Greta Thunberg told world leaders at the U.N. in 2019. "How dare you!"

A year earlier, at age 15, she had begun striking from school outside the Swedish parliament, and her Fridays for Future strikes spread to students worldwide. She received the Right Livelihood Award and became Time's youngest Person of the Year in 2019. She has since broadened her activism beyond climate, including joining Gaza-bound aid flotillas in 2025.

The Leaders Behind Earth Day and America's Public Lands

These Americans shaped the country's public lands and environmental law, from Yosemite and the national forests to the first designated wilderness and Earth Day.

1. Gaylord Nelson (1916–2005)

The January 1969 oil spill off Santa Barbara, California, gave Gaylord Nelson, then a U.S. senator from Wisconsin, the idea for a national teach-in on the environment, and it became the first Earth Day on April 22, 1970. Over 18 years in the Senate, he also authored legislation to preserve the Appalachian Trail and backed the Wilderness Act. "The economy is a wholly owned subsidiary of the environment," Nelson said, as the Nelson Institute's dean recalled to Milwaukee Magazine.

2. John Muir (1838–1914)

"Climb the mountains and get their good tidings," John Muir famously wrote. "Nature's peace will flow into you as sunshine into trees." His 1890 articles in Century magazine helped persuade Congress to create Yosemite National Park, and two years later he cofounded the Sierra Club.

In 2020, the Sierra Club acknowledged that Muir made derogatory comments about Black and Indigenous people, views it notes evolved later in his life. As the club's first president, Muir hosted Theodore Roosevelt in Yosemite in 1903 and led the campaign to keep the Hetch Hetchy Valley from being dammed.

3. Theodore Roosevelt (1858–1919)

"Leave it as it is," Theodore Roosevelt said at the Grand Canyon in 1903. "You cannot improve on it. The ages have been at work on it, and man can only mar it." Five years later, he used the Antiquities Act to make the canyon a national monument. His presidency protected about 230 million acres of public land, including 150 national forests and five national parks, and created the U.S. Forest Service.

4. Aldo Leopold (1887–1948)

As a young Forest Service officer in the Southwest, Aldo Leopold pushed to protect New Mexico's Gila, which became the world's first designated wilderness in 1924. Later, on a worn-out farm along the Wisconsin River, his family planted tens of thousands of trees, and he wrote about the farm in A Sand County Almanac, which has sold more than 2 million copies. "There are some who can live without wild things and some who cannot," he wrote.

The Conservationists Who Taught Us to Plant Forests

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