A new project seeks to kickstart a revival for the world’s largest rainforest by planting new trees — tens of millions of them. 
 
 The project, announced Friday at the “Rock in Rio” music fest in Brazil, aims to restore 73 million trees in the Brazilian Amazon by 2023. Spanning 30,000 hectares of land (about 74,000 acres), the project is the largest tropical forest restoration in the world and helps Brazil move towards its Paris Agreement target of reforesting 12 million hectares of land by 2030. 
 
 “This is a breathtakingly audacious project,” said M. Sanjayan, CEO of Conservation International (CI), one of the partners behind the effort. “The fate of the Amazon depends on getting this right — as do the region’s 25 million residents, its countless species and the climate of our planet.” 
 
 The Amazon forest is home to the richest biodiversity of any ecosystem on the planet — a recent report described some 400 new species discovered in the Amazon between 2014 and 2015 alone — yet is rapidly vanishing with increasing global demand for resources. The economy, essentially focused on the exploitation of natural resources, minerals and agribusiness, has already led to about 20 percent of original forest cover to be replaced by pastures and agricultural crops, without securing the well-being of the local population. The reforestation project fills an urgent need to develop the region’s economy without destroying its forests and ensuring the well-being of its people. 
 
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 “A new chapter is being written for the Brazilian Amazon with this initiative,” said Rodrigo Medeiros, vice president of CI’s Brazil office. “Protecting the Amazon is not something we should think in the future — we have to do it now.” 
 
 The project is a partnership between Conservation International, the Brazilian Ministry of Environment, the Global Environment Facility (GEF), the World Bank, the Brazilian Biodiversity Fund (Funbio) and Rock in Rio’s environmental arm “Amazonia Live.” 
 
 The reforestation effort is part of a broader regional initiative, the Amazonia Sustainable Landscapes Project. This project aims to increase the area of forest ecosystems, promote the connectivity of protected areas within the Amazon, and further develop local productive activities and value chains derived from the sustainable use of Amazonian biodiversity, including production of native species of seeds and seedlings. 
 
 Priority areas for the restoration effort include southern Amazonas, Rondônia, Acre, Pará and the Xingu watershed. Restoration activities will include the enrichment of existing secondary forest areas, sowing of selected native species, and, when necessary, direct planting of native species, Medeiros said. 
 
 Bruno Vander Velde is CI’s editorial director. 
 
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 Further reading ||||| There are more habitable planets in our galaxy than humans living on planet Earth. But the nearest one is about 70 trillion miles away , which means that, for now, and for the foreseeable future, Earth is the only life-supporting rock hurtling through infinite space we’ll ever know. It’s really not the best idea to let it burn up–and key to keeping it cool are the massive rainforests of the Amazon. Sadly, we’ve had a hard time not cutting them down. 
 
 A new project should help prevent–or at least slow down–that hot future. If all goes to plan over the next six years, a project led by Conservation International will become the largest tropical reforestation project in history. Seventy-three million trees will sprout up across what’s known as the “arc of deforestation,” in the Brazilian states of Amazonas, Acre, Pará, Rondônia, and throughout the Xingu watershed. The short-term plan is to restore 70,000 acres (the area of 30,000 soccer fields) that have been cleared for pastureland to their former forested glory. 
 
 
 
 “If the world is to hit the 1.2°C or 2°C [degrees of warming] target that we all agreed to in Paris, then protecting tropical forests in particular has to be a big part of that,” M. Sanjayan, CEO of Conservation International, tells Fast Company. “It’s not just the trees that matter, but what kind of trees. If you’re really thinking about getting carbon dioxide out of atmosphere, then tropical forests are the ones that end up mattering the most.” 
 
 He’s right: Simply stopping deforestation could allow existing forests to absorb up to 37% of our annual carbon emissions; replenishing degraded areas could do significantly more for the planet. 
 
 “This is not a stunt,” Sanjayan says. “It is a carefully controlled experiment to literally figure out how to do tropical restoration at scale, so that people can replicate it and we can drive the costs down dramatically.” 
 
 Over the past 40 years, about 20% of the Amazon has been cut down or destroyed, and scientists worry that another 20% of the rainforest will be lost in the next couple of decades. So, instead of following precedent and planting saplings, which are labor and resource intensive to manage (and, depending on the selected species, may not be best-suited for the territory, resulting in less than ideal survival rates), the organizing coalition is trying something different. 
 
 
 
 Developed in Brazil only a few years ago, the new planting technique is called muvuca. “In Portuguese, it means a lot of people in a very small place,” says Rodrigo Medeiros, Conservation International’s vice president of the Brazil program and the lead on the ground. 
 
 ||||| Assuming everything goes to plan, over the next six years, the Amazon rainforest will get 73 million new trees. The mass planting is part of a project sponsored by Conservation International, the Brazilian Ministry of Environment, and a number of other NGOs and corporations. As John Converse Townsend at Fast Company reports, it is the largest tropical reforestation effort ever attempted. 
 
 According to a press release from Conservation International, the effort will span deforested pasture lands over a 74,000-acre region spanning several Brazilian states—with the greatest focus in Southern Amazonas, Rondônia, Acre, Pará and the Xingu watershed. The purpose of the project is, in part, to revive the 20 percent of the Amazon that has been lost to deforestation due to agriculture and pasturing during the last 40 years. But the effort is also geared toward learning how to restore tropical forests. 
 
 “This is a breathtakingly audacious project,” says M. Sanjayan, CEO of Conservation International, according to the release. “The fate of the Amazon depends on getting this right—as do the region’s 25 million residents, its countless species and the climate of our planet.” 
 
 As Townsend reports, reforestation efforts are typically very costly and time consuming—requiring people to both grow and plant thousands of saplings, many of which will not survive. In this latest effort, the restorationists are trying a new method called muvuca, in which they will spread the seeds of native trees across the slash and burned land and animal pastures. The seeds come from the Xingu Seed Network, which uses a coalition of 400 collectors to gather the seeds from native trees. 
 
 “With plant-by-plant reforestation techniques, you get a typical density of about 160 plants per hectare,” Rodrigo Medeiros, vice president of Conservation International’s Brazil program, tells Townsend. “With muvuca, the initial outcome is 2,500 [trees] per hectare. And after 10 years, you can reach 5,000 trees per hectare. It’s much more diverse, much more dense, and less expensive than traditional techniques.” 
 
 The muvuca experiment is the beginning of a massive effort announced by Brazil to restore 12 million hectares of forest, an area the size of Pennsylvania, as part of an effort to reach their climate change goals under the Paris Accord. Recent studies show that second growth forests—those less than 60 years old that grow after logging or land clearance—can sequester huge amounts of carbon. As Townsend reports, just stopping current deforestation could help mitigate 37 percent of current carbon emissions. Planting or restoring forests could make that number even bigger. 
 
 While the effort is impressive, it’s not the largest reforestation effort in the world. In July, 2016, 800,000 people in Uttar Pradesh, India, planted 50 million trees in just 24 hours, a publicity stunt to highlight India’s Paris Accord commitment to reforest 12 percent of its land by 2030. The world’s largest program, however, is China’s Grain-for-Green effort, a plan to restore 69.2 million acres of forest land, which is an area the size of New York and Pennsylvania combined. 
 
 All of these efforts are encouraging, but replanting is only half of the solution. Twenty-five million acres of forests are cleared each year, writes Doug Boucher, Director of Climate Research and Analysis at the Union of Concerned Scientists. He points out that while the long-term benefits of reforestation are helpful for the climate, the decades it takes for forests to regrow means it will take a while to see benefits. This means other more immediate solutions, such as reducing industrial emissions and halting the removal of forests, are still necessary to make a dent in our changing climate.
– The Amazon rainforest's "arc of deforestation" could soon have 73 million new trees. In an effort to reseed 74,000 acres of the Amazon—20% of which has been destroyed in the last 40 years—Conservation International, the World Bank, Brazil's environmental ministry, and several other groups are working together to spread seeds in the Amazonas, Acre, Pará, Rondonia, and Xingu areas of Brazil, reports Fast Company. Reforestation normally involves saplings, which must be grown and planted. But Conservation International CEO M. Sanjayan hopes dropping seeds from 200 native species per square meter of land, in what is known as the muvuca strategy, will "drive the costs down dramatically" and produce a greater diversity and density of plants. "If you're really thinking about getting carbon dioxide out of [the] atmosphere, then tropical forests are the ones that end up mattering the most," says Sanjayan, noting the move will help Brazil reach its Paris Accord target of reforesting an area the size of Pennsylvania by 2030, per Smithsonian. A release notes it's the "largest tropical forest restoration in the world." Up to 2,000 locals will work together to seed each hectare, with families receiving $700 per hectare. Additional seeds will also be distributed in existing forested areas. Some 90% of seeds are expected to germinate, though only the strongest will survive. A leader of the program predicts there will be 2,500 trees per hectare after six years and up to 5,000 after 10 years. (Deforestation has revealed millennia-old "geoglyphs" in Brazil.)