A team of arborists has successfully cloned and grown saplings from the stumps of some of the world’s oldest and largest coast redwoods, some of which were 3,000 years old and measured 35 feet in diameter when they were cut down in the 19th and 20th centuries. Earlier this month, 75 of the cloned saplings were planted at the Presidio national park in San Francisco.

The initiative is run by the Archangel Ancient Tree Archive, a nonprofit working to reestablish ancient redwood forests to help combat climate change. Coastal redwoods, which can grow an average 10 feet per year, sequester 250 tons of carbon dioxide from the atmosphere over their lives, compared to 1 ton for an average tree.

“We’re excited to set the standard for environmental recovery,” David Milarch, a fourth-generation arborist and co-founder of the Archangel Ancient Tree Archive, said in a statement. “These trees have the capacity to fight climate change and revitalize forests and our ecology in a way we haven’t seen before.”

Today, giant stumps of ancient redwoods dot the landscape from Oregon to northern California, reminders of the old-growth forest that used to stretch across the Pacific Northwest. Many arborists assumed these stumps were dead, but Milarch and his son, Jake, discovered living tissue growing from the trees’ roots, material known as baseless or stump sprouts. The Milarchs collected DNA from stumps of five giant coast redwoods, all larger than the largest tree living today. These included a giant sequoia known as General Sherman with a 25-foot diameter.

They then used this genetic material to grow dozens of saplings, clones of the ancient trees, a process that takes approximately two-and-a-half-years. The Archangel Ancient Tree Archive has already planted nearly 100 of these saplings in the Eden Project garden in Cornwall, England, a couple hundred in Oregon, and is organizing further groves of saplings in nine other countries.

“These saplings have extraordinary potential to purify our air, water, and soil for generations to come,” Milarch said. “We hope [the San Francisco] ‘super grove,’ which has the capability to become an eternal forest, is allowed to grow unmolested by manmade or natural disasters and thus propagate forever.”