The Presidio forest, a refuge of pine, cypress, and eucalyptus trees just outside of San Francisco, got 75 new additions last week: clones of ancient redwood trees bred by the Archangel Ancient Tree Archive, a rogue arboreal archivist group.

According to a news release, the nonprofit Archangel Ancient Tree Archive—founded in 1994 as the Champion Tree Project—created a “super grove” of 75 saplings by taking DNA samples from the stumps of five redwood trees 31 to 35 feet in diameter, which may have been 3,000 years old and 400 feet tall when they were chopped down.

The Archangel Ancient Tree Archive reportedly believed it was impossible to clone dead trees—to be clear, trees can be cloned, but it’s typically done using living tree stems. But the archivists managed to create a tree embryo using tree DNA from the ancient stumps, which they then raised in a “living archive” for 2.5 years before planting last week. (Think of these living archives as the tree versions of the Doomsday Arctic Seed Vault, which is meant to archive preserve species of organisms vulnerable to climate change.)

“These trees have the capacity to fight climate change and revitalize forests and our ecology in a way we haven’t seen before,” David Milarch, co-founder of the Archangel Ancient Tree Archive, said in a press release.

Image: Ancienttreearchive.org

According to the Archangel Ancient Tree Archive, the group’s goal is to reforest vulnerable regions using trees that once made up “old-growth” forests, which have mostly disappeared from the US due to industrial logging. Before the onset of industrial logging in the 19th century, old growth forests trees propagated throughout the US, hosting trees greater than 120 years old with trunks consistently larger than 30 inches in diameter.

Old growth forests are thought of as local "carbon sinks," meaning that they naturally remove carbon from the local atmosphere, and since the trees live for a long time, the carbon stays out of the atmosphere for a long time. In other words, they’re great for the climate.

Of course, cloning trees that once made up an “old growth” forest is not the same thing as actually recreating an old growth forest. The term “old growth” means the trees are, by definition, old. There’s no environmental substitute for an old growth forest except for protecting forests for hundreds of years—and we already cut down most of our old growth forests due to industrial logging, and climate change threatens the ability for forests to sustain themselves for long periods of time.