Updated

After spending two decades producing clones from some of the world's biggest and oldest trees, a nonprofit group says it's time to start planting.

The Archangel Ancient Tree Archive has developed several thousand genetic copies of coastal redwoods and giant sequoias from California at its laboratory in Copemish, Mich. On Monday, several dozen redwoods will be planted in seven countries. Others have been planted in Oregon. Some were developed from the stump of a tree that had lived about 4,000 years.

Co-founder David Milarch says the Earth Day event is a first step toward mass-production of the clones. The group hopes millions will be planted around the world, helping to restore ancient forests and fight climate change by absorbing massive amounts of carbon dioxide.