If someone told you that one mature tree sequesters 50 pounds of carbon dioxide annually, you’d probably think, Great, but what does that mean? Austin Mackrill, vice president of the Arbor Day Farm, part of the Arbor Day Foundation, knows that’s a challenging figure to wrap one’s head around, so instead he likes to tell people to look at it this way: A single mature tree provides enough oxygen for two people each year. In the last 49 years, the foundation has worked to celebrate trees and educate the public on the many ways they help us. “It’s something we know is important to nature, is important to our lives,” Austin says. “There isn’t really another substitute out there.”