For much of history, tree canopies were pretty much completely ignored by science. It was as if researchers said collectively, "It's just going to be empty up there, and we've got our hands full studying the trees down here! So why bother?!" But then, around the mid-1980s, a few ecologists around the world got curious and started making their way up into the treetops using any means necessary (ropes, cranes, hot air dirigibles) to document all they could find. It didn't take long for them to realize not only was the forest canopy not empty, it was absolutely filled to the brim with life. You've heard of treehouses? How about tree gardens?!  This week we journey up into the sky and discover Forests above the forest. We learn about the secret powers of these sky gardens from ecologist Korena Mafune, and we follow Nalini Nadkarni as she makes a ground-breaking discovery that changes how we understand what trees are capable of.  P.S. This episode is a layer cake of arboreal surprises (including the reappearance of a certain retired host).  A few visual tre(e)ats:  We first learned about the magical world of the canopy from this beautiful video from Michael Werner, Joe Hanson, and the PBS Overview team. It features Korena Mafune’s research up in the treetops, as well as the people who have dedicated their lives to saving what’s left of the old growth forests. We highly recommend checking it out! And, if you’re hankering to go climb a tree after this episode, you might enjoy browsing Hallie Bateman’s wonderfully illustrated guide to the best climbing trees in NYC for a little inspiration.Support Radiolab by becoming a member today at Radiolab.org/donate.Radiolab is on YouTube! Catch up with new episodes and hear classics from our archive. Plus, find other cool things we did in the past — like miniseries, music videos, short films and animations, behind-the-scenes features, Radiolab live shows, and more. Take a look, explore and subscribe!