When you get up into the crown of a redwood tree, you lose sight of the ground entirely. You also lose sight of the sky. You’re in a lost world. You’re in an undiscovered, unexplored ecosystem, somewhere between heaven and earth, filled with forms of life, not all of which have been given names by scientists yet. Everything from hanging gardens of ferns, to caves carved into the trees by forest fires. Layers of soil sitting on the limbs — layers that can be up to a meter deep, filled with organisms and then small trees growing on the branches of redwood trees. Trees of many different species — these are bonsai of the canopy.
—Richard Preston, from an interview with Alex Chadwick on NPR