After hearing Richard Preston on the Diane Ream on NPR a few months ago, I decided to read The Wild Trees. I was so fascinated with what I heard on the radio show I wanted to learn more. Basically this biologist/tree climber guy, Steve Sillett found huge layers of soil and a new garden canopy growing on limbs in the giant Redwood Forests in California. Until recently, redwoods were thought to be virtually impossible to climb, but one day in 2006, this Steve guy leaped over into one of the redwoods and made this discovery. He says there are some areas up in the trees where the soil is so thick that you can't even see the forest floor. This is how they describe it:
"The deep redwood canopy is a vertical Eden filled hanging gardens of ferns, reefs of lichens, small animals, and all sorts of plants, including thickets of huckleberry bushes and small trees actually growing on the branches of giant redwoods. There are massive redwood limb systems fused into flying buttresses and carved into “fire caves.” Thick layers of soil sitting on limbs harbor animal and plant life unknown to science" (http://www.richardpreston.net/books/wt.html).
The book was a pretty slow read, but the chapters that talked about the species of animals and plants living above the trees were fascinating. There is so much water in the trees that they found crustations of sorts and a species of aquatic salamanders. I just can't believe how long it must have taken for the soil to pile up and for all those bushes and trees to grow.

The Heart of Poseidon. Fern masses at 275 ft. in Poseidon, a redwood “cathedral tree” formed of dozens of huge trunks. Redwoods contain some of the most massive epiphyte gardens in any forest on the planet. Here, Steve Sillett is tending scientific instruments used for monitoring the fern mass. Photo by Richard Preston, © Richard Preston.
Out of Sight Climbers in the redwood canopy are normally out of sight of the ground.Photo by Richard Preston, © Richard Preston.