This oasis of green in the hyper-developed city has an important job: it can contain one million gallons of water. Here’s how.

Human beings have made enormous changes to Earth, reshaping it, developing it and generally altering it so much that in many cases its pre-human condition has become unrecognizable. In this far-ranging conversation, ecologist Erle Ellis and landscape architect Bradley Cantrell discuss what this means for ecology and architecture … and how we might think about protecting our planet.