Author and conservationist Isabella Tree talks about her book Wilding with EconTalk host Russ Roberts. Tree and her husband decided to turn their 3500 acre farm, the Knepp Castle Estate, into something wilder, a place for wild ponies, wild pigs, wild oxen, and an ever-wider variety of birds and bugs. The conversation covers the re-wilding phenomenon, the complexity of natural systems, and the nature of emergent order.