Is the idea of a pristine landscape an illusion, given that over thousands of years human activity has almost everywhere left its mark? Bridget Kendall asks the gardener Gilly Drummond, the land artist Danae Stratou, the archaeobotanist Dorian Fuller, and the historian William Beinart.

(Photo: Blenheim Palace Park where English landscape architect Capability Brown created a 150-acre lake and planted more than a million trees to make perhaps his finest artificial landscape © Blenheim Palace)