While attending John Jones' funeral, a Cwrier gave the Eleventh Doctor an invitation, in the name of a "lifeform unknown".
This invitation led the Doctor and Alice Obiefune into a planet with a lot of trees, so high that Alice compared them to skyscrapers.
The Doctor told Alice he had visited the planet a year before, and that, in this ocasion, it was predominantly a desert planet. Back then, a humanoid species inhabited the planet.
However, when the Doctor returned to the planet with Alice, all the several million individuals from the species were gone.
The Doctor found corpses of a Nebulon and a Rockra on the planet's surface. (COMIC: Remembrance)
The planet was attacked by the Planting, a virus which replaced all life on the planet with a forest. (COMIC: The Scream)