Jackard wrote:So basically, "tree decay." Set it up so that they will revert to their original state unless you keep them fed with dreams/whatever, similar to repairing a wall.
I meant using items instead of LP, but for that matter, there's no reason why you couldn't have decay with the LP system.
As for moving one's heart tree (or the heart inside, at least), give heart tree's a range of influence which could be used to do various things, such as buffing nearby normal trees, creating the previously suggested special undergrowth, or moving the heart to an appropriately prepared tree. The druid wouldn't be able to remove their heart, but they could teleport it between empty heart trees. If the druid wants to move very far, they have to spend resources to increase their current heart tree's range. To make sure one can't rapidly jump around, there could either be a long timer on the 'teleport heart' option, or the heart tree could be made normal once a heart is moved from it. The point is to give druids some chance of escape in the event an overwhelming number of people decide to start a new village on top of their forest.