First Tree is right near entrance, on an island by it's self with a some kind of tree house in it. Second is past the shields, on left side of the split in the thick of the Wyverns. The third is derictly opposite the Red Hammer Goblin Clans village. You must complete a task for each tree. The first is a goblin you must kill on the island, then you must slay Wyverns bugging the second and correctly answer a riddle asked by the third.