Nurse log

In some forests where the trees grow tall such as in the US Pacific Northwest, when a giant falls it clears a patch of forest letting in light, and provides a new surface for seedlings to take root away from the competition of the forest floor. Sometimes the nurse log is so successful as a sort of creche for the young trees that they will grow along the full length of the fallen trunk. And when the original log decays away it leaves a remarkable, straight line of trees.

Also see: phoenix treesorforest bathing.