Around La Fortuna de San Carlos, the volcanic soil is so fertile that the fence posts take root, sprout, and grow into trees. The fences have to be kept pruned so that they don't sway in the wind and break free of the barbed wire, and the branches that are cut off are used for new fence posts. In the first photo, the trees that form the fence are about ten feet tall, so that gives you an idea of how huge the other trees in the picture really are.