Native flora, especially tall trees, have generally adapted to seasonal storms and rarely come down due to rainfall. At times, though, a particularly strong storm can erode the soil and pound a tree with enough force to cause it to topple, possibly setting off a chain reaction. Anyone in the path of a falling tree must make a DC 14 Reflex save to leap clear or take 3d6 points of damage. Fallen trees can block routes, but travelers can usually Climb over the trees, which measure anywhere from 5 to 20 feet in diameter. Fallen trees can, however, block river travel and require travelers to abandon their boats or to drag them out of the river and portage them around the obstruction.