The soil in a coniferous forest tends to be young and nutrient-poor. The "thinness" of the soil is usually because of the cold, that hinders the development of soil and the ease, which plants can use its nutrients. Fallen leaves and moss can last on the forest floor for a long time in the cool, moist climate, which limits their organic contribution to the soil; acids from evergreen needles further leach the soil, creating spodosol (that is a type of soil). Since the soil is acidic because of the falling pine needles, the forest floor has only lichens and some mosses growing on it.