Epiphytes-plants that grow on the surface of other plants-are typical in rainforests but uncommon in other kinds of plant communities. In the Olympic rainforest the epiphytes are mostly mosses, ferns, and lichens. They often form a dense cover on the trunks and branches of trees in the Olympic rainforest. Douglas fir and bigleaf maple (Acer macrophyllum) have some of the most dense epiphyte covers because they have rough bark that provides an excellent surface on which epiphytes can become established. Big leaf maples can be completely enveloped by lichens that hang from them like a wispy shawl. Their short trunk and broad, spreading limbs are dotted with sprays of licorice ferns (Polypodium glycyrrhiza).

Trunks of red alder can be covered by epiphytic mosses, among which are growing licorice ferns.	This bigleaf maple in the Hoh River valley has a dense cover of epiphytic lichens, mosses, and ferns, such as the licorice fern.

The members of any plant community play different roles in that community. In the rainforest, the huge trees play an important role not only when they are living, but even after they die. Dead trees that remain standing are called snags and provide habitat for spotted owls and other birds and animals, until the decay of their roots causes them to crash to the ground. A prominent feature of the plant communities both on the coast and in the temperate rainforest is the frequent occurrence of nurse logs. Nurse logs are created when one of the huge old trees falls, either after standing as a dead snag or during a storm or lightning strike. In the high moisture environment of these communities, the dead tree will begin to decompose very quickly, which makes many nutrients available for other plants. The gap in the forest canopy created by the fall of the tree allows sunlight to reach the forest floor, and soon the log begins to sprout a covering of mosses and colonizing plants. Over time, various shrubs will become established and even the seeds of the forest trees will begin to germinate, forming seedlings, on the nurse log. This is an example of succession, which in the Olympic rainforests is initiated commonly on nurse logs. We often see tall canopy trees with thick, finger-like roots extending into the soil from four or five feet above ground. These are trees that began their life on nurse logs, and the large spreading roots are those that grew around the girth of the nurse log after the seedling had sprouted on its surface.

A nurse log supports a lush growth of sword ferns.	Mosses and lichens on nurse logs create a moist, fertile environment for the growth of other plants, such as the shrubs shown in this photograph.

The seeds of trees germinate among the mosses of nurse logs, permitting young conifers to establish themselves.

Conifers of Olympic temperate rainforest often have spreading, buttress-like roots. This occurs when trees are established on nurse logs and, as they enlarge greatly, their roots spread around the nurse log into the soil. Eventually, the nurse log decomposes, leaving the younger trees that brooded on it, standing alone with roots curving broadly into the soil.