Passage IV

New Life in an Old Forest

If you hike among the shadows of Olympic National Park in Washington State, you'll notice an unusual feature of this temperate rain forest. Many of the towering trees here grow in straight rows, or colonnades as if they had been planted by a human hand. No forester arranged these trees, however. Consequently, they mark the former location of "nurse logs," fallen trees had provided a friendly environment for tree seeds. This example of ecological succession makes it possible the towering Sitka spruces, western hemlocks, and Douglas firs that dominate this landscape.

The variety of vegetation in the region creates a breathtaking panorama. These logs are crucial to new tree growth because the forest floor is otherwise inhospitable. Seeds that fallen to the forest floor rarely survive, because they can't compete with the dense layers of ferns, shrubs, and other plants that carpet the forest. The decaying logs, in contrast; provide nutrients and moisture—a rich growing environment ideal for these seeds. Amid the damp, spongy mosses that blanket and cover the bark of these nurse logs, new life germinates easily.

Once sprouted, the seeds grow into young trees along the length of the log, drawing nourishment from the nutrients within the fallen tree. Because the climate in the Olympic Peninsula is mild, with cool summers and warm winters, the nurse logs decay very slowly. A fallen Douglas fir or western red cedar can easily take more than five hundred years to decay fully. As the young trees on the nurse logs matured, their roots gradually grow around the dead trunk to reach the ground, often years after the trees first sprouted.

Of the hundreds of seedlings that once covered the nurse log, only a handful will survive to maturity. The root systems of those that endure often provide a kind of memorial for the nurse log that they had once straddled. Throughout their long lives, these trees testify to the complex cycle of birth, death, and renewal in an old-growth forest ecosystem.