A look at Alaska's coastal rain forest

Southeast wild

Posted: Friday, May 05, 2000

Spring is when we appreciate our coastal rain forest the most.

The snow is gone from our lowland trails. The forest is alive with the buzzing calls of the varied thrush and the ``whoop, whoop, whoop'' courtship sounds of the male blue grouse. Blueberry bushes are loaded with tiny white flowers that resemble pink Japanese lanterns. The delicate blossoms of the fern-leaf goldthread stand out against the moss-covered forest floor like tiny comets trailing miniscule streams of light. The bright yellow flags of skunk cabbage have emerged from marshy places within the forest.

This coastal rain forest contains some of the greatest masses of living organisms per square foot on Earth.

Beneath giant western hemlock and Sitka spruce trees is a thick, luxurious carpet of moss that not only covers the forest floor, but also adorns the tree trunks and surrounds their branches. Hugh patches of leafy green lichens grow among the mosses, and long, draping strands of pale ``old man's beard'' lichens hang from tree branches. Open areas among the trees contain miniature forests of 6-foot-high devil's club and patches of blueberry thickets, and ground-hugging dwarf dogwood.

Although we marvel at the large conifers within Alaska's coastal rain forest, it is the mosses, lichens and fungi that make these trees possible.

Mosses act like giant sponges, absorbing rainwater and its dissolved nutrients, and thereby preventing soil erosion. This keeps tree roots moist during dry spells and provides nutrients to the soil over extended periods of time. Lichens are able to fix nitrogen from the air and form nitrate fertilizer. Fungi attach to the tree roots and, with finely divided filaments known as hyphae (HIGH-fee), extend into surrounding soil to pick up water and essential nutrients such as phosphorus, nitrogen, potassium and calcium, which they pass on to the host tree.

The older portions of the coastal rain forest support the greatest number of deer, wolves, brown bears, bald eagles, marbled murrelets, martens, river otters, northern flying squirrels, woodpeckers and salmon.

Stands of trees older than 250 years create a mosaic of various densities, crown sizes and interspersed openings. This allows sunlight to reach the forest floor to stimulate the growth of food plants for deer. The large branches of older trees intercept and hold snowfall in winter, allowing deer access to food when other areas are covered with deep snow. Deer, in turn, are food for wolves and brown bears, and the older trees provide the two predators with denning sites in cavities created by their massive root systems.

Most bald eagles choose large trees more than 400 years old to support their nests, which can weigh as much as a ton after years of use. Marbled murrelets nest on the moss covering the branches of older trees, where a more open crown structure allows access for these small seabirds whose wings are better designed for ``flying'' underwater than among trees. Martens, cat-like relatives of minks and weasels, feed on voles and mice within the older forest, and river otter dens within the root wads of older, larger trees.

Even dead and fallen trees are important. Northern flying squirrels, chickadees and woodpeckers raise their young in cavities of trees that have died of old age. When trees die and fall into streams, they benefit salmon by providing protection from predators, pools for resting adults and rearing areas for the young. As these logs decay, they also contribute important nutrients to the stream's food chain.

In Juneau there are several good areas to experience spring in the coastal rain forest. A few of our favorite places are along Peterson and Fish Creeks on North Douglas Island, and along the Herbert and Eagle River trails.

Bob Armstrong and Marge Hermans will present a slide show and discussion of their new book, ``Alaska's Natural Wonders,'' highlighting volcanos, pack ice, aurora borealis, hot springs, midnight sun and other natural phenomena, at the Juneau Audubon Society meeting at 7:30 p.m. Thursday at the Dzantik'l Heeni Middle School library. The Audubon's annual Berner's Bay cruise is scheduled May 13.

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