Alaska's Coastal Forests

Alaska's coastal forests region, extending approximately 500 miles, comprises much of the largest temperate rainforest remaining on Earth. The region is a sprawl of islands and canals, fjords and glaciers, forests and wetlands, ridges and jagged peaks. Here warm ocean currents collide with coastal mountains, producing plenty of rain and relatively mild temperatures compared to Alaska's interior. In this constantly wet environment, great forests rise at the edge of the sea adn the interchange between the two makes for the most biologically rich and diverse region in Alaska, and one of the more rare rainforest systems -- wet and cool -- in the world.

Water is the controlling element in the region, with much of the forest receiving between 80 and 220 inches of rain annually. Higher elevations can receive as much as 400 inches. On a given day in the forest, water seems to come from everywhere at once; from a fine misty rain, from the ground, which leaks water underfoot, from pools and tumbling brooks, and from the forest itself, which seems to exude a distillation of water and green.

Though Alaska's coastal forest conjure images of towering, majestic trees, only about 4% of the region is capable of growing such giants. Elsewhere there is too much water even for trees; much of the coastal forest low lands are mainly peat bog. Up high, tundr, rock and ice prevail. Cathedral-like forests and the ecosystems they support are therefore less abundant than the vast expanse of the region would suggest, and much of the region's best forest has already been harvested. Yet intact areas of the forest remain, and the challenge ahead is how best to protect them while addressing the needs of the people who live in the region adn those from outside who demand its resources.

One of the keys to protecting the richness of Alaska's coastal forests is understanding their complexity. The most productive and biologically diverse forests are of uneven age. Seemingly ancient trees stand near downed giants and small saplings, and an understory of shrubs and herbs blankets the forest floor. Natural disturbance is the tool that allows the forest to develop in this way. Wind, for example, might knock down one or two old trees at a time, allowing light to the forest floor and so the growth of younger trees and the shrubs and herbs on which animals such as Sitka black-tailed deer depend for food. Standing snags and downed trees provide nutrients for other plants, food for a variety of invertebrates, and nesting and denning habitat for birds and animals. Over centuries, the forest develops into a complex patchwork of small clearings, rotting logs, jumbled blowdown, lush shrubs, and many-aged trees, and so creates rich habitat for numerous species. It is thus the age of the forest and not that of a single tree that is important.

On the other hand, incompatible foresty practices can result in dense, even-age stands, which allow little light for understory growth and even less habitat variety. Indeed, few species find adequate habitat in these young forests. For the Sitka black-tailed deer, as an example, the forest which once provided plentiful shrubs in summer and protection against deep snows in winter may at the onset of secondary growth provide food but little shelter, and then, once the forest canopy has closed, shelter but little food. The deer require both. The complexity of the forest mosaic, the product of hundreds of years of natural cycles and disturbance, has been lost as a result of short-term human actions.

The solution is to ensure that our human actions, particularly our forest practices, are sustainable for the long term. They should, for example, maintain the uneven-aged character of the forest. They also need to fit into a broad, landscape scale because we also need healthy, freshwater habitat for the salmon that return every year. To have that, we must ensure that our forestry practices don't interfere with natural watershed processes. To protect the salmon, we have to protect the forest and vice-versa. It is all intertwined. The Conservancy is working with public agencies, local communities and private partners to develop such solutions for Alaska's coastal forests.

Recommended Reading:
The Book of the Tongass edited by Carolyn Servid and Donald Snow (c) 1999 Milkweed