The Tongass National Forest is unique

Bears at the Anan Wildlife Observatory, as posted at the Tongass National Forest’s Facebook page on Saturday, July 25, 2026. (U.S. Forest Service)

By Mason D. Bryant

Several characteristics of the Tongass National Forest are unique. It is part of the largest temperate rainforest in the world and extends from Yakutat, Alaska to northern California. It is home to healthy populations of five species of Pacific salmon: pink, chum, coho, sockeye and Chinook salmon. The largest population of brown bears is found on Admiralty Island in the Tongass National Forest.

Other wildlife species such as Sitka blacktail deer, black bear, beaver, and flying squirrels are abundant throughout the forest. Supporting these features are intact watersheds throughout the forest. These are watersheds where the effects of human disturbance on their habitat are absent from their headwaters in the mountains to the intertidal zone. These are unique among river systems worldwide.

Throughout human history watersheds were sites of settlement and rivers were viewed as resources to be used or as hazards to be controlled. More than 2,000 years before present ancient civilizations diverted water from Tigres and Euphrates rivers to support widespread agriculture. Extensive and long-term water withdrawal converted the freshwater river systems to the saltwater marshes of today.

With the expansion of agriculture, urbanization and industrialization, every major river in Europe had been diverted for irrigation, entrained to control flooding, or dammed. Evidence of this can be seen in Asia and elsewhere. A similar pattern followed the path of European expansion in North America. Deforestation began with the first European settlers along the Atlantic coast and continued across the country, accompanied by dams, canals, large-scale irrigation, and urbanization. No watershed in North America remains undisturbed from its headwaters to the ocean by human activity with the exception of Alaska. 

In Southeast Alaska, large-scale exploitation of watersheds began only in the past 150 years with mining, timber harvesting and localized urban centers. Timber harvesting and roads are the primary activities affecting watersheds throughout Southeast Alaska. As a result of the size of the Tongass National Forest — restricted access by roads, and a sparse population base, as well as policy decisions — some watersheds remain intact and undisturbed by human effects on their habitats in contrast to watersheds throughout the world. The physical and biological processes of these watersheds are controlled by the natural occurrence of seasonal, climatic, and periodic disturbance events throughout the watershed in the absence of human effects. 

Salmon and the other inhabitants of these watersheds have evolved and adapted to seasonal cycles and natural disturbance regimes that include wind and rainfall. For example, seasonal flow regimes maintain connectivity throughout the watershed from the headwaters to the ocean and across the floodplain. Old-growth trees uprooted by windstorms contribute to forest productivity and diversity as well as large wood in streams.  Even landslides, which are qualitatively and quantitatively different from those in clear-cut hillslopes, contribute to downstream habitats. Intact watersheds are dynamic and diverse ecosystems.

Why do these watersheds matter other than just for their existential value? Perhaps this should be enough for the same reason that people value human-made objects such as buildings, works of art, or historical sites and documents.

For Southeast Alaska, they are some of the more productive salmon watersheds, supporting abundant populations of Sitka Blacktail deer and brown bears that depend on old-growth forest ecosystems. Salmon from these watersheds support sustainable commercial, sport, and subsistence fisheries. Deer and bear contribute to both sport and subsistence hunting. In addition, they provide unique non-consumptive recreational opportunities.

The absence effects of human activity on their habitat offers a unique opportunity to understand the natural connections and processes that control biological productivity. They provide a baseline to understand the effects of management of watersheds elsewhere. This knowledge, in turn, will contribute to better management of other watersheds in addition to improved methodologies of restoration projects. They provide a reference point for a holistic understanding of watershed processes in temperate rainforests. 

Roads into these watersheds are the first step of human interference with the natural processes of intact watersheds. Roads alone can have a significant effect on habitats and connections within a watershed. A more important effect is development within watersheds with increased access. As this occurs, human activity becomes a force shaping the watershed and imposes its effect on natural processes within the watersheds and a unique part of the forest is lost.  

• Mason D. Bryant is a retired research fish biologist who lives in Douglas.