Tongass National Forest

The Tongass National Forest is a huge temperate rainforest in the southeast corner of Alaska, USA. It is the biggest national forest in the United States and one of the largest temperate rainforests on Earth. The Tongass is famous for its giant cedar and spruce trees, its dense salmon runs and its huge populations of grizzly bears and bald eagles.

• Areaapprox. 68,000 km²The biggest national forest in the USA
• Where?Southeast AlaskaHugging the coast and the islands
• TypeTemperate rainforestCool and wet rather than hot
• Famous animalBald eagleThe highest density anywhere on Earth
• Other wildlifeGrizzlies, salmonPlus orcas, wolves and humpback whales
• TreesSitka spruce, hemlockSome over 1,000 years old

The Tongass among the world's rainforests

Area (million km²)

Amazon5.5

Congo2.0

Valdivian0.25

Tongass0.068

The Tongass is small compared to tropical giants but is one of the largest stretches of intact temperate rainforest on Earth.

What is the Tongass National Forest?

The Tongass covers most of southeast Alaska. It is built around the Alexander Archipelago, a chain of around 1,000 mostly forested islands along the coast. The forest gets a huge amount of rain (some parts over 4,000 mm a year) carried by moist Pacific winds that hit the steep coastal mountains. The result is a cool, wet, deep-green wilderness that looks more like Tolkien's Middle-earth than like most other American forests.

Trees and the forest

The Tongass is dominated by three big tree species: Sitka spruce (the tallest spruce in the world, up to 90 metres), western hemlock and yellow cedar. Many trees are over 500 years old, and some over 1,000. The forest floor is covered in a thick spongy mat of mosses, lichens and ferns. Old-growth trees provide essential habitat for many forest animals.

The salmon-forest connection

The Tongass is famous for its salmon runs. Five species of Pacific salmon (chinook, coho, sockeye, pink and chum) return from the ocean every year to spawn in the rivers. The salmon are crucial not just for the rivers but for the forest itself. Bears, eagles and wolves catch salmon and carry them up into the forest to eat. The bones and waste fertilise the soil with nutrients brought all the way from the ocean. Scientists have shown that you can detect ocean-derived nitrogen in spruce trees hundreds of metres from any river. The forest is literally fed by the sea.

Fact The Tongass has the highest density of nesting bald eagles anywhere in the world, around 30,000 birds. They are easy to spot perched in tall trees near salmon streams.

Wildlife of the Tongass

The Tongass supports an exceptional concentration of wildlife. Around 25,000 grizzly bears live in the forest, plus black bears (including a rare white-coated subspecies called the spirit bear), wolves, mountain goats, deer, river otters, sea otters and beavers. The surrounding waters are home to orcas, humpback whales, harbour seals, sea lions and Steller's sea lions.

Did you know? The forest is so wet that nothing really dries out, and old-growth Tongass trees are usually completely covered in mosses and lichens. The mosses absorb so much water that an old-growth tree can be carrying more than its own weight in water.

Deeper dive: old-growth, the Roadless Rule and Tlingit stewardship

The Tongass is the largest remaining intact stretch of the Pacific temperate rainforest, which once stretched in an unbroken belt from northern California to Alaska. The old-growth portion of the forest (trees of 150 years or older) is particularly important: it provides the complex multi-layered habitat that many forest species depend on, stores huge amounts of carbon (often more per hectare than tropical rainforests), and cannot be replaced on any human timescale once logged.

Tongass logging has been politically controversial for decades. In 2001 the US government adopted the Roadless Rule, banning new road construction in roughly 9 million acres of the Tongass and protecting most of the remaining old-growth from large-scale industrial logging. The rule was rolled back in 2020 but reinstated in 2023. Logging continues at much reduced levels, alongside tourism, fishing and recreational use as the forest's main economic activities.

The Tongass has been the home of the Tlingit, Haida and Tsimshian peoples for over 10,000 years. These coastal indigenous peoples developed complex societies based on salmon and cedar, with elaborate art (including the world-famous totem poles), longhouses, and a clan-based social structure. Cedar bark was woven into clothing, hats and ceremonial regalia. Salmon was the staple food. Many Tongass place names and conservation initiatives now incorporate Tlingit traditional knowledge, and the Forest Service co-manages parts of the Tongass with tribal governments.

The other big temperate rainforest is the Valdivian in Chile. The country is the United States.