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  1. Northern Tree Habitats - Geophysical Institute

    Jan 22, 2026 · Interior Alaskan forests have only six native tree species: white spruce, black spruce, quaking aspen, balsam poplar, larch (tamarack) and paper birch. Northern Canadian forests have all …

  2. Tree Rings and History | Geophysical Institute

    Jan 22, 2026 · A tree's age can be easily determined by counting its growth rings, as any Boy or Girl Scout knows. Annually, the tree adds new layers of wood which thicken during the growing season …

  3. More on Why Tree Trunks Spiral | Geophysical Institute

    Jan 22, 2026 · I eventually found a tree with a spiral lightning mark and it followed the spiral grain exactly. One tree, of course, proves nothing. "But why should the tree spiral? More speculation here: …

  4. The secret life of red squirrels | Geophysical Institute

    Nov 27, 2024 · Stan Boutin has climbed more than 5,000 spruce trees in the last 30 years. He has often returned to the forest floor knowing if a ball of twigs and moss within the tree contained newborn red …

  5. Trees as Earthquake Fault Indicators | Geophysical Institute

    Dec 18, 2025 · Then using tree ring dating methods, it may be possible to date earthquakes occurring before historical records were kept. The ability to identify and date very large earthquakes occurring …

  6. Witches' Broom | Geophysical Institute

    Jan 22, 2026 · Witches' broom on spruce trees is caused by a rust disease (a kind of fungus disease). The rust lives on the spruce tree throughout the year. Each spring, small yellow pustules appear on …

  7. Burls - Geophysical Institute

    Dec 18, 2025 · Burls, spherical woody growths on the trunks of spruce, birch and other trees, are commonly found throughout wooded parts of Alaska.

  8. Feltleaf willows: Alaska’s most abundant tree | Geophysical Institute

    May 25, 2023 · The most plentiful moose food in the state — and probably Alaska’s most numerous tree — is the feltleaf willow, which was once called the Alaska willow. As its name implies, the feltleaf …

  9. Tropical Fossils in Alaska | Geophysical Institute

    3 days ago · A 20-inch fossil palm leaf that once waved over a tropical forest in Alaska 45-60 million years ago. The fossil was found in rocks near the Malaspina Glacier. Photo from the U.S. Geological …

  10. Orange trees in the Alaska Range | Geophysical Institute

    Sep 3, 2020 · It was a tree disease known as spruce needle rust, which infects only the current year’s needles of white, black and Sitka spruce trees. The orange powder is composed of millions of tiny …