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  1. Northern Tree Habitats - Geophysical Institute

    Jan 29, 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 …

  2. Tree Rings and History | Geophysical Institute

    Jan 29, 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 …

  3. Tropical Fossils in Alaska | Geophysical Institute

    Jan 29, 2026 · 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 …

  4. More on Why Tree Trunks Spiral | Geophysical Institute

    Jan 29, 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 …

  5. 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.

  6. The Pinhole: Nature's Lens | Geophysical Institute

    Jul 10, 1972 · Sunlight passing through minor apertures between tree leaves is focused like the rays in a pinhole camera (and, just as with a simple lens, the image is upside-down).

  7. Boreal owls perform by daylight | Geophysical Institute

    Mar 20, 2024 · The late biologist Dave Klein attached the nest box to a black spruce tree north of the University of Alaska Fairbanks ski trails many years ago. In search of a mate, the owl sings …

  8. Witches' Broom | Geophysical Institute

    Jan 29, 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 …

  9. 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 …

  10. Bark Beetles in Spruce Trees | Geophysical Institute

    Nov 20, 2025 · Bark beetles attack spruce trees in early summer. These brownish black beetles are common throughout Alaska and Yukon Territory where they kill trees by boring through the …