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  1. Cottonwood and Balsam Poplar | Geophysical Institute

    Apr 3, 2026 · The Klukwan giant holds the national record for black cottonwood diameter. Its nearest rival, a tree near Salem, Oregon, does hold the national height record. The Klukwan giant belies the …

  2. Northern Tree Habitats - Geophysical Institute

    Apr 3, 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 …

  3. Tree Rings and History | Geophysical Institute

    Feb 12, 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 …

  4. More on Why Tree Trunks Spiral | Geophysical Institute

    Apr 3, 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: Foliage …

  5. 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 …

  6. Tropical Fossils in Alaska | Geophysical Institute

    Apr 3, 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 U.S. Geological …

  7. Burls - Geophysical Institute

    Apr 3, 2026 · Burls, spherical woody growths on the trunks of spruce, birch and other trees, are commonly found throughout wooded parts of Alaska.

  8. Bark beetles take Connecticut-size bite out of Alaska | Geophysical ...

    Feb 26, 2004 · Knowing that, forest managers might be able to anticipate an outbreak and plan tree harvests ahead of the beetles or try preventative measures that might work on small outbreaks, such …

  9. Burls and Human Cancer | Geophysical Institute

    Apr 3, 2026 · Photograph of a section cut from a tree with 5 burls that simultaneously grew at the same level on the tree. Annual growth rings can be followed around the tree trunk at center and into each …

  10. 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).