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  • Hi, I’m Ranger Jim and I’d like to share with you a few things that have recently been

  • discovered in the tops of ancient redwood trees, the old-growth redwood forest canopy.

  • Research in old-growth forest canopies has increased dramatically since 1996 with the

  • initiation of scientific tree climbing by Dr. Stephen C. Sillett at Humboldt State University

  • in Arcata, California. His research has revealed a previously under-appreciated ecosystem high

  • in the tops of the treesan arboreal ecosystem that is virtually impossible to study from

  • the ground. As they age over many hundreds of years, and in response to wind, fire, and

  • other falling trees, redwoods develop very unique and individual crown structures. Their

  • complicated crowns consist of re-sprouted, orreiteratedtrunks arising from the

  • main trunk, other trunks, and limbs. Also over many years, these woody structures in

  • the treescrown interact, sometimes rubbing against each other and eventually fusing so

  • that living cambium produces sapwood that bridges regions of the crown hydraulically.

  • Right here I’m standing next to an example of a huge reiterated trunk that came crashing

  • down out of this monster redwood here last wintertime. Fusions, very old limbs, and crotches

  • between reiterated trunks form platforms on which organic soils begin to build from falling

  • leaf litter. These organic soils in turn provide a substrate for epiphytes, or tree-dwelling

  • species like leather fern, which forms huge sprawling mats that develop arboreal soils

  • that are over a meter deep in places. A set of fern mats in an old tree crown can weigh

  • over 1,700 pounds dry mass, and hold over 2,000 gallons of water. Soils beneath fern

  • mats and decaying wood inside trunks and limbs can store huge amounts of water that can sustain

  • drought-sensitive organisms high above the ground throughout the year. The wandering

  • salamander, an arboreal species and the only amphibian denizen of redwood forest canopies,

  • resides in cavities within fern mats and decaying wood and feeds on a rich invertebrate community

  • that includes aquatic crustaceans called copepods that are also found in local streams. In addition

  • to huge leather fern mats, redwood forest canopies are home to at least 265 epiphyte

  • species, or tree dwelling species, including: lichens, mosses, liverworts, flowering plants,

  • ferns, and even other conifers. All of the flowering plants found in the canopy are usually

  • found on the forest floor, including huckleberries, salal berries, tanoak, and bay-laurel. Even

  • in the oldest and most complex redwood forests, just a very few old trees provide the majority

  • of arboreal diversity, because these trees have the majority of gnarly structures available

  • in the forest. What amazes me is that weve only begun to investigate the complexity of

  • the ancient redwood forest canopy, and only about 100,000 of the original 2,000,000 acres

  • is still ancient forest. Thanks to our forbearers, almost half of that is now protected within

  • Redwood National and State Parks.

Hi, I’m Ranger Jim and I’d like to share with you a few things that have recently been

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B2 中上級

レッドウッド・レンジャー・ミニットレッドウッドの森のキャノピー (Redwood Ranger Minute: Redwood Forest Canopy)

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    cyrain に公開 2021 年 01 月 14 日
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