Recent research determines that the coniferous Douglas Fir grows only so tall before it runs out of water. Unable to pull water any higher, the tree begins to experience drought-like conditions. Growth ceases at about 350 feet — the same height as a 35-story tower.
“The foliage is struggling to get enough water and seems to be under drought stress. It’s not unusual to see periodic die-back at the tops of very tall Douglas-fir trees that are near their height limits,” explains Rick Meinzer, a Forest Service scientist at the Pacific Northwest Research Station. The same phenomenon may occur in the famed Redwoods.
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Source: The Telegraph