The coast redwood, or Sequoia sempervirens ("sempervirens" means "forever living") grows in the thin coastal strip from near Brookings, Oregon, to just south of Monterey on the California Big
Sur Coast. It
grows best where fog moderates the typical summer drought
conditions. Here, winters are usually mild with abundant
rain. Frost is common, but hard freezes and snow are unusual.Coast redwoods grow best only as far inland as the extent of the coastal maritime climate. Here, fog often protects the trees from searing summer heat and freezing winter cold. Fog plays an important role in the survival of these trees, and pockets of inland trees usually coincide with foggy canyons. Redwoods can even generate their own fog, using the hugh of transpiring moisture that condenses at night above the cool valley groves.
Each large redwood can release up to 500 gallons of water per day into the air from their needles. As the air cools each evening, this moisture condenses into fog that protects the forest much like a blanket, keeping the day's heat trapped below. Many other plants have taken advantage of this temperature protection and do not have the ability to withstand forest extremes. Cutting these forests destroys orchids, lilies, other plants that depend on the protection of the redwood.
Small pockets of redwoods in isolated groves like Richardson Grove on the South Fork of the Eel River and Grizzly Creek on the Van Duzen River are probably remnants from a wetter and cooler time such as the last ice age that ended 8,000 to 10,000 years ago.
These trees have survived because the mountain valleys trap cool downward moving air on summer evenings that condense moisture into fog. The mountain valleys are also warmer in winter than the surrounding mountain tops. This preserves an isolated temperate environment for the redwoods.
Text from, Coast Redwood. Copyright © 1991 by Larry Eifert. Used with permission.