Last week I was walking through a grove of coast redwoods in the sunshine with not a cloud in the sky and suddenly felt really depressed. What was wrong with this picture? Simple, it was January but felt like September. The forest floor was brittle not soft, the moss was dry and compressed, there were few mushrooms, the ferns were suffering and I was in a t-shirt. This was NOT California’s winter weather. So odd that blue sky and bright sun can be ominous. I looked at the trees and I realized they were at least 600 years old and had seen many winters like this one. So I should not give up hope for the winter rains quite yet.
California has 2 trees for their state tree- the giant sequoia and the coast redwood. Both are incredible biological wonders. The General Sherman tree – a giant sequoia in Sequoia National Park- is the largest tree in the world. And a coast redwood named Hyperion is the tallest tree in the world at 380’. Which is by the way 75’ taller than the statue of liberty!
But 140 million years ago when the worldwide climate was much wetter and warmer, redwoods stretched across the entire northern hemisphere and were one of the dominant conifer. As the climate changed redwoods have become more and more restricted until now they exist in a very narrow band from Big Sur to just over the Oregon border; they range inland no more than 45 miles. The largest specimens thrive in deep valleys with abundant rain and fog where the soil is kept moist all year. But the key to distribution is the presence of coastal fog. The greatest pressure on redwoods occurs during August and September. The winter rains are but a distant memory and hot, dry east winds desiccate the trees creating intense water stress. But moist air in the form of fog rolling in from the ocean is literally a lifesaver.
As the air hits the redwood foliage the water condenses out and drops to the forest floor. The giant trees have tiny root hairs that are ubiquitous and can take up the precious commodity. Scientists estimate that fog contributes 20% of the water needed by redwoods. They have survived this long so I suspect they will make it through this winter just fine.



Posted on

June 3, 2013