This is a short natural history of the coast redwood Sequoia sempervirens forests found nowhere else on earth but the Northern California coast. I recently took a trip to the Redwood National Park in the far northwest corner of California. This article will be illustrated with pictures that I took on that trip.
The coast redwood is a survivor from a much earlier evolutionary time. It can be traced back to the age of the dinosaurs. It's only living close relative is the Sequoiadendron giganteum giant sequoia found in isolated spots in the Sierra Nevada Mountains. In the distant past when the earth's climate was warmer and wetter than much of it is now, related sequoia species appear to have been widely distributed.
The coast redwood is the world's tallest tree.
They commonly reach heights of 250 ft. and exceptional specimens exceed 350 ft. with the present record holder being at 367 ft.
California is one of the six Mediterranean climates. The others are two limited areas in South Australia and Western Australia, the Cape Provence of South Africa, Central Chile and the Mediterranean. They are all located on the west coasts of continents and are at similar latitudes. They are characterized by alternate wet and dry seasons. In California almost all annual rainfall occurs from late October to early May. There is a steady drop in annual rainfall as you move south along the coast. During the summers there are no storms to disturb the upper atmosphere. There is a fairly steady onshore wind from the northwest. This drives an ocean current bringing cold water down the coast from the nothern Pacific. It provides nutrient rich waters for fish and creates heavy fog that hugs the coast for much of the summer.
Native plants must develop an ecological strategy to survive in this climate. Just as plants native to areas with cold winters must have a means of making it through those, Mediterranean natives must get through the long dry season. Temperatures on the California coast seldom reach the point of frost so the winter is a time of cool wet conditions. Many natives do the heavy work of blooming and reproducing during that period and enter some form of semi-dormancy during the summer.
Ecology Of The Redwood Forest
The natural range of the coast redwoods extends over a narrow band of the coast from about Big Sur in the south to just past the Oregon Border in the north. The width of this band is determined by the penetration of the summer fog, since it provides a source of moisture in the absence of rain.
The redwoods grow to the edge of the rocky cliffs and catch the fog in their soaring tops. The moisture drips down to the forest floor. Fog drip adds about 10 ins. of precipitation over the course of the summer. The fog belt extends up to the top of the first major ridge in the coastal mountains. Further inland it burns off in the early morning,
but lingers over the ocean for most of the day.
Two hundred years ago dense redwood forest covered much of the Northern California coast. The characteristics that enable the tree to survive also make it a very attractive source of lumber for construction. Almost all of the natural range was logged over in the 19th and early 20th centuries. Redwood National Park is a mosaic of federal and state parks in Humboldt and Del Norte counties. It is about the only place left where one can see the full natural habitat of the redwood forest as it once existed. The battle to save the old growth redwoods was a classic confrontation between environmentalists and the timber industry. It provided us with that immortal quote from Ronald Wilson Reagan:
"If you've seen one redwood tree, you've seen em all."
One of the many strange things about redwoods is that such gigantic trees actually have very shallow root systems.
The sprouting of new trees from the roots creates a dense network of tall straight trees. This interlocking arrangement provides stability for a grove of trees and shuts out other large trees that would compete with the redwoods.
Redwoods typically live about 700-800 years. Some have lived close to 2000 years. They have very thick bark that protects them from insects and a high level of tannin that protects them from rot. When a large tree eventually falls to the forest floor, it will take more than a century before it fully decomposes. In the meantime it creates an environment that supports a diversity of plant and animal life.
The fallen trees provide a glimpse of what a relatively small root system is holding them up.
Fire is an ever present reality in California forests during the long dry summers. It was a reality to be responded to long before humans came along to add to the problem. Redwoods are extremely resistant to fire and can continue growing after sustaining extensive fire damage.
The floor of the forest provides a moist and deeply shaded environment that supports a think carpet of various pants.
Sunlight penetrates this shadowy world in a sometimes dramatic manner.
When things get too crowded on the forest floor, some plants take to high rise living.
The moss that thrives in such a humid spot catches the sun with an eerie sense of forest spirits.
Older trees develop growths around their base called burls.
Each of these has the ability to sprout a new tree. There are obvious spots in the forest where a tree died and its burls gave rise to a circular cluster of new trees.
Mountain springs keep small creeks flowing through the forest during much of the summer.
The redwood forest is a special place. The trees tower so high above that one can never get a complete perspective on the whole, much less capture it with a camera. It is a place of contemplative peace, where the world's struggles temporarily recede. It reminds us that in human kind's struggle to bend the planet to our greedy wills, we have destroyed so much that will not likely be restored.