Incredible plants: Sequoia sempervirens

The giant redwood of the western US is among the largest organisms on Earth. It is one of fascinating group of conifers and is the tallest tree on earth. Aside from their impressive size, these trees form the foundation of one of the most interesting, productive, and beautiful ecosystems on earth.

Headwaters Forest Reserve, Humboldt County, CA.

Redwoods are members of the Cupressaceae, a family of conifers (usually cone-bearing, but not flower-producing, seed plants) that includes cypresses and the Giant Sequioa of the Sierra Nevada. Fossil distributions show that the ancestors of redwoods used to occur throughout much of the northern hemisphere (Chaney 1990). Today, redwoods are distributed from central California north to the very southwest corner of Oregon. These trees thus occupy a relict distribution, one that is just a fraction of its former empire. All redwood populations are found relatively close to the coast where they thrive in coastal fog (Eckenwalder 2009).

Sequoia sempervirens has a life span of about 2000 thousand years (Eckenwalder 2009), making it one of earth’s oldest organisms in addition to one of its largest. Although plants produce copious amounts of cones (and thus presumably millions of seeds per individual), new trees can also spread vegetatively from the bases of existing trees (e.g., from “burls”). This process in fact, can lead to the circular growth patterns of the trees. Over time, the central older parent tree dies but leaves a ring of younger descendants growing in a ring.

Redwoods reach their full glory in Humboldt County where extensive groves line stream basins and the slopes of the mountains along the coast. They can be found in nearly monotypic (single species) stands, but co-exist with other trees such red-trunked madrone, white-trunked alder, tan oak, big-leaf maple and Douglas fir (Jepson 1984). Tall Trees Grove in Redwood National Park in northern Humboldt County has some of the tallest individual trees known in the world. The trees are immense indeed, but from the perspective of the forest floor, they are so massive that would be hard to discern any difference between the record-breaking individuals and their almost equally tall neighbors.

The southern most populations of redwoods are in Big Sur, the rugged stretch of coastline between San Luis Obispo and Monterey. The forests are fairly extensive around the Big Sur Valley and then just occur in isolated in steep valleys right along the coast farther south.

Redwood is a popular lumber tree. It has soft, but beautifully grained and pleasantly aromatic wood. Previously there was intensive logging of redwood trees to provide lumber for the burgeoning growth of cities such as San Francisco. Unfortunately, a large percentage of original forest has been harvested, leaving only a relatively small percentage of remaining old growth forest today. Much of that old growth is preserved in state or federal park lands (Eckenwalder 2009). With a bit of observation there is an unmistakable difference between the structure of old growth forest and recovering secondary forests. The former is like an open pavilion with huge columns of ancient trees. Recovering forests are darker and more dense, the younger trees vying to not be the ones that will be crowded out as the forest matures.

References

Chaney, R.W. 1990. Redwoods of the Past. Save-the-Redwoods League, San Francisco, 8 pp.
Eckenwalder, J.E. 2009. Conifers of the World. Timber Press, Portland, 720 pp.
Jepson, W.L. 1984. Trees, Shrubs and Flowers of the Redwood Region. Save-the-Redwoods League, San Francisco, 16 pp.