While attending the 2017 Sustainable Design Leaders Winter Summit in California, I had the opportunity to extend my education in sustainability beyond the boundaries of the conference when we hiked the Purisima Creek Redwoods Reserve.
The reserve is a second growth forest, which means that this particular forest was logged in the late 1800s and early 1900s. It is made up of magnificent trees that are about one hundred years old. While this may seem old, the trees of the original forest were about one thousand years old when they were logged, and visitors can still see today the twenty-foot-diameter stumps along the trails.
Redwoods are the tallest trees in the world. Undisturbed, old-growth forests surpass three hundred feet in height, and individual trees may literally have been growing since the Roman Empire. Their grandeur is one of the reasons why redwood forests have long captivated people. We had a blast strolling through the reserve, but not just because the sun came out that morning after raining non-stop during the entire Summit, which prevented us from enjoying the lovely gardens of the retreat center. And it wasn’t even because the forest was especially lovely during that first sunshine after multiple days of rain, or because we had the good fortune of crossing paths with multiple banana slugs and newts. Rather, the visit was so inspiring because of our tour guide who helped us gain an understanding of the importance of the redwood forests on a deeper level.
In addition to being some of the tallest trees in the world, redwoods are also some of the oldest trees. The ancient relatives of the redwoods appeared more than two hundred million years ago—when dinosaurs were still alive—and were the dominant tree in the Northern Hemisphere. Modern relatives have adapted to different environments and live throughout the world today, although many of them are threatened or endangered. However, the sole exemplars considered relic species living today are the Coast Redwood, Giant Sequoia, Dawn Redwood, and Alerce. In North America, Coast Redwood and Giant Sequoia forests are only found along the coast of California. Alerce forests are found in South America, and the Dawn Redwood in China.
These redwood forests sequester more carbon dioxide per hectare than any other forest in the world, including the Amazon rainforest. On average, these trees capture 2,600 metric tons per hectare, which is more than twice the estimated 1,000 metric tons per hectare captured by old conifer forests in the Pacific Northwest, with a record of 5,190 metric tons per hectare set by the Jedediah Smith forest in Northern California. (These findings are the result of a seven-year study by a team of researchers from Humboldt State and the University of Washington in collaboration with UC Berkley and the Save the Redwoods League.)
There are other tree species that can reach the three-hundred-foot mark, but the reason why the redwoods are so adept at storing carbon has to do with their longevity. A redwood can live more than one thousand years. When it dies, its trunk does not rot immediately like most trees but rather is preserved for hundreds of years, locking the carbon within its heartwood.
The high concentrations of tannins, or the bitter chemicals that make redwoods unappealing to insects and fungi—along with the thickness of their bark, which makes them fireproof—are responsible for the trees’ longevity. These same characteristics, as well as the beautiful color or their wood, is what makes them so valuable in the construction industry. In the 1900s, redwood from Purisima Creek was used for making shingles, timber, and even mulch in San Francisco. Still today visitors are able to see the marks of the areas that were once clear cut as well as traces of the seven saw mills in the park.
Another fun fact about redwoods is that a single specimen can live for millennia. Redwoods reproduce in two ways: one is through seed as many other plants reproduce, but they also can sprout from their parent’s trunk, taking advantage of the established root system and creating genetically identical copies of their parents. Even though the parent tree may die, a copy will succeed it, and when it dies a third copy may succeed the second one, and so on. They are different trees, but genetically they are the same specimen.
The services provided by redwood forests to their ecosystems are enormous and hard to quantify. Simplistically, human life depends on the benefits that nature provides every day, everywhere, such as cleaning the worlds’ water and air, and providing nutrients for the soil to produce food, storm, and flood protection, etc. In addition to these daily transactions that provide vast economic benefits to our society, redwood forests may be critical for our planet’s survival because of their ability to sequester large amounts of carbon for long periods of time. As we continue to burn coal, gasoline, and other fossil fuels that release large amounts of carbon dioxide into the atmosphere, these forests become invaluable asset that we need to protect.