I’m writing this post basically as a way of sharing some of my photos of an incredibly beautiful type of forest. Even if you don’t read the rest of the post, just looking at the photos might help reduce stress. But that’s another post for another day.
There are vast types of forests in the world, but I’d like to focus your attention on possibly the most awe inspiring, the Coast Redwood Forests. These are forests dominated by the species Sequoia sempervirens, otherwise known as the Coast or California Redwood.
Like the name implies, the species is found on the Pacific coast of northern California and southern Oregon, in the United States of America. This narrow strip is 750 km long and exists in small pockets where the moisture levels are high coming off the ocean, but not too close to the ocean, as the wind, salt and sand spray are too harsh to for the trees to grow
In summer, costal fog (that nearby cities like San Francisco are well-known for) is a critical water source for the forests. It can provide up to 30% of total water needs for the species. Trees can intercept the moisture directly through their leaves, while excess fog condenses on the branches and leaves, drips onto the soil and gets taken up by the redwoods and surrounding vegetation. In summer, redwoods can get up to 45% of water from fog in the absence of rain as their needle leaves trap moisture.
In Latin, semipervirens means “evergreen” or “everlasting” as when they were first classified they seemingly had timeless lifespans. This is not quite true, but compared to our short lifespans it may as well be. The oldest Coast Redwood is roughly 2,200 years old, so it predates the Roman Empire and most of the world’s major religions.
Not only are they incredibly old, they are incredibly tall too. The tallest trees on earth. Currently the tallest tree on earth is a Coast Redwood named ‘Hyperion’ that is in incredible 115.6 m tall.
Research in 2016 determined that coast redwood forests store more carbon than any other forest in the world, with the wetter, northern rainforests storing 2600 tons of carbon per hectare. Because the wood of the coast redwood and other conifers in the forest are so resistant to decay the carbon that is stored is kept from the atmosphere for huge amounts of time, until there is a fire. So these areas are really important for the carbon balance of our planet.
The forests can reach such incredible levels of biomass (which is plant tissue, like trunk, bark, branches, leaves, roots etc.) because of some nifty traits that redwoods possess that are beneficial to the whole forest. The crown (i.e. the branches, leaves, and reproductive structures extending from the trunk or main stems) become emergent, meaning it sticks out beyond the height of all the other trees in the forest and intercepts light without shading out the species below. Redwoods have special adaptations that make their crown incredibly successful for capturing light for photosynthesis (how plants make their energy). They can change the shape of their leaves to get the most light, their trunks have an exceptional regeneration capacity to create new branches to recover their crown from any damage and their wood and bark is extremely resistant to decay and from fire, allowing them to survive for centuries.
Future of the forests
Only 5% of old-growth coast redwood forests remain. The rest are secondary forests due to current and historical logging. Government protection and a long history of conservation efforts means that the forest aren’t under threat from development, however climate change may be threatening the future of the forests.
Currently, the Western US is experiencing severe wildfires despite breaking their drought with a wet winter. The numbers of extremely hot and dry days are increasing and are creating perfect conditions for fires. New research shows that the increasing aridity and temperature caused by human-induced climate change accounts for an extra 4 million hectares of forest fires in the Western US in the past 30 years.
Fires aren’t necessarily bad, and like Australian species, Sequoia sempervirens needs fires to regenerate. But if the fires are too intense they can be killed and if the fire is too frequent the younger trees will be burnt before they can be big enough to survive the fire.
It is a delicate balance. With climate change other aspects of the trees survival like the reliable summer fog might be declining putting the forests under increasing strain. We all know the importance of addressing climate change and the future of these incredible forests is another reason.
Redwoods in our backyard
If you simply can’t wait to for the opportunity to see these forests, there is good news as you don’t have to buy a plane ticket to US just yet. There is a redwood forest growing in the Otways only 2 hours from Melbourne. Although with a different understory of plants, and not quite as tall yet, this old logging experiment from the 1930’s is the next best thing.
If you have a weekend free I recommend you go and see the exquisite beauty of Australia’s natural history in the Otways and then transport yourself to the Western US coast all in the one day.