Coast Redwoods

(I started writing this while we were evacuated because of the CZU Lightning Complex fire. I finished it tonight.)

Redwood trees are survivors.

We’ve got about 100 substantial coast redwoods in our little piece of the forest. Since we evacuated for the massive wildfire (we’re home now) I’ve been thinking about them a lot. One thing that keeps coming to mind is that these trees have been here for a good long while and they’ve been through quite a lot, wind storms, severe droughts, flash flooding, and yes, even fires. They’ve survived a lot for a long time.

But how long, exactly? How old are the redwoods in our neighborhood and just outside our door?

It’s really difficult to estimate the age of a redwood tree by looking at it. Size doesn’t tell you everything because redwoods can add size at vastly different rates depending on their location. For example, I read about a 400 year old coast redwood on a steep hillside that had a diameter of only 2 feet, while a similarly aged tree growing near the mouth of a stream had a diameter of almost 12 feet.

Redwoods, like most trees, compete for water, soil nutrients, and sunlight. (An aside. Coast redwoods can also cooperate to share nutrients with neighboring trees.) So, like the redwood with a water advantage mentioned above, trees with a sunlight or soil advantage can also grow larger than their neighbors. And trees that are more spread out from each other often enjoy more soil and more sunlight and so tend to grow bigger than more densely packed redwoods.

And if that wasn’t enough, coast redwoods can grow as clones out of the stumps of a previous generation taking advantage of an expansive pre-existing root system to grow fast and large, far out-pacing a redwood that grew from seed.

All that’s to say that size alone is not a great proxy for age

To estimate the age of the trees in our neighborhood and around our home, I took a different approach. I knew that most of the Santa Cruz Mountains had been clear cut in the 19th century so the first thing I did was a lot of reading about when various logging operations happened in our area and I used those dates for some rough estimates of the ages of most of our mature trees.

The first logging in the area that would become our neighborhood was in the late 1860s. Those operations, turning the majestic old growth redwoods into lumber and shingles, continued until the late 1910s when this tract was subdivided for residential use. I think it’s a safe bet that most of the original trees were cut during that half century of logging and so the mature trees here today should mostly be between 100 and 150 years old.

But there are other ways to estimate a tree’s age besides size and historical events like clear cuts. One much more effective way is to count a tree’s rings. Since we’ve moved to the neighborhood, no large redwoods that I know of have been cut or taken down by storms, but several very substantial Douglas Firs have. And though they’re a different species, Doug firs live among the redwoods, live a long time, and were definitely around here and cut during the logging era. So I think they can serve as a reasonable proxy.

Not far up the road, two Doug firs came down from separate wind storms, and a third was cut because it posed a threat to a bridge on the neighborhood’s main road. Two of those trees had clean saw cuts that made counting rings easy. By my count, if I remember correctly, one of them was about 170 years old and the other about 200.

So that suggests some of the larger redwoods and Doug firs right around our home could also be older than 150 years, standing during the logging era, but survived the cuts for some reason.

Why might the loggers have left some trees behind? Perhaps they weren’t quite big enough yet. Or, maybe the tree was twisted or otherwise too irregular for the mills. Or it could be its location made cutting or transport too difficult. What ever the reasons, I think some of the trees in our neighborhood, and perhaps in our yard, survived the clear cutting that destroyed so much of the primeval forest in the area. They aren’t ancient, but they’re probably older than my earlier estimate of 100-150 years.

Based on the obvious difference in size, my guess is that several of our redwoods are two hundred years old (or more?) while most are probably between 100 and 150 years old. But, as I noted earlier, size isn’t well correlated with age, so it’s possible our biggest trees are big not because of age, but because of other advantages like proximity to water or less competition for sunlight. Our biggest tree, with a diameter of 7 feet, is right on the creek and doesn’t have any immediate neighbors so that could explain its size, but our second and third largest trees, both about 6 feet diameter, are well off of the creek and are densely packed with other very tall trees.

As I think about these trees that are probably 150 years old and very well could be two centuries old, I’m also reminded that while 200 years is a long time for us, it’s actually still quite young for a redwood and not terribly old for a Douglas fir either. There’s a redwood less than a mile from our door that’s 1,200 years old. Just about five miles away, there are 1,800 year old redwoods. I think the record for a coast redwood is 2,200 years. And Doug firs are no slouches either when it comes to longevity. They regularly make it to 500 years with some reaching 1,000 years old.

Many of the redwood trees in our yard have been around for more than a century, and some maybe two, and with any luck, most of them will be around for hundreds, or even thousands! of years more — they’ll survive storms and droughts and floods and probably several significant wildfires.

Redwood trees are survivors.

fire-scarred redwood trees in Asa's yard