Transcript:

music; ambience

SS: "Redwoods are not only putting on more wood than they ever have, but nearly all of the wood they produce each year is converted to decay resistant heartwood.”

Redwood trees are known for their incredible resistance to disease, decay, and fire. But it turns out that these attributes come with age. Welcome to Pulse of the Planet's Science Diaries, a glimpse of the world of science from the inside. Steve Sillett is an ecologist at Humboldt State University. His latest research shows that as redwoods grow older, quality wood production increases.

SS: “In some species obviously, as they get older, they succumb to disease and decay. But in this species, where there's incredible resistance to disease, and to decay, and to fire, I don't think it's true that as they age they slow down in their growth. And if anything they actually speed up, in terms of absolute wood production per year.”

Steve Sillett’s team is using dendrochronology, the analysis of annual tree rings, to precisely measure wood growth in the main trunks of old redwoods.

SS: “So even though the annual rings are very small, two to five millimeters on average, on a big tree, when you lay that down over the entire surface of the tree, it adds up to a heck of a lot of wood. On the order of one to two cubic meters of wood a year is being produced by the biggest redwoods.”

This high quality heartwood enables old growth redwood forests to thrive for thousands of years.

SS: “A young tree doesn't have good wood. It has sapwood mostly, and it's not rot resistant, and so even though it's redwood, it's not better than say, hemlock or grand fir, in that regard. The value in redwood, it's in the rot resistance, it's in the tight grain, and those are things that you can't obtain from a young tree.”

Our thanks to Steve Sillett. Please visit our website at pulseplanet.com.

Pulse of the Planet’s Science Diaries are made possible by the National Science Foundation. I’m Jim Metzner.