Science Diary: Redwoods – Clear Cut
Sillett: This tree’s died back and recovered six, seven times here at the top. I’m on the trunk of a trunk of a trunk of a trunk, which is the highest point and I’m tied into the thing. It’s not too comforting. But I’m keeping very still.
Look at an old tree and you can see the signs of the threats it’s faced and survived over the years. 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 and an expert on redwoods. Right now, he’s at the top of the world’s second tallest tree, in California’s Redwood National Park.
Sillett: Looking at that trunk I see lots of small dead branches about a meter from the top, implying that part of it died back, and then it recovered and it kept its lead. Several other little trunks up here also have live tops, but there are scattered dead branches here and there. So, these trees live for thousands of years, and they go through bouts of drought, and then they just recover when the conditions get better.
Adjacent to these old growth redwoods is land that was clear cut just a few decades ago, prior to an expansion of the park in 1978. But Redwoods at the edge of this clear cut land endure full exposure to wind and other elements, which take their toll on trees.
Sillett: I suspect that the die back on that clear cut edge and extending several hundred meters into the forest was probably coincident with that severe drought that we had in the mid-1970s, because this is about when that was cut. So not only were they more exposed to wind from the edge of the clear cut. But it was a really dry year. And so this die back I’m seeing here at the top of this tree and then recovery probably coincides with that.
We’ll hear more about Steve Sillett’s discoveries in the canopies of these Redwood giants in future programs.
Pulse of the Planet’s Science Diaries are made possible by the National Science Foundation. I’m Jim Metzner.