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Rings on the move
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A tree’s natural habit is to grow straight up, but environmental conditions like wind or ground instability can cause trees to lean. Ground subsidence from permafrost thaw is a common way that trees around Fairbanks lean or appear "drunken."
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Trees in seasonal environments like Fairbanks add a growth ring each summer, which provides an archive of past environmental conditions.
Conifer trees like spruce respond to leaning by growing a distinct, darker ring. This is called reaction or compression wood. Such rings have more lignin, a structural component of wood. These rings are thicker on the down-lean side of the trunk, which helps right the leaning tree |
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As part of the Permafrost Grown Project, we use the tree ring record of reaction wood in leaning spruce trees around Fairbanks to reconstruct permafrost thaw over the past 150 years. The aim is to better understand how sensitive permafrost thaw will be to future climate warming.
The painted spruce “cookies” below illustrate the effects of tree lean from permafrost thaw.
The reaction wood is at the top half of the cookie. Painted silhouettes of spruce trees are oriented perpendicular to the concentric rings.
The painted spruce “cookies” below illustrate the effects of tree lean from permafrost thaw.
The reaction wood is at the top half of the cookie. Painted silhouettes of spruce trees are oriented perpendicular to the concentric rings.
Art by Iris Sutton, an artist, farmer and farmer-collaborator on the Permafrost Grown Project.
Research by Benjamin Gaglioti, research assistant professor at the Institute of Northern Engineering and research member of the Permafrost Grown Project.
Research by Benjamin Gaglioti, research assistant professor at the Institute of Northern Engineering and research member of the Permafrost Grown Project.
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