Carbon uptake, storage, and allocation patterns contribute to blurring of annual 14C signals in tree rings.
Hessl AE, Richardson AD, Filwett R, Andreu-Hayles L, Walker M
Phenology
Every tree ring in the old oak at the edge of your yard is a diary entry — but this research reveals that some trees write their entries weeks or months late, depending on how they stockpile and spend their sugar reserves before laying down new wood.
Scientists use tree rings like a calendar to read the history of Earth's atmosphere, including rare solar storms that leave a chemical fingerprint in a single year's ring. But it turns out different trees write that fingerprint at slightly different times, because they store up sugars from old photosynthesis and mix them with fresh sugars before building new wood. This blurring effect means the same atmospheric event can look a little earlier or later depending on which tree — or which species — you're reading.
Key Findings
Significant variability in radiocarbon signals exists between individual tree samples even when measuring the same atmospheric event, limiting the precision of tree-ring-based dating.
The lag between when a tree captures carbon through photosynthesis and when it actually incorporates that carbon into wood — mediated by nonstructural carbohydrate storage — is a key source of signal blurring in tree rings.
Phenology of carbon uptake and wood formation timing varies by species and interacts with stored carbohydrate use, meaning no single tree can be assumed to be a perfectly faithful recorder of annual atmospheric radiocarbon.
chevron_right Technical Summary
Trees don't all record atmospheric radiocarbon equally in their annual rings — how a tree stores and uses carbon sugars before building wood can blur or delay the chemical signal, meaning the same year's air chemistry may show up differently across species and individuals.
Abstract Preview
Tree rings are considered the gold standard for observing variation in past atmospheric radiocarbon (14C), yet little attention has been paid to whether different trees record tropospheric 14C even...
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