Low-cost “tree fitbits” can pinpoint the precise timing of tree activities, like spring bloom or autumn leaf change, according to a new CU Boulder study. Researchers outfitted two East Boulder ash trees with high-resolution accelerometers, efficiently tracking how the trees responded to changing seasons. And in the coming years, arborists could efficiently monitor trees by the thousands with this technology—ultimately giving researchers insight into how tree phenology is changing with a warming climate.
“Accelerometers are in cars, smartphones and fitbits—they track movement in real time. When we put them on trees, accelerometers detect vibrations on the trunk as the tree sways in the wind,” said Deidre Jaeger, recently minted CIRES PhD researcher and lead author of the study out this week in Agricultural and Forest Meteorology. “That sway corresponds to the tree's mass, which tells us what the tree is doing.”
A tree’s mass all depends on its water uptake throughout the seasons, creating the structural differences that determine how it dances in the wind. In the winter, trees are dry and brittle. “Think of the quick, shaky rattling sound of leafless trees in the dead of winter,” Jaeger said. “Now think of spring: the trees are lush with leaves, full of water, and sway with flexibility.”
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