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.