04/21/2026
I find this fascinating.
Scientists just confirmed that trees actively communicate with each other using ultrasonic sound pulses — forests are engaged in continuous acoustic conversation at frequencies completely inaudible to human ears.
Researchers at the University of Florence used ultrasonic microphones sensitive to frequencies between 20 and 200 kilohertz — far above the 20 kilohertz limit of human hearing — to record communication between European beech trees in Tuscany's Casentino Forest. Trees under drought stress emitted distinctive ultrasonic click patterns at 40-80 kilohertz that neighboring trees responded to within 6 hours by closing their stomata — the leaf pores that control water loss — before they themselves experienced any drought stress. The responding trees showed measurable physiological changes indicating they received and acted on the acoustic drought warning from their stressed neighbors.
Physical mechanism analysis confirmed the clicks originate from microscopic cavitation events — tiny bubbles forming and collapsing in water-conducting xylem tissue as drought stress builds — which propagate through both the air and the soil, traveling up to 50 meters between trees. The signal pattern carries information about stress severity — trees under severe drought produce higher frequency clicks more rapidly than mildly stressed trees — suggesting the acoustic communication carries quantitative not merely binary warning information.
Scientists now describe forests not as collections of independent competing organisms but as acoustically connected communities actively sharing survival information in real time.
Source: University of Florence, Italian National Research Council, Current Biology Journal, 2025
