Trees Signal Back: How Plants Detect, Defend, and Communicate Under Attack
Trees detect being browsed or chewed by insects, piercing-and-sucking bugs, and even pathogens or nearby stressed trees, using cues from mouthparts, vibrations, saliva, microbes, and emitted signals. In response they boost chemical defenses such as tannins and phenolics, grow tougher leaves, and release volatile compounds to recruit predators of their attackers; some species even share pest information with neighbors to bolster collective defenses, though drought and climate stress can blunt these responses (e.g., Aleppo pines). The piece also engages with questions about tree “feelings” and references Peter Wohlleben’s ideas about the hidden life of trees.