An arborist in Royal Oak,14 Michigan, received the usual calls from people worried about their trees suddenly dropping huge numbers of acorns and had to inform them about mast years, a temporal phenomenon in which trees coordinate to drop their fruit all at once. (Describing masting in pecan trees, Robin Wall Kimmerer points to studies that suggest the trees may be using underground mycorrhizal networks—in other words, talking to one another—in order to enact such a “unity of purpose.”)
