Trees Possess a 'Heartbeat' of Their Own, Scientists Discover

Article by Alanna Ketler of Collective Evolution

Each day, researchers uncover fresh insights about trees and their hidden complexities. While we already understood they are living organisms, new findings suggest they are far more dynamic than previously imagined. Trees are linked below ground and can exchange information; now scientists have identified that trees possess a kind of pulse—one so gradual that it had escaped detection until now.

Earlier, the prevailing view held that water travels through trees via osmosis in a steady, uninterrupted flow. However, recent observations reveal that tree trunks and branches undergo rhythmic contraction and expansion, actively pushing water upward from roots to leaves—similar to how a heart circulates blood.

In contrast to the human heartbeat, a tree’s pulse is extraordinarily slow—occurring roughly once every two hours. Its function is not to manage blood pressure but to regulate the water pressure coursing through the tree.

András Zlinszky from Aarhus University in the Netherlands stated, “We’ve observed that the majority of trees undergo consistent, cyclical shape variations that are coordinated throughout the entire plant, indicating cyclical shifts in water pressure.” What method led to this finding?

In a 2017 study, Zlinszky and his collaborator Anders Barfod employed terrestrial laser scanning to track 22 distinct tree species, aiming to document canopy shape variations over time.

All observations occurred inside greenhouses during nighttime hours to eliminate sunlight and wind as potential causes of movement. For multiple trees, branches were seen rising and falling roughly one centimeter every few hours. Upon concluding the nocturnal experiment, the team formulated a hypothesis: this motion indicates that trees are actively drawing water from their roots and dispersing it throughout their limbs.

The scientists suggest this finding implies that trees may indeed possess a form of heartbeat. Zlinszky explained to New Scientist, “Traditional plant physiology describes most transport mechanisms as steady streams with minimal temporal variation. Current models do not account for fluctuations occurring on cycles shorter than 24 hours.”

Currently, the precise mechanism behind this pumping remains unknown. Researchers hypothesize that the trunk may compress water, forcing it upward through the xylem—a network of tissue responsible for conveying water and nutrients to every branch and leaf.