Image credits: Sebastian Unrau.

To the naked eye, a forest is a quiet place, and the trees are the quietest. However, researchers like Dr. Richard Karban, a formally trained ecologist and member of the UC Davis Entomology Department since 1981, are changing the narrative. It turns out, the woods are actually quite noisy—we just can’t hear them.

The media often calls Dr. Karban the “Plant Whisperer,” a title he was unaware of until we spoke. He humbly shies away from the label, noting that he is just one of a growing number of experts dedicated to the field of plant communication.

Karban, who covers an array of intriguing topics, from “eavesdropping” plants to distinct plant “personalities”, is fully aware of the controversy surrounding his field. But he emphasizes that plant communication isn’t a fantasy; it is a biological response to specific cues.

These cues generally happen in three zones: through the air, under the soil, and within the plant tissues themselves. Karban’s research begins with the first zone: the invisible signals floating on the breeze.

Chemical Warfare and Airborne Signals

Image Credits: Richard Karban.

Advanced plant behavior now sits at the center of one of ecology’s most heated debates. Decades ago, little was known about it. Today, both researchers and scientists have become more responsive to the idea that trees and plants aren’t passive organisms. In fact, many researchers, such as Dr. Karban, argue that forests are highly communicative biological networks.

These are sophisticated behaviors, but Karban attributes them to evolution and natural selection, not hidden sentience. He cautions against projecting human emotions onto biology, but suggests that to understand plants, we must understand their version of a “Hierarchy of Needs.” Plants’ top priorities are simple but non-negotiable: light, water, nutrients, and not getting eaten by insects.

Dr. Karban didn’t expect plants to take center stage in his career. He initially set out to understand animals in crowded conditions. While studying cicadas early in his career, a colleague mentioned that the trees the insects fed on were not unresponsive.

This piqued his curiosity. He learned that when threatened, plants release specific chemicals that act as warning signals for their neighbors.

“I initially became interested in induced responses,” Karban says. He began studying interactions between plant species, specifically sagebrush, wild tobacco, and tomato plants.

Image credits: Matthew Smith.

His work focuses on Volatile Organic Compounds (VOCs). These are airborne chemicals that trees release when stressed or attacked by pests. “Plants don’t have ears, but they absolutely perceive airborne chemical signals,” he explains.

His experiments with sagebrush in California revealed something remarkable: plants exposed to the VOC “conversations” of their damaged neighbors suffered up to 40% less insect damage than unexposed control plants. Essentially, they heard the warning scream and raised their shields.

The Wood Wide Web

While Karban looks at the air, other researchers look underground. Dr. Karban’s work aligns with a massive shift in ecology over the last three decades. Researchers like Dr. Suzanne Simard of the University of British Columbia argue that forests are not collections of solitary organisms, but connected systems.

Image credits: Eilis Garvey.

Simard’s research popularized the term “Wood-Wide Web.” She found that trees connect via mycorrhizal networks—vast webs of underground fungi that link tree roots. These networks act as a transit system for water, nitrogen, phosphorus, and signaling molecules. For decades, these sophisticated survival strategies were invisible to the human eye. Today, however, we can use technologies like carbon isotope tracing, microelectrode sensors, and advanced root imaging. Armed with this tech, ecologists have uncovered hard evidence that trees are constantly exchanging chemical warnings, firing electrical impulses, and even shuttling carbon through underground fungal highways.

The role of fungi in this mechanism should not be underestimated. Since fungi cannot photosynthesize, they depend on the trees for sugar (carbon). In exchange, the fungi act as a vast, subterranean mining operation, scouring the soil for water, phosphorus, and nitrogen that tree roots cannot reach on their own. It is through these fungal filaments that physically link root systems that the forest becomes a communicative network.

Her research suggests that up to 40% of the carbon produced by a mature tree can later appear in nearby seedlings, implying a purposeful redistribution of nutrients. This has led to terms like “mother trees,” suggesting that older trees help younger kin survive.

Nutrient exchanges and communication between a mycorrhizal fungus and plants. Image via Wiki Commons.

The Skeptics Weigh In

The topic of the Wood Wide Web, however, is far from settled. In fact, it’s bitterly debated.

Dr Kathryn Flinn, an ecologist at Baldwin Wallace University, believes that while mycorrhizal networks move resources, this does not mean the tree sending those resources is making a strategic or selfless decision. She explains that ecology is often more mechanical than metaphorical. A 2023 review in Trends in Plant Science noted that while network transfers exist, interpreting them as intentional cooperation remains ‘scientifically unsettled.’

One of the most polarizing findings in the field has been the discovery that plants send electrical impulses across tissues when wounded or stressed. These pulses activate defense genes and travel far faster than chemical signals.

Meanwhile, Dr. František Baluška of the University of Bonn explains in the book, Long‑Distance Systemic Signaling and Communication in Plants, that electrical signaling allows plants to coordinate responses across their entire bodies in seconds. This is not a nervous system in the animal sense, but it is unquestionably a form of communication, in Dr Baluška’s opinion.

Critics remain cautious in the way these findings are communicated to the public. They argue that comparing these signals to neurons risks misleading the public. They believe it needs to be better clarified what counts as a ‘signal’ and what counts as ‘information’.

Another notion gaining mainstream attention is that of a ‘Mother Tree’ recognising family members. Some scientists believe trees can actually recognize family members and redistribute nutrients accordingly. This claim is currently heavily debated. Yet, the scientific evidence suggests that there is more to this theory than mere fantasy. Studies on Douglas firs and beech trees show that related individuals compete less for root space and channel more carbon to genetically similar neighbors.

A Shift in Perspective

Image credits: Periklis Lolis.

Regardless of disagreements over interpretation, there is increasing consensus that communication, whatever its mechanism, does occur between trees and that this appears to improve forest resilience.

Trees connected through fungal networks show higher drought survival rates, recover faster after fire, and store more carbon per acre than fragmented forests. As climate change accelerates heatwaves, floods, and pest outbreaks, understanding how forests redistribute resources could influence global conservation policy. Scientists agree on the mechanism, but debate the intention of these signals.

Karban believes that we shouldn’t be afraid of these arguments and that skepticism is a healthy part of science. It is in asking questions that answers can be fine-tuned and become reliable and evidence-based.

“I have had a mixed bag of reactions to my studies,” he says. “To those who are skeptical, I explain that with science, it is only credible if the experiment is repeatable by another person, with reliable and measurable results.”

“There are many sweeping claims about plants which aren’t necessarily scientifically-backed though experiments which aren’t always repeatable, for example, that plants grow towards music.”

“An idea which stands up to scrutiny can be accepted,” he says.

He says that his career has not been marked by ‘eureka moments’. Rather, it has involved a slow, incremental gaining of knowledge and understanding about plant species and their responses to the environment and to each other. But he still has plenty of challenging ideas. For instance, he is now interested in studying the ‘dialects’ used by sagebrush plants, as well as different plant ‘personalities,’ as he calls them.

In time, technology should help researchers catch up to these questions. With the rise of nanotech sensors, AI-assisted ecosystem models, and MRI-like root imaging, our instruments are finally becoming sensitive enough to hear the forest. As the data clears, the argument may shift from “Do trees talk?” to “Just how complex is their conversation?”

For now, we can enjoy the mystery and the wonder of forests, while leaving much to science and a little to the imagination.