Bayou-Diversity (13 January 2019) At the top of my long driveway through a patch of diverse forest that is at least 130 years old, there was a peculiar episode of mortality not long ago. The deaths involved three large trees that, up until the time their leaves withered and transpiration failed, appeared healthy. They all died within a two month period. The victims were within forty feet of each other, and though there were many others nearby, none were affected. Adding to the mystery was the fact that the trees were of three different species – a white oak, a mockernut hickory, and a southern red oak. Other than a couple of recent droughty summers that likely stressed the forest to some degree, common causative signs of tree deaths were absent the scene. Evidence of lightning strikes, injurious insects, diseases, or chemical poisoning was missing. However, recent discoveries involving plants’ ability to communicate offer a plausible explanation.
We now know that trees have an intelligence of sorts that includes relationships with others of their own kind and even different species. Intelligence is expressed in their abilities to communicate with soil bacteria and fungi. Tree roots converse with fungi, sending chemical messages through the soil that attract fungi and stimulate them to grow toward the roots. Root and fungus then exchange sugar and minerals for their mutual benefit. In a mature forest a mesh of fungi develops that connects the root tips of adjacent trees like a botanical fiber optic network. Through this system trees can send nutrients and chemical messages between each other. A tree attacked by insects can communicate this to nearby trees via the root/fungi network, resulting in the neighbors’ fortifying their own leaves with insect deterring chemicals. A weak, shade-stunted sapling can obtain nourishment from a parent tree whose lofty boughs manufacture an abundance of sugar via photosynthesis.
As for my three trees that died, they were friends in something more than a metaphorical sense. They grew up together and lived side by side for over a century. They communicated, warned each other of dangers, and helped their cohorts in hard times. I surmise that for some unknown reason, perhaps drought on top of old age, one of the trees died. By then the lives of all three were so intertwined beneath the ground that the other two could not survive the loss and they perished also. It is hard for many people, especially those of us with hard science backgrounds, to think of plants in this manner with abilities and senses so foreign to our world views, to accept that in essence plants “talk” among themselves. I suspect though that in this field at this time, we don’t even know what we don’t know.