While I was gardening

The art of gardening and the science of life.

Does a Tree know its Age?

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Galaxies are the biggest units of material (that we know of) in the universe.  They are the nurseries and graveyards of stars.  Contained within them are nebulae and black holes, planets and moons – all grouped within countless solar systems.  Stars are composed of hydrogen and helium under enormous pressure and heat, with smaller amounts of heavy metals such as carbon, nitrogen, and oxygen.  From these basic elements life on our planet developed – through these basic elements all biological life is kin.

From the smallest basic building block of life – a cell – to the largest organism known – a fungus in the Blue Mountains of Oregon, we have observed a symmetry of structure and function within the biological world that has astounded, confounded, and amazed our species.  It should humble us.

For instance, we now know that our species is far from the only group that uses tools.  Other primates use and make tools; some species of birds, insects, fish, mammals, and cephalopods use tools for problem-solving with ease.  I have observed my resident crow use small sticks to empty a seed feeder with hardly the ruffle of a feather.  I’ve watched as he and his mate use a tag-team approach to empty the feeders and to trick the squirrels who travel through my garden into dropping the peanuts they find.  The discovery that other animals use tools caught scientists by surprise; some still refuse to acknowledge this discovery, attributing it instead to mimicry or to misinterpretation by the researcher.

Recent studies done by behavioral researchers have shown that animals other than humans have a highly developed sense of self – something any pet owner already senses.  These demonstrable results, also controversial among some scientists, have caused many people in a variety of fields to reassess their definition of consciousness, cognition, and communication.

But what of plants?  Within the past 2 decades, botanists, ecologists, and foresters have discovered and are proving that plants communicate with each other using a variety of methods; via chemicals, via fungal life in the soil, or through emissions from their roots.  How do they do this?  For example, when plants are being attacked by insects they will alert their neighbors of the threat by emitting chemical signals into the surrounding air.  Plants ‘know’ they are being attacked because they sense the vibrations from the chewing of insects.  How?  Plants don’t have central nervous systems; they can’t hear; they can’t see.  But, they know when they are in danger.  They sense a problem.  Plants defend themselves by flooding their tissues with toxic, foul tasting chemicals that discourage the pest.  Insects sometimes respond to the toxins by developing an immunity to the substance.  They adapt, and the process starts anew.

We now know that many shrubs leaf out earlier than others of their species in different locations if those shrubs are planted below trees.  When the trees leaf out, this prevents the shrubs from obtaining adequate energy (sunlight), so the shrubs respond with early budburst.  This enables the shrubs to obtain as much energy as possible before the trees leaf out.*  What triggers the shrub to leaf out earlier than others in its species in different locations?  Shrubs sense the amount of time needed for early budburst, but how?

Research by Suzanne Simard, Ph.D., has shown that Pseudotsuga menziesii, Douglas Fir mother trees, share nutrients via their root system and fungi network with their seedlings.  This connects one tree with another.  Dr. Simard uses the term communication to describe these interactions.  The fungus works in concert with the trees.  How does the mother tree know to do this?  What does it sense that allows it to work with the fungi to create this beneficial network among its kin?

I’ve often wondered if the most ancient of plants on our planet sense the passage of time.  Do these plants, trapped in place, have a sense of their longevity?  These ancient pines, sequoias, junipers, yews, aspen groves, figs, cypress, oaks, and so many others interact with their surroundings with such success that they have outlived countless other species.  If nothing else, do they sense the passing of others of their genus?  Do they sense the movement of seasons through the availability of nutrients and water?  Of lean times?  Of storms, fire, insect infestation or disease, of threats from animals?  If so, what would they tell us?  What would they communicate to us?

And most of all, would we listen?



*American Scientist, March-April 2016



Author: dphare2014

Horticulturist, Lead Steward Carkeek Park Demonstration Gardens, Author

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