SUSTAINABILITY
DEBRA KNAPKE
Stayin’ Alive: Plant Strategies
Do plants have their own underground internet?
Consider the plight of the plant: It is immobile, at least to the extent that it can’ t pick up its roots and move to another location. A plant cannot talk, go in search of food or run away from predators.
In order to build sustainable landscapes, we must understand how a plant sustains itself. Without that knowledge, we will continue to create gardens and landscapes that rely on the overuse of precious natural resources and synthetic inputs to survive.
“ Plants breathe without lungs, digest without a stomach, see and hear without eyes and ears and think without a brain,” said Stefano Mancuso, co-author of Brilliant Green and director of the International Laboratory of Plant Neurobiology in Florence, Italy. Plants do all the things that animals do to survive, but they do them differently. It is those very differences that help plants to thrive in a world where most other organisms consider plants to be food.
A PLANT CANNOT TALK
In a recent lecture at Ohio State University, Mancuso demonstrated how plant roots make sounds. He classifies these as clicks and admits that we don’ t yet know how plants produce these sounds, but research indicates that they are perceived by other plants [ Gagliano, M., Mancuso, S. and Robert, D.“ Towards Understanding Plant Bioacoustics.” Trends in Plant Science 17, no. 6( 2012): 323-25 ].
Other researchers are also exploring plant communication strategies— how plants“ talk.” Suzanne Simard, a professor at the University of British Columbia’ s Department of Forestry and Conservation Sciences, has spent more than 30 years researching the exchange of information or nutrients among different species of trees. In her TED Talk on July 29, 2016, she presented her case for a“ massive underground communication network” among forest species. In one study, she used two isotopes of carbon dioxide and a Geiger counter to show that birch and Douglas fir trees
The above-ground network of this tree’ s roots provides only a glimpse of the complex system that lies below.
exchange these different carbon compounds via their roots, aided by mycorrhizal fungi. In further studies she documented that the trees communicate“… not only in the language of carbon, but also nitrogen and phosphorus and water.”
Simard also found seasonal differences in these nutrient exchanges. For instance, in summer, birches send minerals to Douglas firs, while in winter the exchange is reversed. This is differential communication based on sensed need.
A PLANT CANNOT SEARCH FOR FOOD
A technical distinction needs to be made here. Plants make their own food( carbohydrates and sugars) through the process of photosynthesis. But for the purpose of this article, food refers to the nutrients that a plant takes up from soil, decomposing materials and fertilizers: nitrogen, potassium, phosphorus, other macro- and micro-nutrients and trace elements.
Animals can move to different locations to look for food. They can wait, pounce and then consume. The only plants that have evolved the ability to wait and pounce are carnivorous plants, which have adapted to absorbing some nutrients by digesting the soft parts of animal bodies. But the vast majority of plant species have had to make some deals.
As noted above, mycorrhizae have become the communication pathway between plants in the forest. While we do not truly know the percentage of plant species that have relationships with mycorrhizae, the most recent estimates are
© PHOTO COURTESY DEBRA KNAPKE
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