The Intelligence of Trees – Part 2 of 4

Painting by Emily Carr.

Painting by Emily Carr, one of the Canadian Seven. Photo courtesy of WikiArt..

by Ray Grigg

A different scale of time accounts for one of the reasons we have difficulty understanding the intelligence of trees. We interpret events with reference to our human sense of normal. Comparatively, trees seem to respond slowly, their life cycles sometimes approaching millennia — in the words of the German forester, Peter Wohlleben, they “exceed the human attention span.” They feed on the raw material we call dirt and produce their energy by the perplexing process of photosynthesis. As very different creatures, it’s not surprising we haven’t been able to understand them.

Because trees are “rooted” in one place, they have devised and used their own ways to relate and communicate with their surroundings —ways that happen to be outside the range of our usual perception. And why should they behave as we do? This expectation is one of our major shortcomings. Children, with their special innocent wisdom, recognize and accept trees as living beings with purposeful and deliberate behaviour, and so do Peter Wohlleben and Suzanne Simard.

In the beech forests of Germany, Wohlleben documents parent trees “nursing” their offspring. The young saplings, attempting to grow beneath the shadowed canopy with 97% of the sunlight already consumed, are kept alive and healthy with sugars and nutrients provided by their parents through interconnecting root structures — “nursing their babies,” is Wohlleben’s expression. When the parents eventually die, the saplings are ready to succeed them as strong and able inheritors of the available space in the forest.

One tree “caring” for another makes scientists feel uncomfortable, particularly when the paradigm of competitiveness is the one we have been using to explain how trees and forests grow. But Wohlleben has evidence of trees sharing space and nutrition, of neighbours feeding sugars to nearby stumps to keep them alive. In a beech forest he has examined the living stump of a tree that fell about 400 years ago, still alive from the sustenance provided from nearby trees. And it’s possible to find occasional fir stumps, fed for so long by neighbouring trees, that the bark has grown up over the severed wood to heal the wound — the base of the amputated tree is still alive without a functioning trunk, branches or needles.

Science, of course, as part of its effort to be objective, is averse to using words that have an emotional connotation. The behaviour in one category of living beings, particularly anthropomorphizing, is not to be confused with the behaviour in another. So our sensitive response to touch, sunlight, heat and water becomes, for trees, the technical terms of thigmotropism, heliotropism, thermotropism and hydrotropism. But a response is a response. And behind the different words is the implication that trees have some kind of sentience or awareness. This, of course, is the point being made by Wohlleben and Simard.

Of significance, Wohlleben is not some unrealistic dreamer. He conducted about 25 years of scientific research in Canada’s West Coast rainforests, confirming the claims in his book, The Hidden Life of Trees. And Suzanne Simard, the eminent forest ecologist from UBC, has created her own stir in academic circles. Part 3 of 4 next week.