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Saturday, November 12, 2022

Humans and Trees: They like each other, they hate each other


The Wochecha Mariam church in Addis Ababa. In a generally dry landscape, wherever you see a green circular area in Ethiopia, it is often around a Church. The Ethiopians have recognized long ago the value of trees as part of the spiritual experience of being human.

Humans and trees have had a difficult relationship over the past few tens of thousands of years, when humans started using stone tools and they discovered that, with some patience, a stone axe could take down a large tree. The age of deforestation is still ongoing, actually accelerating. It was not so long ago, in this extended time perspective, that the English landlord Jonah Barrington who lived in Ireland during the early 19th century, uttered a sentence that summarizes the ruthless kind human attitude toward trees: "Trees are stumps provided by nature for the repayment of debt." Somehow, we have created a frame of thought that sees no value in a tree until it is felled and sold on the market.

And yet, humans have a more complicated relationship with trees than simply cutting them down with chainsaws. It is a minority view, often disparaged with the term "tree-hugging," but it is there. Trees are something that we cannot ignore. They have been with us from the remote origins of humankind. And, sometimes, we truly feel that we need to hug a tree. Sometimes, we do, and I think it can't be so bad for one's health. In the picture, you see Grazia (Ugo Bardi's wife), hugging a Cupressus sempervirens in Italy.

Do trees perceive the presence of humans? A good question. They have a complex and sophisticated sensory system that perceives light, chemicals, and vibrations. It may well be possible that a tree can sense a human walking nearby as a combination of sounds and smells. Does a tree like to be hugged? Some questions are beyond our understanding, but they are still worth asking. And, who knows? Can we exclude that the trees of the sacred forest around a church in Ethiopia pray to God just like humans do? 


  1. The bible talks a lot about trees - but mainly in terms of "do not cut them down as they bring us fruits and thus life". Even in times of war this logic held, as in Deuteronomy 20:19:

    "When you besiege a city a long time, to make war against it in order to capture it, you shall not destroy its trees by swinging an axe against them; for you may eat from them, and you shall not cut them down. For is the tree of the field a man, that it should be besieged by you? Only the trees which you know are not fruit trees you shall destroy and cut down, that you may construct siegeworks against the city that is making war with you until it falls."

    Cutting down trees to pay a debt therefore is even worse than that - but unfortunately the path mankind seems to follow. Let's see where this will take us.

    Thanks for sharing these beautiful thoughts, Ugo!

  2. As a kid I always liked trees, liked climbing in them, being in them, built "tree-forts" in them by pulling up boards with a rope to nail in platforms...
    I felt kinship with trees.
    What did the trees feel with the boy nailing boards?

    1. I think they understood that you had no intention of harming them. The bark is not damaged by a few nails, actually it must be permeable to oxygen, so maybe the trees felt better afterward!

    2. You're just saying that to make me feel good, Ugo.

    3. Not at all! If trees have a form of consciousness, it is delocalized over the mycorrhizal network. Single trees don't care about losing a branch -- they can just regrow it. The forest doesn't care about losing a tree. It can regrow it. Single trees are nothing, the forest is everything.

  3. Yes. They know harm/exploitation/indifference. I’ve come cross a 500 yr old Quercus agrifolia that gave up the ghost in the SF Bay Area when the owner built on their property around it (even w/ arborist supervision), on a project I worked on 5 years ago. Also a NOPAL/Opuntia that the owners nominally built around for effect, but didn’t like (hated cactus) that felled itself over the last few months. Finally an Opuntia that nearly fell on one of my guys last week when he was trying to remove invasive Kikuyu grass around it (had been subject to a lawn and bad construction practices before, so I see how it was confused/already rotted out). Jacaranda seem to be among the most tolerant.