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" Even in a forest, there are loners, would-be hermits who want little to do with others. Can such antisocial trees block alarm calls simply by not participating? Luckily, they can't. For usually there are fungi present that act as intermediaries to guarantee quick dissemination of news. These fungi operate like fiber-optic Internet cables. Their thin filaments penetrate the ground, weaving through it in almost unbelievable density. One teaspoon of forest soil contains many miles of these "hyphae." Over centuries, a single fungus can cover many square miles and network an entire forest. The fungal connections transmit signals from one tree to the next, helping the trees exchange news about insects, drought, and other dangers. Science has adopted a term first coined by the journal Nature for Dr. Simard's discovery of the "wood wide web" pervading our forests. What and how much information is exchanged are subjects we have only just begun to research. For instance, Simard discovered that different tree species are in contact with one another, even when they regard each other as competitors. And the fungi are pursuing their own agendas and appear to be very much in favor of conciliation and equitable distribution of information and resources. "
― Peter Wohlleben , The Hidden Life of Trees: What They Feel, How They Communicate: Discoveries from a Secret World
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" So trees communicate by means of olfactory, visual, and electrical signals. (The electrical signals travel via a from of nerve cell at the tips of the roots.) What about sounds? Let's get back to hearing and speech. When I said at the beginning of this chapter that trees are definitely silent, the latest scientific research casts doubt even on this statement. Along with colleagues from Bristol and Florence, Dr. Monica Gagliano from the University of Western Australia has, quite literally, had her ear to the ground. It's not practical to study trees in the laboratory; therefore, researchers substitute grain seedlings because they are easier to handle. They started listening, and it didn't take them long to discover that their measuring apparatus was registering roots crackling quietly at a frequency of 220 hertz. Crackling roots? That doesn't necessarily mean anything. After all, even dead wood crackles when it's burned in a stove. But the noised discovered in the laboratory caused the researchers to sit up and pay attention. For the roots of seedlings not directly involved in the experiment reacted. Whenever the seedlings' roots were exposed to a cracking at 220 hertz, they oriented their tips in that direction. That means the grasses were registering this frequency, so it makes sense to say they "heard" it. "
― Peter Wohlleben , The Hidden Life of Trees: What They Feel, How They Communicate: Discoveries from a Secret World
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" Young developing leaves on normal trees are often tinged red thanks to a kind of sun block in their delicate tissue. This is anthocyanin, which blocks ultraviolet rays to protect the little leaves. As the leaves grow, the anthocyanin is broken down with the help of an enzyme. A few beeches or maples deviate from the norm because they lack this enzyme. They cannot get rid of the red color, and they retain it even in their mature leaves. Therefore, their leaves strongly reflect red light and waste a considerable portion of the light’s energy. Of course, they still have the blue tones in the spectrum for photosynthesis, but they are not achieving the same levels of photosynthesis as their green-leaved relatives. These red trees keep appearing in Nature, but they never get established and always disappear again. Humans, however, love anything that is different, and so we seek out red varieties and propagate them. One man’s trash is another man’s treasure is one way to describe this behavior, which might stop if people knew more about the trees’ circumstances. "
― Peter Wohlleben , The Hidden Life of Trees: What They Feel, How They Communicate: Discoveries from a Secret World
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" When the interwoven birches and firs were spiked with stable and radioactive isotopes, I could see, using mass spectrometers and scintillation counters, carbon being transmitted back and forth between the trees, like neurotransmitters firing in our own neural networks. The trees were communicating through the web! I was staggered to discover that Douglas firs were receiving more photosynthetic carbon from paper birches than they were transmitting, especially when the firs were in the shade of their leafy neighbors. This helped explain the synergy of the pair’s relationship. The birches, it turns out, were spurring the growth of the firs, like carers in human social networks. Looking further, we discovered that the exchange between the two tree species was dynamic: each took different turns as “mother,” depending on the season. And so, they forged their duality into a oneness, making a forest. This discovery was published by Nature in 1997 and called the “wood wide web. "
― Peter Wohlleben , The Hidden Life of Trees: What They Feel, How They Communicate: Discoveries from a Secret World