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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
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" recent research has discovered something that at least calls into question the effects of transpiration and the forces of cohesion. Scientists from three institutions (the University of Bern; the Swiss Federal Institute for Forest, Snow, and Landscape Research; and the Swiss Federal Institute of Technology in Zurich) listened more closely—literally. They registered a soft murmur in the trees. Above all, at night. At this time of day, most of the water is stored in the trunk, as the crown takes a break from photosynthesis and hardly transpires at all. The trees pump themselves so full of water their trunks sometimes increase in diameter. The water is held almost completely immobile in the inner transportation tubes. Nothing flows. So where are the noises coming from? The researchers think they are coming from tiny bubbles of carbon dioxide in the narrow water-filled tubes.30 Bubbles in the pipes? That means the supposedly continuous column of water is interrupted thousands of times. And if that is the case, transpiration, cohesion, and capillary action contribute very little to water transport. "
― Peter Wohlleben , The Hidden Life of Trees: What They Feel, How They Communicate: Discoveries from a Secret World