Throughout history we have always perceived trees as lone strangers, each living on its own, in constant battle for its share of sunlight, water and soil. Surprisingly, recent studies are very much challenging this idea. According to them trees are much more complex, social and sophisticated than we have ever imagined.
Scientists have discovered that the trees in forests cooperate and communicate with each other through underground fungal networks called mycorrhizal networks. The tips of their roots are covered with microscopic fungi, with which they form a symbiotic relationship. The trees produce sugar through photosynthesis and pump it straight into the ground. There, a portion of it is absorbed by the fungi and used to help them scavenge the soil for different minerals, which are in turn consumed by the trees. This is the reason why soil in the forest is so rich in nutrients. In a way the old trees produce the food that the young ones need to grow, as they are still too small and get almost no sunlight.
As an added bonus, the fungi can help the trees to communicate. In case of drought, disease, insects or any other kind of danger they can send chemical, hormonal or electrical signals, which are amplified and transmitted by the fungi. Based on these signals the other trees can react and alter their behavior accordingly. Even trees outside the forest communicate through the air using scents and pheromones. For example, in the savannah acacia trees emit ethylene gas when a giraffe starts chewing on their leaves. Nearby acacias detect this and start filling their leaves with tannins – a type of compound, which in high quantities can sicken and even kill. Giraffes themselves are aware of this and have evolved their own tactic – when eating they always move against the wind, so that the trees ahead of them cannot receive the warning.