How Fungi Built a Social Safety Net Under Your Feet

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Quick shot

• Plants, including trees, can communicate through thread-like structures called mycelium.

• Mycelium is the part of fungi that forms its own biological kingdom, separate from plants.

• The mother tree acts as a hub and nourishes the young saplings.

• Communication is achieved by a variety of methods, including advective mass flow driven by source-sink gradients.

A walk through the forest is a treat for the senses. Just stop and look, listen, and touch everything around you. The sun shone through the branches, the leaves rustled, the rough texture of the bark beneath my fingertips. But this is only a small part of the bigger picture. The life of the forest continues underground in complex networks you can’t see or feel. Without these networks, the forests and many other plants we love so much would not be possible.

The important role of fungi

Trees have an important communication network for sharing information with each other. Information is transmitted through thread-like structures called mycelium, which is actually part of the fungus. Mycelium is the root-like structure of fungi that is usually hidden beneath the soil out of sight. It’s also the part that does all the work and forms a huge network.

Crucially for trees, mycelium wraps around or burrows into its roots. This allows trees to use this network to share water and nutrients. It’s called a mycorrhizal network.

Trees take care of their offspring

In a healthy forest, each tree is connected to every other tree through this network. However, these trees give priority to some of their neighbors. Research shows that saplings have difficulty taking root in shady areas because not enough light reaches them for adequate photosynthesis. This is the mechanism by which green plants convert sunlight into a form of energy they can use. Therefore, older and taller trees with access to sunlight use mycorrhizal networks to deliver nutrients and sugars to younger, struggling trees. Some experts believe that trees release carbon and nutrients in favor of their relatives.

Trees make carbon trade-off

Rather than being exploited by trees as a free plumbing system, fungi gain advantage from this relationship. By providing this service to trees, the fungi receive a regular and reliable supply of carbon. In fact, the fungus can retain 20 to 30 percent of the sugars it transports. Trees also benefit from phosphorus and other mineral nutrients, which are collected by the mycelium and transported to the tree.

mother tree forming center

Not all trees connected to this network are created equal. Some are called “mother trees” and act as hubs. They are older and usually have the most fungal connections. Because their roots penetrate deep into the soil, they have access to water sources that other trees cannot. When they pass it on to the saplings, they help nourish the next generation. However, communication is not just one-way. The mother tree uses fungal connections to sense when another tree is in trouble (sending a distress signal) and helps it by delivering nutrients to it.

The science of tree communication

Scientists have made significant progress in understanding how trees use mycorrhizal networks to communicate, although many details remain to be discovered. Currently, experts believe it involves a combination of biochemical signals, resource transfer, or electrical signals driven by action potentials.

Overall, trees form relationships with multiple fungal species, and a single fungal species can colonize many different plant species. However, some are dependent on a single host. That is, plants tend to remain loyal to a certain type of fungus. The most common are arbuscular mycorrhizal fungi. This fungus is most commonly found in temperate grasslands, tropical forests, and agricultural systems, but is also associated with some temperate forest trees. In contrast, ectomycorrhizal fungi are associated with conifers and temperate and boreal forests. While mycorrhizal networks are more common among related plants, they can also connect different species, allowing for communication and resource sharing between species.

How does material move along the mycelium?

It is likely that different substances pass through the mycorrhizal network in different ways. For example, carbon is transported over long distances by advective mass flow driven by source-sink gradients. Basically, this means that carbon moves from an area of ​​high concentration (source tree) to an area of ​​low concentration (sink tree). Consider the case of a struggling sapling: due to its age and location, the sapling will have high respiratory needs as it grows and therefore will inevitably have a lower carbon concentration because it will run out of carbon very quickly. Therefore, the gradient persists and the flow remains unidirectional.

fast pressure signal

Perhaps the most striking feature of the mycorrhizal network is its ability to rapidly transmit stress signals from injured to healthy plants. It only takes as little as six hours for healthy neighbors to receive stress signals from herbivores or pathogens.

Neighboring plants upregulate their own defense-related genes, essentially preparing for the same dangers that affect neighboring plants. This early warning system allows other plants to produce defense enzymes to protect themselves. This is just a small part of the story, we are just beginning to discover the wonders of the forest social safety network!

The post How Fungi Build a Social Safety Net Under Your Feet appeared first on AZ Animals.