When we walk through a forest, we admire the tall trees, green leaves, and warm sunlight. Yet the forest's most important connections are hidden beneath our feet. Deep underground, an invisible network quietly supports the life of the entire forest. Around tree roots are tiny fungal threads called hyphae. When fungi and tree roots work together, they form mycorrhiza, creating a vast mycorrhizal network that connects trees across the forest. Because it functions much like the Internet, scientists often call it the "Wood Wide Web".

              Trees and fungi depend on each other. Trees share sugars produced through photosynthesis, while fungi absorb water and nutrients from the soil and deliver them to the trees. There are two main types of mycorrhiza: endomycorrhiza, which grow inside plant cells, and ectomycorrhiza, which surround root cells and are common in many forest trees. The network does more than transport nutrients. It also carries chemical warning signals. When one tree is attacked by insects or diseases, nearby trees receive the signal and begin producing defensive chemicals before the danger reaches them. Canadian forest ecologist Suzanne Simard also found that large Mother Trees can send carbon and nutrients through this network to young trees growing in the shade, showing that forests are connected communities rather than isolated trees.

              This underground network is far larger than most people imagine. Scientists estimate that all the fungal threads on Earth together would stretch about 450 quadrillion kilometers—roughly 730 million times the distance between the Earth and the Sun. Mycorrhizal fungi also store enormous amounts of carbon in the upper soil, helping reduce carbon dioxide in the atmosphere and slow climate change. These discoveries have changed the way scientists view forests. Instead of seeing forests only as places where trees compete for sunlight and nutrients, researchers now recognize that cooperation is equally important. Through the mycorrhizal network, trees share resources, warn one another of danger, and help young trees survive, forming a connected living community.

                Although mycorrhizal networks are essential for healthy forests, they are being damaged by deforestation, soil disturbance, and the overuse of chemical fertilizers and pesticides. As these underground connections disappear, forests become less able to recover from drought, diseases, and other environmental challenges. Protecting forests means more than planting trees. It also means protecting the underground network that helps forests store carbon, recover from damage, and support biodiversity. By protecting this hidden system, we can help keep forests healthy for the future.

                  Trees do not survive alone. They share resources, warn one another of danger, and help young trees grow. In many ways, people live the same way. We depend on our families, friends, schools, and communities to learn and grow. The next time you walk through a forest, remember that the most important connections are hidden beneath your feet. Protecting these invisible networks means protecting the future of our forests—and our planet.

English Reporter, Cho Ye-jin