고등학교 영어Ⅱ (미래엔 김성연) 연계 글

When people walk through a forest, they mainly notice the leaves, branches, and flowers above the ground. Beneath the surface, however, most forest plants rely on partners that people rarely see. Their roots live in close contact with certain fungi, and scientists call this partnership between a root and a fungus a mycorrhiza. This partnership is one of the oldest relationships on land, because it appears to have begun with some of the earliest land plants.

The two partners trade with each other. The fungus spreads thin threads called hyphae into the soil beyond the roots, and these threads gather mineral nutrients such as phosphorus and nitrogen and pass them to the plant. In return, the plant uses photosynthesis to make food and shares some of its carbon with the fungus. The plant benefits greatly from this trade: according to one review, these fungi can supply up to 80 percent of a plant's nitrogen and phosphorus. Without such partners, many plant species would grow poorly, and some would not survive at all.

A 2018 review of plant species worldwide found that more than four out of five vascular plants form mycorrhizas, while only about 8 percent never form them. If it were not for these fungi, most land plants would have to collect every nutrient with their roots alone.

Because fungal threads can link the roots of several plants, trees in a forest may be joined underground by a shared fungal network. In recent years, one of the most popular stories about forests has been that trees use these networks to share food and send warnings to one another. In some versions, large old trees feed their own young, and without that help, many seedlings would struggle to grow.

In 2023, however, three researchers from Canadian and American universities examined the evidence behind three common claims about these networks. They judged two of the claims to be poorly supported: that the networks are widespread in forests and that they help seedlings grow. Results from field studies, they noted, varied too widely or were too limited. One of the boldest claims, that old trees send food and warning signals mainly to their own offspring, was not supported by a single published, peer-reviewed study. The researchers also reported that unsupported statements about these networks doubled in scientific papers during the twenty-five years before their study. None of this weakens the evidence that most plants need their fungal partners. The review reminds us, rather, that one of the most important habits in science is to check whether a popular story still matches the data.