Fairy ring fungi create circular patterns in grasslands by forming dense underground networks that dramatically change soil properties and plant communities. The study found that these fungal rings reduce plant diversity by 40% at their advancing edge while boosting grass growth inside the ring, creating a stark ecological shift. The fungi produce calcium oxalate crystals that make soil very water-repellent, causing nearby plants to dry out and die. This research shows how a single fungus species can reshape entire ecosystems through physical and chemical changes in the soil.