What phenomenon is caused by fungal development in the soil?

The phenomenon of a Fairy Ring is indeed caused by fungal development in the soil. In ecology, a Fairy Ring describes a circular pattern of mushrooms or grass that appears in a lawn or pasture, often characterized by a ring of enhanced growth around a central area of dead or discolored grass. This occurs as the fungi grow and expand outward from their original source, utilizing nutrients in the soil.

As the fungi decompose organic matter, they can release certain nutrients that may promote grass growth in a circular pattern while inhibiting growth where the fungal bodies are decomposing. This creates a distinct visual effect that is commonly seen in lawns affected by fungal activity. The formation of Fairy Rings is a natural process linked closely to the life cycle and growth habits of specific fungal species that thrive in the soil and interact with grass roots.

The other options represent different phenomena: Root Knot is associated with nematode infestations, Thatch Accumulation is related to a buildup of organic material in the thatch layer, and Mycorrhizal Growth refers to a symbiotic relationship between fungi and plant roots aiding in nutrient absorption. Each of these processes is distinct from the fungal growth that leads to the formation of Fairy Rings.