Fungal biodiversity refers to the variety of fungus on the planet. Fungal biodiversity may be used, for example, to measure soil quality and fertility.

Specific to mycorrhizal fungi, fungal biodiversity plays an important role for life on Earth. Based on what we are learning, belowground biodiversity plays an important role in supporting aboveground biodiversity.

Evidence suggests that mycorrhizal biodiversity underpins biodiversity on Earth, and can play a significant role in driving restoration and recovery. The loss of mycorrhizal biodiversity is irreversible. Both mycorrhizal biodiversity, and biodiversity in general, function as a databank or library of solutions. In other words: biodiversity contains the solutions needed for ecosystem recovery and restoration

For example, by enabling nutrient transfer, helping carbon cycling, and keeping tree and plant communities healthy through pathogen, pest, and drought-resistance.