Fungi in soil: a rich community with diverse functions

Fungal taxa that play important roles in soil are diverse, including at least five phyla and hundreds of thousands of species. Well-known ecological niches include root pathogens, decomposers, and mycorrhizal symbionts. These categories can be further subdivided into guilds such as brown, soft and white rot decomposers and ericoid, ecto-, and arbuscular mycorrhizae. Attributes of these guilds are becoming more predictable, yet each of these guilds encompasses enormous ecological and functional diversity. Furthermore, certain functional attributes can overlap across guilds. This is convincingly illustrated by the subset of ectomycorrhizal fungi that retain potent peroxidase enzymes thought to have been present in their white rot ancestors. Soil fungi are highly responsive to various global change drivers; “response traits” of certain taxa and guilds of fungi are also becoming more predictable as studies of their environmental tolerances and climate niches accumulate. Efforts to catalog fungal traits should help to make sense of the astounding diversity of soil fungi in light of general ecological theories.