From Lilliput to Brobdingnag: Extending Models of Mycorrhizal Function across Scales

Mycorrhizae are nearly ubiquitous symbioses formed between plants and fungi. Plants provide fungi with carbon captured through photosynthesis, while fungi provide plants with soil resources. Historically, research has focused on the effects of mycorrhizae on nutrient uptake and the fitness of individual plants. More recently, there has been a growing appreciation for the importance of mycorrhizal functions at higher levels of organization, including populations, communities, and ecosystems (figure 1). Mycorrhizal fungi influence soil carbon storage, nutrient cycling, and soil stability within ecosystems. Populations of plants and mycorrhizal fungi interact to influence community structure, and mycorrhizal fungi influence size and reproductive hierarchies in plant populations. Thus, research on the outcome of individual plant–fungus relationships must evolve to include mycorrhizal functions at higher levels of organization. Much as Gulliver’s travels through Lilliput, a land of miniatures, and Brobdingnag, a land of giants, provide insights into the human condition (Swift 1726), studies of mycorrhizal relationships across scales can provide insights into the mechanisms and consequences of their functioning. Mycorrhizal functions include the additive effects of individual mycorrhizae as well as emergent properties of the symbiosis.