Dr. Peay's lab studies the ecological processes that structure natural communities and the links between community structure and the cycling of nutrients and energy through ecosystems. The lab focuses primarily on fungi, as these organisms are incredibly diverse and are the primary agents of carbon and nutrient cycling in terrestrial ecosystems.

Much of their research focuses on plant-fungal root associations, better known as mycorrhizas, which constitute one of the most pervasive mutualisms in terrestrial ecosystems. They work on questions at three scales of this symbiosis, (1) how does environmental variation and functional variation in mycorrhizal fungi affect the symbiosis at the root tip scale, (2) how does dispersal contribute to the predictability of community assembly patterns at the landscape scale, and (3) how does biogeography affect mycorrhizal community structure and ecosystem function? By integrating these three levels of research the lab hopes to build a 'roots-to-biomes' understanding of plant-microbe symbiosis.