Mycorrhizal fungal and tree root functional traits: Strategies for integration and future directions

Abstract Plant functional traits offer ecologists quantifiable characteristics that may be used to determine the underlying mechanisms and drivers of processes at scales ranging from individual plants to entire ecosystems. While research on belowground functional traits has increased in recent years, most of this work has not fully considered the traits of mycorrhizal fungi, key symbionts responsible for much nutrient uptake and soil exploration in trees. We argue that, because of the important role of mycorrhizae in resource uptake, the measurement of belowground plant traits without the inclusion of mycorrhizal fungal traits potentially misses key mechanistic factors affecting plant performance, which has implications across ecological scales. In doing so, we provide a synopsis of current and past work on plant root traits and mycorrhizal fungal traits. Finally, we suggest potential key fungal traits to be measured and possible methods for measurement as ways to address the current gaps in our knowledge.