Predictive promise and pitfalls of incorporating mycorrhizal fungal traits into Earth System Models

Mycorrhizal fungi are ubiquitous in terrestrial ecosystems and affect plant productivity and soil carbon storage. Yet, we lack an integrated empirical and modeling framework to represent these fungi in Earth System Models (ESMs). While it is tempting to broadly define different mycorrhizal fungal functional groups (e.g., arbuscular mycorrhizal fungi, ectomycorrhizal fungi) as separate microbial pools in soil carbon models, trait heterogeneity and plasticity within these functional groups may undermine this approach. We compare empirical observations with results from a newly developed global land model to highlight when and how integrating mycorrhizal fungal traits can improve soil carbon and nitrogen projections.