Connecting the dots: network structure as a functional trait in arbuscular mycorrhizal fungi

Societal Impact Statement: Soil health and sustainable land management are critical to addressing global challenges such as food security, climate resilience, and biodiversity loss. Arbuscular mycorrhizal (AM) fungi form underground networks that enhance plant nutrient uptake and improve soil structure, yet their functional diversity remains poorly understood, limiting their application in agriculture and ecosystem restoration. By proposing potential fungal transport strategies, we provide a framework for predicting AM fungal contributions across different environments. This knowledge can inform agricultural practices, conservation strategies, and land-use policies, ultimately supporting efforts to harness beneficial microbes for resilient and sustainable ecosystems. Summary: Arbuscular mycorrhizal (AM) fungi construct extensive mycelial networks in soil, serving as critical mediators of plant–soil interactions and nutrient exchange. However, the ability to harness AM fungal diversity for ecosystem management remains constrained by gaps in functional understanding. Trait-based frameworks offer a promising approach to overcoming these limitations, yet their development has been hindered by methodological challenges and the complexity of AM fungal symbioses. Here, we propose that mycelial network connectivity, a structural trait reflecting the organization of fungal hyphae for nutrient transport, provides a mechanistic basis for distinguishing AM fungal functional groups. Drawing on network theory, we identify two key trade-offs that shape AM fungal transport strategies: (1) a trade-off between transport efficiency and resilience to structural disruption and (2) a positive correlation between network heterogeneity and soil heterogeneity. Based on these relationships, we classify AM fungi into potential functional groups and argue that these connectivity-based classifications provide a predictive framework for understanding AM fungal ecological strategies across environmental gradients, with implications for sustainable land management. Future research should integrate experimental measurements of fungal carbon allocation, network plasticity, and species-specific responses to environmental change to refine this framework further. By linking mycelial architecture to functional diversity, this approach enhances our ability to predict AM fungal contributions to ecosystem processes and optimize their use in applied contexts.