Background and Aims

Plant roots and mycorrhizal fungi are key players in plant nutrient acquisition and thus are critical in determining plant performance and ecosystem stability. However, how roots coordinate with mycorrhizal fungi for nutrient foraging under complex environmental conditions remains largely elusive, especially for ectomycorrhizal (ECM) trees.

Methods

To examine the collaborative relationship between roots and ECM fungi in nutrient foraging, we measured the functional traits of absorptive fine roots and ECM fungi, as well as environmental factors, across four elevations (2850, 2950, 3060, and 3200 m above sea level) in the coniferous forests (Abies faxoniana Rehder et Wilson) on the eastern Tibetan Plateau.

Results

We observed a complementary relationship between fine roots and ECM fungi in nutrient foraging along the elevation gradient. Specifically, as the elevation rises, fine roots decreased nutrient foraging capacity with decreasing specific root length and absorptive fine root biomass, while increased the reliance on ECM fungi of short-distance exploration type to scavenge nutrients. Moreover, the ECM fungi community, dominated by contact and short-distance exploration type, exhibited a preference for longer-distance ECM fungi with thicker roots, suggesting complementarity between fine roots traits and ECM exploration types for nutrient acquisition. Further, temperature rather than rhizosphere soil nutrients drives the coordination between roots and mycorrhizal fungi.

Conclusions

These results highlight the complementary relationship between fine roots and ECM fungi in acquiring soil resources, and offer a new insight into the mechanism of plants nutrient maintenance and their adaptation to environmental changes.