Tree Canopies Reflect Mycorrhizal Composition

Mycorrhizae alter global patterns of CO2 fertilization, carbon storage, and elemental cycling, yet knowledge of their global distributions is currently limited by the availability of forest inventory data. Here, we show that maps of tree-mycorrhizal associations (hereafter mycorrhizal maps) can be improved by the novel technology of imaging spectroscopy because mycorrhizal signatures propagate up from plant roots to impact forest canopy chemistry. We analyzed measurements from 143 airborne imaging spectroscopy surveys over 112,975 individual trees collected across 13 years. Results show remarkable accuracy in capturing ground truth observations of mycorrhizal associations from canopy signals across disparate landscapes (R-2 = 0.92, p < 0.01). Upcoming imaging spectroscopy satellite missions can reveal new insights into landscape-scale variations in water, nitrogen, phosphorus, carotenoid/anthocyanin, and cellulose/lignin composition. Applied globally, this approach could improve the spatial precision of mycorrhizal distributions by a factor of roughly 10(4) and facilitate the incorporation of dynamic shifts in forest composition into Earth system models.

Automated summary

Imaging spectroscopy technology can improve maps of tree-mycorrhizal associations by capturing accurate ground truth observations through forest canopy signals. This approach could greatly enhance the spatial precision of mycorrhizal distributions globally and facilitate the incorporation of dynamic shifts in forest composition into Earth system models.