Fine-resolution global maps of root biomass carbon colonized by arbuscular and ectomycorrhizal fungi

Despite the recognized importance of mycorrhizal associations in ecosystem
functioning, the actual abundance patterns of mycorrhizal fungi
belowground are still unknown. This information is key for better
quantification of mycorrhizal impacts on ecosystem processes and for
incorporating mycorrhizal pathways into global biogeochemical models. Here
we present the first high-resolution maps of fine root stocks colonized by
arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) fungi (MgC ha−1).
The maps were assembled by combining multiple open-source databases
holding information on root biomass carbon, the proportion of AM and EcM
tree biomass, plot-level relative abundance of plant species and intensity
of AM and EcM root colonization. We calculated root-associated AM and EcM
abundance in 881 spatial units, defined as the combination of ecoregions
and land cover types across six continents. These maps serve as a basis
for future research where continuous spatial estimates of root mycorrhizal
stocks are needed.