Information on the spatial distribution and activity of nitrogen-fixing trees at large scales is needed by forest and watershed managers, as well as modelers to quantify nitrogen availability for forest growth and carbon uptake. University and federal scientists used two new approaches to quantify the spatial distribution of nitrogen fixation by trees across the US. Their results revealed previously uncharacterized spatial patterns in tree-based nitrogen fixation, with especially large inputs across much of the western US. The new approaches used to estimate nitrogen fixation in this work provide examples for improving future continental and global scales estimates. Importantly, total natural nitrogen-fixation inputs across the US were lower than prior estimates, which implies an even greater human impact on the nitrogen cycle than previously recognized.

Staccone, A., Liao, W., Perakis, S.S., Compton, J.E., Clark, C., Menge, D.N., 2020, A spatially explicit, empirical estimate of tree-based biological nitrogen fixation in forests of the United States: Global Biogeochemical Cycles, https://doi.org/10.1029/2019GB006241