A spatially explicit, empirical estimate of tree-based biological nitrogen fixation in forests of the United States.

ABSTRACT: Quantifying human impacts on the N cycle and investigating natural ecosystem N cycling depend on the magnitude of inputs from natural biological nitrogen fixation (BNF). Here, we present two bottom-up approaches to quantify tree-based symbiotic BNF based on forest inventory data across the coterminous US plus SE Alaska. For all major N-fixing tree genera, we quantify BNF inputs using (1) ecosystem N accretion rates (kg N ha-1 yr-1) scaled with spatial data on tree abundance and (2) percent of N derived from fixation (%Ndfa) scaled with tree N demand (from tree growth rates and stoichiometry). We estimate that trees fix 0.30-0.88 Tg N yr-1 across the study area (1.4-3.4 kg N ha-1 yr-1). Tree-based N fixation displays distinct spatial variation that is dominated by two genera, Robinia (64% o

SUBMITTER: Staccone A 

PROVIDER: S-EPMC7359885 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature