January 18, 2019

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Factors controlling reactive Nitrogen Oxides (NOy) emission from deciduous forest soils

Microbial mechanisms and ecosystem flux estimation for aerobic NOy emissions from deciduous forest soils

The Science

Reactive nitrogen oxides (NOy; NOy = NO + NO2 + HONO) decrease air quality and trap heat and radiative energy in Earth’s atmosphere, yet the factors responsible for their emission from soils remain poorly understood. The difficulties in determining this at a large scale is due to the variability of nitrogen cycling processes within and between large forest systems. This study looks to the two types of symbiotic root fungus that often determine soil biotic composition for insight into reactive nitrogenous gas fluxes in forests.

The Impact

A better understanding of the biogenic sources of NOy will help in reducing sources of emissions originating from human activity, help determine hotspots of NOy emissions, and lead to better land surface models for predicting soil NOy emissions into the atmosphere.


A common way to determine ecosystem scale effects of forests is to look toward the dominating symbiotic root fungus of the forest because of the large influence the fungus has on soil characteristics and biotic composition of the surrounding soils. There are two primary types of root fungus associated with trees; arbuscular mycorrhiza (AM) and ectomycorrhiza (ECM). It was determined that the soil characteristics and biotic makeup of AM dominated trees resulted in higher production of NOy. These finding allowed for the prediction of NOy flux throughout the eastern United States based on percentage ECM tree abundance.

Principal Investigator

Joshua Fisher
University of California, Los Angeles/NASA Jet Propulsion Laboratory

Program Manager

Daniel Stover
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science


U.S. Department of Energy, Office of Biological and Environmental Research, Terrestrial Ecosystem Science Program, and National Science Foundation Ecosystem Science.


Mushinski, R. M., R. P. Phillips, Z. C. Payne, et al. "Microbial mechanisms and ecosystem flux estimations for aerobic NOy emissions from hardwood forest soils". Proceedings of the National Academy of Sciences 116 (6), 2138–145  (2019). https://doi.org/10.1073/pnas.1814632116.