Effects of Nitrogen and Sulfur Deposition on Tree Growth, Survival, and Carbon Sequestration Across the U.S.

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There is scientific controversy about whether nitrogen deposition increases forest carbon sequestration. All tree species do not exhibit the same response to nitrogen and responses may be complicated by interactions with biotic and other abiotic factors such as sulfur deposition. 

USGS and international researchers characterized the relationship of nitrogen and sulfur deposition on the growth and survival of 71 common U.S. tree species. Results elucidate nitrogen and sulfur impacts on individual tree species and continental-scale patterns of forest carbon sequestration. There was a huge diversity in response to both nitrogen and sulfur deposition for different tree species and in different geographic regions. Responses could not simply be explained by ecological traits such as evergreen versus deciduous or mycorrhizal association. Averaged across all species, results indicate increasing carbon uptake, but also a small decrease in survival which may have a long-term impact on tree density and drive shifts in forest composition.  

 

Horn, K.J., Thomas, R.Q., Clark, C.M., Pardo, L.H., Fenn, M.E., Lawrence, G.B., Perakis, S.S., Smithwick, E.A., Baldwin, D., Braun, S., Nordin, A., Perry, C.H., Phelan, J.N., Schaberg, P.G., St. Clair, S.B., Warby, R., Watmough, S., 2018, Growth and survival relationships of 71 tree species with nitrogen and sulfur deposition across the conterminous U.S.: PLoS ONE, v. 13, no. 10, p. e0205296, https://doi.org/10.1371/journal.pone.0205296