Anthropogenic nitrogen (N) enrichment of ecosystems, mainly from fuel combustion and fertilizer application, alters biogeochemical cycling of ecosystems in a way that leads to altered flux of biogenic greenhouse gases (GHGs). The magnitude and direction of the flux varies among ecosystems and within ecosystems depending on the current suite of environmental factors.  Some studies show shown the amount of N deposition is functionally related to the magnitude of GHG flux, however it is unclear if these relationships are retained over larger spatial scales. A literature search was conducted to gather data quantifying the N addition to GHG flux relationship. This dataset was analyzed to determine if statistically significant functions between N addition and GHG flux are present when data from large spatial scales are considered together.  Additionally the spatial distribution of data was evaluated to identify under represented areas and ecosystems.

Results/Conclusions

We evaluate 313 observations across 109 studies that investigated the effect of N addition on the flux of three major GHGs (CO₂, CH₄ and N₂O). Studies that evaluated N total ecosystem carbon flux, CH₄ emission and uptake and N₂O emission were included in the dataset. Significant relationships between N addition and GHG flux were not found for any of the GHGs evaluated when all ecosystems were considered together. There are limited cases which relationships are present within ecosystem types.  Out of 319 observations, 285 provided sufficient geographic information to plot using GIS mapping.  Ecosystems and sites in the U.S and EU are best represented in the literature.  Few, if any, studies are reported from sites in South America, Africa, Asia and Australia.