Increases in nitrogen input from human action are unlikely to increase the uptake of carbon dioxide on land and in the ocean by more than 10% concludes a review article published online this week in Nature Geoscience. This will not be enough to keep pace with predicted increases in atmospheric CO2 over the coming century. A related progress article suggests that careful management of European forests has led to increases in carbon storage over the past 50 years while accommodating demands for timber.
Dave Reay and colleagues present an overview of studies on the effect of increasing nitrogen deposition on forest, soil and ocean storage of CO2. The response of soil and ocean carbon uptake varies between studies and is limited in magnitude. However, forests take up significantly more carbon when fertilized with nitrogen ? an additional 10% of annual carbon dioxide emissions derived from human activity could be taken up by 2030, although an increase of 1?2% is more likely. Either way, this will not be enough to prevent future predicted increases in CO2 emissions caused by humans.
Philippe Ciais and co-workers compare European forest inventories with timber harvest statistics between 1950 and 2000 and find that forest biomass increased faster than harvests. They conclude that well-managed forests can act as a carbon sink on timescales of 10s of years.
Both studies highlight the importance of human influence ? by forest management or increasing nitrogen deposition ? on carbon storage in global ecosystems.