Geophys. Res. Lett. doi: 10.1029/2009GL041009(2009)

As ecosystems 'fix' nitrogen, converting it to ammonia, they may also be affecting their own ability to soak up carbon.

Ying-Ping Wang of CSIRO in Aspendale, Australia, and Benjamin Houlton of the University of California, Davis, have modelled how the terrestrial biosphere responds to interactions between factors such as nutrient flux, nitrogen fixation and light availability. The team found that ecosystems absorbed less carbon after they ran out of soil nitrogen to fix.

Calculations of future warming and carbon uptake need to take this factor into consideration, the authors say, suggesting that warming could proceed at a faster pace than expected in nitrogen-limited ecosystems.