Trees use Nitrogen as Carbon Dioxide Buffer

It has long been known that trees grow faster with more carbon dioxide, but new research suggests that they may absorb more nitrogen from rocks to boost their growth and therefore, their carbon uptake. Researchers from the University of California, Davis, have reported the findings in the journal Nature.

If trees can utilize more nitrogen, they will absorb more carbon and effectively act as a buffer to climate change. “Findings from this study suggest that our climate-change models should not only consider the importance of nitrogen from the atmosphere, but now we also have to start thinking about how rocks may affect climate change," says Professor Benjamin Houlton, a biogeochemist co-authoring the study.

Nitrogen has traditionally been thought to enter the biosphere from the atmosphere, either through rainwater or some nitrogen absorbing organisms, but it is clear that nitrogen also enters the system from rocks rich in the gas. The study found carbon storage was as much as twice the level in areas with nitrogen rich rocks than in those that were nitrogen poor and this effect has been seen in other areas across North America, not just in the localized area of the study.

The findings have important significance for climate change. As much as Seventy-five percent of the planet’s land surface is covered in sedimentary rocks, which are high in nitrogen. Professor Houlton believes that “this discovery may also help explain several other studies that have found that the nitrogen budgets of forests are out of balance, the nitrogen accumulation in their soil and plants being substantially greater than the apparent nitrogen inputs,” and that this could have major implications for climate projections.

Nitrogen has previously not been included in climate models however; studies have suggested that the previously understood levels could lead to a 1.8°C warming of the climate – this is now not likely to be the case. More nitrogen than predicted may lead to less carbon dioxide in the atmosphere and a reduced greenhouse effect.

Further studies are obviously needed to understand how extensive this phenomenon is worldwide.