Plants Ability to Absorb Carbon Dioxide Limited

A new study that focuses on an important factor that is responsible in mitigating fossil fuel emission comes out with a damning conclusion - the plants are not necessarily cleaning up the Earth of greenhouse gases, especially the deadly carbon.

The plants may not receive enough of the nutrients they need from typical soils to absorb as much Carbon Dioxide as scientists had previously estimated.

The study reveals that, plants' ability to absorb increased levels of carbon dioxide in the air may have been overestimated. The ability of plants to absorb carbon from the atmosphere is limited by the fetility of the soil.

Nature magazine reports that the capacity for land plants to absorb more CO2 will be much lower than previously thought, owing to limitations in soil nutrients.

The research by Peter Reich and Sarah Hobbie from the University of Minnesota is based on the 13 years of research at the Cedar Creek Ecosystem Science Reserve north of the Twin Cities.

These researchers monitored nearly 300 open-air plots planted with perennial grasses with varying levels of atmospheric carbon dioxide and soil nitrogen.

After two years, plant growth became limited by the availability of nitrogen in the soil. Plants use carbon dioxide to drive photosynthesis and to grow but with no nitrogen there was no growth or absorption of carbon dioxide.  

"Rather than building a time machine and comparing how ecosystems behave in 2070 -- which is hard to do -- we basically create the atmosphere of 2070 above our plots," Reich says.

On conducting the study they learnt that limited levels of fertility typical in most soils likely eliminate a large fraction of the capacity of plants to scrub CO₂ out of the atmosphere

Reich says, "It would be better if there were experiments like ours in tropical rain forest, temperate forest, and tundra, to see how well responses there match with what we have found. But as such experiments do not exist, our results play an important role in addressing this issue for ecosystems everywhere."