Recently, the analysis of more than 100 experiments shows that when the increase of carbon dioxide level leads to the increase of plant biomass, the amount of carbon that can be stored in soil will decrease. Because the current terrestrial carbon sink model does not consider this trade-off, the future forecast data is likely to need to be revised. Related papers were published in the journal Nature on March 25th.

Terrestrial ecosystems can remove about 30% of carbon dioxide emitted by human activities every year. Plants fix carbon dioxide in the process of promoting their own growth through photosynthesis, while soil can store carbon as decomposed biomass. However, it is not clear how this carbon sink will cope with the continuous increase in carbon dioxide emissions.

One hypothesis is that the increase of atmospheric carbon dioxide level will increase the carbon fixation capacity of plants and soil, but the research of César Terrer of Stanford University and his colleagues in the United States shows that this may not be the case.

The researchers analyzed the experimental data of 108 increasing carbon dioxide level and found an opposite relationship, that is, when the biomass of plants increases with the increase of carbon dioxide level, the carbon storage of soil will decrease. In their experiment, the increase of carbon dioxide level will increase the carbon storage of grassland soil (about 8%), but the carbon storage of forest soil will not increase-this is still when the forest biomass increases by about 23%.

Experts pointed out that this relationship may be related to the way plants get nutrition. During the growth process, the roots of plants will absorb nutrients from the soil, which researchers believe may reduce the carbon sequestration capacity of the soil.