Tree exposure to elevated Co₂ increases availability of soil phosphorus

摘要

Future high levels of atmospheric carbon dioxide will increase biomass production of terrestrial plants, however depletion of soil mineral nutrients may act as a negative feedback to increased growth. To test this, an ecosystem phosphorus budget was calculated in poplar grown under field conditions at ambient and elevated atmospheric CO2for 5 years. The pools of total, plant available, weatherable and organic P were estimated, as well as the P storage in tree biomass components. While as a non-significant increase in amount of P taken up by the trees we observed, plant available P pools in the soil increased significantly. An increase in all soil P extractions was seen, with the greatest increase in an acid soluble P fraction which is considered to be the weatherable fraction. The formation of this P fraction may be biogenically driven and this additional P probably originates from weathering of occluded mineral pools.