PJB-2010-91
TREE EXPOSURE TO ELEVATED CO2 INCREASES AVAILABILITY OF SOIL PHOSPHORUS
FAISAL N. KHAN1, MARTIN LUKAC2,*, FRANCO MIGLIETTA3, M. KHALID4 AND DOUGLAS L. GODBOLD1
Abstract
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 CO2 for 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.
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