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Effects of Elevated CO2 on Nitrogen Fixation in Leguminous Acacia Species
Schortemeyer, M., Atkin, O.K., McFarlane, N. and Evans, J.R.  2002.  N2 fixation by Acacia species increases under elevated atmospheric CO2Plant, Cell and Environment 25: 567-579.

What was done
Seedlings of seven Acacia species native to Australia were grown for nearly five months in environmental chambers receiving atmospheric CO2 concentrations of 350 and 700 ppm to study the effects of elevated CO2 on nitrogen-fixation and growth in these leguminous plants.

What was learned
Elevated CO2 enhanced rates of net photosynthesis by 19 to 56% in all species, which led to relative growth rate increases of 7 to 24% in six of the seven species.  Consequently, atmospheric CO2 enrichment enhanced total plant dry weights by an average of 86%.  In addition, it increased the total amount of nitrogen fixed per plant by an average of 65%.

What it means
As the atmospheric CO2 concentration rises, it is likely that Acacia species will exhibit enhanced rates of photosynthesis, growth and biomass production.  In addition, the rising CO2 concentration should increase nitrogen fixation in these plants, thus improving soil nitrogen fertility in communities where they are found.

Reviewed 5 June 2002