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Effects of Elevated CO2 on Oak Seedlings Germinated from Acorns Produced on Ambient and CO2-Enriched Trees
Reference
Polle, A., McKee, I. and Blaschke, L.  2001.  Altered physiological and growth responses to elevated [CO2] in offspring from holm oak (Quercus ilex L.) mother trees with lifetime exposure to naturally elevated [CO2].  Plant, Cell and Environment 24: 1075-1083.

What was done
The authors collected acorns from mature holm oak (Quercus ilex L.) trees that had been growing naturally at ambient and twice-ambient atmospheric CO2 concentrations for their entire lifetimes due to their different distances from a CO2-emitting spring in central Italy.  After germinating the acorns, the resulting seedlings were grown for eight months at both atmospheric CO2 concentrations to determine if atmospheric CO2 enrichment of parent trees had any effect on seedling response to atmospheric CO2 enrichment.

What was learned
Elevated CO2 increased whole-plant biomass by 158 and 246% in seedlings derived from acorns produced in ambient and twice-ambient atmospheric CO2 concentrations, respectively, such that the final biomass of the CO2-enriched seedlings that had been derived from acorns produced in the CO2-enriched air was 25% greater than that of the CO2-enriched seedlings derived from acorns produced in ambient air.  In addition, gas exchange measurements indicated that CO2-enriched seedlings derived from acorns produced on CO2-enriched trees exhibited less-pronounced photosynthetic acclimation to elevated CO2 concentrations than did CO2-enriched seedlings derived from acorns produced on trees exposed to ambient air.

What it means
As the air's CO2 content rises, it is possible that holm oak - and perhaps other trees and plants - will exhibit positive responses to this phenomenon that will further increase the positive responses of their progeny to atmospheric CO2 enrichment.  In other words, trees and other plants that grow and develop in CO2-enriched environments may well produce offspring that will be even more responsive to elevated CO2 than they were.