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Effects of Four Years of Elevated CO2 on Loblolly Pine Seedlings: Photosynthetic Rates and Biomass Production
Tissue, D.T., Thomas, R.B. and Strain, B.R.  1997.  Atmospheric CO2 enrichment increases growth and photosynthesis of Pinus taeda: a 4-year experiment in the field.  Plant, Cell and Environment 20: 1123-1134.

What was done
Seedlings of loblolly pine (Pinus taeda L.) were grown for four years in open-top chambers receiving atmospheric CO2 concentrations of 350 and 650 ppm to study the long-term effects of elevated CO2 on the photosynthesis and growth of this abundant pine species.

What was learned
Throughout the four-year study, seedlings grown in elevated CO2 displayed photosynthetic rates that were 60-130% greater than rates exhibited by seedlings grown in ambient air during the warmer summer months.  During the colder winter months, atmospheric CO2 enrichment continued to boost seedling photosynthetic rates by 14 to 44%.  These persistent increases in net carbon uptake led to a mean biomass accumulation in the CO2 enriched seedlings that was 90% greater than that attained by the ambiently-grown controls after four years of treatment exposure.

What it means
As the atmospheric CO2 concentration increases, it is likely that loblolly pine seedlings will respond by exhibiting enhanced rates of photosynthesis and biomass production.  In fact, because the CO2-induced biomass response was so large in this species even after four years, the authors stated that "these trees could be a large sink for fossil fuel carbon emitted to the atmosphere."   Thus, carbon sequestration by this wide-spread coniferous species is likely to become ever larger as the air's CO2 content continues to increase.

Reviewed 20 March 2002