Soil C Accumulation in a White Oak CO₂-Enrichment Experiment via Enhanced Root Production

After four growing seasons, soil below white oak trees exposed to elevated atmospheric carbon dioxide levels (ambient + 300 ppm) had an average of 14% more soil carbon than soil below trees exposed to ambient levels of carbon dioxide. The soil carbon inventories in five soil cores collected from ambient chambers and six soil cores collected from elevated chambers at the Global Change Field Research Site, Oak Ridge, Tennessee, were measured. The authors conclude that the increase in soil carbon was due to an increase in belowground soil carbon input, because aboveground litter inputs were excluded by experimental design. These findings are consistent with the hypothesis that elevated carbon dioxide levels are increasing the amount of carbon stored in soil.