RUI: Fine root production and architecture in a loblolly pine forest exposed to FACE: interactive effects of atmospheric CO2-enrichment with soil N availability

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Project Abstract: RUI: Fine root production and architecture in a loblolly pine forest: interactive effects of atmospheric carbon dioxide-enrichment with soil nitrogen availability.Seth Pritchard (PI) and Allan Strand (Co-PI), College of CharlestonEfforts to characterize carbon cycling between the atmosphere, forest canopies, and the soil are hindered by a poor understanding of how long tree roots live. The influence of elevated atmospheric carbon dioxide (CO2) concentrations and fertilization on the smallest roots of loblolly pine trees has been studied since 1998 in the Duke University Forest. The lifespans of the smallest tree roots are being documented by periodically inserting a miniature camera into clear tubes installed permanently in soil. Using sequential digital images to measure the lifespan of roots of different sizes will be combined with analysis of root architecture and chemical analysis to better understand how root biology will be affected by elevated atmospheric CO2 concentrations. Carbon dioxide emitted from burning fossil fuels and deforestation is accumulating in the atmosphere. Some unknown quantity of this extra CO2 will be removed from the atmosphere by plants during photosynthesis and then moved by the plants into the soil where some of it may remain for centuries. Understanding how elevated CO2 will influence the lifespan of the smallest and most ephemeral roots is particularly important because these roots absorb most of the nutrients and water acquired by trees and when they die they transfer a large amount of carbon into the soil. A better understanding of root biology is needed to predict the potential for carbon storage in the soil.