|Wiemann, Michael - USDA FOREST SERVICE|
|Kretschmann, David - USDA FOREST SERVICE|
|Rudie, Alan - USDA FOREST SERVICE|
|Idso, Sherwood - RETIRED USWCL|
Submitted to: Government Publication/Report
Publication Type: Other
Publication Acceptance Date: February 2, 2008
Publication Date: February 1, 2008
Citation: Wiemann, M.C., Kretschmann, D., Rudie, A., Kimball, B.A., Idso, S.B. 2008. Long-term effects of elevated carbon dioxide on sour orange tree specific gravity and anatomy. Government Publication/Report. Research Paper FPL-RP-648 Interpretive Summary: The long-term responses of trees to elevated CO2 are important for determining the likely engineering qualities of lumber and the pulping qualities of wood fiber for paper in the future. Therefore, at the end of a 17-year experiment was conducted from 1987 to 2005 with sour orange trees in open-top CO2 enrichment chambers by USDA-ARS at Phoenix, Arizona, samples of the wood from the trunks were sent to the USDA-FS Forest Products Laboratory, Madison, WI, for analyses of wood properties. There was a small but statistically significant increase in wood basic specific gravity and number of rays per mm. However, other anatomical characteristics (percentages of tissues, number of vessels per square mm, vessel diameters, and fiber wall thicknesses) were unaffected by the elevated CO2 concentration. These data suggest that impacts of elevated CO2 on lumber quality will probably be minimal in the future. This research especially benefits foresters and consumers of all wood products.
Technical Abstract: Exposure to elevated levels of atmospheric CO2 for a period of 17 years resulted in small but statistically significant increases in wood basic specific gravity and number of rays per mm. Other anatomical characteristics (percentages of tissues, number of vessels per square mm, vessel diameters, and fiber wall thicknesses) were unaffected by treatment. Differences due to distance from pith were important, but cardinal direction (north, south, east, west) were not.