Wood properties of trembling aspen and paper birch after 5 years of exposure to elevated concentrations of CO2 and O3
Katri Kostiainen (1), Seija Kaakinen (1), Elina Warsta (1), Mark E. Kubiske (2), Neil D. Nelson (2), Jaak Sober (3), David F. Karnosky (3), Pekka Saranpää (4) and Elina Vapaavuori (1, 5)
1. Finnish Forest Research Institute, Suonenjoki Research Unit, FI-77600 Suonenjoki, Finland / 2. USDA Forest Service, North Central Research Station, Forestry Sciences Laboratory, 5985 Highway K, Rhinelander, WI 54501,
USA / 3. School of Forest Resources and Environmental Science, Michigan Technological University, Houghton, MI 49931, USA / 4. Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland / 5. Corresponding author () / Received June 28, 2007; accepted October 24, 2007; published online March 3, 2008
Summary
We investigated the interactive effects of elevated concentrations of carbon dioxide ([CO2]) and ozone ([O3]) on radial growth, wood chemistry and structure of five 5-year-old trembling aspen (Populus tremuloides Michx.) clones and the wood chemistry of paper birch (Betula papyrifera Marsh.). Material for the study was collected from the Aspen FACE (free-air CO2 enrichment) experiment in Rhinelander, WI, where the saplings had been exposed to four treatments: control, elevated [CO2] (560 ppm), elevated [O3] (1.5 × ambient) and their combination for five growing seasons. Wood properties of both species were altered in response
to exposure to the treatments. In aspen, elevated [CO2] decreased uronic acids (constituents of, e.g., hemicellulose) and tended to increase stem diameter. In response to elevated
[O3] exposure, acid-soluble lignin concentration decreased and vessel lumen diameter tended to decrease. Elevated [O3] increased the concentration of acetone-soluble extractives in paper birch, but tended to decrease the concentration of these
compounds in aspen. In paper birch, elevated [CO2] decreased and elevated [O3] increased starch concentration. The responses of wood properties to 5 years of fumigation differed from those previously
reported after 3 years of fumigation.
