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EFFECTS OF CO2 AND TEMPERATURE ON FINE ROOT PRODUCTION AND MORTALITY IN DOUGLAS FIR
Citation:
Johnson, M G., P T. Rygiewicz, D T. Tingey, AND D L. Phillips. EFFECTS OF CO2 AND TEMPERATURE ON FINE ROOT PRODUCTION AND MORTALITY IN DOUGLAS FIR. Presented at 4th North American Forest Ecology Workshop, Corvallis, OR, June 16-20, 2003.
Description:
Little is known about the effects of global climate change on the production and mortality of fine roots. We conducted a 4-year study to determine the effects of elevated CO2 and temperature on Douglas fir fine ( 2 mm in diameter) roots. The study was conducted in sun-lit controlled-environment chambers located in Corvallis, Oregon, USA. The experiment had a 2 by 2-factorial design [2 levels of CO2 (ambient CO2 and ambient CO2 + 200 mmol/mol) and 2 levels of air temperature (ambient temp. and ambient temp. + 4?C)] with 3 replicates. Four horizontal clear plastic minirhizotron tubes were installed in the soil compartment of each chamber. Seedlings were planted in a reconstructed native forest soil in June 1993. Root images were recorded every four weeks using a minirhizotron camera. The majority of roots observed were very fine ( 1 mm in diameter). Elevated temperature increased the production of very fine roots in the first year at both CO2 levels. Overall, elevated temperature increased the mortality of very fine roots. Elevated CO2 had no significant effect on the production and mortality of the very fine roots. More roots in the 1-2 mm diameter size class were observed in the elevated CO2 treatment. Limitations of soil nitrogen availability likely influenced the response of Douglas fir seedlings to elevated CO2 and temperature in this experiment.