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ELEVATED CO2 AND ELEVATED TEMPERATURE AFFECT CARBON AND NITROGEN CONCENTRATIONS BUT NOT ACCUMULATION IN PSEUDOTSUGA MENZIESII SEEDLINGS
Citation:
Olszyk, D M., D T. Tingey, M G. Johnson, AND P T. Rygiewicz. ELEVATED CO2 AND ELEVATED TEMPERATURE AFFECT CARBON AND NITROGEN CONCENTRATIONS BUT NOT ACCUMULATION IN PSEUDOTSUGA MENZIESII SEEDLINGS. Presented at Ecological Society of America 2001 meeting, Madison, WI, August 5-10, 2001.
Description:
To determine the impact of climate change on concentrations and accumulation of C and N in trees, we grew Pseudotsuga menziesii (Mirb.) Franco (Douglas-fir) seedlings treated with ambient or elevated (+180 mol mol-1) CO2, and with ambient or elevated (+3.5 C) temperature for four years in outdoor, sun-lit, chambers under a wet-winter/dry-summer soil moisture regime and without added fertilization. Elevated CO2 decreased leaf % C and % N and increased the C/N ratio. In contrast, elevated temperature increased leaf % C and % N and decreased the C/N ratio. Branch and stem % C and % N were not affected by elevated CO2, while elevated temperature increased branch % C and % N, and decreased the C/N ratio in branches and stems. In roots, %C and % N were not affected by elevated CO2 or elevated temperature. However, despite changes in % C and % N in some tissues, the total accumulation of C and N in the plant and relative allocation of C or N to different tree organs was not affected by elevated CO2 or elevated temperature. Therefore, for Pseudotsuga menziesii seedlings growing under natural soil moisture and nutrition conditions, both elevated CO2 and temperature affect above-ground but not belowground tissue quality in terms of C and N concentrations, and may not affect the amount of C or N in the plant.