Seasonal Patterns of Photosynthesis in Douglas Fir Seedlings During the Third and Fourth Year of Exposure to Elevated CO2 and Temperature

Authors

James D. Lewis, National Research CouncilFollow
Melissa S. Lucash, Portland State UniversityFollow
David M. Olszyk, US Environmental Protection Agency Western Ecology Division
David T. Tingey, US Environmental Protection Agency Western Ecology Division

Sponsor

The research described in this article has been funded by the U.S. Environmental Protection Agency.

Published In

Plant, Cell & Environment

Document Type

Article

Publication Date

5-2001

Subjects

Acclimatization (Plants), Carbon dioxide, Douglas fir -- Seedlings -- Growth, Douglas fir -- Climatic factors

Abstract

The interactive effects of elevated atmospheric CO₂ and temperature on seasonal patterns of photosynthesis in Douglas fir (Psuedotsuga menziesii (Mirb.) Franco) seedlings were examined. Seedlings were grown in sunlit chambers controlled to track either ambient (~400 p.p.m.) CO₂ or ambient +200 p.p.m. CO₂, and either ambient temperature or ambient +4 °C. Light-saturated net photosynthetic rates were measured approximately monthly over a 21 month period. Elevated CO₂ increased net photosynthetic rates by an average of 21% across temperature treatments during both the 1996 hydrologic year, the third year of exposure, and the 1997 hydrologic year. Elevated mean annual temperature increased net photosynthetic rates by an average of 33% across CO₂ treatments during both years. Seasonal temperature changes also affected net photosynthetic rates. Across treatments, net photosynthetic rates were highest in the spring and autumn, and lowest in July, August and December–January. Seasonal increases in temperature were not correlated with increases in the relative photosynthetic response to elevated CO₂. Seasonal shifts in the photosynthetic temperature optimum reduced temperature effects on the relative response to elevated CO₂. These results suggest that the effects of elevated CO₂ on net photosynthetic rates in Douglas fir are largely independent of temperature.

Description

The research described in this article has been funded by the U.S. Environmental Protection Agency. This document has been prepared at the EPA’s Western Ecology Division in Corvallis, Oregon, through co-operative agreement CR- 824072 with the National Research Council and through contract 68-C6–0005 with Dynamac, Inc.

This work was authored as part of the Contributor's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.

The published article is copyrighted by Wiley Blackwell and can be found at: http://dx.doi.org/10.1046/j.1365-3040.2001.00700.x

DOI

10.1046/j.1365-3040.2001.00700.x

Persistent Identifier

http://archives.pdx.edu/ds/psu/12659

Citation Details

Lewis, J. D., Lucash, M., Olszyk, D., & Tingey, D. T. (2001). Seasonal patterns of photosynthesis in Douglas fir seedlings during the third and fourth year of exposure to elevated CO2 and temperature. Plant, Cell & Environment, 24(5), 539-548.