Wednesday, August 8, 2007

PS 43-69: A meta-analysis of plant responses to elevated CO2 and temperature

Dan Wang1, Scott A. Heckathorn1, and E. William Hamilton III2. (1) University of Toledo, (2) Washington and Lee University

Interactive effects of rising atmospheric CO2 and temperatures on plants have not been reviewed with consideration for both increasing mean temperatures and acute heat stress.  Here, we use meta-analysis of 55 individual studies to examine CO2 and warming effects on total biomass, net photosynthesis (Pn), Photosystem II efficiency (PSII), stomatal conductance (gs), total non-structural carbon (TNC) and nitrogen concentration (%N).  Data were categorized by photosynthetic type (C3, C4) and treatment temperatures (AM, ambient; EL, elevated, =AM+1-8oC; HS, heat stress, =AM+>8oC).  In C4 plants, elevated (vs. current) CO2 altered Pn by 9.4, 23.7, and -10.9% for AM, EL, and HS treatments, respectively, compared to 25.9, 20.1, and 24.4% for C3 species.  PSII was not affected by CO2 in C3 species, but was decreased by high CO2 in C4 species at EL and HS.  High CO2 reduced gs in C3 and C4 species at all temperature treatments, with larger reductions for C4.  Total mass was increased more by high CO2 in C3 (AM=36.0, EL=36.1, HS=23.5%) than in C4 species (AM=-16.5, EL=10.6, and HS=7.0%).  TNC for C3 species was decreased in roots, but increased in leaves, by elevated CO2 at all temperature treatments, while the reverse was true for C4 species.  At HS, elevated CO2 decreased %N in leaves and roots for C3 and C4 species.  These results indicate that CO2 can have positive, negative, or neutral effects on plant response to increasing temperatures, which may vary between C3 and C4 plants and for moderate warming vs. heat waves.

See more of PS 43 - Climate change
See more of Contributed Oral and Poster Abstracts

See more of The ESA/SER Joint Meeting (August 5 -- August 10, 2007)