Symposium 14: Respiratory Control of the Global C Cycle in a Changing Environment
Organized by: M Gonzalez-Meler and W Schlesinger
Wednesday, August 6. 1:30 PM to 5:00 PM, SITCC Chatham Ballroom B.

Respiratory control of the carbon cycle in a changing environment: synthesis and discussion.

De Lucia, Evan *,1, Schlesinger, William*,2, 1 University of Illinois, Urbana, IL, USA2 Duke University, Durham, NC, USA

ABSTRACT- Oxidative respiration from terrestrial ecosystems releases approximately 120 gigatons of carbon annually to the atmosphere, roughly 20 times the amount from the combustion of fossil fuels. The difference between photosynthesis and the sum of respiratory processes determines the rate of ecosystem carbon storage. For example, in a young pine forest in the Piedmont of North Carolina, autotrophic and heterotrophic respiration were 1704 and 216 gC/m2/y, respectively, or 71% and 9% of gross primary production. After respiratory losses, the rate of carbon accumulation in this forest was approximately 428 gC/m2/y. Fundamental questions remain about how respiration will respond to the components of global change and about the effectiveness of current methodologies for estimating respiration at different spatial and temporal scales. In this symposium we will discuss the relationship between respiration and increasing levels of carbon dioxide in the atmosphere. We will critically examine the potential limitations of extrapolating rate-based measurements to total ecosystem respiration. We will also discuss isotopic methods for partitioning respiratory fluxes between autotrophic and heterotrophic components and evaluate the importance of mean residence time as a control of carbon cycling in the soil. This symposium will contribute to a new vision for improving estimates of ecosystem respiration.

Key words: global change, respiration, stable isotope, scaling