PARENT SESSION
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.

Interpreting ecosystem respiration fluxes using stable isotopes.

Bowling, David^*,1, Yakir, Dan², ¹ Dept of Biology, Salt Lake City, Utah² Dept of Environmental Sciences and Energy Research, Rehovot, Israel

ABSTRACT- Respiration by terrestrial ecosystems is one of the most important fluxes in the global carbon cycle. Stable isotopes have been an integral component of carbon cycle studies for several decades, and both , ¹³C and ¹⁸O in CO₂ have been used to assess the magnitude of respiration fluxes at the global scale. During the last decade, application of stable isotopes to ecosystem carbon cycle studies gained popularity and progress was made in several areas of biosphere-atmosphere exchange research. In this talk, we will review the application of stable isotope studies to analyses of respiration, focusing primarily on measurements conducted at the ecosystem scale. We will discuss linkages that have been observed between mean annual precipitation, atmospheric vapor pressure deficit, and soil moisture availability with the carbon isotope ratio of total ecosystem respiration (¹³C_R). We will also describe results from continental-scale networks of stable isotopes in ecosystems (BASIN, Carboeuroflux-Stable Isotopes Network) showing variation in ¹³C_R that follows general trends with seasonal, meteorological and geographical parameters. We will explore the potential for using dynamics of ¹³C_R to improve estimates of ecosystem discrimination ¹³C_E for regional and global-scale models of carbon source/sinks in the land biosphere.

Key words: carbon cycling, respiration, isotope, ecosystem