Application and Analysis of Keeling Curve in Terrestrial Carbon Cycle

D. E. Pataki1 J. R. Ehleringer1 L. B. Flanagan2 D. Yakir3 D. R. Bowling1 C. J. Still4,5

1 Department of Biology, University of Utah 2 Department of Life Sciences, University of Lethbridge 3 Weizmann Institute 4 University of California Berkeley Atmosphere Center 5 Department of Geography, University of California

GLOBAL BIOGEOCHEMICAL CYCLES, VOL. 17, NO. 1, 1022, doi:10.1029/2001GB001850, 2003

Abstract: The effects of photosynthesis and respiration on the atmosphere can be used to study global carbon sink/source estimates and to distinguish ecosystem fluxes. Therefore, Keeling plot's research methods are increasingly being used to determine the carbon isotope composition of ecosystem respiration (d13CR) to better understand the isotope identification of ecosystems. In this paper, we analyzed 146 keeling curves from 33 experimental sites in North and South America to study the pattern of ecosystem respiration (d13CR). To resolve the results from different studies, we discussed the assumptions for the Keeling curve method and recommended standard methods that can be used to determine ecosystem respiration. Methods include regression calculations for interpreting x-variable errors and estimates of ecosystem respiration during the night. We uniformly calculated the ecosystem respiration of all habitats. We found that the C3 ecosystem has a large number of spatiotemporal changes, ranging from -19.0 to -32.6. The average C3 ecosystem value is -18.3 ‰. Rainfall is the main driving force for the spatial and temporal changes of ecosystem respiration. (1) Newly fixed carbon has a great impact on ecosystem respiration; (2) Early climatic conditions have a significant impact on ecosystem respiration. These results explain the importance of available water as a key control factor for atmospheric 13CO2, highlighting the potential of ecosystem respiration (d13CR) as an effective tool to explain the impact of the environment on vegetation canopy and ecosystems.

Keywords: carbon cycle, carbon isotope, ecosystem respiration, carbon dioxide, terrestrial ecosystem