Related Experiment Video
Updated: Jul 19, 2026

Measurements of CO2 Fluxes at Non-Ideal Eddy Covariance Sites
Published on: June 24, 2019
Using continuous stable isotope measurements to partition net ecosystem CO2 exchange
Jianmin Zhang1, Timothy J Griffis, John M Baker
1Department of Soil, Water, and Climate, University of Minnesota-Twin Cities, 439 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN 55108, USA. jzhang@umn.edu
This study combined micrometeorology and stable isotopes to estimate ecosystem photosynthesis and respiration. The isotopic method showed more variation than traditional approaches, offering a more detailed view of carbon exchange processes.
Area of Science:
- Ecosystem Ecology
- Biogeochemistry
- Micrometeorology
- Stable Isotope Ecology
Background:
- Accurate ecosystem-scale estimation of photosynthesis and respiration is crucial for understanding carbon cycling.
- Traditional micrometeorological methods for partitioning CO2 fluxes have limitations.
- Stable isotope techniques offer a complementary approach to flux partitioning.
Purpose of the Study:
- To partition net ecosystem CO2 exchange (FN) into photosynthesis (FA) and respiration (FR) in a corn-soybean rotation ecosystem.
- To compare the performance of a stable isotope method with a conventional regression-based approach.
- To examine the dynamics of ecosystem respiration isotope ratios and photosynthetic discrimination.
Main Methods:
- Combined micrometeorological measurements with stable isotope analysis of CO2 (¹²CO2 and ¹³CO2).
- Utilized tunable diode laser (TDL) absorption spectroscopy for continuous gas mixing ratio measurements.
- Partitioned net ecosystem CO2 exchange during the corn phase of a corn-soybean rotation in summer 2003.
Main Results:
- Ecosystem respiration isotope ratios (δR) exhibited significant seasonal variation, correlating with canopy phenology.
- Daytime net ecosystem CO2 exchange isotope ratios (δN) ranged from -12 to -4‰, while canopy discrimination (δ canopy) was stable around 3‰.
- Isotopic flux partitioning revealed greater short-term variability and symmetry compared to the regression method, but with higher uncertainties.
Conclusions:
- The TDL-micrometeorological technique combined with stable isotopes provides a dynamic assessment of ecosystem carbon fluxes.
- Uncertainties in δN and daytime δR estimates were the primary drivers of isotopic partitioning uncertainty.
- Reducing measurement uncertainties in stable isotope ratios can enhance the understanding of ecosystem photosynthesis and respiration processes.
More Related Videos
10:16Design and Operation of a Continuous 13C and 15N Labeling Chamber for Uniform or Differential, Metabolic and Structural, Plant Isotope Labeling
Published on: January 16, 2014
06:02A Low-Cost Method of Measuring the In Situ Primary Productivity of Periphyton Communities of Lentic Waters
Published on: December 16, 2022
Related Concept Videos
The Carbon Cycle
¹³C NMR: ¹H–¹³C Decoupling
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...