Related Experiment Video
Updated: Mar 24, 2026
10:19
A CO2 Concentration Gradient Facility for Testing CO2 Enrichment and Soil Effects on Grassland Ecosystem Function
Published on: November 21, 2015
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Quantification of ecosystem C dynamics in a long-term FACE study on permanent grassland
Katharina Lenhart1, Claudia Kammann1,2, Pascal Boeckx3
1Department of Plant Ecology, Justus-Liebig-University Giessen, Heinrich-Buff Ring 26-32, D-35392, Giessen, Germany.
Rapid Communications in Mass Spectrometry : RCM
|March 13, 2016
Summary
Elevated carbon dioxide (CO2) in grasslands increases carbon turnover but does not enhance soil carbon storage. This suggests grassland ecosystems may become less effective carbon sinks as increased carbon is released back to the atmosphere.
Area of Science:
- Ecology
- Environmental Science
- Soil Science
Background:
- Grasslands are vital to the global carbon cycle due to their extensive coverage and high soil organic carbon content.
- Changes in grassland carbon input/output rates significantly impact soil carbon and atmospheric carbon dioxide (CO2) levels.
Purpose of the Study:
- To investigate whether increased carbon supply under elevated CO2 conditions enhances soil carbon pools in grasslands.
- To analyze the impact of elevated CO2 on respiration processes, including CO2 emission rates and their sources (plant vs. soil).
Main Methods:
- The Giessen-FACE experiment utilized moderate CO2 enrichment (+20% and +30%) on an extensively managed grassland.
- Respiration processes were examined over 30 months after 6 years of CO2 enrichment, with a switch in the isotopic signature of enrichment CO2.
- Control plots and plots with varying CO2 enrichment levels were used to assess treatment effects.
Main Results:
- After 9 years, elevated CO2 (+20%) resulted in 37% new carbon in the topsoil, decreasing with depth.
- No significant CO2 effect on overall soil carbon content was observed.
- Elevated CO2 (+20%) increased ecosystem respiration by 13%; root respiration contributed significantly to soil respiration.
Conclusions:
- Increased carbon turnover under elevated CO2, without net soil carbon sequestration, indicates a potential decrease in grassland ecosystem sink strength.
- Additional carbon supplied by elevated CO2 may be rapidly released back into the atmosphere as CO2.
- Future grassland management strategies should consider these dynamics to maintain carbon sequestration potential.
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