Final Report on "Rising CO2 and Long-term Carbon Storage in Terrestrial Ecosystems: An Empirical Carbon Budget Validation"
The primary goal of this report is to report the results of Grant DE-FG02-97ER62458, which began in 1997 as Grant DOE-98-59-MP-4 funded through the TECO program. However, this project has a longer history because DOE also funded this study from its inception in 1985 through 1997. The original grant was focused on plant responses to elevated CO2 in an intact ecosystem, while the latter grant was focused on belowground responses. Here we summarize the major findings across the 25 years this study has operated, and note that the experiment will continue to run through 2020 with NSF support. The major conclusions of the study to date are: (1 Elevated CO2 stimulated plant productivity in the C3 plant community by ~30% during the 25 year study. The magnitude of the increase in productivity varied interannually and was sometime absent altogether. There is some evidence of down-regulation at the ecosystem level across the 25 year record that may be due to interactions with other factors such as sea-level rise or long-term changes in N supply; (2) Elevated CO2 stimulated C4 productivity by <10%, perhaps due to more efficient water use, but C3 plants at elevated CO2 did not displace C4 plants as predicted; (3) Increased primary production caused a general stimulation of microbial processes, but there were both increases and decreases in activity depending on the specific organisms considered. An increase in methanogenesis and methane emissions implies elevated CO2 may amplify radiative forcing in the case of wetland ecosystems; (4) Elevated CO2 stimulated soil carbon sequestration in the form of an increase in elevation. The increase in elevation is 50-100% of the increase in net ecosystem production caused by elevated CO2 (still under analysis). The increase in soil elevation suggests the elevated CO2 may have a positive outcome for the ability of coastal wetlands to persist despite accelerated sea level rise; (5) Crossing elevated CO2 with elevated N causes the elevated CO2 effect to diminish, with consequences for change in soil elevation.
- Research Organization:
- Smithsonian Institute, Washington, DC (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- FG02-97ER62458
- OSTI ID:
- 986309
- Report Number(s):
- DOE/ER62458-1
- Country of Publication:
- United States
- Language:
- English
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