Modeled CO2 Emissions from Coastal Wetland Transitions to Other Land Uses: Tidal Marshes, Mangrove Forests, and Seagrass Beds

Authors

Catherine E. Lovelock, University of Queensland
James W. Fourqurean, Department of Biological Sciences, Florida International UniversityFollow
James T. Morris, University of South Carolina

Date of this Version

5-15-2017

Document Type

Article

Rights

by

Abstract

The sediments of coastal wetlands contain large stores of carbon which are vulnerable to oxidation once disturbed, resulting in high levels of CO₂ emissions that may be avoided if coastal ecosystems are conserved or restored. We used a simple model to estimate CO₂ emissions from mangrove forests, seagrass beds, and tidal marshes based on known decomposition rates for organic matter in these ecosystems under either oxic or anoxic conditions combined with assumptions of the proportion of sediment carbon being deposited in either oxic or anoxic environments following a disturbance of the habitat. Our model found that over 40 years after disturbance the cumulative CO₂ emitted from tidal marshes, mangrove forests, and seagrass beds were ~70–80% of the initial carbon stocks in the top meter of the sediment. Comparison of our estimates of CO₂ emissions with empirical studies suggests that (1) assuming 50% of organic material moves to an oxic environment after disturbance gives rise to estimates that are similar to CO₂ emissions reported for tidal marshes; (2) field measurements of CO₂ emissions in disturbed mangrove forests were generally higher than our modeled emissions that assumed 50% of organic matter was deposited in oxic conditions, suggesting higher proportions of organic matter may be exposed to oxic conditions after disturbance in mangrove ecosystems; and (3) the generally low observed rates of CO₂ emissions from disturbed seagrasses compared to our estimates, assuming removal of 50% of the organic matter to oxic environments, suggests that lower proportions may be exposed to oxic conditions in seagrass ecosystems. There are significant gaps in our knowledge of the fate of wetland sediment carbon in the marine environment after disturbance. Greater knowledge of the distribution, form, decomposition, and emission rates of wetland sediment carbon after disturbance would help to improve models.

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 License.

Comments

Originally published in Frontiers in Marine Science.

Identifier

FIDC006329

Recommended Citation

Lovelock, Catherine E.; Fourqurean, James W.; and Morris, James T., "Modeled CO2 Emissions from Coastal Wetland Transitions to Other Land Uses: Tidal Marshes, Mangrove Forests, and Seagrass Beds" (2017). Center for Coastal Oceans Research Faculty Publications. 8.
https://digitalcommons.fiu.edu/merc_fac/8