Modeling Methane Dynamics in a Bottomland Hardwood Wetland

Authors

Kabi Raj Khatiwada1* (kabik@uark.edu), Benjamin Runkle1,2, J. B. Moon3,4, Gary Stinchcomb5, Bassil El Masri4,6

Institutions

1Environmental Dynamics, University of Arkansas–Fayetteville, AR; 2Department of Biological and Agricultural Engineering, University of Arkansas–Fayetteville, AR; 3Biological Sciences Department, Murray State University, Murray, KY; 4Watershed Studies Institute, Murray State University, Murray, KY; 5Department of Earth Sciences, University of Memphis, Memphis, TN; 6Department of Earth and Environmental Sciences, Murray State University, Murray, KY

Abstract

Climate and environmental changes have a significant effect on wetlands, making it urgent to accurately model their methane (CH4) dynamics. There have been limited attempts in modeling the fluxes and pathways of CH4 dynamics in bottomland hardwood forested wetlands. This research study aims to improve the representation of wetland CH4 dynamics by incorporating emissions from temperate bald cypress (Taxodium distichum) trees and their knees—woody structures that form above the root of the bald cypress—in the CH4 modeling systems.

The Peatland Ecosystem Photosynthesis Respiration and Methane Transport (PEPRMT) model is a process-based biogeochemical model designed to estimate wetland carbon dioxide and CH4 fluxes (Oikawa et al. 2017). Currently, the team is modifying this model to represent methane release from the bottomland hardwood wetland ecosystem. Data from five eddy covariance flux towers representing upland and bottomland hardwood and forested wetland sites from different parts of the United States and data from cypress swamps owned by Murray State University, KY, are being arranged to fit into the model. Researchers are customizing the model to incorporate emissions from bald cypress knees into the model’s carbon/methane cycle. The model will then be validated at the flux sites. This improved representation and understanding of methane dynamics will increase the accuracy of the assessment of methane releases from woody wetland ecosystems in their current state and provide better knowledge for future climate change scenarios.

References

Oikawa, P. Y., et al. 2017. “Evaluation of a Hierarchy of Models Reveals Importance of Substrate Limitation for Predicting Carbon Dioxide and Methane Exchange in Restored Wetlands,” Journal of Geophysical Research: Biogeosciences 122(1), 145–67.