Determining Methane Uptake in Tropical Agroforestry Soils: A Case for Inclusion in REDD+

Presenter Information

Callie L. Mills
Richard S. Mbatu, University of South Florida St. PetersburgFollow
Yasin Elshorbany, University of South Florida St. PetersburgFollow
James Ivey, University of South Florida St. PetersburgFollow
Bob Wang, University of South Florida St. Petersburg

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Faculty Advisor: Dr. Richard Mbatu

Description

This study measures methane fluxes in tropical agroforestry soils to determine agroforestry’s uses as a potential methane sink within the Reducing Emissions from Deforestation and Forest Degradation (REDD+) program. Agroforestry is a sustainable agriculture method which uses the intermingling of crops and trees for eventual timber harvesting, providing carbon sequestration benefits and food security to small communities while maximizing soil health. Belize is participating in the REDD+ program, which does not yet have methane-specific language. Methane fluxes were measured several times per week during April and July for a seasonal study. Samples were collected using six static soil chambers and analyzed with GC-FID. Temperature, rainfall, and soil volumetric water content were also measured alongside methane fluxes. Average methane flux for the dry season campaign was -0.01 mg CH4 m-2 h-1 and -0.03 mg CH4 m-2 h-1 for the wet season campaign, where negative values are indicative of uptake. Overall, fluxes only ranged by 0.07 mg CH4 m-2 h-1 for both seasons. There was a strong negative correlation between methane flux and rainfall in the dry season, and a weak positive correlation in the wet season. With acknowledgement of uncertainties, no significant p-values were seen, and thus more rigorous study of agroforestry soils must be completed to solidify its status as a methane sink, if only seasonally. By understanding methane fluxes in tropical agroforestry soils, agroforestry can be utilized as a tool for climate change mitigation as part of the REDD+ program.