Abstract ID: 565

Methane production of aboveground termite colonies in the Tapajos National Forest of Brazil.

Quantifying and understanding the dynamics of methane (CH₄) sources and sinks across the globe is critical because it is 23 times more efficient than CO₂ in trapping solar radiation in the atmosphere and atmospheric concentrations have increased more rapidly than any other greenhouse gas since the beginning of the industrial revolution. Methane is also an ideal target for curbing climate change since its mean residence time in the atmosphere is 12 years compared to >100 years for CO₂. The magnitude and sign of the CH₄ flux for tropical forests is unclear since the soils are generally a sink, while the canopy appears to be a source. However, the mechanisms for canopy CH₄ production have not been clearly identified. Therefore, we asked the question: what is the CH₄ production from aboveground termite colonies in an Amazon basin forest? Over a three day period in July 2008, we made in situ measurements of CH₄ fluxes from individual aboveground colonies in the Tapajos National Forest. We also estimated the number and total volume of aboveground colonies in three 1.25 ha plots: one located in a virgin forest, one in a stand selectively harvested in 1999, and one in a stand selectively harvest in 2003. Mean CH₄ production across all measured colonies was 86.0 mg C m^-3 hr^-1. Methane production was positively correlated with colony size. The density of aboveground termite colonies was 2.5 times higher (26 colonies ha^-1) in the plot harvested 5 years ago compared to the plot harvested 10 years ago and the virgin plot (~10 colonies ha^-1 in each). Finally, CH₄ production was 14.9, 2.3 and 9.5 g C ha^-1 hr^-1 for the 2003, 1999 and virgin plots, respectively, indicating that disturbance age may be an important factor in determining the contribution of termites to the Amazon CH₄ budget.

Session:  Biogeochemistry - Sources, sinks, and atmospheric chemistry of trace gases.

Presentation Type:  Oral