The effects of soil properties and condition on methane oxidation in Australian Alpine ecosystems with different fire histories

Aerated soils such as those found in forests and woodlands can be important sinks of the atmospheric greenhouse gas, methane (CH4). The magnitude of CH4 fluxes at the soil surface is determined by methanotrophs (oxidisers) and methanogens (producers), and there are several factors that control these microbial communities along with the transport of CH4 through the soil substrate. For example, soil moisture affects methane diffusion with consumption being shown to decrease with increasing soil moisture. Inorganic nitrogen is also an important controlling factor and has been shown to inhibit CH4 oxidation as ammonium and nitrate compete with methane for active sites on methane monooxygenase, an enzyme that catalyses methane oxidation. Other soil properties that influence CH4 uptake include pH, soil depth and soil particle size.  Fire can affect all of these soils properties which in turn affect CH4 uptake.

The aim of this project is to investigate the activity of methanotroph populations in response to varying a range of soil properties and condition. This will provide a better understanding and allow prediction of the effects that changing weather patterns and fire will have on the uptake of methane in alpine ecosystems in the Bogong High Plains. Molecular studies (T-RFLP) are also planned to be used to characterise populations of methanotrophs and methanogens from these soil systems.