Methane is an important greenhouse gas, and the uptake of methane by upland (i.e., well-drained, oxic) soils is the primary biological sink.  Sequencing studies of methanotroph functional genes have identified six major groups of methanotrophs.  Although rates of methane consumption by upland soils differ in space and time, we have only a weak understanding of the importance of methanotroph community composition for driving differences in uptake rates. In this study, we used enzyme kinetics assays and DNA sequencing techniques to investigate if methanotrophic community composition could explain differences in methane consumption we see at three Long Term Ecological Research (LTER) sites that fall along a precipitation gradient:  Konza Prairie, Shortgrass Steppe, and Sevilleta.

Results/Conclusions

Our findings reveal that communities differ in rates of methane uptake, and that these biochemical differences correspond with variation in community composition.  In addition, our results, when compared with other published measures of methanotroph community composition, reveal an emerging pattern:  methanotroph biogeography appears to depend on soil pH levels and the local soil moisture regime.  These findings suggest that shifts in methanotroph community structure likely modulate the biogeochemical response of methane uptake to changes in the environmental controls.