Localization of methane consumption and nitrification activities in some boreal forest soils and the stability of methane consumption on storage and disturbance

Methane consumption was studied in intact cores and bulk samples of soils from aspen, pine, and spruce sites at the northern study area in Manitoba of the Boreal Ecosystem-Atmosphere Study (BOREAS) program. Activity of aspen and spruce soil samples showed negligible change with time of refrigeration storage, but pine soil showed increased activity. Laboratory-determined core fluxes were in agreement with field chamber flux measurements. Most methane consumption was restricted to the subsurface (lower organic or mineral) layers. Activity was slightly increased or not affected by physical disruption of intact core sections. Nitrification was restricted to horizons in which maximal methane consumption occurred and was low or negligible at pH < 5. Potential for methane production was shown in pine organic horizons and sporadically in intact organic layers of aspen soil.