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

Abstract

Abstract. 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 p H < 5. Potential for methane production was shown in pine organic horizons and sporadically in intact organic layers of aspen soil. 29,255

Organic matter composition and potential trace gas production of permafrost soils in the forest tundra in northern Siberia

“…The high methanotrophic activity in P1 was restricted to the A horizon, and the subsoil of P1 did not show enhanced CH 4 uptake. This pattern corresponds with the observations that maximum rates of methane uptake are localised in the upper mineral soil or only a few centimetres below the soil surface (Crill, 1991;Adamsen and King, 1993;Amaral and Knowles, 1997). There was no clear temperature effect on CH 4 uptake (Fig.…”

“…The high methanotrophic activity suggests that this soil also shows larger CH 4 uptake than the permafrost soils under field condition. This assumption is supported by Amaral and Knowles (1997), who found that field CH 4 uptake of boreal forest soils was reflected adequately by laboratory-determined CH 4 fluxes. Our results indicate that permafrost distribution is an important control of CH 4 uptake in our research area.…”

Biogeochemical controls on methane, nitrous oxide, and carbon dioxide fluxes from deciduous forest soils in eastern Canada

“…Furthermore, well‐drained soils in OGF responded more significantly to changes in %WFPS in terms of CO 2 :CH 4 emission ratios (Figure 4) than similar soils in the SMF signifying the role of porosity and soil moisture content in diffusion limitation of CH 4 into consumption zones. These findings show that soils under American beech with a thicker O horizon have a larger porosity facilitating faster atmospheric CH 4 and O 2 diffusion into zones of CH 4 consumption in soils [ Amaral and Knowles , 1997] compared to soils under sugar maple with a thinner O horizon.…”

“…Faster N mineralization in soils under sugar maple may produce more N 2 O than under American beech and hemlock. Forest soils with higher mineral N contents, particularly NH 4 , may have smaller CH 4 consumption potentials, as NH 4 competitively inhibits the oxidation of CH 4 by the methane mono‐oxygenase enzyme [ Amaral and Knowles , 1997]. Bodelier et al [2000] reported no inhibition effect due to N fertilization; however, the soils used by the authors were from rice paddies where in situ CH 4 production is higher than in well‐drained forest soils.…”

Greenhouse Gas Emissions — Fluxes and Processes

“…Boreal forests act as a small CO 2 sink with respect to the atmosphere due to longterm carbon accumulation in soils (Schlesinger 1990), and dry upland boreal soils are an important sink for atmospheric CH 4 via microbial oxidation (Crill 1991;Amaral and Knowles 1997). Boreal forests act as a small CO 2 sink with respect to the atmosphere due to longterm carbon accumulation in soils (Schlesinger 1990), and dry upland boreal soils are an important sink for atmospheric CH 4 via microbial oxidation (Crill 1991;Amaral and Knowles 1997).…”