Pullman, Erik Ross, 2001, Carbon cycle dynamics in a taiga peatland: Clemson University.
Summary
In this study carbon dioxide and methane fluxes were measured in three dominant vegetational communities in a taiga peatland located within the zone of discontinuous permafrost in the Alaskan interior. Trace gas (CO2 and CH4 ) flux measurements were made across spatial scales from excised roots to in situ peatland ecosystems. Temperatures increases and local water tables decreases from 1991 to 1993 affected methane emission two sites. Mid season methane emissions in the tussock meadow was fairly constant, ranging from 56.3 ± 29.8 mg CH4 /m2 /day in 1991 to 62.3 ± 37.2 mg CH 4 /m2 /day in 1993. Emissions dropped in the drier dwarf spruce scrub from 12.2 ± 8.1 mg CH4 /m2 /day in 1991 to zero in 1993. In the floating meadow, methane efflux [...]
Summary
In this study carbon dioxide and methane fluxes were measured in three dominant vegetational communities in a taiga peatland located within the zone of discontinuous permafrost in the Alaskan interior. Trace gas (CO2 and CH4 ) flux measurements were made across spatial scales from excised roots to in situ peatland ecosystems. Temperatures increases and local water tables decreases from 1991 to 1993 affected methane emission two sites. Mid season methane emissions in the tussock meadow was fairly constant, ranging from 56.3 ± 29.8 mg CH4 /m2 /day in 1991 to 62.3 ± 37.2 mg CH 4 /m2 /day in 1993. Emissions dropped in the drier dwarf spruce scrub from 12.2 ± 8.1 mg CH4 /m2 /day in 1991 to zero in 1993. In the floating meadow, methane efflux doubled between 1992 and 1993 (361 ± 331 to 716 ± 567 mg CH4 /m2 /day to due to warming, soils Based on assimilation measures made in 1993 the tussock meadow had a mean uptake of 99 g C/m2 /day while the dwarf spruce scrub had mean loss of 101 g C/m2 /day and the floating meadow lost 47 g C/m2 /day. The presence of live vegetation enhanced methane production in microcosms grown for 48 days in a growth chamber experiment. Microcosms from sphagnum lawns (n = 10) had very low rates of gross assimilation (171 ± 83.6 g CO2 /m2 ) and respiration (256 ± 82 g CO 2 /m2 /day) compared to microcosm supporting live tussocks (n = 8), which had mean gross assimilation of 2758 ± 1889 g CO 2 /m2 and respiration of 2374 ± 1295 g CO 2 /m2 . Dead tussock cores (n = 6) had rates the fell between the other two treatments. Methane increased with mean net uptake values. In addition, peatland sedges play an important role in ventilating the rhizosphere by acting as a conduit for methane and providing an important microsite for methane oxidation. Carbon exchange within the core of Lemeta in 1993 showed a net emission of 54 metric tons of carbon as carbon, dioxide, and 1.3 metric tons as methane. Simulated colder, and wetter conditions resulted in a net uptake of 11.5 metric tones of carbon reduced methane emissions to 0.7 metric tones. Warmer and drier condition increased the rate of carbon flux to the atmosphere by enhancing both methane carbon dioxide efflux from soils.
