PROCEEDINGS: Index of Abstracts
METHANE EVOLUTION FROM MINNESOTA PEATLANDS
North Central Forest Experiment Station. Grand
Rapids, MN 55744.
Peatlands in the northern hemisphere (346 x 108 ha)
store large amounts of carbon; estimated at 455 petagrams (Pg) (=1015)
(Gorham 1991). This is about 30% of the world's pool of soil carbon
(excluding peat), about 64% of the atmospheric pool (Bolin 1983),
and about 55% of total plant biomass. This stored organic matter
is passed to the atmosphere as both carbon dioxide (CO2)
and methane (CH4) through aerobic or anaerobic decomposition,
respectively. This review summarizes the annual evolution of methane
from peatlands in north central Minnesota (1990-1993), its seasonal
variance, its variance with air pressure, and its dependence on
active transport through the stems of peatland emergents. Soil temperature,
and water table position are major factors correlated with methane
evolution. Modeling studies of possible climate changes (associated
with 2X changes in CO2 concentrations in the atmosphere)
show that methane in the Lake Region will not change water levels.
However, extended growing seasons and elevated peat temperatures
will lead to additional methane evolution at rates 50 to 80 % higher
than currently experienced. In this scenario, warming begets warming.
However, field studies in 1994 testing the impact of elevated ammonium
sulfate loading on peatlands, show that methane evolution is suppressed
under atmospheric loading rates typical of Europe today.