Sponsor: INTECOL
Co-Chairs:
Dr. Donald D. Adams
Professor of Environmental Sciences
Center for Earth and Environmental Science
State University of New York
Plattsburgh, NY
USA 12901
Phone: (518) 564-2028
Fax: (518) 564-3152
E-mail: donald.adams@plattsburgh.edu
and
Dr. Bernhard Wehrli
Limnological Research Center, EAWAG/ETH
Kastanienbaum
Switzerland CH-6047
Overview of Symposium:
The symposium has invited papers on the theme of greenhouse gas cycling processes and site specific studies of gas production and consumption, bubble transport, and diffuse gas flux across the sediment-atmosphere interfaces of fresh water and saline wetlands. Greenhouse gas cycling in both natural and constructed wetland systems would also be considered. Studies of greenhouse gases in wetlands from countries normally receiving little attention in the literature are particularly invited.
Jukka Alm (jukka.alm@joensuu.fi), S. Juutinen, T. Larmola, M. Morero, S. Saarnio and J. Silvola, Department of Biology, University of Joensuu, Joensuu, Finland - Annual methane dynamics simulated for a flooding boreal lake catchment.
Lake associated or landscape oriented methane (CH4) fluxes are poorly known. Landscape scale methane fluxes over a year were simulated for a lake catchment in eastern Finland by integrating vegetation maps, CH4 flux studies in the littoral and pelagial zones, weather data, and digital terrain model using GIS. Both methane emission and oxidation rates were estimated for upland sites and peatlands in the catchment. The extend of spring flood was varied in the simulation and the landscape CH4 fluxes thereby estimated for a range of different seasons. In flooded mineral soils the CH4 emissions ceased and turned to net consumption soon after the drawdown of the spring flood, but peaty substrates retained the emissions longer. Lake associated minerotrophic peatlands may depend on the lake water level in their hydrology and CH4 release. The highest emission rates in the gently sloping meadows and elsewhere followed the declining water line, and persisted in a narrow band near the water line over the ice-free season. Vegetated littoral areas and peatlands emitted CH4 also throughout the winter. Peatlands and lakes may form a highly patterned landscape with significant and dynamically changing CH4 emissions. Biogeochemistry of the lake and associated wetlands may thus reflect many disturbances in the catchment, including land use and climate change.
M. Glagolev (allan@inmi.host.ru), V. Lebedev, O. Glagoleva, V. Erohin, P. Olenev and A. N. Nozhevnikova (nozhevni@eawag.ch) - Plant-mediated methane transport in West Siberian bog.
Methane fluxes through plants were monitored in Big Vasyuganskoe Bog, Tomsk Region, west Siberia, during the summer of 1998-1999, using micro-chamber methods. The intensity of methane fluxes differed from species to species and also was dependent on the season. The results obtained in the experiments with individual plants correlated with the data observed at the sampling areas where the same species dominated. Methane oxidation was estimated by stable isotope analysis of methane. Maximum oxidation and minimum methane emission were observed with soils under Eriophorum vaginatum and Menyanthes trifoliata vegetation. Minimum oxidation and maximum methane emission were observed with Carex rostrata and Equisetum palustre. An increase in methane emission was observed at the end of the summer. Up to 60% of total methane emission was plant-mediated transport.
O. Kotsyurbenko (allan@inmi.host.ru) and A. M. Nozhevnikova (nozhevni@eawag.ch) - Microbial methanogenesis in acidic taiga bog.
Siberian acid bogs represent one of the main global sources of atmospheric methane. Anaerobic microbial processes were studied in samples from the west Siberian Lowlands, the world's largest wetland (south taiga region, 57 oN, 82 oE). Experiments were performed at different temperatures (1-30 oC) and pH (4.3, 5.0 and 6.2). The highest rates of methanogenesis from bog soil organic matter (peat) was observed at 20 oC and pH 5.0. The Q10 was 3.2 in the temperature range 1-30 oC. High rates of glucose metabolism occurred at all temperatures at a pH of 4.3, resulting in production of H2, CO2, CH4, acetate and butyrate. At a pH of 4.3, methanol and H2/CO2 were the main precursors of methanogenesis at low temperatures (1-10 --oC). Results obtained during this study indicated the existence of acidophilic bacteria in these peat systems. Mesophilic enrichment of acidophilic methanogens was obtained on the medium, with very low mineralization, using H2/CO2 as a substrate.
Gerald P. Livingston (gerald.livingston@uvm.edu), D. Williams and L. Morrissey - Monitoring extent and seasonal inundation of eastern Siberian wetlands .
Knowledge of the presence or absence of surface waters is essential to understand biogeochemical dynamics in northern ecosystems, yet observational data on the extent and seasonality of inundation at regional to circumpolar scales is lacking. Similarly, published estimates of the extent of northern wetlands are widely cited but remain both largely unverified and static with regard climatic change in the northern high latitudes. This study demonstrates the potential of satellite remote sensing to monitor seasonal inundation and the extent of emergent wetlands for the purpose of estimating regional and circumpolar methane (CH4) exchange. Our primary data were calibrated Radarsat (microwave) data acquired between May and September 1997 and 1998 over study areas in the Kolyma and Indigirka River watersheds in Eastern Siberia (6 x 1010 m2 study area). Our results reveal significant error in existing 1:106 scale landcover data widely employed in carbon and hydrological modeling studies. Errors in published estimates of open water (without emergent vegetation) and emergent wetlands ranged from 20 to 100% respectively across the Arctic coastal plain. Seasonal patterns of inundation varied regionally but decreased slowly throughout the thaw period following spring runoff. Simulated estimates of CH4 exchange demonstrate that inaccuracies in existing landcover estimates of northern wetlands are a significant source of uncertainty in circumpolar budgets.
Shamil Maksyutov (shamil@nies.go.jp), G. Inoue, and M. Sorokin, National Institute for Environmental Studies, Tsukuba, Japan; T. Nakano, Tokyo Metropolitan University, Hachioji, Tokyo, Japan; O. Krasnov, Institute of Atmospheric Optics, Tomsk, Russia; and N. Kosykh, N. Mironnycheva-Tokareva, and S. Vasiliev, Institute of Soil Science and Agrochemistry, Russian Academy of Sciences, Novosibirsk, Russia - Methane fluxes from a wetland in West Siberia during April-October 1998.
An automatic sampling and analysis system for measuring CH4 and CO2 fluxes from wetland soils was developed and applied to the methane flux measurements at two wetland sites in the southern part of west Siberia. The observations cover the period from April 23 to Nov 1, 1998. Measurements were performed at two distinct types of open wetlands typical for the area: mesotrophic open bog and patterned wetland with forested ridges, flarks and water pools. The methane analysis was performed using a semiconductor sensor. Seasonally averaged methane flux rates were determined to be 12.7 mg /m2 /h at the open mesotrophic bog, while values were lower at the patterned wetland, with an average flux of 2.1 mg /m2 /h. The temporal variations of flux correlated with soil temperature in the short term (3 days averages), but in the long term the decay of the methane flux in autumn was delayed for up to a month behind the decline in the soil temperature.
L. A. Morrissey (lmorriss@nature.snr.uvm.edu), G.P. Livingston, and W. J. Degrott - Carbon emissions due to wildfires in boreal peatlands.
Climatic change over the next century is expected to significantly enhance the release of gaseous carbon from northern peatlands by increasing both rates of microbial decomposition and the frequency, extent, and intensity of wildfires acting on the vast carbon stores underlying these ecosystems. Based on observations of carbon and moisture profiles and burn areas of peatlands across North America, we estimate that wildfires in boreal peatlands worldwide contribute about 29 Tg of carbon to the atmosphere each year on average. Nearly 94% of all carbon emissions due to wildfires are from fires in subarctic permafrost bogs (66%) and forested swamps (27%). Incomplete combustion within the near-surface peat (0-20 cm depth) accounts for 70% of carbon emissions from wildfires, even though the areal extent of peat fires is only 18% that of surface fires. Atmospheric loading of CO2 due to wildfires is estimated at 25.2 Tg-C /yr. Emissions of CO, CH4 and NMHC are estimated at 3.0, 0.3 and 0.27 Tg-C /yr respectively. These estimates of direct carbon emissions to the atmosphere due to wildfires suggest a globally significant, but relatively small source in contrast with biogenic emissions from peatlands. No estimates of emissions due to the indirect effects of fertilization due to wildfires is possible at this time.
M. Sorokine (msorokin@spamer.gsfc.nasa.gov), S. Maksyutov and G. Inoue - Whole-season measurements of the soil temperature profile and water level in West Siberian wetland .
Wetlands occupy extensive areas of western Siberia from forest-steppes in the south to tundra in the north. The different climatic and geological conditions define a variety of wetland types. Methane emissions depend on bog temperatures and water conditions, and these regimes can be different for a variety of bog types. Methane emission measurements, temperature profiles and water level data in wetland soils were evaluated. Data from the 1998-99 field campaign, for an extensive bog 120 km west of Tomsk, will be described here. The measurements of temperature profiles and water levels were conducted with unmanned data-loggers from snowmelt in April to the beginning of snowfall in November. Two research sites were selected - eutrophic and oligotrophic bogs. Inside each bog type were several vegetative coverings: open flat humidified bog, basically covered by grass and moss; patterned bog covered by peat moss; fens within a chain of small lakes; ridges overgrown with undersized pines and shrubs, etc. Each bog type had more than ten measuring locations. The temperature profile measurements were carried out in methane-generating soil layers, up to 60 cm depth. Against a background of common seasonal characteristics, the obtained data showed differences in soil warming within the different vegetative coverings. Water levels showed diurnal dynamics in the soil, depending on different relief and intensity of evaporation. The seasonal dependence of temperature and water regime in the methane-generating soil layer can be utilized for models of methane emissions for different types of wetlands.
Hisayoshi Terai (hitera@ihas.nagoya-u.ac.jp), S. Shidara, K. Ohta and D. D. Adams - Methane and hydrogen fluxes and distribution of nitrogen cycling bacteria in Kushiro wetland, Hokkaido, Japan .
Wetlands are a major natural source for atmospheric methane, which is one of the important greenhouse gases. In this study we compared methane and hydrogen fluxes, and bacterial populations concerned with nitrogen-cycling bacteria, to evaluate the importance of the microbial processes related to methane emissions. Three different vegetative sites (low moor, high moor and alder moor) in a Kushiro wetland, Hokkaido, Japan, were compared. Methane and hydrogen fluxes were measured with static chambers consisting of plastic cylinders (50 cm dia., 80 cm height). After enclosing the vegetation, chamber air gas concentrations were monitored with a semi-conducter detecter gas chromatograph. Viable bacterial populations were also estimated with a plate count method (aerobic heterotroph) or MPN method (nitrifier, denitrifier and free-living nitrogen fixer) by inoculating wetland soils into culture media at a field station. The highest methane flux (11-28 mg CH4 /m2 /h) was observed in the low moor, while the high moor had the lowest flux (4-12 mg CH4 /m2 /h). Nitrifier and denitrifier populations were abundant in low moor soils and were lacking in the high moor, whereas free-living nitrogen fixers were abundant in the high moor but not detected in the low moor. Emission of hydrogen from low moor sites was observed while uptake occurred at the high moor. These results suggest that the nutritional conditions between the different types of wetland vegetation might be important in controlling the microbial processes associated with methane production and hydrogen flux.
Jeffrey R. White (whitej@indiana.edu). R.D. Shannon, S.D. Bridgham and J. Pastor - Effects of climate change and plant community composition on methane cycling in boreal peatlands.
Abstract is unavailable.
Kimberly P. Wickland (kpwick@usgs.gov) U.S. Geological Survey, Boulder, Colorado, USA - Carbon dioxide and methane dynamics in vegetated and unvegetated areas of a mountain wetland.
The effects of vegetation on CO2 and CH4 fluxes were examined during the 1998 growing season in a sub-alpine wetland in Rocky Mountain National Park, Colorado, USA. Fluxes were measured in four (1 m2) plots, two in which all the vegetation was removed. CO2 flux from respiration averaged seven times greater in the vegetated plots (57-170 mmol CO2 /m2 /d) than in the unvegetated plots (13-44 mmol CO2 /m2 /d). However, CH4 emissions were five times greater in the unvegetated plots, due primarily to ebullitive flux (vegetated: 3.9-14.7 mmol CH4 /m2 /d; unvegetated: 2.3-448.7 mmol CH4 /m2 /d). This is inconsistent with the concept that plant transport of CH4 results in greater CH4 flux from vegetated areas. Dissolved CH4 concentrations in the top 30 cm of sediment ranged from 0.001 to 0.92 mmol CH4 L-1 in the vegetated area compared to 0.01 to 1.67 mmol CH4 L-1 in the unvegetated area. The difference in the fractionation factor between stable carbon isotopes of DIC and CH4 in the vegetated and unvegetated areas (1.055 and 1.065, respectively) suggests that acetoclastic methanogenesis was greater in the vegetated areas.
