CALCULATION OF CARBON STORAGE IN WESTERN SIBERIAN PEATLANDS USING GIS-MODELING TECHNIQUES

Peatlands are more and more recognized as potentially important in the global carbon cycle, because these terrestrial ecosystems formed a sustainable sink of carbon during the Holocene. A major area of undisturbed peatlands is situated in the Western Siberia plain, Russia. However, the amount of peat and carbon stored in these Siberian peatlands is not yet calculated.

The purpose of the study was to estimate the total amount of accumulated peat and carbon in Western Siberian peatlands by means of GIS-modeling techniques. Therefore I used remote sensing data, topographical maps, Russian cross sections of peatlands and field measurements of organic matter and carbon content.

I created a digital elevation model (DEM) of the peat surface and mineral soil beneath the peat of the Bakchar peat bog complex (82°48’E, 56°49’N) in the watershed area between the rivers Ob and Irtish. From Russian research in the 1960s cross sections with elevation data of the peat surface and the mineral subsoil were available. Together with elevation data and streams from topographical maps these data were interpolated with the Topogridtool in ArcInfo to build the two DEMs. The Topogridtool creates a hydrologically correct DEM. The difference between the peat surface and the mineral subsoil is an estimate of the present peat volume. Furthermore, the peat area was estimated by classification of a Landsat 7 ETM+ image. The difference in spectral emission of various peatland types was used to make the classification model. The average dry bulk density and organic matter content were estimated in various peatland types within the peat bog complex.

The total area of peat in the studied peat bog is 521.6 km². The total volume of peat in this area as derived from the DEMs is 1.136 *10⁹ m³. With an average measured dry organic matter content of 62.33 kg m^-3 the average mass of dry organic matter per unit area is 135.74 kg m^-2. The average carbon content (mass percentage of dry organic matter) has been found to be 52.2%. Using this value the average carbon storage per unit area in the studied area is 70.86 kg C m^-2.

A recent estimate of the peatland area in Western Siberia is 1036169 km². Using this area the total carbon storage in Western Siberian peatlands is 73.42 Pg C (1 Pg=1015 g).