EFFECT OF CHANGING TEMPERATURE AND WATER-TABLE ON TRACE GAS EMISSION FROM MINEROTROPHIC MIRES

Peatlands, hydromorphous soils with high organic matter content, displ ay, as a result of anaerobic conditions, a delayed litter decompositio n and therefore constitute important terrestric sinks for carbon and n itrogen compounds. In spite of their relatively small area proportion of approx. 3% (3.88-4.38 x 10(6) km(2)), peatlands contain approx. 30% of the world's soil carbon and nitrogen reserves. Several signs indic ate that substantial drainage and increasing temperatures due to the i ncreasing cultivation of peatlands and the global climate change could result in a large-scale conversion of peatlands from C/N sinks to C/N sources. Irrespective of many uncertain details and complex interacti ons with other factors, the lowering of the groundwater table of peatl ands actually seems to strongly enhance the net release of the radiati vely active trace gases carbon dioxide and nitrous oxide, reducing at the same time the high emissions of methane that occur in natural peat lands. The antizipated climate change will probably induce large-scale shifts in the distribution of the different peatland ecosystems along with considerable changes of the trace gas emissions. In view of this development, a net loss of global peatland area along with an increas e in their contribution to the greenhouse effect must be expected.