Atmospheric CO2 sequestration in restored mined peatlands

This study comparing the net ecosystem CO2 exchange in natural, restored, a nd naturally regenerated peatlands assesses the significance of peatland re storation as a global biotic offset under the Kyoto Protocol. Maximum gross photosynthesis (GP) at the restored peatland (-17.5 g CO2 m(-2) d(-1)) was more than two times that at lawns in the natural peatland (-8.2 g CO2 m(-2 ) d(-1)) and almost three times that of the naturally regenerated peatland (-6.5 g CO2 m(-2) d(-1)). However, GP(max) at hummock sites (-18.1 g CO2 m( -2) d(-1)) in the natural peatland exceeded that of the restored peatland. Total rainfall during the study period was similar to 75% of the 30-year me an and these drier conditions resulted in all sites being a net source of a tmospheric CO2 during the summer. From May 5 to August 23, 1998 respiration followed the trend: mined (398 g C m(-2)) > restored (169 g C m(-2)) > nat ural (138 g C m(-2)) peatland. While restoration did not return the net car bon sink function, it resulted in a significant decrease in the source of a tmospheric CO2 (229 g C m(-2)) over the summer season. Approximately 70% of this decrease was due to the increase in gross ecosystem production, while the remaining 30% was due to a decrease in total respiration. The presence of Sphagnum mosses at the naturally regenerated peatland also resulted in a similar to 45% decrease in total respiration (soil and plants), indicatin g that an increase in volumetric soil moisture content during restoration h as the potential to lower soil respiration at abandoned mined peatlands. Co nsidering the area of drained and mined peatlands globally, peatland restor ation on abandoned mined peatlands has the potential to represent an import ant biotic offset through enhanced carbon sequestration.