Peat CO2 production in a natural and cutover peatland: Implications for restoration

Abstract

Although studies have shown that peatland drainage and harvesting alter local hydrology, microclimate, and peat characteristics, little is known about the effects of these changes on CO2 production rates. This study examines the different factors affecting CO2 production from natural and cutover peatlands. Laboratory peat incubations were performed under aerobic and anaerobic conditions to determine the influence of temperature, soil mois- ture, and peat depth on CO2 production rates from peat samples taken from: (1) a natural peatland; (2) a 2-year post-cutover peatland and; (3) a 7-year post-cutover peatland. CO2 production rates ranged from 0.21 to 4.87 µmol g −1 d −1 under anaerobic conditions, and from 0.37 to 15.69 µmol g −1 d −1 in the aerobic trials. While no significant differences were found between the CO2 production rates of the two cutover sites, the natural site consist- ently displayed higher production values. The natural site was also the only site to exhibit strong depth dependent trends, thus indicating the importance of the upper peat layer with respect to substrate quality. Higher production rates were found under aerobic than anaerobic conditions, with the greatest response to oxygen observed at the natural site. Production rates increased with both temperature and soil moisture, with maximum production rates found at 20 ◦ C and 92% moisture content. Temperature responses were generally greater at the cutover sites, while soil moisture had greater effects on the natural site peat. Results of this work agree with previous studies that suggest that it is essential to begin restoration once a cutover peatland is abandoned. Re-wetting a cutover peatland (through restoration practices) is necessary to prevent an increase in peat temperature and CO2 produc- tion since cutover peat has higher Q10 values than natural peat. A decrease in overall peatland oxidation should reduce the persistent source of atmospheric CO2 from cutover peatlands and the irreversible changes in peat structure that impede Sphagnum re-establishment.