Publication Date:
2014-08-22
Description:
Northern peatlands are a globally significant carbon (C) reservoir, yet also function as dynamic methane (CH 4 ) sources to the atmosphere. The fate of peatland C stores and related climate system feedbacks remain uncertain under scenarios of a changing climate and enhanced anthropogenic pressure. Here, we present a synthesis of Holocene peatland C dynamics for the Hudson Bay Lowlands (HBL), Canada, in relation to the past atmospheric CH 4 trends, glacial isostatic adjustment, and paleoclimate. We report that peatland age and trophic status, together with paleoclimate, contribute to explaining some of the temporal variation in C accumulation rates (CARs) in the HBL. Our results show that younger, minerotrophic peatlands accumulate C faster, and although detailed paleoclimate data are not available, the results suggest the possibility of higher CARs in association with warmer Holocene climates. Peat initiation rates and CARs were greatest during the mid-Holocene; however, our results reveal that two-thirds of the HBL C pool is stored in peat of late Holocene age, owing to long-term peatland expansion and development. Whereas the HBL has been a net C sink since mid-Holocene peat initiation, the HBL also appears to have been a modest C source, with 85% of the losses occurring during the late Holocene as a consequence of the gradual decay of previously accrued peat. Late Holocene peat decay, under wetter climatic conditions, and from a landscape occupied by an abundance of minerotrophic peatlands, indicates that the HBL may have been a natural terrestrial source of CH 4 to the late Holocene atmosphere. While the peatlands of the HBL may continue to function as a globally significant C store, ongoing C losses from the HBL may have important implications for the global C budget and climate system.
Print ISSN:
0959-6836
Electronic ISSN:
1477-0911
Topics:
Geography
,
Geosciences
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