Amazonian peatlands: an ignored C sink and potential source

In tropical lowlands, peatlands are commonly reported from Southeast Asia, and especially Indonesian tropical peatlands are known as considerable C sinks and sources. In contrast, Amazonia has been clearly understudied in this context. In this study, based on field observations from 17 wetland sites in Peruvian lowland Amazonia, we report 0-5.9 m thick peat deposits from 16 sites. Only one of the studied sites did not contain any kind of peat deposit (considering pure peat and clayey peat). Historic yearly peat and C accumulation rates, based on radiocarbon dating of peat samples from five sites, varied from 0.94 +/- 0.99 to 4.88 +/- 1.65 mm, and from 26 +/- 3 to 195 +/- 70 g C m(-2), respectively. The long-term apparent peat and C accumulation rates varied from 1.69 +/- 0.03 to 2.56 +/- 0.12 mm yr(-1), and from 39 +/- 10 to 85 +/- 30 g C m(-2) yr(-1), respectively. These accumulation rates are comparable to those determined in the Indonesian tropical peatlands. Under altered conditions, Indonesian peatlands can release globally relevant amounts of C to the atmosphere. Considering the estimated total area of Amazonian peatlands (150 000 km(2)) close to that of the Indonesian ones (200 728 km(2)) as well as several factors threatening the Amazonian peatlands, we suggest that the total C stocks and fluxes associated with Amazonian peatlands may be of global significance.