Implications of Peat Accumulation at Point Escuminac, New Brunswick

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Abstract
The world's peatlands contain about 450 GT of readily decomposeable organic carbon. Peat-forming systems have two main layers, of which the lowest is the thickest and includes the peat proper. The upper layer fixes carbon by photosynthesis, loses it by selective decay, and passes on about 15% to the lower zone; here decay continues, although very slowly. One consequence is that as for Point Escuminac, New Brunswick, the relation of age to depth may be concave. Although the surface of the peatland is as productive as ever, the true rate of carbon accumulation is decreasing; after 10,000 yr it is only 33% as efficient at sequestering carbon as it was when the peatland began to grow. Peatlands are usually thought to represent sinks for carbon, but a warming climate could make some peatlands carbon sources rather than sinks, thus initiating positive feedback.