The role of natural soil pipes in water and carbon transfer in and from peatlands

Natural piping has been reported in peatlands around the world. This chapter reviews the role of natural pipes in peatland hydrology and carbon fluxes. There is a growing body of evidence to suggest that pipes are important hydrological agents in peatlands typically delivering over 10% of streamflow. Deep and shallow pipes respond rapidly to rainfall inputs demonstrating strong connectivity with the peat surface. While ephemeral pipes respond quickly to rainfall events, they also appear to obtain water from deep peat layers and underlying mineral strata. This mix of different sources of water results in highly variable concentrations of dissolved organic carbon and dissolved carbon dioxide and methane within pipe water. Early results from an intensive monitoring study in a blanket peatland in northern England suggest that pipe flows may account for around half of the dissolved organic carbon that is delivered to the stream network. Episodic pulses of particulate organic carbon from pipe outlets are common during storm events. Work that is underway to understand more about the sources of carbon being released from pipe networks is outlined, and several areas of further research are highlighted including examination of the role of natural pipes in bog pool hydrology and carbon cycling.