Peatlands occupy just three per cent of the world’s land surface area but store a similar amount of carbon to all terrestrial vegetation, as well as supporting unique biodiversity. In their natural state, they can mitigate climate change by continuously removing CO2 from the atmosphere and storing it securely under waterlogged conditions for thousands of years. Many peatland areas have however been substantially modified by human activity, including drainage for agriculture and forest plantations.
A large proportion of the global greenhouse gases from peatlands are produced in Europe and Southeast Asia, with the total land area of many countries including the UK now a net source, not a sink, of GHGs due to emissions from degraded peat. The authors of the study say there is a growing recognition of the significance of peatlands for the global climate system, with efforts to curb emissions by conservation of undrained peatlands and rewetting of drained sites intensifying.
The scientists point out that there is plenty of scope to partially rewet agricultural peatlands without severely affecting production, because many sites are over-drained – sometimes to over two metres – and often no crop is present. In addition to increased emissions, drainage of peatlands causes land subsidence and soil compaction, which affects soil health and exposes low-lying areas to increasing flood risk. It also deprives rare wetland-adapted plants, insects and mammals of important habitats.
Professor Vincent Gauci of the University of Birmingham says: “Our findings show that in altering only one variable, raising the water table, it is possible to avoid greenhouse gases emissions from managed peatlands. The challenge then comes with adopting appropriate crops to maintain livelihoods. […] In deforested peatlands, such as those in the tropics, this may mean planting more water-tolerant, but still useful trees that may more closely resemble those of the original peat swamp landscape”.