J.Pniewski & L.Infeld Colloquium

The role of wetlands, and especially peatlands, in biosphere processes and global ecological stability involves several global and regional mechanisms, which so-far have not been adequately synthesized and linked to Earth system science. In my lecture, I will argue that wetland ecosystems, especially peatlands, have been critically important to several major transformations in Earth's history and remain key mechanisms of the planetary homeostasis. I will present arguments that the evolution of this homeostasis, involving the interplay of feedbacks between the Earth's biotic and physical systems, as originally proposed by Lovelock and Margulis (1974), would not have been possible without the numerous processes occurring in wetlands, including the burial of organic carbon (responsible for the removal of atmospheric CO2 and the long-term increase in O2), the regulation of nitrogen and other nutrient cycling in landscapes and ‘riverscapes’, the maintenance of regional water cycling and hydrological regimes, the protection of permafrost in discontinuous permafrost zones, and several other processes. At the same time, these ecosystems, when disturbed, can shift to destabilizing functions, such as the rapid release of greenhouse gases (CO2 and methane [CH4]), nutrient emissions to surface waters, loss of water-holding capacity and catastrophic decline in biodiversity. Therefore, the protection of remaining mires and rewetting of drained peatlands is necessary in sustainable climate policies (mitigation and adaptation). Peatlands should also be key elements in predictions of the future developments of Earth system, including in post-apocalyptic scenarios following catastrophic climate change and hothouse Earth (their enormous potential of cooling and stabilising climate can be instrumental in long-term recovery).

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