Peat definitions: A critical review

Abstract

Peatlands are carbon-rich ecosystems that comprise the largest terrestrial carbon store. Peatland preservation has been acknowledged on the global scale as a key nature-based component in addressing climate change. Despite their importance, there is no globally recognised definitions for peat or peatland, which influences efforts in quantifying global peat carbon stocks. We present a critical review on peatland definitions, including peat nomenclature and changing criteria for peatland classification through time. We focus on two important criteria: the minimum depth of the surface organic layer and the minimum percentage of organic carbon. We highlight the disparity between definitions, peatland nomenclature and peatland classifications. It is challenging to determine whether one definition should take precedence over another, even when considering the most common criteria. We propose that future peatland definitions focus on carbon storage and potential greenhouse gas emissions. This involves four physical and chemical characteristics of the peatland deposit: (1) Peatland extent, (2) peat thickness, (3) peat carbon content and (4) peat bulk density (volumetric carbon content). The growth dynamics and carbon flux of the peatland deposit should also become a routine part of inventories. In future, international technical agencies and experts can advise on the standardisation of concept definitions and methods, these must focus on the preservation of peatlands from the perspective of climate science.