Mapping peat soils in Ireland: updating the derived Irish peat map

Abstract

Determining the spatial extent of peat soils is essential for measuring soil carbon (C) stocks. The Derived Irish Peat Map (DIPM) estimated the spatial extent of peat soils as 13.8% of the national area. The DIPM was derived from the Peatland Map of Ireland, CORINE land cover database (CORINE) 1990 and the General Soil Map of Ireland. This paper presents an updated version, the Derived Irish Peat Map Version 2 (DIPMV2), using the same rules-based decision tree methodology, but CORINE 2000 and the Indicative Soil Map of Ireland (ISMI) replaced CORINE 1990 and the General Soil Map of Ireland. The DIPMV2, a best-estimate, illustrates that peat soils occur more extensively than previously mapped, especially in the ‘drumlin belt’ of counties Cavan, Monaghan and Louth. The producer, user and overall accuracies are 88, 91 and 85%, respectively. This is an improvement on the DIPM (87, 84, and 85%). The DIPMV2, estimates that peat soils cover 1,466,469 ha, or 20.6%, of the national land area. The DIPM methodology may provide a long-term tool for updating national peat soil map data. It can be concluded that data for peat soils will become more important because peat has high carbon density and modifications to peat soils have implications for climate change.