Machair (geography)

Machair (Scottish Gaelic pronunciation: [ˈmaxɪɾʲ]; sometimes machar in English) refers to a fertile low-lying grassy plain found on part of the northwest coastlines of Ireland and Scotland, in particular the Outer Hebrides. The best examples are to be found on North and South Uist, Harris and Lewis.

Machair is a Gaelic word meaning "fertile plain", but the word is now also used in scientific literature to describe the dune grassland unique to Western Scotland and north-west Ireland. It had been used by naturalists since 1926, but the term was not adopted by scientists until the 1940s. The word is used in a number of placenames in Ireland and Scotland, even in areas where no machair has ever been supported. In Scotland, some Gaelic speakers use "machair" as a general term for the whole dune system, including the dune ridge, while others restrict its use to the extensive flat grasslands inland of the dune ridge. In Ireland, the word has been used only in place-names, and the habitat’s existence there was only recently confirmed.

In 1976, an effort was made to strictly define machair, although a number of systems still evade classification. This proved a difficulty when the habitat was listed on Annex I of the Habitats Directive in 1992, leading to the distinction between "machair grassland" and the "machair system."

Machair is distinguished from the links on the east coast of Scotland by a lower mineral content, whereas the links are high in silica. Machair plains are highly calcareous, with calcium carbonate concentrations of between 20% to 80% on the beaches, and decreasing further away from the shore. The pH of a machair is typically greater than 7, i.e. it is alkaline.

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