Machair
A fertile, calcareous dune grassland of northwest Ireland and Scotland.
A machair is a low, grassy plain with fertile soil, located along the northwestern coasts of Ireland and Scotland. The finest examples are on North and South Uist, Harris, and Lewis. In Ireland, these habitats are a top priority under the EU Habitats Directive, giving them the strongest legal protection.
Quick Facts
- First use by naturalists
- 1926
- Calcium carbonate concentration range
- 20% to 80%
Facts from the source article.
Etymology
Machair is a Gaelic word meaning "fertile plain," now used in scientific literature for dune grasslands unique to western Scotland and northwest Ireland. Naturalists used the term from 1926, but scientists adopted it only in the 1940s. The word appears in Irish, Scottish, and Manx place names for low-lying fertile ground, even away from duneland. In Ireland, the word appeared only in place names, and the habitat's existence there was confirmed in 2013. In Manx Gaelic, 'magher' is a common term for a field. An attempt to strictly define machair was made in 1976, though some systems still evade classification. Listing on Annex I of the Habitats Directive in 1992 led to a distinction between "machair grassland" and the "machair system."
Geography
Machair soil is alkaline, with a pH above 7, and is rich in calcium carbonate—levels range from 20% to 80% on the beaches and drop further inland. This sets it apart from the links on Scotland’s east coast, which are high in silica and have a lower mineral content. The inner parts of a machair are often wet or marshy and can contain lochs. William MacGillivray first described how machair forms in 1830: waves push shell fragments toward the shore, where they break down further, and wind then blows the tiny pieces up the beach into mounds that drift inland. People have shaped the machair for millennia. Archaeological evidence shows trees were cleared for farming as early as 6000 BC, though some woodland survived on the coast of South Uist until 1549. Early farmers added seaweed, which protected the soil and supplied nutrients. Cattle and sheep keep the grass short, and their trampling creates tussocks that benefit certain bird species. The soil lacks key nutrients like copper, cobalt, and manganese, so cattle need supplements or summer grazing elsewhere. Because the sandy soil does not hold nutrients well, artificial fertilizers are ineffective, and only specific crops—such as certain oats, rye, and bere barley—can be grown.
Ecology
Machair ecosystems are so unusual that they have drawn a lot of attention from ecologists and conservationists. The process starts offshore, where kelp cushions the force of waves and cuts down on erosion. When storms wash this kelp onto the beach, it creates a natural barrier. As it rots, the kelp becomes a habitat for sand flies, which are then eaten by starlings, other small songbirds, wintering waders, gulls, and more. If sand covers the kelp, it breaks down into rich compost that supports annual coastal flowers and marram grass. These grasslands can host rare carpet flowers, including orchids like Irish lady's tresses and the Hebridean spotted orchid, along with yellow rattle. Birds such as the corn crake, twite, dunlin, common redshank, and ringed plover live there, as do rare insects like the northern colletes bee, the great yellow bumblebee, and the moss carder bee. The machair faces threats from shifting land management. The traditional croft system is weakening because there are fewer crofters and modern methods are taking over. Changes in the Common Agricultural Policy, which stopped linking subsidies to production, led to less grazing in many crofting areas, leaving some land undergrazed or abandoned. A shortage of native seed means more fertilizer and herbicides are needed. Rising sea levels from global warming also endanger low-lying coastal areas by increasing erosion. In January 1993, a storm that ran the MV Braer aground off Shetland wore away three meters of machair along the whole length of Uist and Barra. Another storm on January 11 and 12, 2005, blew consistently above hurricane force 12 and destroyed hectares of machair.
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