Lichens: grass and trees are encroaching in heathland

The lichens of heathlands and active inland dunes are under threat from the encroachment of grasses and trees.

Trends

Dutch heathlands and active inland dunes are the habitat for many ground lichens. Lichens are the main vegetation on active dunes. A well-developed lichen vegetation currently contains about 25 species; there used to be more, but the rarer species have declined sharply.

The area of active inland dunes in the Netherlands has decreased dramatically, primarily because of the encroachment of grasses and trees that has been accelerated by the atmospheric deposition of nitrogen. The result is that open patches have been vegetated with grasses and other plants, and the sites suitable for lichens have vanished.

One species that has declined drastically is Iceland moss, a striking lichen that used to occur locally in wet and dry heathland and on active inland dunes. It has disappeared from wet heathland and nowadays occurs only in a few active dune areas. Often there are only a few dozen specimens present.

Of the 326 lichen species included in the Red List, 10 are characteristic of heathland and 8 are characteristic of active dunes.

Heather areas and active dunes are important not only for ground lichens but also for certain rare lichen species that grow on the stems of old heather plants and on the stumps of conifers.