Red List habitat classification > RLE - Grasslands > RLE1.B Heavy-metal grassland in Western and Central Europe

Heavy-metal grassland in Western and Central Europe

Quick facts

Red List habitat type code RLE1.B
Threat status
Europe Endangered
EU Endangered
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)

Summary

This habitat comprises dry, short grasslands on soils with a high natural or anthropogenic content of heavy metals such as zinc, lead, copper, nickel, cobalt, cadmium or chromium, occurring in western and central Europe. The characteristic plant taxa (mostly subspecies or ecotypes) are metallophytes, species that developed various mechanisms for tolerating these heavy metals in the soil. The vegetation often has an open cover of vascular plants and is rich in lichens and mosses. The typical grasslands of the order Violetalia calaminaria are dominated by metallophytes, but on non-optimal sites also grasslands of other types (belonging to the classes Koelerio-Corynephoretea, Festuco-Brometea, Molinio-Arrhenatheretea) may contain lower numbers of metallophytes, and these also are regarded as belonging to this Red List type.

Heavy metal grasslands of this habitat are found in Ireland, England and Scotland, Northeast-Belgium and adjacent Netherlands, Northern France, Germany, Poland, Austria and Slovenia. They occur on natural sites where bedrocks with zinc or lead lie close to or at the surface. Secondary habitats have been created by mining the metal ores, which has resulted in contaminated soils in the vicinity of mines, along transporting routes and in storage areas. Tertiary locations occur where heavy metals have contaminated the soil by air or water transport from other sources. In many places, grazing by wild herbivores such as rabbits helps maintain an open sward and prevents the disappearance of cryptogam-rich early stages in the development of the vegetation and the greater dominance of grasses and dicotyledons.

Exploitation of the heavy metals ores is recorded from Roman times, but has probably occurred since the Bronze Age. Exploitation increased strongly from the Middle Ages, with an optimum industrial exploitation in the 19th century. In that period, the Belgian area of La Calamine (Kelmis) and Plombières (Bleiberg) was the world centre of zinc mining. Ores were transported to this area from mines in the surrounding to be washed and processed and because of this industry large amounts of zinc have been loaded into the environment, especially into the river Geul (Geulle), resulting in tertiary sites of metallophytes in its floodplain grasslands. The maximum distribution of the habitat type probably occurred in the first half of the 20th century.

In habitat type E1.B only those heavy metal grasslands are included that have traditionally been placed in the order Violetalia calaminariae.  In several countries, inside and outside the range of this order, other habitats occur on metal-rich soils, like grasslands and scree vegetation on ultramafic soils (serpentine soils and other copper-rich soils). These habitats are not included here, but are considered under other grassland or scree types. According to this definition, the resulting Red List type E1.B is equivalent to the Annex 1 habitat type 6130.

Indicators of good quality:

In good conditions these grasslands are rich in and dominated by metallophytes. In heavily contaminated spots even 100 years after mining no plants may grow at all. In soils with low concentration of heavy metals and where grazing declines, succession slowly leads to overgrowing with taller grasses (for instance Holcus lanatus) or shrubs and trees. In such cases, sites may be managed by mowing, removing trees and shrubs or sod cutting. Eutrophication, manuring and addition of chalk reduces the availability of zinc to the plants, causing a decrease in metallophytes.

The following characteristics are indicators of good quality:

·      High cover of metallophytes

·      Areas with open soil and characteristic lichens

·      Low vegetation structure

·      Low cover of encroaching tall grasses, tall herbs and shrubs

Characteristic species
For full habitat description, please download the habitat factsheet.

Threat status

Synthesis of Red List assessment

Based on a recent reduction of over 50% in area, the habitat type is Endangered (EN). Both the long-term quantitative reduction and the small current area of occurrence would result in a Vulnerable status (VU). A significant reduction in biotic and abiotic quality results in a Near-threatened status (NT).
EU
Red List Category Red List Criteria
Endangered A1
Europe
Red List Category Red List Criteria
Endangered A1

Confidence in the assessment

medium
Red List of habitat categories and criteria descriptions

Pressures and threats

  • Agriculture
    • Abandonment of pastoral systems, lack of grazing
  • Sylviculture, forestry
    • Forest planting on open ground (native trees)
  • Natural System modifications
    • Recultivation of mining areas
  • Natural biotic and abiotic processes (without catastrophes)
    • Abiotic (slow) natural processes
    • Biocenotic evolution, succession

Habitat restoration potential

When overgrown by tall forbs or woody species, mowing or removal of woody encroachment can help, but this cannot counteract in the long run the leaching of heavy metals.

Trends in extent

Average current trend in quantity

Decreasing Decreasing
EU28 EU28+

Trends in quality

Average current trend in quality

Decreasing Decreasing
EU28 EU28+

Conservation and management needs

Ultimately, the gradual shrinkage of the area of this habitat type due to abiotic and biotic succession can hardly be prevented. Grazing by stock, which is one standard measure to keep other semi-natural habitats open, cannot be recommended in this case because the plant material contains toxic concentrations of heavy metals, though access to wild herbivores can be maintained. The only sure way to counteract succession and keep at least some sites of the endemic heavy metal plants can be mowing and removal of woody encroachment, but also then the question is how to get rid of this contaminated plant material. Since the remaining sites are small, they should at least be legally protected and any damage by quarrying, construction activities or trampling be prevented as far as possible.

List of conservation and management needs

  • No measures
    • No measure known / impossible to carry out specific measures
  • Measures related to agriculture and open habitats
    • Maintaining grasslands and other open habitats
  • Measures related to spatial planning
    • Establish protected areas/sites

Distribution

For each habitat a distribution map was produced from a wide variety of sources indicating known and potential occurrences of the habitat in 10x10 km grids within Europe. Occurrences in grid cells were given in two classes: actual distribution from relatively reliable sources (surveys, expert knowledge), and potential distribution based on models or less reliable indicators. Please download the fact sheet to see the map.

Geographic occurrence and trends

EU28 Present or presence uncertain Current area of habitat (Km2) Recent trend in quantity (last 50 years) Recent trend in quality (last 50 years)
Austria Present 1 Decreasing Decreasing
Belgium Present 0.51 Decreasing Unknown
France mainland Present 1.5 Decreasing Decreasing
Germany Present 2 Decreasing Decreasing
Ireland Present 0.14 Decreasing Decreasing
Netherlands Present 0.006 Decreasing Decreasing
United Kingdom Present 8 Decreasing Decreasing
Northern Island Uncertain 8 Decreasing Decreasing
Slovenia Present 0.79 Stable Stable
EU28 + Present or presence uncertain Current area of habitat (Km2) Recent trend in quantity (last 50 years) Recent trend in quality (last 50 years)

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 1505800 186 15
EU28+ 186 15
AOO = the area occupied by a habitat measured in number of 10x10 km grid cells.
EOO = the area (km2) of the envelope around all occurrences of a habitat (calculated by a minimum convex polygon).

Characteristic species

The full list of characteristic species and genus are available above from the Summary. The species available in the EUNIS database are shown here.
Flowering Plants Agrostis capillaris
Flowering Plants Cardaminopsis halleri
Flowering Plants Cochlearia pyrenaica
Flowering Plants Festuca rubra
Flowering Plants Galium verum
Flowering Plants Holcus lanatus
Flowering Plants Holcus mollis
Flowering Plants Minuartia verna
Flowering Plants Pimpinella saxifraga
Flowering Plants Potentilla tabernaemontani
Flowering Plants Rumex acetosella
Flowering Plants Silene otites
Flowering Plants Spergularia rubra
Flowering Plants Viola calaminaria
Fungi Cladonia pocillum
Mosses & Liverworts Polytrichum piliferum
Species scientific name English common name Species group
Agrostis capillaris Flowering Plants
Cardaminopsis halleri Flowering Plants
Cochlearia pyrenaica Flowering Plants
Festuca rubra Flowering Plants
Galium verum Flowering Plants
Holcus lanatus Flowering Plants
Holcus mollis Flowering Plants
Minuartia verna Flowering Plants
Pimpinella saxifraga Flowering Plants
Potentilla tabernaemontani Flowering Plants
Rumex acetosella Flowering Plants
Silene otites Flowering Plants
Spergularia rubra Flowering Plants
Viola calaminaria Flowering Plants
Cladonia pocillum Fungi
Polytrichum piliferum Mosses & Liverworts

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

This habitat may be equivalent to, or broather than, or narrower than the habitats or ecosystems in the following typologies.
Classification Code Habitat type name Relationship type
EUNIS Habitat Classification 200711 E1.B Heavy-metal grassland same
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