Grassland: Selecting indicators of success for grassland enhancement (TIN050)

Calaminarian grassland

Where calaminarian grassland is present this indicator should be used. It might be present on sites under HK07 if there is semi-improved grassland with isolated spoil mounds, or natural mineral outcrops on skeletal soils, that have the calaminarian grassland feature.

Agreement year

For restoration sites it is possible that the calaminarian grassland feature might have been overgrazed, had applications of fertiliser or suffered other similar damage. It might also have remained more or less intact, having received different management to the rest of the field because of its topography. Unless the soil has been ameliorated in some way it is unlikely to have been over-run by non-calaminarian species.

Species in text

Indicator species include: alpine pennycress, moonwort, mountain pansy, Pyrenean scurvy-grass, sea campion, spring sandwort and thrift. Some sites have other species for example, early purple orchid and dyer’s greenweed. These are presumably ecotypes tolerant of heavy metals and are of particular interest. The current indicator only allows for the number of indicators to be set. If a range of notable plants is present in the grassland you can use indicators 9 or 10 to be more specific about the frequency of particular named species.

Lichens can be a major component of calaminarian grassland and rare lichens are often present. When setting indicators lichens should be treated in the same way as the higher plant species.

Frequency/Density/% Cover

Indicators singly or together should be at least occasional. The current wording does not allow a higher level of cover to be specified. If a higher cover is present at the start of the agreement and you would not want it to be reduced, use indicators 9 or 10 to set target frequencies for particular named species.

Average sward height in summer on most sites should be less than 5cm. Most of the characteristic species require open ground, hence the need to maintain at least 20% and up to 90% open ground, although mountain pansy and spring sandwort can persist in short closed turf around mine spoil.

Landscape/historic considerations

Mine workings are also historic features, and although open ground is required, heavy disturbance, for example by putting feeders on mine spoil, will be damaging to the historic as well as the botanical interest. Bare ground should mainly be the result of soil conditions rather than trampling by stock. Cattle may need to be removed if they deposit too much dung.

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