Carex atrata

Tracheophyta MagnoliopsidaCyperaceaeCarexCarex atrata

Ecology

A perennial herb found on ungrazed faces and ledges of wet or dry calcareous cliffs. It grows in short vegetation or amongst tall herbs, or in dwarf Salix scrub. Populations are probably maintained by vegetative growth. From 550 m in Coire Ghamhnain (Main Argyll) and usually above 700 m, reaching 1095 m on Ben Lawers (Mid Perth).

Status

Native

World Distribution

Circumpolar Boreo-arctic Montane element.

© Pete Stroh

Broad Habitats

Light (Ellenberg): 7

Moisture (Ellenberg): 5

Reaction (Ellenberg): 6

Nitrogen (Ellenberg): 3

0

Salt Tolerance (Ellenberg): 0

January Mean Temperature (Celsius): -0.3

July Mean Temperature (Celsius): 11.1

Annual Precipitation (mm): 1980

Life form information

Height (cm): 50

Perennation - primary

Perennial

Life Form - primary

Hemicryptophyte

Woodiness

Herbaceous

Clonality - primary

Tussock-forming graminoid, may slowly spread

Count of 10km squares in Great Britain: 57

Count of 10km squares in Ireland: 0

Count of 10km squares in the Channel Isles: 0

Atlas Change Index: -0.02

Distribution information

JNCC Designations

NBNSYS0000002453

Scarce Atlas Account

Scarce Atlas Account: 

Carex atrata L.        

Black alpine-sedge

Status: scarce

 

A strictly montane plant, C. atrata grows on ungrazed faces and ledges of calcareous cliffs of the higher mountains, as scattered tufts or small clumps in both dry and moist places. Typical associates are other montane calcicoles, such as Carex capillaris, Cerastium alpinum, Dryas octopetala, Persicaria vivipara, Poa alpina, Saxifraga aizoides, S. nivalis, S. oppositifolia, Silene acaulis and Thalictrum alpinum; and more widespread plants such as Carex flacca, Festuca ovina agg. and Thymus polytrichus. On more stable ledges with taller herbaceous communities, it grows with Angelica sylvestris, Geum rivale, Oxyria digyna, Saussurea alpina, Sedum rosea and Trollius europaeus. C. atrata also occurs amongst open growths of Salix lapponum and other montane willows. The attitudinal range is from 550 metres at Coire Ghamhnain in Glen Orchy to 1060 metres on Beinn Heasgarnich.

A perennial, C. atrata flowers and produces ripe fruits in most localities, but there is no information on germination. Probably most populations are maintained by vegetative growth, and this species appears to have little capacity for spread under present conditions, although this may be mainly a grazing limitation.

South of the Scottish Highlands, the best population is on Snowdon, and it is very rare elsewhere. It is almost plentiful on the Breadalbane mountains, but is nowhere abundant. It may once have had a wider distribution at high levels, and if so it has evidently become restricted to steep rock habitats through grazing. It is probably still present in most of the 10 km squares for which only pre-1970 records are available.

This is a circumpolar arctic-alpine species, occurring in the high mountain systems of central Europe, Asia and the Rockies, as well as widely at higher latitudes. In southern Norway it grows in open birchwood and willow scrub as well as in montane herbaceous and rock communities, while in Norwegian Lapland it grows down to sea level in closed herb-rich grassland.

 

D. A. Ratcliffe

PLANTATT - Attributes of British and Irish plants. (.zip 1455KB) This dataset was compiled and published in 2004, and last updated in November 2008. Download includes an Excel spreadsheet of the attributes, and a PDF explaining the background and nomenclature. Note that the PDF version is the booklet as published, whereas the Excel spreadsheet incorporates subsequent corrections. A hardcopy can be purchased from the Centre for Ecology and Hydrology.

Atlas text references

Atlas (363c)
Hultén E, Fries M
1986.  Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
Jermy AC, Chater AO, David RW
1982.  Sedges of the British Isles. Botanical Society of the British Isles Handbook no. 1, edn 2.
Meusel H, Jäger E, Weinert E
1965.  Vergleichende Chorologie der zentraleuropäischen Flora. Volume 1. 2 vols.
Stewart A, Pearman DA, Preston CD
1994.  Scarce plants in Britain.