Arctostaphylos alpinus
Ecology
A strictly calcifugous shrub growing on acidic mineral soils or peat. It occurs on exposed upland heath, and in the northern Highlands of Scotland also on drier blanket bog. It is possibly long-lived, and fruiting is often sparse. It mostly occurs at mid-elevations, but descends to 100 m in North Roe (Shetland) and ascends to 945 m on Tom a`Choinich above Glen Affric (Easterness).
Status
Trends
The distribution of A. alpina has probably remained essentially unchanged over recent decades, and it probably still occurs in many of the squares for which there are only pre-1970 records.
World Distribution
Circumpolar Arctic-montane element.
Broad Habitats
Light (Ellenberg): 7
Moisture (Ellenberg): 6
Reaction (Ellenberg): 2
Nitrogen (Ellenberg): 2
Salt Tolerance (Ellenberg): 0
January Mean Temperature (Celsius): 1.6
July Mean Temperature (Celsius): 11.6
Annual Precipitation (mm): 1750
Height (cm): 20
Perennation - primary
Life Form - primary
Woodiness
Clonality - primary
Count of 10km squares in Great Britain: 134
Count of 10km squares in Ireland: 0
Count of 10km squares in the Channel Isles: 0
Atlas Change Index: -0.22
JNCC Designations
Scarce Atlas Account
Arctostaphylos alpinus (L.) Sprengel
Mountain bearberry
Status: scarce
The best known habitat for this plant is on dry, windswept ridges and moraines at about 600 metres altitude (Raven & Walters 1956). In this montane heath habitat its associates include prostrate Calluna vulgaris, Carex bigelowii, Empetrum nigrum subsp. hermaphroditicum, Loiseleuria procumbens, Salix herbacea, Racomitrium lanuginosum and lichens. Where the vegetation becomes taller, A. alpinus tends to disappear. In the northern Highlands it also grows in undisturbed blanket bog with Betula nana, Calluna vulgaris and Eriophorum vaginatum (McVean & Ratcliffe 1962). In all its Scottish habitats, A. alpinus is a strict calcifuge, growing on acidic mineral or peat substrates. It is mainly a middle elevation plant, but reaches at least 945 metres on Tom a'Choinich above Glen Affric, and descends to 130 metres in Sutherland.
A. alpina is a woody perennial, possibly with a long life-span, flowering in May or June before the leaves expand. The white bell-flowers are small and have small openings so that self-pollination may be the rule (Raven & Walters 1956). Fruits ripen in late July or August, but crops are commonly sparse. The plant is partially deciduous, many leaves displaying brilliant scarlet autumn colours and some surviving the winter. As the winter winds remove snow from its habitat, it may be left vulnerable to grazing. Bird-carried berries are possibly the source of new populations.
There is little evidence for a widespread decline of this species, which is probably still present in most of the 10 km squares for which only pre-1970 records are available. However, it appears to retreat when its habitats are burned, recovering only slowly after moorland fires.
A. alpina has a typical arctic-alpine distribution, occurring widely in Fennoscandia, through the Eurasian Arctic and in North America and Greenland. Southwards it reaches the Alps, Pyrenees and New Hampshire mountains.
The south-eastern edge of the plant's distribution closely follows the mean July isotherm for 14.5°C. Horticulturists find difficulty with the plant to the east of this isotherm (R. Macbeath pers. comm.), A few outlying colonies occur but at a higher altitude. The less distinct western edge runs near the mean January isotherm for 4°C, which passes through Skye near Kylerhea, where J. Lightfoot found the plant in 1772. Further attempts to find the species here failed until it was rediscovered by Mrs C. W. Murray in 1990 (Murray 1991).
A. Slack