The High Mountain Habitats

The mountain heights of Wales may seem an inhospitable environment, but there are some surprising species that thrive amongst the crevices, ledges, rocks and scree slopes of even our highest mountains.

Ledges and crevices

High mountain ledges and rock crevices are important places for some of the rarest mountain plants, particularly where veins of base-rich rock break the surface. Their inaccessibility to sheep makes them a refuge for many plants with a sensitivity to grazing.

Such places include the tall-herb ledges, where the mineral-rich water flushing through them and the shade of the north-facing slopes create conditions suitable for species that would normally be associated with woodland. In summer, these aptly named tall-herb ledges can provide some of the most attractive and spectacular displays of wild plants in the mountains. They often have the appearance of hanging gardens, supporting plants with names such as wild angelica, ladies mantle, globeflower and roseroot (pictured).

Also well adapted to this mountain habitat are the arctic-alpines – plants usually found in high Alpine mountains or far north in the arctic. They are found here in Wales on the very edge of their distribution, and include the Saxifrages, mountain avens and moss campion.

Many of these species survive by growing in pockets of soil in cracks and crevices. They are generally small and often hug the rock by means of creeping stems, or by adopting a cushion shape to minimise their exposure to strong winds. They survive in this hostile environment because under gentler conditions they would soon be overcome by competition from more aggressive species.

These plants would appear to be safe in their mountain refuges but even they face challenges – from rising temperatures, acid rain, overgrazing by sheep and the attentions of increasing numbers of feral goats in parts of North Wales.

Scree slopes and summits

Another rocky habitat of the mountains occurs on scree slopes. These distinctive landforms are widespread, reflecting the geology of their parent cliffs. Where screes are unstable and acidic (the most common type in Snowdonia), the vegetation is usually composed of a pioneer community of parsley fern, with various mosses and fine-leaved grasses.

Extremes of wind and temperature on the summits of the higher mountains mean that few plants can survive. Nevertheless, species such as the stiff sedge and the hardy dwarf willow are virtually confined to this high ground. The latter species is locally common in montane heath communities in Snowdonia that are not too heavily grazed. The small size of its stems and leaves initially give the impression of a low-growing bilberry, but closer inspection reveals it to be a tree in miniature.