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
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
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
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.