Leven Valley

Also within

Inverness County Ben Nevis and Glen Coe Scenic Area 14. Rannoch - Nevis - Mamores - Alder Wild Land Area

Condition (NatureScot)

Climate exposure

This is about exposure to a nationwide pressure this habitat type carries — not a verdict on this site's own management.

Habitats

Ancient woodland, Bracken scrub, Fast flowing river and stream

Geology & landscape

Rock Type: Schist

Landscape processes: Peatland / Mire

Description

LEVEN VALLEY The Leven Valley SSSI lies between Kinlochleven and the Blackwater Reservoir and straddles most of the length of the River Leven. Geology. The main geological interest is concentrated along the River Leven where there are excellent exposures of metamorphic slates, micaschists and quartz belonging to the Dalradian Supergroup, a group of metamorphosed sediments laid down in Scotland and Ireland between 800 and 600 million years ago. The Dalradian rocks display a sedimentary transition from the Grampian Group into the Lochaber Subgroup of the Appin Group. The Grampian Group is considered to represent the first infilling of the Dalradian Basin. Although lithologically and geochemically similar to the older Moine series rocks of the northern highlands, structural and stratigraphic evidence indicates the Grampian Group belongs to the Dalradian series. Leven Valley is the only site where Grampian Group rocks can be seen grading into Appin Group rocks. Structurally, the area lies on the eastern limb of the Kinlochleven antiform, a major large-scale fold. Stratigraphically, the site displays a section from the Binnein Schist of the Lochaber Subgroup down into the critical change in depositional conditions from the relatively restricted marine character of the Grampian Group to the more open tidal character of the Appin Group. This site provides crucial evidence of major environmental changes in the development of the early Dalradian depositional basin. This site is irreplaceable, as it is the principal location where a sedimentary transition can be demonstrated between the Grampian Group and the rest of the Dalradian. Biology. The valley of the River Leven supports an extensive example of birch-dominated woodland and represents one of the largest and most intact areas of ancient semi-natural woodland in Lochaber. The woodland occupies steep south and north-facing slopes along some 10 km of the Leven Valley, as well as two major side valleys and several small ravines. It extends from near sea-level at Kinlochleven to about 300 m at the head of the valley. Important transitions between mature birch woodland and open ground habitats are well represented together with the active spread of woodland by natural regeneration. Birch dominates the canopy with smaller amounts of oak and rowan. In the ravines and elsewhere on richer soils small amounts of ash, hazel and wych elm occur. On wetter soils along watercourses, common alder and willows Salix spp. are co-dominant with the birch. Scattered individuals of Scots pine occur locally and may represent a remnant of a far more extensive cover of native pine forest. The ground flora includes a good representation of both vascular plants and bryophytes and is richest in the shaded ravines and along stream-sides, notably the Allt na h-Eilde and Allt Dearg. Dog’s mercury, upland enchanter’s nightshade, smooth hawksbeard and mountain melick occur, as does stone bramble. Fern populations include beech-fern Phegopteris connectilis, northern buckler-fern Dryopteris assimilis and oak-fern Gymnocarpium dryopteris. The Allt na h-Eilde also supports Wilson’s filmy-fern and a diverse bryophyte flora including ‘Atlantic’ species; these are features more typical of woods further west in Lochaber. Throughout most of the woodland, purple moor-grass, wavy hair-grass and other grasses are abundant. Bracken is also very abundant in clearings and as a broad fringe to the woodland cover. Woodland herbs are well represented and include wood-sorrel, chickweed wintergreen and cow-wheat. In the damper hollows and depressions there is an extensive ground layer of Sphagnum and Polytrichum mosses.

Species mentioned

Plant communities