The Mire of Loch a'Bhogaidh, Islay

Abstract

A valley mire at Loch a'Bhogaidh, Islay, part of an SSSI, was briefly examined because of its rich flora and deep sediments. A mixture of fen, aquatic and raised bog vegetation now occupies the site which earlier had more open shallow water. Vegetation, temperature profiles and conductivity were sampled along an EW transect and water samples removed for laboratory analysis. Stratigraphic profiles were made for eight sediment cores from the transect, and pollen analysis was carried out in one of these. Three vegetation zones correlated exactly with water chemistry and hydrology; a central species-rich and relatively eutrophic reedswamp with moving water was flanked by a drier ombrotrophic bog and a floating, successional, species-poor eutrophic Sphagnum carpet. Stratigraphic profiles showed deposits of probable lateglacial age overlain by gyttja and then fen peat as the lake basin filled in. The pollen record showed a predominance of tree and shrub pollen at the lowest levels succeeded by bog and open grassland species. The site is recommended for future comparison with similar Inner Hebridean sites and for its conservation value.

The Late‐Quaternary vegetational history of Loch a'Bhogaidh, Rinns of Islay S.S.S.I., Scotland

“…The depths of sediment available have produced the longer record anticipated when the LABX profile was constructed (Agnew et al, 1988). The latter profile covered perhaps 3600 '^C years over a depth of 7-75 m and would promise considerable resolution for later prehistoric and modern periods; a danger would be that its mire edge location (desirable for detecting anthropogenic influences) couid have resulted in periodic drying out, thus creating similar problems to those manifested in core LABII.…”

“…The pollen profile of Agnew et al (1988) (LABX), appears to cover the post-alder rise and probably post-elm decline periods corresponding witb LABIe-g and LABlIf/g (Fig. 11).…”

“…At the deepest point along the transect (Fig. 3) the bottom was not reached although it extended to over Kv65 m. The penultimate core at the eastern end of the transect was sampled for pollen analysis (core LABX, Figures 2 and 3 -the pollen diagram appears in Agnew et al, 1988). On a subsequent visit to tbe site in 1987, an additional core 1 IO m in depth (core LABI) was taken from 1 75 m west of core LABX on tbe line ofthe transect.…”

“…The site was used as a shallow distillery reservoir in the early years of this century and there are the remains of a low earth dam at the southern end. In 1985, the flora and water chemistry along a 400 m south-west to north-east transect were examined and stratigraphic borings were carried out at approximately 50 m intervals (Agnew et al, 1988). At the deepest point along the transect (Fig.…”