Welsh Journals

The vegetation of Gors Goch, an upland mire in mid Wales The moorland peats of upland Mid-Wales are generally shallow, but where topographic conditions allow substantial accumulations of peat occur. Such areas show far greater vegetation and habitat diversity compared to the monotonous moorland. Gors Goch is an upland mire situated between the Elan and Claerwen valleys at an altitude of 457.2 meters (Fig. 1). The mire occupies a north facing armchair-shaped depression within which peat has accumulated to depths in excess of six metres. The studied area is the discrete eastern-half of the mire and is approximately 200 m from east to west, 400 m from north to south (Fig. 2). The area displays a limited range of internal relief, there being a difference only of 1.5 m between the highest point in the west and the lowest point in the central eroded area. The northern, western and eastern peripheries to the central area display mire communities of relatively low but not insubstantial Sphagnum cover. The southern area is composed of an expanse of virtually intact Sphagnum carpet. It is this Sphagnum carpet and the general lack of disturbance to the bog which has allowed it to be designated as an SSSI Grade 2 (Nature Conservancy Council 1977). The purpose of this paper is to describe both the large and small scale vegetation patterns present at Gors Goch, and to discuss reasons for such habitat diversity. Field observations clearly show that not only is the vegetation of Gors Goch very different from the surrounding moorland, but that distinct patterning at both large and small scales occurs within the mire itself. In order to investigate the nature of vegetation patterning, intensive sampling of the species and their frequency of occurrence was undertaken. Transects were established and vegetation was recorded by systematically placed quadrats. The species and their percent frequency of occurrence were tabulated and ordered according to the method recommended by Mueller-Dombois & Ellenberg (1974). The validity of the derived vegetation communities was tested and confirmed statistically. Wanda. J. Fojt The first result to be considered is the nature of the difference in vegetation species and their characteristics between the moorland and Gors Goch. (A full species list, with appropriate authorities, is given in Table 1.) The species poor moorland is dominated by well- developed tussocks of Molinia caerulea which may occasionally be associated with Deschampsia flexuosa and Galium saxatile. Nardus stricta is found on thinner peats and Juncus effusus with Sphagnum recurvum are co-dominant where there is flowing water. But when deeper peats (in excess of 50 cm) are encountered, three distinct changes are found in the characteristics of the vegetation. Firstly, there is a marked increase in the total number of species occurring in a given area. Aim2 sample area within Gors Goch may yield between 6-16 species, but Fig. 1 Gors Goch-situation