The Vegetation of The Islands of Canna and Sanday, Inverness-Shire

Publisher Website
Google Scholar
Abstract
The basic rocks of which the islands of Canna and Sanday are composed may account for the presence of spp. such as Anthyllis vulneraria, Koeleria cristata, Avena pubescens, Daucus carota and Gymnadenia conopsea, but their effect is overshadowed by the major factor of climate in which a relatively high rainfall is associated with high atmospheric humidity. In general, topography accounts for the distribution of grassland, Calluna heath and moorland, the latter being confined to flat, poorly drained areas such as the plateaus of Canna. Grazing and burning have allowed grassland to spread at the expense of Calluna heath on the slopes and mounds, but these two factors may be responsible for the spread of moorland vegetation. It is impossible to deny the resemblance of the moorland to blanket bog and the Scirpus climatic moor of Fraser; no great depth of peat is to be found, however, and although Sphagnum spp. undoubtedly play a part in its formation, in so far as they impede surface drainage and induce acid conditions, it is the short forms that are prevalent, hummock formation being only local and largely confined to boggy depression. It is suggested that woodland and shade-loving spp. on the n. and n.-e. cliffs may be relicts of former woodland. At present, natural tree growth is confined to an occasional stunted rowan (Sorbus aucuparia) on the cliffs and to a small patch at the base of the cliffs in the s.w. Neighboring islands of Soay and Eigg support natural oaks, birches and willows, and there would seem to be no edaphic or climatic reason why oak-birch woodland or scrub should not be found on Canna and Sanday. When the islands were more thickly populated, destruction of trees for fuel, especially here where there is little peat development, combined with non-regeneration due to seedling destruction by sheep, cattle and rabbits, may account for the present paucity of natural woodland.

This publication has 3 references indexed in Scilit: