Calanais Survey and Excavation, 1979-88
20. The Vegetation Survey 20.1 Introduction Alan Fairweather and Marion Wade-Evans carried out the survey. The text here is largely that produced by them (Technical Note 20.1). A brief overall description of the vegetation was produced in 1980. The main survey was undertaken in 1981. A subjective overall view of the site was taken. In all about 20 areas with different communities from their neighbours were discernible (Illus 20.1). Species occurrences and their relative frequencies were recorded. In the time available it was not possible to write a detailed comparative description of each of the 20 areas discerned but a general account of broad areas are given. 50 species of flowering plants were recorded as growing on the site (Table 19.1). Some species in addition to those identified were not seen at full expression complete with inflorescence so specific attribution could not be made. Gramineae identifications were aided by Hubbard, (1954) and flora by Keble Martin (1965); the most important aid to plant community identifications was McVean & Ratcliffe (1962). 20.2 Factors affecting the vegetation Areas tended to merge from one community to the other and the differences were rarely clear cut. They owed more to varying abundance of dominant species than to the existence of totally different communities. Most species were present in most areas and those that were infrequent or rare within the survey area as a whole did not form a very significant part of any one community. (Exceptions to species absence versus dominance were Calluna vulgaris, Ciprus Caespitosus, Juncus squarrosis, and Juncus effusis). 20.2.1 Previous agricultural use. The mixed nature of the vegetation covering the area investigated and the comparatively rich nutrient status is in large part attributable to agriculture. The making and cultivating of cultivation
beds probably involved the incorporation of seaweed, dung and shell sand (most probably at the same time) and not only improved nutrient status but changed local topography. 20.2.2 Peat stripping Before cultivation (the visible remains of which probably belong in the 18th and early 19th centuries, peat was stripped from the site and the activities involved in this operation, including soil disturbance, trampling, soil peat mixing and exposure have contributed to the current vegetation mosaic. 20.2.3 Grazing The grazing regime has had a considerable affect in that most of the site shows evidence of having been closely grazed by sheep until shortly before 1980 with a very high and ubiquitous incidence of Plantago lanceolata, Hypochaeris radicata, Bellis perennis and an almost complete absence of Polygala spp.(Milkwort). It is not detrimental to the maintenance of a close sward to allow grazing to continue; indeed now that sheep have been excluded the site could soon revert to a coarser rank growth of tussocks requiring mowing and reseeding etc. 20.2.4 Victorian and later repairs Conservation of the archaeology involved the introduction of turf composed of Festuca species, Poa Plantago maritima and other species associated with a turf from a seaside or machair. This was especially noticeable on the cairn itself. 20.2.5 Disturbance by visitors Visitor presence and pressure has caused a good deal of soil compaction and wear on the site round the stones and the cairn and on both formal (Lady Matheson’s Path) and informal paths between entrances and points of interest. This was shown by the dominance of Plantago lanceolata and Poa species, with other trampling-resistant species present. The vegetation survey \ 815