Calcium and magnesium in plants and soil from a serpentine area on Unst, Shetland.
Soils derived from serpentine rock (including those developed on spoil heaps around chromite mines) on Unst, Shetland are similar in calcium and magnesium status to those on serpentine areas at Greenhill, Aberdeenshire and Kraubath, Austria. The exchangeable cation fraction of all the soils contained appreciably more magnesium than calcium. The soil of the north-west slope of the Keen of Hamar was found to be remarkably constant in calcium and magnesium content. Analysis of plants growing on this area indicated that species differed both with respect to their mean calcium and magnesium contents, and the extent of the variation about the mean. Species growing on the serpentine sites differed considerably in their response to the high levels of magnesium and low levels of calcium. Whereas individual shoots of Silene maritima contained high calcium and low magnesium, individual shoots of S. acaulis contained high magnesium and low calcium. Analysis of roots and shoots of Agrostis stolonifera indicated that shoots accumulated calcium and excluded magnesium. These results suggest that ion selection may be due to specific transport mechanisms.