Geo-ecological insights on the island of Inchcailloch in Loch Lomond, Scotland: a small serpentine outcrop in a mixed geological setting

Abstract

Inchcailloch hosts a small serpentine (ultramafic) site in Loch Lomond that is unusual in the Scottish context in being covered with broad-leaved woodland; along with serpentinite, serpentine breccias and sandstones are also found. In order to look at plant-soil relationships in more detail here, I analysed soil and foliar chemistry from sampling locations on and around the ultramafic outcrop. Soils situated directly on the outcrop had elevated concentrations of metals such as Co, Cr, Mg, Mn, Ni and Zn and a lower Ca-to-Mg ratio. Foliar elemental composition was influenced more by species than sampling location although some metals (Ni and Mn) were at greater concentrations in plants on the ultramafic outcrop. Foxgloves (Digitalis purpurea) had the highest foliar Ni concentration as well as Al and Zn, indicating an ability to accumulate multiple metals. Overall, the high Ca-to-Mg ratio indicating the calcareous nature of the soils due to mixing of soils from contrasting geologies, the low metal concentrations, and the high soil P are all considered to act together to prevent this site from exhibiting some of the more extreme features, such as skeletal soils and sparse vegetation cover, found at other Scottish serpentine sites.