Edaphic influences on a New Zealand ultramafic ('serpentine') flora: a statistical approach

Ultramafic ("serpentine") soils from and adjacent to the Dun Mountain Ophiolitic Belt, South Island, New Zealand were analysed for 11 elements in order to establish to what degree edaphic factors influenced the character of the overlying vegetation. Using principal components analysis with a mutual plot of the first two principal components, involving the total elemental concentrations in the soils, it was possible to divide the soils into 6 virtually nonoverlapping fields, each of which represented a specific vegetation community. Component 1 was essentially an "ultramafic plot" with heavy loadings from the elements chromium, cobalt, iron, magnesium, manganese, and nickel. Component 2 was a "non ultramafic" plot with heavy loadings from aluminium, copper and zinc. For elements extracted from the soils at pH 5.9, discrimination was somewhat poorer but confirmed the great importance of magnesium and nickel as controlling elements for the serpentine vegetation. It was concluded that the results indicated the overriding importance of edaphic factors in controlling the serpentine vegetation.