Geobotanical and biogeochemical associations at the Thackaringa Serpentinites, south-western New South Wales [also includes Ultramafic soils and their vegetation: a literature review]

Vegetation on the Thackaringa serpentinites in south-western New South Wales, is significantly different from adjacent vegetation. An absence of Acacia aneura and Alectryon oleifolius on the serpentinites has created two distinct lacunae. Differences in understorey composition are subtle, with both aspect and other edaphic factors influencing composition. Serpentine understorey has a relatively low species richness and diversity, and an absence of endemics. Landscape controls, transported material, soil pH and bedrock may be influencing soil chemistry. A soil chemistry gradient from serpentine to nonserpentine includes decreasing soil pH, calcium and magnesium, and increasing potassium, sodium, zinc and manganese. This correlates with changes in plant community composition and structure. Morphological differences for serpentine vegetation was limited to two species and included strong sclerenchymatic development, and stunted leaves and height. Minimal morphological differences in plants of both substrates may be due to regulation of elements in plant tissue. Preliminary biochemical analyses of leaf tissue indicate that plants cope with serpentine chemistry by nutrient accumulation and elemental exclusion. Two species express an ability to accumulate relatively high levels of some trace metals. These processes may function as deterrents for herbivores and pests