Variation of Tasmanian vegetation from East to West
Tasmania can be broadly divided into two distinct regions, eastern and western, that exhibit major differences in climate, geology and vegetation.
[3] The vegetation changes occur principally due to variations in soil types, which are a result of the geological composition, and the vast difference in climate across the state.
Western Tasmania contains a vast variety of ancient, deeply folded metamorphosed and non-metamorphosed rocks, namely the Mesoproterozoic quartzite, schist and phyllite.
[5] Other more recent geologic signatures are scattered across the west, such as Ordovician limestone, Neoproterozoic dolomite basalt, Devonian granite (in the northwest) and Cambrian sediments.
Exposed to lengthy periods of erosion, the Mesoproterozoic rocks were worn down to shallow, acidic and infertile soil due to their high silica content.
[7] The weathering of eastern dolorite intrusions produces clay based soils that (with enough water), like basalt, will allow higher levels of plant production than in the west.
Due to the mountain ranges that are scattered predominantly along the west and centre of the east-west divide, the Föhn effect of descending air mass results in a warmer and drier east.
The wetter western environments have many similar plant groups to New Zealand and South America due to the persistence of ancient Gondwanan flora that the wet climate permits.
[4] The dominant species in these communities are Gymnoschoenus sphaerocephalus (buttongrass) in muck peat and Lepidosperma filiforme on more skeletal soils.
[13] Moorland and sedgeland vegetation is characteristic of western Tasmania, however also occurs sparsely in areas of low rainfall and poorly drained soils towards the east of the state.
To the east dry winds and greater sun exposure result in vegetation bearing smaller leaves and thick waxy cuticles.
[14] Eucalyptus species form the canopy layer and are varied across dry sclerophyll forests depending on altitude, soil type, amount of water and aspect.
