2. BIOREGIONS
Bioregions are the broad-scale classification of distinct landscapes based on climate, topography, geology, soils and vegetation. Twenty-eight Bioregions are recognised within Victoria. Three; Goldfields, Victorian Volcanic Plain (VVP) and Central Victorian Uplands (CVU), occur within the Hepburn Shire and surrounds. The distribution of some flora species fall quite neatly within bioregion boundaries, however usually there is considerable overlap of species between one bioregion and another.
Right: Orange=Goldfields Bioregion, White=VVP Bioregion, Blue= CVU Bioregion
(Map copied from www.environment.vic.gov.au)
Goldfields Bioregion
Areas around Hepburn Springs, Shepherds Flat and Porcupine Ridge are local exemplars of the Goldfields bioregion . This bioregion occurs largely to the north of the dividing range and on the northerly slopes of the uplands. It is characterised by steep slopes and ridges and often low fertility yellow, grey and brown soils. Rainfall is typically between 400 to 700mm annually, with average temperatures becoming higher with increasing latitude. Comparitively dry and infertile conditions promote open forests and woodlands dominated by a drought-hardy suite of eucalypts. Many areas are ablaze with colour in the spring owing to a diverse understory of wattles, everlastings, pea-flowers, lilies and the like.
Drought tolerant species such as Grey Everlasting, Matted Bush-pea and Sticky Everlasting are promoted by the conditions of the Goldfields Bioregion.
Victorian Volcanic Plain Bioregion
Much of the indigenous vegetation throughout the VVP has been lost to agriculture. Volcanic lava flows formed this extensive undulating plain with occasional stony rises, hills and volcanic cones. Soils are fertile, reddish-brown (iron-rich) loams and clays. Plains Grassy Woodland and Plains Grassland ecosystems were a significant component of this bioregion. Some areas of grassland (often degraded by weeds and disturbance) are still extant, particularly around the Clunes area. Due to the similarity in elevation and climate, there is an overlap of species from the Goldfields Bioregion. However, the basalt-derived soils, open aspects and a past frequent fire regime has promoted some species synonymous with the VVP. Many of these flora and fauna species are a focus for conservation efforts, being rare or endangered due to the widespread loss of vegetation and habitat within the bioregion.
Small patches of remnant grassland in Clunes support (declining) populations of nationally endangered species such as Button Wrinklewort and Spiny Rice-flower.
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Central Victorian Uplands Bioregion
In terms of geology, elevation and climate, the CVU bioregion varies significantly from one point to another. Lower elevation areas within the CVU, such as around Creswick, floristically bear many similarities to the Goldfields and VVP Bioregion. However, upon reaching the higher elevation areas of the Wombat Forest, many of the species associated with lower elevations and the Goldfields and VVP bioregions, are absent. Cooler conditions and rainfall in excess of 1000mm per annum promotes tall forest, an often dense understory and gully lines thick with moisture loving plants including a diversity of ferns and mosses.
Many of the regions rivers begin as streams or low-lying swamps in the CVU bioregion. These areas favour species that prefer shade and moisture, such as these ferns pictured in the Wombat Forest.
