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Open Access Publications from the University of California

How far into a forest does the effect of a road extend? Defining road edge effect in eucalypt forests of South-Eastern Australia

  • Author(s): Pocock, Zoe
  • Lawrence, Ruth E.
  • et al.

The concept of the road-effect zone has been developed and researched predominantly in the Northern Hemisphere. This study measures the extent of road impacts into a temperate eucalypt forest ecosystem in southeastern Australia. The Epsom-Barnadown Road is a two-lane arterial road connecting regional centres in northern Victoria to the City of Greater Bendigo. Passing through the Bendigo Regional Park, the Epsom-Barnadown Road carries more than 1,600 vehicles per day. Transects of 1 km in length cited perpendicular to the road were established to measure road impacts on the flora and fauna of box-ironbark forest. Exotic vegetation was found to extend about 50 m from the road. Traffic noise and light penetration varied according to topography and vegetation cover, but averaged of 350 m and 380 m, respectively, from the road. Mammal surveys indicated there was an increase in species richness once traffic noise reached ambient levels (40 dB) and traffic light penetration ceased. Bird surveys resulted in the identification of four species (9%) that only occurred within 150 m of the road (edge species) and 21 species (58%) that only occurred at distances of 150 m or more from the Epsom-Barnadown Road (interior species). A core habitat area for bird species was identified at about 900 m from the road. It was found that the average width of forest in the Bendigo Regional Park impacted by the Epsom-Barnadown Road was 1800 m, which translates to an area of 1.8 km² per kilometre of road.

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