Construction of access tracks in National Parks and other reserves in the south-west of Western Australia is an essential feature of Park management, as is the clearing of firebreaks. Yet they are also responsible for disrupting the vegetation in this region which is extremely rich in its unique flora and fauna (notably insects).

Construction of tracks and firebreaks appears to have been carried out with little or no appreciation of soil and slope characteristics and potential erodibility, or the effect of slope and stream sedimentation on terrestrial and aquatic flora and fauna. Firebreaks are constructed at right angles across the contour on steep slopes; side drains on tracks are not maintained and eventually surface runoff along the track either breaks through them or the drains become clogged with sediment. In both cases rilling develops on the tracks, sometimes to gully dimensions; sediment is deposited on the naturally vegetated slope, resulting in diminished species diversity; and pools in adjacent streams may be filled with sediment, destroying breeding sites.

The paper reports on the findings of a study carried out in a Western Australian National Park. Tracks and firebreaks were surveyed and the extent of erosion and sedimentation measured. Track erosion severity was related to the extent and nature of the area contributing runoff (both on- and off-track), considering slope, soil and vegetation characteristics. The use of the Park by visitors (using an on-site questionnaire survey) as well as current management methods were also assessed in order to evaluate the need for the access tracks.

An understanding of the erosion mechanisms and the pedo-geomorphic properties of the Park makes it possible to recommend several management measures. These fall into two groups: those relating to track closure or realignment (to avoid the most erosion-susceptible sites); and those relating to actual track design and maintenance.