Patterns of road surface movement after three endurance horse-riding events in protected areas, south-east Queensland

Reviews of horse-riding impacts usually mention degradation of trails, watercourses and vegetation. These potential impacts are of current relevance within some south-east Queensland protected areas where the future of horse-riding is subject to studies on biophysical and social impacts. This study aimed to provide an indication of soil movement patterns on vehicular roads in response to three separate endurance riding events, which represent the most intense horse use of these roads with up to 300 passes in one day. A measure of the areal extent and depth of erosion was obtained from at least 16 sections of road at each event. Across the study, there was an average increase in eroded area of less than 2 per cent and decrease of erosion depth by less than 1 mm. Linear mixed effects modelling revealed that soil movement was weakly related to slope and field texture, where the steeper the slope and softer the surface the more movement. Soil movement could be predicted using pre-existing road characteristics alone and the number of horse passes was not significant in soil redistribution. While no other data on horse-related soil movement from such roads is known, this study supports the contention that harder surfaces (i.e. graded, built-up vehicular roads) would suffer less soil loss than other track types. There was no evidence to suggest that the combination of vehicle tracks and horse use compounded soil loss. Where other maintained vehicle tracks elsewhere within protected areas are like those studied here, it is expected that high-use horse-riding would have little impact on the road surface additional to other uses.