Monitoring the impact of feral horses on vegetation condition using remotely sensed fPAR: A case study in Australia's Alpine Parks

Throughout the world, feral horses (Equus caballus) are causing environmental degradation and a decline in ecological integrity. Evidence from scientific monitoring is needed to inform the public debate and help land managers make informed decisions. We used field observations of vegetation condition at a network of sites in the Australian Alps where horses were present or absent. The data were combined with the remotely -sensed fraction of photosynthetic active radiation (fPAR) and topographic condition. Vegetation condition was assessed in the field by rangers using a modified version of the Landscape Function Analysis (LFA) index. We found significant differences in the LFA index between sites where horses were present or absent. Sites with presence of horses have 10 per cent lower fPAR than sites with absence of horses. The results also indicated a significant correlation between LFA and fPAR. Our analysis supports the hypothesis that feral horses have a negative impact on the condition of Australian alpine vegetation. This study provides a useful and relatively cost-effective method for monitoring the impact of feral horses on native vegetation, and can be used to support decision making and management interventions.