Natural area conservation has become more challenging with the worldwide growth in tourism.Increasing numbers of visitors lead to trampling of vegetation and soils with accompanying erosion and adverse ecological impacts. Although visitors accelerate erosion rates and can cause ecological damage, visitor amenity is in turn negatively affected by eroded pathways. Effective and timely management intervention requires information on which to act but conducting detailed track deterioration assessments places heavy demands on data sources and/or skills of personnel. A simple indicator of track erosion may provide a workable interim measure. In a preliminary investigation along the Coast Walk in Royal National Park, twenty sites were selected and assessed within a three-category erosion severity classification which included visitor-generated deterioration. Erosion losses were estimated using measured cross-sectional area and a soil erosion model. We found reasonable convergence between the erosion sever¬ ity classification and results from the cross-sectional area and erosion model, although both needed interpretation of outlying data. A measure of maximum erosion depth emerged as the simplest general indicator of erosion loss. This indicator also places the least demand on personnel and data resources, an important consideration for budget-challenged park manag¬ ers tasked with simultaneously providing environmental protection and visitor amenity.

Natural area tourism may contribute to deterioration in biophysical environments important for sustainable conservation of biodiversity and/or historically significant sites. Levels of protection within the IUCN guidelines provide general descriptors of desirable outcomes, and the Limits of Acceptable Change (LAC) management tool has often been implicitly applied. This article presents an initial attempt to assess the value of Thresholds of Potential Concern (TPC) relative to LAC as management frameworks for protected areas, using the example of trail width as an indicator of visitor impacts on vegetation, soil, water and, potentially, visitor safety. Visitor preferences relating to trail width were incorporated when applying the TPC and LAC principles. Sections of three walking trails in a high-visitation national park near Sydney, Australia, were measured at ~10.7 m intervals: the mean trail widths were 1.6 m, 1.8 m and 2.14 m. Of the 115 recreationists surveyed, 16% of those having the greatest tolerance towards management interventions (‘Non-purist’ wilderness category) viewed a trail ≥ 2 m wide as acceptable, but 96% of ‘Purists’ nominated a maximum of ≤1.5 m. The TPC was found to provide a broad strategy for identification, assessment and grading of multiple biophysical thresholds within an ecological framework. Combined with stakeholder information, the TPC allows for timely, proactive and calibrated management responses to maintaining biophysical and social sustainability.