How is visitor carrying capacity being measured in natural areas? Methods and global trends from a systematic literature review

Natural areas are very popular for visitation, offering a range of outdoor recreational activities available for visitors. The public use of natural areas requires a range of techniques to manage visitation, including limiting the number of visitors, also known as carrying capacity, and assessing levels of change in the natural environment. But how is the carrying capacity of visitors in natural areas being assessed worldwide? We conducted a systematic quantitative literature review looking at publications on carrying capacity using three different search databases. A total of 294 publications were identified, including research articles (230 publications), conference proceedings (40), experts’ opinion (13), thesis (7) and technical reports (4), with research increasing in the last decade. The Cifuentes method was the most frequently used methodology (106 publications), followed by other alternative quantitative methods (122) and less frequently, by qualitative methods (28). The Cifuentes method was more commonly used in countries in Central and South America and Asia, whereas qualitative frameworks were more frequently used in North America. Data collected in Cifuentes method case studies included more often abiotic and biotic features when compared to other quantitative frameworks, that focused more on social data. Additionally, terms used in case studies to define carrying capacity were dispersed and key factors applied in frameworks to assess carrying capacity were not standardized. These findings can improve the understanding of how carrying capacity calculations have been developed globally and help identify more tangibly research gaps for future research in the management of public use in natural areas.