Human trampling as a threat factor for the conservation of peripheral plant populations

Abstract

In recent years, peripheral plant populations have been gaining more and more interest from a conservation point of view, as they normally grow in non-optimal ecological conditions and, consequently, are more sensitive to environmental stresses if compared to the core population. In a 7-year study (1999–2005) we examined the effects of human trampling on an alpine plant species (Senecio incanus subsp. incanus) at the southern extreme of its distribution (Northern Apennines), where it occurs in only one isolated and fragmented population. Two trampled and two untrampled permanent plots, monitored yearly, showed highly significant differences relative to S. incanus cover and reproduction, and cover by other plant species. Specifically, S. incanus cover and sexual reproduction were lowest in the trampled plots. The evidence of human trampling damage was also clearly demonstrated in a logistic regression analysis, since S. incanus cover and reproduction were significant variables. On the basis of these results, for the first time, human trampling has been identified as a real threat for the conservation of small and isolated peripheral populations, especially if coupled with climate warming. Finally, in situ and ex situ management recommendations are suggested.

Keywords:

• Alpine plants
• conservation biology
• plant viability
• protected areas
• Senecio incanus
• tourist impacts

Acknowledgements

We thank Prof. Carlo Blasi (University of Rome “La Sapienza”, Italy), Julie Crawford (Mancos, Colorado, USA) and two anonymous referees for the critical revision of the manuscript. Special thanks to Charlotte Seal (Royal Botanic Gardens, Kew, Seed Conservation Department, UK) for the linguistic revision of the manuscript. We are also grateful to Roberto Dellavedova (Verbania), Roberto Gentili (University of Milan) and Andrea Leonardi, who helped to monitor the plots over the years, and to managers of the Tuscan-Emilian Apennines National Park for assistance in field activities and with logistics. This research was funded by the University of Pavia (Italy).