The Puy de Dôme: Natural or Anthropogenic? Understanding, managing and protecting an original landscape in a UNESCO World Heritage site

Humans are part of nature, so natural landscapes can contain human impacts. The limit of this natural anthropomorphic influence, where landscape stops being natural, is not defined clearly, but major infrastructure, urbanization etc. are clearly non-natural elements. When a natural feature becomes important for humans, such as the iconic Puy de Dôme volcano in central France, it tends to attract human modification. The Puy de Dôme was a Druidic and Roman sacred site, with added temples and paths. Yet, outside these, the majority of the mountain remained in a natural state, evolving by erosion, slope movement, and accumulating debris on its lower flanks. The natural state can still be seen in the detailed morphometry of its flanks. Since the turn of the 20^th century, increased human activity has further modified the site, with the construction of a spiral cog railway track, and infrastructure: restaurants, observatories, military and communication buildings, including the iconic spike – that inhabitants are so attached to. Despite this increased activity, the essential natural values of the mountain have been mostly maintained, although the spiral railway track has cut / modified the natural drainage to some extent. With UNESCO World Heritage inscription in 2018, visitation is on the increase, and with more visitors, further pressure has been seen. Occasional debris flows and landslides have also become newsworthy events, impacting the railway operation. New slope stability plans have been drawn up for the cog railway and the footpaths, which have included large scale bolting of outcrops, wire meshing and rock removal. These have been implemented only very partially due to opposition from ecology and geoheritage actors.

To provide a clear picture of the natural state of the Puy de Dôme and to guide natural protection and risk management, a full geomorphological and morphometric analysis is needed. This abstract gives the first results of this work, presenting the geomorphology and morphometry, including a geomorphon and shape analysis, and 3-D Virtual Reality LiDAR topography. The resulting information allows us to determine the state of 'naturality' of the Puy de Dôme and establish the natural system and determine its anthropogenic influences. The volcano, since its eruption 11,000 years ago, has been slowly evolving under different climatic regimes, that have contributed to its present shape. Ongoing processes, which include natural-compatible pastoral and forest activity continue to shape the dome.

Despite the human presence, the volcano is large enough to presently maintain its natural evolution in the long term and adapt to changing climatic conditions. However, there are many sites of concern, where installations have the potential to alter this, and to generate enhanced risk to the geological nature and to visitors. With our analysis, we can propose management strategies that can minimize impact, can be monitored, and which can protect the geoheritage and the fragile ecology, while allowing continued access to the site. Human access needs to respect and to be adapted to the natural conditions.