Mechanical impacts of climbing on cliff vegetation: Contrasting management concepts

Abstract Climbing a boulder for the first time often means entering a previously inaccessible ecosystem, many of which are inhabited by rare species. Little is known about the impacts of first ascents on cliff vegetation, especially with respect to different rock types. Our study builds on this knowledge gap and investigates how climbing activities affect undisturbed rock ecosystems. We experimentally climbed three previously unclimbed boulders (sandstone, limestone and granite) 500 times. Although limited to a single boulder per rock type, our experiment provides preliminary insight into how vegetation cover responds to climbing activities in different lithologies. The loss of vegetation was analysed using a time series of images of hand and footholds. For one site, vegetation recovery was quantified 3 years after climbing treatment. In addition, Raman spectroscopy was used to analyse possible microplastic abrasion of climbing shoes. The vegetation cover on climbing holds decreased by 0%–15%, with the first ascents being particularly decisive. Vegetation loss varies between rock types, with soft sandstone showing the highest loss due to abrasion of the rock surface. A partial recovery of the cover of the microbial community was observed over 3 years after climbing treatment on the sandstone boulder. Raman spectroscopy identified black particles found on climbing footholds as microplastic abrasion from climbing shoes. The mechanical stress caused by boulderers damages rock vegetation locally on climbing holds and is one of the impacts induced by climbing. Even moderate frequency and no prior cleaning of routes can lead to longer lasting damage to cliff vegetation. In sensitive areas, appropriate management actions should be developed by climbing associations, experts and nature conservation organizations. The strong effect on vegetation caused by first ascents suggests that climbing management should favour closing entire rocks while leaving others open (zonation concepts), promoting spatial concentration of impacts. Further studies on microplastics caused by climbing are recommended. Read the free Plain Language Summary for this article on the Journal blog.