A University of Bayreuth experimental study has found that outdoor bouldering introduces microplastic pollution directly into cliff ecosystems while simultaneously damaging vegetation and abrading natural rock surfaces, raising new conservation concerns for one of the sport’s fastest-growing segments.
The research, published in the journal People and Nature, involved 500 repeated ascents on previously untouched blocks of limestone, granite and sandstone. The team documented moss and lichen losses of up to 15 percent on handholds and footholds, with the largest losses occurring during initial climbs. For the first time, researchers also used spectroscopic methods to identify microplastic particles consistent with abrasion of climbing shoe soles on limestone surfaces.
Sandstone proves most vulnerable to repeated use
“Our study is the first to demonstrate that the impact of bouldering varies according to rock type and that ecosystem recovery is slow,” Sofie Paulus, a research associate in the Sport Ecology research group and initiator of the study, said in the journal article.
Sandstone emerged as particularly vulnerable because particles and vegetation are more easily removed. Recovery of vegetation cover on sandstone was only partial even after three years, according to the paper. The mechanical impacts – removal of bryophytes, lichens and thin-soil vascular plants – reduce habitat quality for rock-dwelling species and can be long-lasting on more friable rock types.
Microplastic shedding adds chemical dimension to physical damage
“Bouldering therefore introduces microplastics directly into sensitive ecosystems, which could affect, among other things, microbial communities,” Prof. Dr. Manuel Steinbauer, Chair of Sport Ecology at the University of Bayreuth, said in the study.
The Bayreuth team identified microplastic particles on limestone even after moderate use. Common practices such as applying climbing chalk or cleaning rock surfaces before first ascent are likely to amplify these effects, the authors note.
The finding echoes recent field and laboratory studies linking outdoor footwear and synthetic gear to microplastic pollution in wilderness areas. A lake-comparison study in the Adirondack Mountains reported microplastic concentrations roughly 23 times higher in a lake adjacent to heavy hiker traffic than in a remote lake, and attributed much of that increase to soft-soled trail shoes and synthetic clothing.
Chalk residues and trampling compound ecosystem stress
Concerns about climbing-related impacts extend beyond microplastics. Independent research and management agencies have documented additional ecological harms: climbing chalk alters rock-surface chemistry and can inhibit germination and survival of rock-dwelling ferns and mosses, while concentrated visitor use creates informal social trails, modified landing zones and cleared boulder bases that degrade habitat.
Government stewardship guidance from the US National Park Service and a comparative People and Nature analysis both report lower plant and lichen diversity on climbed faces and highlight the suite of mechanical and chemical stressors associated with climbing.
Indoor-climbing research adds another dimension. Studies of indoor facilities have detected rubber-derived compounds and other chemical byproducts from shoe sole abrasion in dust and air, raising questions about both environmental pathways and human exposure. While indoor contamination studies do not map directly onto outdoor ecosystems, they reinforce the conclusion that climbing-footwear materials abrade and release measurable polymers and additives during routine use.
Zone-based management and gear innovation could reduce impacts
The Bayreuth researchers recommend differentiated, zone-based strategies that could include seasonally or permanently closing sensitive boulders to allow recovery, restricting the cleaning of rock surfaces, and promoting gear choices and practices that reduce abrasion and microplastic shedding. Such measures would aim to protect rare and protected rock-dwelling species while allowing continued outdoor recreation.
The Adirondack and industrial studies suggest product-design changes – lower-shedding soles and more durable textiles – could reduce source shedding, while park managers can apply local rules and visitor education to limit damage at high-use sites. The scientific record now connects material abrasion, chemical residues and physical trampling into a coherent picture of how climbing and broader outdoor recreation can alter cliff ecosystems, and it frames management as a mix of regulatory closure, visitor behavior change and product innovation.
About
The University of Bayreuth Sport Ecology research group focuses on the environmental impacts of outdoor recreation and has published multiple peer-reviewed studies on climbing ecology. Sofie Paulus is a research associate specializing in rock-climbing impacts, while Prof. Dr. Manuel Steinbauer chairs the Sport Ecology department and leads research on how recreational activities affect alpine and rock ecosystems.
The study appears in People and Nature, a peer-reviewed, open-access journal published by the British Ecological Society that covers research on human-nature relationships and conservation.
