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The WorldClimb Project

In recent years, rock climbing has become very popular. The number of climbers grows annually at a rate of 15-20%, with current estimates at 50 million climbers worldwide, and a projected increase for the next 30 years. Moreover, in countries such as Spain, more than 50% of the climbing routes are located in Natural Protected Areas. All this poses an increasing pressure on cliff ecosystems and their unique and emblematic biodiversity. However, little is known about the climbing impact on cliff biodiversity, and previous studies has been conducted at local scales and using inconsistent methodologies.

Photo taken in Patones (Madrid). Marks left by the repeated ascent of climbers along different routes are highlighted with red arrows, causing the alteration of the ecosystem. This alteration includes the elimination of vascular plant species, lichens, and mosses. White dots represents climbers present in the study area at the time that the picture was taken.


In the WorldClimb project, we carried out the first large-scale study evaluating the effects of climbing on Mediterranean cliff vegetation. We performed field-surveys across the whole Mediterranean biome including: the Mediterranean basin, the Southwestern Cape of South Africa, California in the USA, central Chile and Southwest Australia. All Mediterranean regions are considered biodiversity hotspots, and Mediterranean cliffs are particularly under pressure due to the great amount of climbing tourists they receive throughout the entire year. Within the project, we applied a novel sampling design in 43 locations and 281 climbing routes sampled from eight countries in the five Mediterranean regions

To examine differences between unclimbed and climbed routes, we designed a closely-adjacent case-control sampling design with a 3 m wide × 3 m high quadrat placed along the climbing route. The quadrat was composed by a central Climbed (C) plot of 1 m wide and 3 m high, two immediately adjacent plots of 0.5 m wide and 3 m high, which were not surveyed, and two Unclimbed (U) plots of 0.5 m wide and 3 m high on the left and right side of the 3 m × 3 m quadrat that were used as controls, since they represent areas not reached by climbers. 

The use of a closely adjacent paired design is essential to adequately evaluate the impact of rock climbing on cliff vegetation, since this precludes the possibility that variations in biotic or abiotic factors such as aspect, micro-topography and insolation that could act as drivers of differences between climbed and unclimbed plots. Closely-paired transects have the added benefit of avoiding an observer’s interference in the undisturbed areas, since unclimbed transects can be surveyed from the same anchor with the help of directional gear placements.

With this worldwide project, we AIM to unravel the threats that cliff biodiversity is facing due to recreational activities such as climbing using a robust and standard sampling methodology, to describe the variety of cliff flora in Mediterranean environments, and to better understand the patterns and processes of cliff ecosystems to promote appropriate conservation strategies.

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