Climbers rub on their hands to improve grip, and the powder transfers to the rock. The white marks can be seen and cleaned, and what happens in the places that look clean is less clear. What was found there?
Chalk where nothing showed. Along routes, raised quantities of chalk appeared at 65 per cent of the sampling points that looked clean. A further experiment grew on rock under different chalk concentrations, and recorded harm to and survival. That does not prove every climbing site loses vegetation because of chalk, and it does point to a chemical effect beyond the visible mechanical wear.
Climbing damage to vegetation has been attributed mainly to direct contact: trampling, abrasion or the removal of soil. The researchers wanted to examine a further effect, of chalk that stays on the stone and changes the tiny living environment of the plants.
They sampled points along routes on gneiss rock. Raised chalk concentrations were found at 65 per cent of the points where no white mark was visible. So looking clean is a poor measure of the absence of the material.
In the laboratory four fern species and four moss species were exposed to different chalk concentrations. The responses were not identical between species, and significant harm to germination and survival appeared as the quantity of chalk rose.
A laboratory is not open rock in rain and wind, so the scale of damage at any site cannot be calculated from it alone. It does supply a possible mechanism and a basis for further field measurements and for climbing habits that reduce accumulation.
wat. Chalk can remain on climbing rock even where the eye sees none, and it may harm small plants.
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Conservation at climbing sites has to consider the powder left on the rock as well, and not only trampling and broken plants.
How do we know?
Measurements along bouldering routes were examined alongside a controlled experiment with four moss species and four fern species.
What is still unknown
The experiment ran in controlled indoor conditions and on a limited number of species. It does not directly measure how many plants were lost on any route in the wild.
Learn something?
Where to next
Does climbing chalk really help you hold on to rock?climbing
Does climbing a wall begin while you are still standing below it, looking?climbing
What drags rocks across the floor of Death Valley?rocks