Since ancient times, and in many parts of the world, when walking through the countryside, a small pile of stones appeared from time to time on the side of the road or on the edge of a crop. This practice of a traditional nature and present only in certain enclaves, previously anecdotal, has become in recent years a fashion that has spread throughout natural territories throughout the world .
The origin of these little piles of stone
The native peoples of the Andes had this tradition of forming small piles of stones, of varying sizes, the so-called ‘apachetas’ . The most mystical explanation of this peculiar custom is that it is a rite to come into contact with the Pachamama, the ‘Mother Earth’, the goddess of the earth and Inca fertility.
A similar ritual, also with mystical significance, is found in Zen Buddhism. In this case, it seems that he is looking more for the balance of the pieces, apparently chaotic, but which remain standing in a column. Similar rituals are found in Celtic culture. In Galicia they are called ‘milladoiros’ , in Ireland ‘cairn’ , and in Wales ‘carnedd’ .
In other parts of the Iberian Peninsula you can also find piles of stones. In La Mancha there are, sometimes large, on the edge of the fields, called ‘majanos’ . And marking the crossroads of Castilian roads you can find small mounds of rocks stacked in a conical shape, which are known as ‘morcueros’ .
Less religious and more practical explanations seem to indicate that these piles are marks left by travelers to remember the path traveled, or in order to measure distances, like a primitive version of road markers that indicate kilometers. These uses seem most likely for the milladoiros found along the Camino de Santiago , and also for morcueros, who are named after the Roman god of messengers, Mercury. The majanos from La Mancha have an even simpler use: they are the result of piling up the rocks that are removed from the cultivated fields .
Whatever its origin, the truth is that it is very fashionable to stack little piles of stones in natural environments. And it’s not a good idea .
A fashion with environmental impact
Perhaps the gesture seems harmless, even innocent, and its punctual and isolated practice probably is. But you know how this works: throwing a single stone into a river surely has no consequences, but throwing tons can divert the course. Similarly, a cairn of stones marking a crossroads is not the same as hundreds or thousands dominating a natural landscape.
Stone stacks have been found even in protected natural areas . Places where morcueros or apachetas had never been placed, now appear flooded with these constructions, whose sole purpose seems aesthetic: to take the perfect photo for the tourist on duty to upload to their social networks. They are trending .
The most direct impact of the massive construction of these cairns on the ecosystem is related to the process of erosion . By removing stones and rocks, the soil loses its cohesion capacity and erodes more easily. This changes the structure of the habitat for the great diversity of organisms that inhabit it and alters its functions, which in many cases are essential for the maintenance of the ecosystem.
Alterations of microhabitats
The rocks form microhabitat conditions ; It doesn’t rain under a rock, but water does come through runoff. The rocks cast shade, retain the sun’s heat and dissipate it slowly, mitigating the effects of extreme temperatures. This is particularly relevant in arid areas. Some form spaces under them, which are used by living beings, or serve as support for the settlement of lichens and mosses.
In some ecosystems, many species depend on the physical conditions associated with rocks , which use them as resting areas, for feeding, for shelter, or for other purposes, generally related to the thermal, hydric or structural aspects of said rocks.
In this sense, the size, structure or type of rock, its location in the soil, humidity levels influence the physiological performance and behavior of living beings that inhabit these rocks or that use them.
The distribution of rocks in an environment is also related to the interactions between living beings , either between individuals of the same species, or between different species, modulating competition or predator-prey relationships.
Rock removal, displacement, overturning or breaking can affect these microhabitats in multiple ways. It alters the thermal profile of the landscape, modifies exposure to meteorological events, and even changes the relationships between living beings. It eliminates places where plants and animal shelters settle, exposing the organisms that live below to inclement weather for which they are not always adapted. Nests can even be destroyed, or the landscape altered in such a way that birds returning from their migration no longer recognize the environment and do not nest in it again.
Placing the stones in a different place forms a new microhabitat that did not exist before, which could inhibit the growth of plants that had previously germinated in that area, or hinder the organisms that existed before.
Soil erosion associated with the removal of stones generates the disappearance of horizons and, with them, decomposers, destabilizing ecosystems from their base.
In general, these types of actions, especially when they are carried out indiscriminately, without justification and without knowledge of what is being done, generate very significant impacts on the organisms that inhabit the rocks. And in sensitive ecosystems or with a high number of endemisms, it can become a factor promoting extinction .
References:
Gross, M. 2018. Global tourism’s growing footprint. Current Biology, 28(17), R963-R965. DOI: 10.1016/j.cub.2018.08.049
Rocha, R. et al. 2020. Stone-Stacking as a Looming Threat to Rock-Dwelling Biodiversity. Human-Wildlife Interactions, 14. DOI: 10.26077/secn-2a27
Savannah Blackman. 2022. Public perceptions of salamanders in Great Smoky Mountains National Park [Master of Science, University of Tennessee].
