Biocrust is the real secret of the immortality of the Great Wall of China

The Great Wall of China is one of the seven wonders of the modern world. It is more than eight thousand kilometers long and dates back to B.C. It was built from compressed earth, stone and brick in different periods, starting from 215 BC, with the most famous and monumental sections being built during the Ming Dynasty and dating back to a period. 1368 to 1644 AD After more than five centuries, this massive engineering project is mostly still standing, perfectly visible even from space. What protects it from the effects of time? A team of Chinese, Spanish and American scientists appears to have found the answer to that question: It’s all thanks to the biocrust, the layer of moss, lichens and bacteria that covers nearly every rock surface exposed to the elements.

A protective layer

The research, published in the journal Science Advances, was born with the aim of finding an answer to an old dilemma of experts in the context of cultural heritage conservation. Prevailing tradition and common sense recommend removing plants and other vegetative organisms from ancient stone structures to prevent their root systems from destroying them. However, Geology and Earth sciences suggest a different approach: Biocrust is a ubiquitous phenomenon on the surface of our planet and has long been discovered to contribute to keeping soil and rock structures intact by protecting them from the effects of precipitation. Atmospheric agents resulting from intense heat and cold.

If the biocrust is so beneficial for natural rocks, couldn’t it do the same for ancient artificial structures, wrapping them in a kind of “biological armor”? The authors of the new study asked themselves this question and decided to examine different sections of the Great Wall built from rammed earth to find an answer. More than two-thirds of the structures analyzed were covered by a biocrust composed mostly of cyanobacteria and algae; Occasionally bits of lichen also colored the scene.

I study

By performing microscopic sampling, the researchers discovered that sections of wall covered by biocrust were less porous and more durable than those analyzed in bare areas. In their opinion, the results clearly show that whatever risks bacteria and microplants may pose to the stability of the wall, the benefits in terms of increased resistance to atmospheric agents are far superior.

Therefore, leaving the biological crust in place seems the best way to ensure the survival of ancient monuments of the past. The authors of the study admit that this is not always possible, because the eye wants its fair share, and a wall completely covered with moss and micro-vegetation is probably not the most beautiful sight that can greet visitors to the Great Wall and other great monuments of China. The past is scattered across the planet. So the problem is balancing tourist and museum needs with the preservation of these ancient finds, and this is something that cannot be proven based on science alone.

But knowing the effects of biocrusts is definitely the best way to make informed decisions. With climate changes increasingly putting the great treasures of the past at risk, it is possible that awareness that this layer of algae, bacteria and plants may be valuable in further extending their survival will help us all become more tolerant of some blemishes. Easily moss when we find ourselves visiting ancient monuments.

Source: Today IT

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