'Biocrusts' Protecting Great Wall of China from Erosion

Researchers suggest that these organic layers, which enhance the wall's mechanical stability and reduce its erodibility, could be a key strategy for preserving heritage structures.

• Large sections of the Great Wall of China are being preserved by 'biocrusts', thin layers of organic materials including cyanobacteria, mosses and lichens.
• The biocrusts, which cover two-thirds of the studied sections, help protect the wall from erosion, enhance its mechanical stability and reduce its erodibility.
• Biocrusts are more effective on sections of the wall built with rammed earth, a mix of organic materials like soil and gravel.
• Biocrusts can be three times stronger than plain rammed earth samples, with moss-containing samples showing particular resilience.
• Researchers suggest that conserving naturally occurring biocrusts on heritage structures could be a beneficial strategy for preservation, especially in the face of climate change.

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