The Great Wall of China, facing erosion and natural degradation, finds an unexpected protector in the form of biocrusts. These 'living skins' made up of plants and microorganisms cover 67% of the surveyed sections of the Great Wall, enhancing its mechanical stability and reducing its erodibility. Biocrust-covered sections have decreased porosity, water-holding capacity, erodibility, and salinity, while increasing compressive strength, penetration resistance, shear strength, and aggregate stability. With only 5.8% of the Great Wall well preserved, the role of biocrusts in protecting this heritage site is crucial. Biocrusts are made up of cyanobacteria, algae, moss, fungi, and lichen.
