Biocrusts: Unseen protectors of the Great Wall of China

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.