Data for: Protective functions of Biocrusts on the Great Wall of China

The Great Wall of China, one of the most emblematic and historical
structures built by humankind throughout all of history, is suffering from
rain and wind erosion and is largely colonized by biocrusts. Yet, how
biocrusts influence the conservation and longevity of this structure is
virtually unknown. Here, we conducted an extensive biocrust survey across
the Great Wall and found that biocrusts cover 67% of the studied sections.
Biocrusts enhance the mechanical stability and reduce the erodibility of
the Great Wall. Compared with bare rammed earth, the biocrust-covered
sections exhibited reduced porosity, water-holding capacity, erodibility,
and salinity by 2%–48%, while increasing compressive strength, penetration
resistance, shear strength, and aggregate stability by 37%–321%. We
further found that the protective function of biocrusts mainly depended on
biocrust features, climatic conditions, and structure types. Our work
highlights the fundamental importance of biocrusts as a nature-based
intervention to the conservation of the Great Wall, protecting this
monumental heritage from erosion.