Identification of the key factors influencing biodeterioration of open-air cultural heritage in the temperate climate zone of China

Biodeterioration is known to cause irreversible damage to open-air cultural heritages. China has numerous open-air cultural heritages constructed of stone and brick, but very little information is available about the factors involved in their biodeterioration. In this study, different kinds of open-air cultural heritages (steles, towers, temples, Tang-ling carvings, and stone bridges) from 14 different locations in temperate climate zone of China were collected and investigated. Microbiological characteristics of these cultural heritages revealed that both cyanobacteria and lichens were the mainly dominant groups on these open-air stone and brick cultural heritages with visible deterioration. Cyanobacteria were closely associated with the severely deteriorated Tang-ling carvings wile lichens were most commonly found on temples and bridges. The main cyanobacteria were Oscillatoria, Pleurocapsa, and Lyngbya, and the dominant lichens were Xanthoria Th. Fr., Lepraria. Ach. and Camellia on the surface of cultural heritage. In addition, the extent of deterioration associated with cyanobacteria exhibited an increasing trend with higher annual mean sunshine intensity, calcite content, and cultural heritage age though not statistically significant. Redundancy analysis indicated that sunshine intensity and the age of the archeological structures were the key factors that significantly affected the biodeterioration of cultural heritages. This study provides more understanding of the microbial community associated with deterioration of open-air cultural heritages situated at the temperate climate zone of China.