Current knowledge regarding biological recolonization of stone cultural heritage after cleaning treatments

Abstract

Biocolonization causes physical-chemical and aesthetic biodeterioration, which depreciates the artistic value of outdoor works of art, leading to the use of (often expensive) treatments to remove the colonizing organisms. Such treatments are generally considered successful if they eliminate the biocolonization; however, subsequent recolonization of the cleaned substrate is generally overlooked by both public administrations and researchers. This review aimed to gather current scientific knowledge about the biological recolonization of stone-built cultural heritage after cleaning treatments. It is difficult to draw strong conclusions from the few studies on recolonization of cultural heritage, as each study involves different treatments, target organisms, substrates and climatic conditions. However, recolonization by fungi appears to be faster than recolonization by other organisms. Long term studies should be conducted to identify recolonization processes that may take some time and also involve various types of organisms. Short-term studies have only detected recolonization by generalist species, while long-term studies have shown recolonization by specialist species similar to the previous colonizer community.