FACTORS AFFECTING THE WEATHERING AND COLONIZATION OF MONUMENTS BY PHOTOTROPHIC MICROORGANISMS

Phototrophic microorganisms are common inhabitants of monuments. This paper reviews different aspects of their culture, ecology and deterior ation mechanisms. Opportunistic species of cyanobacteria and chlorophy tes, present in soils and in the air, are commonly found on the surfac es of monuments. Their growth represents a significant input of organi c-matter to the stone, as estimated through chlorophyll a quantificati on. Monuments provide unusual niches for the growth of algal communiti es, as in the case of black sulfated crusts, or endolithic and hypogea l niches, where more specific processes and/or communities occur.