Transsylvania Nostra Journal

Since ancient times, fortresses have represented local population’s means of defence against invaders. Erected initially from earth, timber or stone, they evolved throughout time, becoming adapted to the more and more destructive offensive systems. Exposed to the direct influence of environmental factors, they suffered degradations caused by variations in humidity, temperature, light and, during the past decades, by pollution emissions. Colonisation by various biological populations started soon after the constructions were completed, with “pioneer” organisms, like blue algae and lichens, and continued for centuries with a complex process involving both inferior and superior plants, as well as a wide range of other invertebrates and even vertebrates. The action of these factors “undisturbed” by human intervention can lead to the complete destruction of buildings with high historical value.
Keywords: fortresses, colonisation, biological population, bacteria, algae and cyanobacteria, fungi, lichens, bryophytes, vascular plants, climbing plants, ivy