Abstract

Megalithism is a universal human phenomenon which has been present since prehistoric times. In the field of biodeterioration, natural and artificial stone materials are studied the most because of their wide distribution and as they are the main elements of the archaeological, monumental heritage and due to their outdoor locations, they are subjected to the adverse environmental factors like sunlight, frost, wind and rain etc. Moreover, biological activity also plays a role in its interaction with physico-chemical integrity of the rock materials. Colonization of microorganisms on historic building materials and deterioration is usually linked to environmental conditions. Lichens, algae and mosses growing on prehistoric rock art pose a major worldwide threat for its preservation and conservation. Lichen colonization affects the rock art by both mechanical and chemical actions, through rhizines penetration, expansion and contraction of thallus, production of oxalic acids and other lichenic acids, and chelation of metal ions etc. This study is an effort to identify the lichen colonization as the deteriorating factors of the prehistoric megaliths of Manipur. Lichen samples were collected from five different megalithic sites of Manipur and to study the changes taking place in the lichen-rock interface. The challenges and possible prospects of this research will help to compile the information available on the lichen taxa growing on different megalithic sites of Manipur, for identification of the lichen species present on each megalithic site and to call upon various researchers, scientists and conservators to study the present condition of the megaliths, and come up with possible preservation and conservation schemes.

Keywords: Prehistoric megaliths; Biodeterioration; Lichens; Identification