Wonder plant
What may appear to the untrained eye as a patch of scaly growth are in fact one of the world's best natural indicators of pollution. Thanks to their extensive surface, lichens are increasingly being used worldwide to assess pollution levels. A combination of fungi and algae, they can grow just about anywhere. But they are highly sensitive to pollution. It is these characteristics that make them very effective bioindicators. When exposed to pollution, they start bleaching, blackening and register a decline in growth.
In India, lichens are being used by researchers of the Chennai-based M S Swaminathan Research Foundation (MSSRF) for monitoring pollution in Siruvani hills of Western Ghats. During their study, they mapped lichen biodiversity of the area and analysed the response of different varieties of lichens to pollution. According to them, areas with less abundance of sensitive varieties show high pollution levels and viceversa. The institute is also educating teachers and officials about how to use in lichens. During another study carried out by Lucknow-based National Botanical Research Institute, lichens were transplanted from unpolluted areas to polluted areas of Lucknow. When thus transferred, the lichens quickly accumulated lead, iron, chromium, zinc and copper ions in their tissues.
During another research carried out in Canada, samples of two varieties of lichens were collected from 80 sites that were located at varying distances from an oil refinery and a thermal power plant. Even at the farthest distance they showed the presence of traces of pollutants.