• Scientists promote awareness of this bioindicator of pollution 

BY Sumudu Chamara In Sri Lanka, the discussion of protecting and identifying crucial parts of the environment is often confined to large-scale environmental challenges and political or policy-level matters pertaining to the environment. However, there are a plethora of elements of the environment that have not received adequate attention to the point where Sri Lanka has almost forgotten about them despite the country being rich in natural resources. Lichens are one such extremely important organism that has not received the authorities’ attention, and during the past few years, local experts have pointed out the importance of studying and using lichens for various purposes. However, there is not even a proper discussion about lichens. Lichens According to the general definition, lichens are plant-like organisms that consist of a symbiotic association of algae (a diverse group of aquatic organisms that have the ability to conduct photosynthesis, the latter the process through which green plants and certain other organisms transform light energy into chemical energy) or cyanobacteria (microscopic organisms found naturally in all types of water that use sunlight to make their own food; also called blue-green algae) and fungi (a kingdom of usually multicellular eukaryotic [possesses a clearly defined nucleus] organisms that cannot make their own food). They are found in various parts of the world, and can be found in a multitude of environments and on various surfaces such as tree barks, rocks, and in the soil. Scientists have estimated that there could be approximately 20,000 types of lichens in the world.  Certain studies conducted with a focus on South Asia claim that there could be more than 4,000 to 5,000 species of lichens in Sri Lanka, some of which are endemic, even though the majority of them are yet to be identified. On several occasions during the past few decades, a large number of species of lichens were identified in Sri Lanka by foreign and local scientists such as Natural History Museum, London, UK Senior Curator of Lichens and Slime Moulds Dr. Gothamie Weerakoon. Among the areas from which lichens were identified are the Horton Plains National Park, the Knuckles Mountain Range, and Kandy.   According to a report titled “Fascinating Lichens of Sri Lanka” authored by Dr. Weerakoon, many of the lichens recorded from Sri Lanka are found in the Central Highlands, in the West, and the South West of the island, and these lichens have close relatives in similar geographic areas in India, South East Asia, the Andaman Islands, South Australia, and Tasmania. It was further stated that lichen species in the mountain areas of Sri Lanka are related to the northern hemisphere “Gondwanan (an ancient supercontinent that broke up about 180 million years ago)” species and “bipolar (species that can live in both the North and South Poles)” species of the Alpine and Polar regions. “In the drier areas of Sri Lanka, especially the dry evergreen forests, deciduous (a type of forest dominated by deciduous trees which lose their leaves seasonally) forests and mangrove forests of coastal areas, the lichen flora show strong similarities to mainland India. These lichens underline the ecological and climatic affinities of the two regions, and the frequency of past land connections. Some lichens are known to be endemic to Sri Lanka (circa 60 species), i.e., restricted to a very local geographical area. A considerable amount of the lichen species of Sri Lanka are closely related to the lichens of the Indo-Malaysian floristic region, sharing many common families and genera. The close relationships between them are credited to their common origin in the ancient supercontinent of Gondwana,” the report said. Industrial, environmental, and medicinal uses According to scientists, lichens, although having not attracted sufficient attention as far as their economic, environmental, and medicinal importance and uses are concerned, are crucial in a number of ways.  One of the most important uses includes lichens serving as an important and reliable biological indicator of pollution, as they do not grow in cities and in industrial areas. The reason, according to researchers, is them being extremely sensitive to various pollutants, especially atmospheric pollutants such as sulphur dioxide. At the same time, they are used to estimate the mean sulphur dioxide level in a season by studying lichens on trees. Lichens are also used as a source of medicines and as an ingredient to produce certain medicines. Researchers say that they have been used to treat fever, diarrhoea, skin diseases, epilepsy, hydrophobia, respiratory diseases, and jaundice, among other diseases. In addition, they are used to produce anticancer medicines and antibiotics. It has a number of industrial uses as well. While some lichens are used in the dye, leather, and tannin industries, lichens’ use in cosmetics and perfume industries has also been identified by scientists.  Moreover, some species of lichens are used in industries that involve distilling and brewing. In some countries, such as Russia and Sweden, certain types of lichens are used to manufacture alcohol, and in confectionary industries. Some species of lichens in fact serve as food for various types of animals and humans. Humans using certain species of lichens as a food article can be seen in countries like Iceland, Norway, and in certain Asian countries, according to researchers. However, there are also harmful aspects of the presence and growth of lichens. According to studies, some types of lichens growing on fruit trees and sandalwood trees can be harmful to those trees, and some types of lichens may even be a risk factor for wildfires because during the dry season, they are likely to become dry and inflammable. What is more, some types of lichens have been identified to be poisonous. Using lichens to face environmental challenges According to scientists, lichens play a special role with regard to studying the nitrogen footprint (the total amount of nitrogen released to the environment as a result of an entity’s consumption pattern), which scientists say has received inadequate attention compared to other similar environmental issues such as the carbon footprint. They state that lichens can be used as a bioindicator to understand and estimate nitrogen pollution in various geographical areas where lichens exist. A recent study titled “Estimating the nitrogen risk to Himalayan forests using thresholds for lichen bioindicators” authored by C.J. Ellis, C.E. Steadman, M. Vieno, S. Chatterjee, M.R. Jones, S. Negi, B.P. Pandey, H. Rai, D. Tshering, Dr. Weerakoon, P. Wolseley, D. Reay, S. Sharma, and M. Sutton, had used different types of lichen response to estimate the nitrogen situation in the Himalayan forests. It had found that over 80% of the Himalayan forests have exceeded critical levels and loads, and that lichen bioindicators had signalled the potential for widespread negative effects associated with atmospheric nitrogen pollution. Even though a large number of practical uses of lichens have been identified and they are being used for various environmental, industrial, and medicinal purposes, researchers say that the world is not obtaining the full benefit of lichens. Depending on the types of lichens that are available, some countries have already started using them for commercial and environmental activities.  In the US, various types of lichens are monitored in order to identify crucial sources and overall levels of air pollution, and in Germany, lichens are used as a bioindicator for air pollution, according to the international media. Media reports also say that in certain countries in Europe, lichens are being used to map and monitor nitrogen and ammonia pollution patterns, and that such initiatives have led to discoveries such as lichens’ response to global warming. Sri Lanka too has taken some initiatives. A research carried out in Sri Lanka’s tea estate sector has also focused on monitoring lichens in order to understand the situation of the nitrogen footprint in those areas. Studying, conserving lichens in Sri Lanka As far as Sri Lanka is concerned, several local experts including Dr. Weerakoon have pointed out the importance of Sri Lanka paying more attention to understanding the seriousness of the nitrogen footprint, and that it can be more harmful than the carbon footprint. In a recent interview with a local media institution, Dr. Weerakoon had pointed out the importance of studying the impact of nitrogen released by nitrogen-based fertilisers. She had further stated that cases of families and farmers in Polonnaruwa and other paddy farming areas getting sick have been reported, and that more studies need to be conducted to look into this situation with the use of lichens.  These concerns were raised in a context where Sri Lanka’s fertiliser consumption has been on the rise during the past few decades, and farmers’ associations have raised concerns about farmers using excessive amounts of fertilisers hoping to get more harvest. At the same time, following the fertiliser crisis triggered by the Government’s plan to go organic, it was nitrogen fertiliser that the Government imported. In this context, there is also a need to look into the adverse effects of using nitrogen fertilisers, especially if they are being used in excessive amounts and without adhering to the directions on using them. In the aforementioned report by Dr. Weerakoon, she further stressed the importance of conserving lichens in Sri Lanka, and noted that as a result of human activities, some lichens suffer adversely. She explained the threats to lichens, noting: “Most lichens found in Sri Lanka are very tiny micro lichens, hence it is not possible to immediately notice the loss of species or changes in the distribution pattern. The loss of lichens mainly results from habitat destruction owing to atmospheric and aquatic degradation. Lichens quickly respond to air pollution and habitat changes. Their ecological roles and requirements are totally different from those of macro organisms. Often without lichens, the survival of macro organisms is in danger as lichens are vital components of the ecosystem function. Both at the species level and at a community level, much of the lichen flora is confined to montane (a forest situated in mountains), sub-montane (a forest situated in the foothills or lower slopes of a mountain or a mountain range), and rain forests in Sri Lanka. These vegetation types have the highest risk in the country.” Dr. Weerakoon further said that the utmost threat to Sri Lankan lichens is via habitat destruction, and that when natural vegetation is replaced, be it agricultural land or plantation forests or monoculture plantations (such as cardamom and tea), a substantial and irreplaceable segment of lichen diversity is inevitably lost. As has been pointed out by many international experts, more attention needs to be paid to various uses of lichens, especially economic and environmental uses, given the fact that compared to other countries, Sri Lanka is home to one of the highest number of species of lichens compared with the country’s size. However, according to local experts, such efforts will entail a great deal of investments for experiments and studies, and also awareness-raising activities to create more interest regarding this subject and the practical benefits of lichens in the Sri Lankan context.