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By: Prof. Isidro T. Savillo
Savillo, I. 2003. The Common Abundance of Pyxine cocoes (Swartz)Nyl. in district parks of Iloilo City, Philippines at http://www.geocities.com/lichens_airquality/index.htm or at http://www.biologybrowser.org/bb/Organism/Plantae/Lichenes/index.shtml or at
http://www.biologybrowser.org/bb/Geography/Asia/Philippines/index.shtml
Three district parks (Plaza Libertad, the Plazas of Molo and Villa) and a church yard (of the St. Clement's Church, La Paz) in the City of Iloilo were examined for the presence of the most common lichen. The corticolous lichen which was found to be predominant in these parks/ church yard was Pyxine cocoes, a foliose. These parks/ church yard are adjacent to vehicular traffic and may be exposed to type(s) of vehicular exhaust(s) (World Bank Group, 2002). This may be one of the conditions which have contributed to their favorable presence in these district parks/ church yard. In Northern Europe, Lecanora conizaeoides was found to grow favorably in the presence of sulfur dioxide, one of the notorious atmospheric pollutants (Baron, 1999). It was observed not to grow favorably in places where sulfur dioxide is deficient. Through inspection, P. cocoes, could hardly be found in areas where there are absence of running vehicles such as extremely interior lowland areas.
Lichens have been known as excellent bioindicator for atmospheric pollution (Richardson, 1991). They absorb atmospheric pollutants, freely, because they lack the stomatal apparatus (Hyvarinen et al, 1993). One of the pollutants is the vehicular exhaust. Vehicular exhausts examined from pollution tolerant lichens in France included Sulfur as an element, Benzo(a)anthracene, Chrysene, Benzo(b)flouranthene, Benzo(k)flouranthene, Benzo(a)pyrene, Benzo (g,h,i)perylene and Indeno (1,2,3, c d)pyrene (Lallemant, 2001. personal communication).
Among the study sites, St. Clement's interior park or church yard had almost all their trees harboring Pyxine cocoes on their trunks in contrast to the few trees harboring P. cocoes in Plaza Libertad. Pyxine cocoes was observed to favorably grow if the trees were not directly located near the busy road but at least a few meters away from it. This lichen was also observed on trees inside school campuses where running vehicles predominate. Pyxine cocoes was reported by Thrower, 1988 as a pollution tolerant lichen. She also reported that P.cocoes were commonly found on city parks, gardens and roadside trees.
Other lichens such as Physcia sorediosa (Vain.) Lynge, Physcia sp . (without the lower cortex) (Sipman, 2001. personal communication), Chrysothrix xanthina (Vain.) Kalb (Sipman, 2001. personal communication), were also found to co- exist but lesser in number. As city dwelling lichens, they may be pollution tolerant to some extent but Pyxine cocoes being abundant, may serve as a good bioindicator and further cellular analysis would reveal its actual physiological characteristics.
References:
Baron, G. 1999. Understanding Lichens. The Richmond Publishing Co., Ltd.
Hyvarinen, M., K. Soppela, P. Halmen and M. Kauppi. 1993. A Review of Fumigation Experiments in Lichens. Aquillo. Ser. Bot. 32:21-31.
Kalb, K. 1999. Pyxine species from Australia. Herzogia, 10.
Lallemant, R. 2001. Personal Communication.
Moreberg, R. 1990. The lichen genus Physcia in Central and South America. Nord. J. Bot. Sec. Lichenology 10(3).
Richardson, D.H.S. 1991. Lichens as Biological Indicators. Recent Developments. Bioindicator and Environmental Management. Academic Press Limited.
Sipman, H. 2001. Personal Communication.
Swinscow, T.D.V. and H. Krog.1988. Macrolichens of East Africa. British Museum (Natural History). Cambridge Photosetting Services and Henry Ling Ltd, The Dorset Press, Dorchester.
Thrower, S. 1988. Hongkong Lichens. The Urban Council, Hongkong.
World Bank Group. 2002. Philippines Environment Monitor 2002. (Focus of the Issue : Air Quality). World Bank Office in Manila at www.worldbank.org.ph
ACKNOWLEDGEMENT: This research study was issued a Gratuitous Permit from the DENR: WildLife Gratuitous Permit No. 101.
