DIVERSITY AND DISTRIBUTION OF LICHENS AT SELECTED MANGROVES IN GALLE DISTRICT

Abstract

Manglicolous lichens are specific group of lichens growing on the mangrove plants. Although the island of Sri Lanka harbors a diverse floristic biodiversity there is no systematic study have been carried out on Manglicolous lichen diversity.In Sri Lanka conservation of lichen diversity is essential due to the important values of lichens. During the current study the lichen community on mangrove species and effects of tree factors (Bark pH, DBH, height of the tree, Tree aspect) on the distribution and Diversity of Manglicolous lichens in Galle district, Sri Lanka were examined. Lichen species were determined by using standard methods. Correlations of the Manglicolous lichen diversity with tree factors were examined with Spearman correlation test. Relationships among variables were examined by using Regression analysis. The study of the diversity and distribution of Manglicolous lichens at 10 plots within Galle district, in Sri Lanka, revealed 226 species including 175 crustoses, 18 folioses and 33 sterile crusts, belonging to 85 genera. Absence of fruticose lichens were significant in all sites. The highest lichen diversity has been recorded from the Madu Ganga Ramsar site while the lowest was at Unawatuna area. The mangrove species of Rhizophora apiculata was identified as the most common host mangrove species for the lichens. Genus Graphis was the most abundant lichen Genus within the studied area. Lichen diversity and the tree height showed the insignificant positive correlation (p ≥ 0.05) and the intermediate height of trees showed the highest lichen diversity. Lichen species were higher in the pH values of the bark within the range of 4.9-5.1. Most lichens were distributed within North, Northwest, Southwest directions. DBH was the putative key factor controlling the diversity and distribution and showed Strong positive correlation with significant difference (p ≤ 0.05). The results of this study can be used for conservation and management of lichens and these unique habitats within the changing world.