Information on lichen flora in Sri Lanka is scarce. Therefore a study was carried out to investigate lichens growing on a tree species common to all five eco regions (Montane, Wet, Intermediate, Arid and Dry zone) of Sri Lanka. The common tree species found in all regions was Artocarpus heterophyllus Lam. (jak). Lichen flora found on bark of jak trees between 1.5 m and 2 m above the ground level was studied. Six hundred and sixty three specimens from hundred and twenty trees were studied. Twenty five genera and thirteen families were found among them. Twenty genera were found to be crustose and five were folioses. No fruticose lichen was found in any region. Of all identified lichens 40% were belonged to the family Graphidaceae and it was the most frequently found lichen family in all regions and the second highest (17%) was belonged to family Phyciaceae. The most frequently found genus was Graphis.
Heterodermia and Pertusaria were found only in montane zone while Leptogium was found only in lowland wet zone. Thelotrema, Ocellularia, Myriotrema and Chrysothrix were found only in Intermediate zone. Parmelia was restricted to wet zone while Dirinaria, Dimerella and Porina were restricted to dry zone. Differences in distribution of some of these lichens can be explained with rain fall, temperature and humidity.
Graphis and Opegrapha were found on jak tree trunks in all studied sites indicating that it has been well adapted to any environmental conditions in Sri Lanka.
M M K Karunarathne 1, W J S K Weerakkody 1 and D S A Wijesundara2
1 Department of Plantation Management, Wayamba University of Sri Lanka, Sri Lanka
2Royal Botanical Gardens, Peradeniya, Sri Lanka