Chiang Mai Journal of Science

Lichens are widely known as indicators because of their sensitivity to changes in environmental qualities. This study investigated the effects of human activities on lichens in the Chiang Mai-Lamphun basin, Thailand. Lichen frequencies were surveyed in 47 study sites using a 20 x 50 cm² grid frame divided into 10 small square units. The surveying frame was put on the tree trunk at 100 cm above ground level to count the frequency of each lichen species. Four epiphytic lichen species were selected, and their distributions were mapped. These maps illustrated that each species has different ranges of tolerance to anthropogenic effects. Hyperphyscia adglutinata (Flörke) H. Mayrhofer & Poelt and Pyxine cocoes (Sw.) Nyl. showed a wide distribution. P. cocoes was abundant in areas with a high degree of human activities, while H. adglutinata was found particularly along main roads and in crowded residential areas. Dirinaria picta (Sw.) Clem. & Shear was observed in high frequency in areas with low human activities, while Peltula corticola Büdel & R. Sant. exhibited the narrowest distribution and was present in areas where high anthropogenic impact and high traffic occurred.