An ecological investigation was conducted on epiphytic macrolichens inhabiting five Quercus species within reserve forests of Kumaun Himalaya. A total of 3765 individuals of macrolichens representing 41 species from 20 genera and 8 families were recorded across 625 Quercus trees. Quercus leucotrichophora exhibited the highest alpha diversity (3.12), species richness (28 species) and number of macrolichen individuals (1187), followed by Q. semecarpifolia and Q. lanata. Parmotrema reticulatum had the highest abundance, density and relative importance, while Heterodermia albidiflava and Peltigera collina had the lowest representation. The macrolichen distribution followed a contagious pattern, with the elevation of 2053 m supporting the highest diversity. Host specificity analysis showed that some species were present on all Quercus species while others, such as Canoparmelia texana and Collema coccophorum, were restricted to specific hosts. Hierarchical cluster analysis grouped the Quercus species into two main clusters based on their lichen communities, with Q. leucotrichophora forming a distinct cluster due to its higher species richness. The highest similarity in lichen composition was observed between Q. leucotrichophora and Q. semecarpifolia. Our results highlight the role of host tree species and elevation in shaping macrolichen diversity and distribution, providing valuable insights for conservation and ecological studies. Keywords: diversity; distribution; host specificity; lichenised fungi; species composition.