The symbiotic coevolution of algae and fungi in lichens has been instrumental in overall success of lichens in some of the most unfavourable habitats of the planet. Himalayas by virtue of their fragile temperature regime and diverse topography allow variety of lichen functional groups to flourish. Among these, soil-inhabiting terricolous lichens have proved to be good indicators of habitat heterogeneity and zooanthropogenic pressures. Photobiont diversity of terricolous lichens of Garhwal Himalayas showed the dominance of Chlorophyta (70 %) over Cyanoprokaryota (30 %) as photobionts. The ecological preference analysis of the photobionts indicated that majority of photobionts preferred lichens belonging to terricolous or terricolous–rupicolous ecological subgroups. Asterochloris dominated in the both subgroups, whereas Nostoc was common in muscicolous–rupicolous subgroup. The comparative dominance of the photobionts in ecological subgroups was a function of hydration preferences of photobionts. Cyanobionts dominate niches which can hold water for longer period, whereas dominate green algal chlorobionts dominate the rest. The altitudinal preferences showed that lichen species with Asterochloris were found in the range of 2,300–3,700 m, followed by Scytonema at 1,700–3,900 m, Nostoc at 2,100–3,500 m and Trebouxia at 2,800–4,000 m. As the maximum richness was within the range of 2,800–3,500-m altitude, it is evident that the diversity drivers of lichen photobionts were climatic factors (i.e. light intensity, humidity/precipitation and temperature).