192 species of lichen grow in GHNP, representing 31 families and 65 genera Â‒ more than 10% of the lichens recorded in India and 50% of those recorded in the central Himalaya. Tirthan Valley has 101 species, Jiwa Valley 100, and Sainj Valley 67.
78% of the species belong to the corticolous (bark-inhabiting) category of lichens, whilst others are saxicolous (rock-inhabiting), terricolous (ground-inhabiting), and foliicolous (leaf-inhabiting).
Tirthan and Sainj valleys each have 40 saxicolous species ‒ attributable to their large alpine meadows with exposed rocks.
The maximum diversity of lichens can be found at 2,500m to 3,000m, probably because of a lower degree of pollution and higher tree density in these areas. Kharsu oak forests support especially rich lichen diversity.
At lower altitudes, the smooth bark of the holly tree and banjh oak host the species Pyrenula and Anthracotheclum (both types of lichenised fungus). Nephromahelviticum can be found growing exclusively on the bark of Prunus cornuta (Himalayan bird cherry), whilst Sulcarla sulcata is restricted to conifers.
Ochrolechia rosella (a crabseye lichen), Menegazzia terebrata and Hypogymnia vittata grow abundantly only on the kharsu oak. Interestingly, these species seem to follow a distinct vertical distribution pattern, associated with the tree species that represent different climatic zones.
The Himalayan musk deer depends heavily on Usnea longissima (Methuselah’s beard ‒ the world’s longest lichen) during winter.