Distribution Ecology of Soil Crust Lichens in India: A Comparative Assessment with Global Patterns

Abstract

Soil-inhabiting terricolous lichens along with other cryptogams such as mosses and cyanobacteria form a functional entity, referred to as biological soil crust (BSC). Lichen-dominated BSCs occur worldwide. The formation of BSCs and their species diversity is governed by factors such as, climate, soil-type, calcareousness, soil-texture, hydrology, and zooanthropogenic pressures. In India, soil crust formation and terricolous lichen diversity is governed by the same set of factors that govern soil crusts globally. The western dryer region of the country is poor in soil crust lichens due to dryer climate, sandy-textured soils, and high zooanthropogenic perturbations. Terricolous lichens in these regions are restricted to some high altitude, moist habitats and largely composed of calcicolous species such as the genus Collema. The Himalayan habitats harbour maximum diversity of biological soil crusts and terricolous lichens dominated by species of Stereocaulon and Cladonia, followed by Peltigera and Xanthoparmelia. The soil crust lichens in these temperate habitats are constrained by grazing pressures and decrease in soil cover along increasing altitudinal gradient.