Investigation of Factors Controlling Temporal Trend of Lichen Diversity in Arid Region of India

Lichens are sensitive indicators of changes in climatic condition of an area at both micro and macro scales. The present study analyzes the lichen diversity change in the last forty years compared with the temporal trends of meteorological conditions in arid region of India. The available herbarium records of lichen diversity of the year 1975 when compared with fresh lichen collection of 2015 revealed substantial change in the species composition and richness of the certain individual species and communities. A positive shift in species composition of thermophilous and poleotolerant species indicates steady change in the species composition. Significant increase in member of the lichen family Physciaceae has been observed which may correlate with the rise in temperature. The carbon isotope ratio technique has been applied to investigate eco-physiological changes at temporal scale. Carbon stable isotope data indicated shift of δ¹³C values from − 27.65‰ to − 19.24‰ (r = − 0.9958) reflecting significant change in carbon fixation in the species. The strong shift in δ¹³C values is may be due to change in photosynthetic pathway indicating probable change from C₃ pathway, which indicates adaptation of lichens toward changing water regimes and carbon dioxide consumption pattern in drier climatic conditions.