Lichens are among the most sensitive biomonitors of ecosystem health and human induced disturbances. Terricolous lichens of Chopta-Tungnath (Garhwal, western Himalaya, India) were analysed for their ability to indicate habitat variability and disturbances induced by livestock grazing. Terricolous lichens were sampled from 12 sites, distributed across the three macrohabitats between 2,700 and 4,001 m, using 50 9 10 cm narrow frequency grids having five 10 9 10 cm sampling units. The terricolous lichen community of the area constituted, 20 species belonging to 10 genera, five families and four growth forms. Altitude and relative humidity were the major habitat factors found influencing the terricolous lichen community of the landscape. Fruticose and compound soil lichen growth forms were found indicative of habitat disturbance largely caused by grazing induced trampling. Terricolous lichen diversity of the area was delimited by grazing pressure at mid-altitudes (3,000-3,400 m) and by decreasing soil cover at higher altitudes ([3,400 m).

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ABSTRACT

Silver nanoparticles synthesized using plant metabolites provide an edge over chemically synthesized compounds due to their comparatively efficient antimicrobial activity. In the present study, AgNPs was prepared by bioreduction of silver nitrate (AgNO 3 ) using the aqueous extract of Cladonia rangiferina collected ≥3500 m in Uttarkashi district of Uttarakhand, western Himalaya. The formation of Ag NPs was indicated by yellow-brown color after 72 h. The AgNPs were characterized by UV-Vis spectrophotometry, Fourier transformed infrared (FTIR) spectroscopy, scanning electron spectroscopy (SEM) analysis. Ag-NPs thus obtained were tested for antimicrobial activity against selected gram-negative (i.e. Escherichia coli, Klebsiella pneuomoniae, and Pseudomonas aeruginosa) and gram-positive (i.e. Bacillus subtilis, Staphylococcus aureus, and Staphylococcus epidermidis) bacterial strains employing Bauer-Kirby's disk diffusion assay using Gentamicin as positive control and distil water as negative control. The bioreduction of AgNO 3 yielded stable spherical and rod-shaped Ag-NPs showing characteristic UV-Vis spectral band peak with specific color change. The FTIR showed the role of many functional groups of different organic lichen secondary metabolites in AgNPs fabrication and stabilization. The synthesized AgNPs showed enhanced activity to positive control (i.e. Gentamicin). The study highlighted that lichen AgNPs can be used as better antibacterial material.

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