Advances in Zoology and Botany 11(3): 171-180, 2023 http://www.hrpub.org DOI: 10.13189/azb.2023.110303 Understanding Lichen Ecology using Detailed PCA in Temperate – Alpine Gradient of Uttarakhand, India Pulak Das 1,* , Santosh Joshi 2 1 School of Human Ecology, Dr. B. R. Ambedkar University, India 2 Department of Applied Sciences and Humanities, Invertis University, India Received July 27, 2022; Revised October 20, 2022; Accepted December 22, 2022 Cite This Paper in the Following Citation Styles (a): [1] Pulak Das, Santosh Joshi , "Understanding Lichen Ecology using Detailed PCA in Temperate – Alpine Gradient of Uttarakhand, India," Advances in Zoology and Botany, Vol. 11, No. 3, pp. 171 - 180, 2023. DOI: 10.13189/azb.2023.110303. (b): Pulak Das, Santosh Joshi (2023). Understanding Lichen Ecology using Detailed PCA in Temperate – Alpine Gradient of Uttarakhand, India. Advances in Zoology and Botany, 11(3), 171 - 180. DOI: 10.13189/azb.2023.110303. Copyright©2023 by authors, all rights reserved. Authors agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License Abstract The paper presents classification of lichen regions from temperate (Loharkhet) to alpine zones (Pindari Glacier) using Principal Component Analysis (PCA) of growth forms and habitat preferences of lichens in Himalayas. The study is based on published literature, preserved lichen specimens at lichen herbarium in National Botanical Research Institute, Lucknow, India, and lichen collections from the valley. Varied growth forms of lichens are observed such as foliose, crustose, fruticose, squamulose, and leprose. Habitat preferences of lichens are corticolous, saxicolous, terricolous, and muscicolous. Some lichens exhibit a range of habitat preferences like corticolous-saxicolous-terricolous-muscicolous, corticolo us-terricolous-muscicolous, corticolous-saxicolous-terrico lous, saxicolous-terricolous, corticolous-terricolous, corticolous-saxicolous, terricolous-muscicolous, and terricolous-lignicolous. These two different features, growth form and habitat preferences are used to run PCA to see their role in distribution of lichens across different altitudinal variations and whether it can be used to categorize the region into different types. As the region is under continuous anthropogenic pressure and lichens are highly sensitive to changes in environmental conditions where they exist, this classification can be of help in conservation of the region on the basis of priority areas. Keywords Bageshwar, Ecological Traits, Lichen Forms, PCA, Pindari Glacier 1. Introduction Lichens are known to constitute the major part of floristic diversity in high terrains of Uttarakhand Himalayas. They prefer different substratum such as on rock, soil, tree bark, and even mosses and leaves and attain different forms such as crust like, foliar like, and fruit like. Mishra [1] in a study in Uttarakhand reported 630 species of lichens of which more than 67% preferred bark and around 30% preferred rock substratum. Crustose and foliose represented the dominant growth forms with around 42% and 39% respectively. Mishra and Saini [2] reported 429 species of corticolous lichens in Uttarakhand, where 88% of all lichens exhibited either foliose or crustose form, and fruiticose, squamulose, and leprose represented 8%, 3%, and 1% respectively. They observed that varied substratum provided by different tree species helped species richness of lichens. Although the region has been explored earlier for floristic studies of various plant groups, high-altitude glacier valleys have been neglected for the extensive exploration of cryptogams especially lichens. Pindari Glacier valley is situated in Bageshwar district of Uttarakhand at an altitude that ranges from 1700 m to 3660 m. The valley lies at about 30°15.30 "N latitude and 79°13' – 80°2" E longitude and forms the southeast part of NandaDevi Biosphere Reserve. The unique topography, wide altitudinal range, and varied climatic conditions favor the diverse flora and fauna in the region. Lichens are excellent indicator of forest ecosystem and climatic conditions. A number of studies regarding lichens as excellent indicators of environmental changes are available