Terricolous lichen Cladonia verticillata as indicator of atmospheric lead deposition along land-use and elevation gradients in Kumaon, Western Himalaya
Creators: name: Rai, Himanshu
name: Gupta, Rajan Kumar
name: Upreti, DK
Publisher: name: figshare
Year: 2020
Subjects: Botany

description: Atmospheric deposition of lead (Pb) has been of grave concerns among both environmentalists and the general public due to its high toxicity, bioaccumulation and prolonged persistency in the environment. Anthropogenic input forms the major part of the total atmospheric lead deposition worldwide. However, monitoring atmospheric Pb deposition using conventional methods is both challenging and expensive, and can provide data for a limited time period. Biomonitors such as lichens can overcome these limitations because, due to their slow growth rate and longer life span, they serve as long term integrators of Pb and can deliver reliable information on atmospheric deposition of Pb along natural and anthropogenic gradients in various ecosystems. Soil inhabiting terricolous lichens form a considerable presence at mid elevations in the Himalaya. A trampling resistant dimorphic terricolous lichen Cladonia verticillata (Hoffm .) Schaer was assessed for its ability as bioindicator of Pb deposition in various land uses along an elevation gradient. In Kumaon, western Himalaya. Lichen samples were collected from ten samples, following a two-way random stratified sampling method. The diversity of lichens was studied as quadrat frequency. The diversity of C. verticillata was quantitatively assessed as percentage quadrat frequency at each collection site. The Pb content of lichen samples was analysed by inductively coupled plasma optical emission spectrometer, employing Watling’s Nitric (HNO3)-Perchloric (HCIO4) acid digestion method for the sample preparation. An indirect gradient ordination method, principal component analysis (PCA), was used to summarise the diversity differences of C. verticillata between the sites, along elevation gradient. Pearson's correlation coefficients were calculated to compare explanatory variables (i.e. elevation, vehicular frequency, soil cover) and response variables (PCA axis score, diversity and Pb accumulation). Sampling sites were subjected to hierarchical cluster analysis using Euclidean distance and unweighted pair-group moving average (UPGMA) on six criteria: diversity and Pb concentration of C. verticillata; elevation, vehicular frequency, soil cover and land use types of sampling sites. The study revealed that change diversity of C. verticillata along increasing elevation was at one hand correlated with natural (elevation and soil cover) factors, on the other hand was largely negatively correlated with lead bioaccumulation in lichen thallus which in turn were correlated with land use and vehicular frequency in the study area. Vehicular exhaust was apparently found as the major source of atmospheric Pb deposition in the region. The study suggests the change in diversity of C. verticillata in correlation with Pb bioaccumulation in the thallus as a good indicator of patterns of atmospheric Pb deposition in Himalaya. The finding presented suggests that long term monitoring of C. verticillata communities can be utilised in restrictive management of largely anthropogenic sources of Pb deposit ion in the ambient atmosphere of Himalayan habitats.