Browsing by Author "Ratan Kar"

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Modern pollen assemblages from Hamtah and Chhatru glaciers, Lahaul-Spiti, India: Implications for pollen-vegetation relationship in an alpine arid region of western Himalaya
(Elsevier Ltd, 2015) Ratan Kar; Ruchika Bajpai; A.D. Singh
The present study deals with the pollen analysis of 25 surface samples, 15 from the outwash plain of the Hamtah Glacier and 10 from the Chhatru glacial valley, Lahaul-Spiti, Himachal Pradesh, India. The samples were collected in a linear transect from the respective sites at an altitudinal range of ~3200masl to ~4000masl. The area is a high altitude cold desert in the western Himalaya, characterised by scrub type of vegetation. The pollen assemblages reveal an overall dominance of extra local arboreals (conifers) over the local non-arboreals. Though it is a vegetation sparse area, the alpine meadow is well represented by the presence of non-arboreal elements, such as Rosaceae, Asteraceae, Artemisia, Lamiaceae, Poaceae, Apiaceae and Chenopodiaceae/Amaranthaceae. However, predominance of Pinus has been observed along with moderate values of Abies and Picea. The overwhelming values of Pinus pollen can be attributed to its profuse production and efficient dispersal through wind currents from the temperate forests and eventual deposition around the study sites. Temperate broad-leaved taxa including Alnus, Ulmus, Betula and Corylus are present in low abundance. The consistent low frequencies of fern spores, algal and fungal elements, and absence of aquatic and marshy taxa reflect the dry climatic conditions in the region. Impact of anthropogenic activities can be observed in the form of degraded patches of tree-line and evidence of extensive grazing. Palynological data from the surface samples is not coherent with the actual vegetation around the study area due to the prolific over-representation of extra local pollen over the local herbaceous taxa. Palynological studies have been initiated in the vicinity of Hamtah and Chhatru glaciers on sub-surface sediment profiles, and this data will be helpful in developing modern analogues for understanding the past vegetational changes with respect to palaeoclimatic conditions in and around the study area. © 2015 Elsevier Ltd and INQUA.
Modern pollen–vegetation relationships along an altitudinal transect in the Western Higher Himalaya, India: Palaeoclimatic and anthropogenic implications
(SAGE Publications Ltd, 2022) Amit Kumar Mishra; Ruchika Bajpai Mohanty; Ruby Ghosh; Kriti Mishra; Uma Kant Shukla; Ratan Kar
Palynology is one of the most reliable tools for the reconstruction of past vegetation and climate and modern pollen analogues are important for the calibration of fossil pollen assemblages. The present study analyses the pollen–vegetation relationships along a steep altitudinal gradient (2700–3680 m), in the western Higher Himalayan region. On the basis of altitude, three vegetation zones were demarcated: Zone I (2700–3100 m) is composed of mixed-temperate forest vegetation, dominated by Quercus semecarpifolia and Rhododendron arboreum; Zone II (3100–3250 m) is marked by sub-alpine forest vegetation, characterised by R. campanulatum and R. barbatum, along with Abies spectabilis and Q. semecarpifolia; Zone III (3250–3680 m) is above the tree-line (3250 m) and represented by alpine-scrub and meadows. Thirty-five surface soil samples (twenty, seven and eight from each zone, respectively) were analysed along the altitudinal transect to decode the representation of the extant vegetation in the pollen-rain. The pollen–vegetation relationship is non-linear due to the over-representation of extra-local Pinus pollen in each zone. Nonetheless, the modern pollen assemblages show a general correlation with the local broad-leaved taxa and the herbaceous elements; with the exception of Rhododendron pollen, which is under-represented. Among the non-pollen palynomorphs (NPPs), the presence of coprophilous fungal spores is compatible with the grazing activities in the area. Multivariate statistical analyses performed on the surface pollen data indicate that the dataset can efficiently distinguish the different vegetation zones across the altitudinal gradient. This work provides the modern analogues for pollen-based palaeoclimatic reconstructions for the Western-Higher Himalayan region, and would also help to decipher the inception and intensification of anthropogenic activities in the region. © The Author(s) 2022.