Browsing by Author "Pratima Pandey"

Now showing 1 - 2 of 2

Characteristics of modern biotic data and their relationship to vegetation of the Alpine zone of Chopta valley, North Sikkim, India: Implications for palaeovegetation reconstruction
(SAGE Publications Ltd, 2018) Jyotsna Dubey; Ruby Ghosh; Shailesh Agrawal; M.F. Quamar; P. Morthekai; R.K. Sharma; Anupam Sharma; Pratima Pandey; Vaibhava Srivastava; Sheikh Nawaz Ali
We examined the modern pollen palynomorphs (PP) distribution complemented with non-pollen palynomorphs (NPP) and stable carbon isotopic data of soil organic matter (SOM) to explore relationships of these proxies to vegetation communities in the Chopta valley, a closed valley in alpine zone of the North Sikkim, India, in an attempt to check the efficiency for reconstructing past vegetation and climate. A total of 24 surface soil samples were collected from both the windward and leeward sides of the valley and they did not show any significant difference in the palynoassemblages. The average value of δ13C is −26.6%, which clearly indicates a C3-dominated vegetation in this valley which is also corroborated by the palynological data. However, signature of upthermic wind transport was evident by the significant presence of extra-local and regional forest elements in the palynoassemblages. NPP data indicated grazing activity in the valley and is in conformity with the present-day scenario. Furthermore, cluster analysis (CA) and principal component analysis (PCA) done on the PP and NPP data broadly grouped the samples according to the location of collection to some extent and reflected the relationships among the taxa with the extant vegetation. This study provides a basis for future palaeovegetation and palaeoclimate reconstruction from the region. © 2017, © The Author(s) 2017.
Glacial Geomorphology and Landscape Evolution of the Thangu Valley, North Sikkim Himalaya, India
(Springer, 2019) Jyotsna Dubey; Sheikh Nawaz Ali; Anupam Sharma; P. Morthekai; Rupendra Singh; R.K. Sharma; Pratima Pandey; Biswajeet Thakur; Vaibhava Srivastava
The present study describes glacial-geomorphological landforms in and around Thangu area, North Sikkim, India, and also provides significant insights about the evolution of pro- and paraglacial landscapes. Paraglacial processes are the governing mechanism of landscape evolution in deglaciating valleys and are now studied to understand the deglacial and postglacial landscape dynamics. We here present and describe detailed glacial geomorphology of Lashar and Chopta valleys as the area is strongly modified by the erosional and depositional imprints of late Pleistocene glaciations (MIS 2). Using geomorphological and stratigraphical methods, field surveys, SRTM DEM, Landsat ETM + and Google Earth Pro data, we have mapped glacial and glaciofluvial landforms and established moraine stratigraphy in the study area. Based on the morphostratigraphical mapping of the moraines supported by limited optical chronology, four events of glaciations have been identified in the in the Lashar, Chopta and Kalip valleys and date back to last glacial maximum and advocate for a widespread ice cover with large outlet tributary glaciers. The disposition of the lateral and terminal moraines has been used to estimate the area of paleoglacial extent and their corresponding ice volume during different stages. The presence of proglacial lakes, sensitive indicators of climate change, suggests that the glaciers in the region are melting and radically responding to global warming and are potentially vulnerable for generating glacial lake outburst floods. © 2019, Indian Society of Remote Sensing.