Palaeovegetation and climatic variations in the Parvati Valley, Himachal Pradesh, India since last deglaciation

Abstract

Pollen proxy records from 1.2 m deep sediment profile from Tundabhuj, Parvati Valley (H.P.) reveals that between 15,260 and 13,280 yr BP, the sub–alpine belt supported alpine–scrub vegetation dominated by Betula and thermophillous broad–leaved allies viz. Quercus, Corylus and Carpinus, interspersed with meadows comprising grasses, Asteraceae, Impatiens, etc. under a warm and moderately moist climate. The dry scrubby element, Juniperus occurred in restricted pockets on the sunny mountain slopes. The frequent record of conifers such as Pinus cf. wallichiana, Cedrus, Abies and Picea implies the proximity of the temperate belt to the study site. Around 13,280 to 7,340 yr BP, the considerable expansion of Betula and broad–leaved allies and a simultaneous reduction in Juniperus elucidate the replacement of alpine scrub forests by temperate Betula–broad–leaved forest in response to onset of a relatively warm and more–moist climate. This change occurred by the upward shift of the timber line as reflected by the improvement in the conifers. The climate deteriorated and turned cold and dry around 7,340 to 5,030 yr BP as manifested by the abrupt reduction in the alpine–scrub vegetation and meadow constituents. Subsequently, between 5,030 and 2,000 yr BP this region witnessed a warm and moist climate again as evidenced from moderate expansion in the alpine–scrubs and conifers. Since 2,000 yr BP onwards deterioration in climate is demonstrated by the depletion in Betula and broad–leaved associates and substantial increase in Juniperus and Ephedra.