Holocene vegetation and climate change in Central Ganga Plain: A study based on multiproxy records from Chaudhary-Ka-Tal, Raebareli District, Uttar Pradesh, India

Pollen, sediment texture and organic/inorganic carbon analyses of a 2.1 m thick sediment profile from Chaudhary-Ka-Tal (lake) of Raebareli District, reveals that around 8470 to 6422 cal BP grasslands comprising grasses, Asteraceae, Cheno/Am, with interspersed forest groves of Madhuca indica, Holoptelea integrifolia, Shorea robusta, and Acacia, thrived in the region under a warmer and moderately-humid climate than today. This is also substantiated by the finer clay sediment with increasing concentrations of moisture and organic carbon. The appearance of Cerealia pollen ∼7500 cal BP suggests incipient agrarian practice. The record of aquatic elements, Lemna and Typha, reflects the existence of lake. Between 6422 and 3150 cal BP, the forest groves became diversified with the invasion of more trees, Capparis, Butea monosperma, and Symplocos, reflecting a warm and more-humid climate compared to the previous phase, attributed to the strengthening of the SW monsoon. The higher concentration of organic carbon further confirms good vegetation cover, and an increase in aquatic flora depict the expansion of lake. A similar vegetation scenario existed ∼3150 to 1110 cal BP. However, the forest groves became less varied due to prevailing moderately-humid climate owing to weakening of the SW monsoon. This is also validated by more carbonate in the sediments. From 1110 cal BP, a further diminishing trend of trees implies that the region supported open grasslands owing to reduced rainfall under a warm and less-humid climate, which is corroborated by a further increase in carbonate content.