Equatorial rain forests that maintain a balance between rate of speciation and extinction are hot-spots for tropical biodiversity. Tropical rainforest vegetation has a complex geological history, having been severely affected in response to changing climatic conditions of the geological past. During its northward journey till its eventual collision with Eurasia, the Indian plate lay within the equatorial zone at the time of late Paleocene-early Eocene (55.5-50Ma) extreme global warming event. Carbonaceous shale, coal and lignite deposits from the western and north-eastern margins of the Indian subcontinent are important archives that hold information regarding the floral turnover at low latitude. The rich fossil flora from these shows that highly diversified tropical rain forest community was widespread in many parts of the Indian subcontinent during early Paleogene. Equatorial positioning coupled with excessive global warm climate during early Paleogene resulted in high precipitation and low seasonality, a key factor in the development of tropical rain forest.on the Indian subcontinent. Many common Late Paleocene-early Eocene pollen flora of India shows generic similarity with the palynofossils of mid-high latitudinal belt of similar age indicating extension of low seasonality tropical rain forest vegetation in the subtropics and high latitudes during periods of global warming. An attempt has been made to trace the nearest living relatives (NLR) of early Paleogene fossil palynomorphs of India. The study shows a striking similarity of fossil palynomorphs with the extant pollen of tropical rain forest of South East Asia, Sri Lanka, Africa, Madagascar and Western Ghats of India. These studies, besides providing paleogeographic clues, offer understanding of most recent extreme global warming condition of the geologic past and its effect on the distribution pattern of tropical vegetation at low latitude. The study demonstrate that present day high diversity of tropical rain forest is a legacy of globally warm climate of early Paleogene which was much higher and widespread over a greater part of mid and high latitudinal belts.
Speaker : Dr. Vandana Prasad, Birbal Sahni Institute of Paleobotany, Lucknow, India
Organisers : Department of Ecology, French Institute of Pondicherry
Venue : Nehru conference hall, French Institute of Pondicherry, 11, Saint Louis Street, Pondicherry - 605 001
