Modern pollen assemblages of surface samples from Cherrapunjee and its adjoining areas, Meghalaya, northeast India

Abstract

Cherrapunjee, the wettest place on Earth, holds two Guinness Book of World Records for receiving the maximum amount of rainfall in a single year and in a single month. A dataset of 65 surface pollen samples from Cherrapunjee, the gateway of the Indo-Burma hotspot region, was analyzed in order to explore the relationship between the modern pollen assemblage and contemporary vegetation patterns. The study reveals the occurrence of subtropical pine forest along with broad-leaved taxa with scattered patches of Pandanus during the recent past. Due to large scale deforestation and massive soil erosion (wettest area), the flora gradually converted into grassland under a xeric climate. Laitkynsew is enriched with evergreen forest consisting of Lauraceae, Mesua and Schima along with patches of Pandanus and Rhizophoraceae indicating high precipitation under the influence of coastal habitation. However, other areas such as the Duwan Sing Syiem Bridge show primary subtropical pine forest with broad-leaved taxa, which are gradually being replaced by Combretaceae, Ilex and Schima as indicated by their continuous presence in the sediments. Probably, the absence of Pandanus pollen suggests some regional impact. Occurrence of anthropic pollen of cereals, Brassicaceae, and Plantago indicates human activity in and around the study area. The presence of Diplodia, Glomus, Meliola, Pleospora, Xylaria and other fungal hyphae strongly indicates the massive soil erosion. Judging from the present data, long term vegetation and climate shifts induced a xerophytic trend from high altitude to lowland resulting from regional and global climate change. This xerophytic trend as observed through modern palynological records was well corroborated with the present situation.