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One 2.5 m lacustrine sedimentary profile dated back to 6340 years BP from Deosila swamp under Rangjuli Reserve forest of Assam, Northeast India has been pollen analyzed for tracing past vegetation vis à vis climate variability since mid-Holocene. The pollen diagram has deciphered that during 6340 to 2970 years BP, tropical tree savannah type of vegetation grew in the region chiefly constituted of grasses interspersed with scattered trees of Salmalia, Dillenia, Emblica, Meliaceae along with sporadic presence of Artocarpus chaplasha, Symplocos, Ilex, Schima and Shorea robusta under relatively less cool and dry climatic condition with a little ameliorating trend at the upper column. The vegetation scenario implies poor growth of arboreals due to harsh abiotic dynamics causing changes in drainage system. Subsequently during 2970 to 1510 years BP, tropical mixed deciduous forest succeeded tree savannah with invasion of Shorea robusta, Lagerstroemia, Lannea, Semecarpus and Acacia under warm and humid climate. The gradual enrichment of organic soil might have been conducive for better growth of both deciduous and semi evergreen arboreals as found today. However, during 1510 to 540 years BP, the forest groves became more strengthened resulting establishment of tropical deciduous Sal forest. Steady increment of Shorea robusta along with Lannea, Lagerstroemia, Terminalia, Sapotaceae, Albizia and Adina was observed probably due to influence of active SW monsoon under increased warm and humid climatic regime. This is well substantiated by the consistent occurrence of marshy and aquatic taxa along with ferns and fungal remains. Finally during 540 years BP onward the reduced forest floristics have obviously been envisaged the change in climate which turned to warm and relatively dry probably attributable to the weak monsoon rainfall. The acceleration in human settlement during this phase is evidenced by Cerealia and by the increase of Melastoma, Ziziphus and Areca catechu implying forest clearance. [ABSTRACT FROM AUTHOR]

This study examines the pattern of preservation of pollen and non-pollen palynomorphs on bat guano samples in Eraaning Cave in relation to the current vegetation of the surrounding Garo hills of Meghalaya. It is observed that, the recorded pollen data does reflect the tropical mixed deciduous forest with an admixture of riparian and evergreen plant taxa from the local and regional vegetation. The presence of evergreen and riparian taxa namely, Mesua , Schima , Duabanga , and Syzygium in the pollen assemblage is strongly indicative of the high rainfall in the region. The recovery of fern and fungal spores in the pollen assemblage also reflects the warm and humid climatic condition in this region. The forestland and open-land samples from the vicinity of the cave were also studied to understand the nature of pollen preservation in relation to the bat guano samples. The presence of cereal, Areca , Psidium , and Citrus along with Melastoma pollen in both bat guano and open-land samples is indicative of the anthropogenic activities in and around the study area. Multivariate principal component analysis (PCA) and box plot were applied to the quantified data obtained from pollen frequency analyses which clearly revealed a significant variation and similarity in vegetation types among the surface samples collected in and around Eraaning Cave. The generated pollen data from the bat guano, forestland, and open-land samples reveals that, bat guano in cave sediments provides a reliable substrate to understand the modern pollen and vegetation relationship and can fruitfully be utilized as a baseline for the reconstruction of the palaeoecology in the Garo hills of Meghalaya. The study also suggested that the bat species utilized the mixed vegetation composition and different landforms as their preferred habitats as demonstrated by the pollen data from the bat guano samples. • Palynology of bat guano samples from the cave of Meghalaya. • Comparative modern pollen records from surface soil and moss-cushion. • A close pollen precipitation was observed in bat guano and forest substrates. • Bat guano from the cave floor proved to be a reliable pollen trapper. • Non-cereal and Mimosa pollen in open-land indicate anthropic activities. [ABSTRACT FROM AUTHOR]