Characteristic modern pollen assemblages in relation to vegetation types in the East Khasi Hills, northeast India

ABSTRACT

This paper presents characteristic modern pollen assemblages in relation to various vegetation types from one of the wettest regions of the world. Four characteristic modern pollen assemblages were recorded based on the major pollen taxa recovered from the surface samples. The Pinus–Tsuga–Betula–Quercus–Rhododendron–Chenopodiaceae assemblage was observed in pine forests under cold and wet climate in the region. The broad leaved forests were characterised by the Quercus–Betula–Alnus–Rhododendron–Pinus–Impatiens assemblage. The evergreen forest assemblage Castanopsis–Mesua–Betula–Magnoliaceae–Dipterocarpaceae–Nepenthes was suggestive of a cold and wet climate due to seasonally high rainfall activity. Grassland was identified by the recovery of a Poaceae–Cyperaceae–Asteraceae–Chenopodiaceae–cerealia assemblage in the surface samples under relatively dry climate with seasonal rainfall. The study revealed that the grasslands of East Khasi Hills are not the primary vegetation, but that it is converted from the primary dense forest as evidenced by the recovery of pollen from evergreen and broadleaved taxa in the surface samples. The presence of cerealia in almost all samples strongly indicates human activity in and around the study areas. Ferns, especially Cyathea, Gleichenia and Pyrrosia, in the palynoassemblage were suggestive of wet conditions in the region. Fungal remains such as Meliola, Microthyriaceae and Xylaria along with high organic matter in the palynoassemblage also suggest the same. The thrust of this study was to investigate the characteristic pollen assemblage in the surface samples in relation to the present vegetation of northeast India.

Keywords:

• Surface samples
• pollen assemblages
• rainfall
• vegetation
• anthropogenic activity
• northeast India

Acknowledgements

We thank Professor Sunil Bajpai, Director, BSIP, Lucknow, India, for the laboratory facility and permission to publish the paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Sadhan K. Basumatary

Sadhan K. Basumatary was awarded a BSc from the University of Gauhati in 1995, a M.Sc. in botany (special paper Microbiology) from the University of Gauhati in 1998 and a Ph.D. on Quaternary palynology from the University of Lucknow in 2011. He is currently a Scientist “C” at the Birbal Sahni Institute of Palaeobotany in Lucknow, working on Quaternary palynology using multiproxy data. He has 14 years' research experience, and has published 65 papers in national and international journals.

Bikash Gogoi

Bikash Gogoi was awarded a B.Sc. (Honours) from the University of Dibrugarh in 1997, a M.Sc. in geology from the University of Gauhati in 2000 and a Ph.D. on sedimentology and palaeontology from the University of Dibrugarh in 2006. He is currently an Assistant Professor in geology, Gauhati University, Assam (India), working on palynology and lithofacies analysis. He has 15 years' research experience and published numbers of research articles in reputed journals.

Vandana Prasad

Vandana Prasad was awarded a M.Sc. in botany from the University of Lucknow in 1985 and a Ph.D. from Lucknow University in 1992. She is involved in the study of silicified remains of plants (phytoliths) preserved in Late Cretaceous (65 Ma) dinosaur coprolites and evolutionary history of tropical rain forest vegetation. Her interest lies in the study of dinoflagellates, pollen spore and phytoliths to decipher palaeoclimatic fluctuations during Pre-Quaternary and Quaternary. She is currently working as a Scientist “E” at the Birbal Sahni Institute of Palaeobotany in Lucknow. She has published numbers of research papers in reputed national and international journals.