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.